阅读说明：本技术 采用应力预测分析玻璃层叠体制品的冷成形性以及相关方法 (Analysis of cold formability of glass laminate articles using stress prediction and related methods ) 是由 V·巴蒂亚 朴娥英 Y·K·卡洛士 王能 于 2018-10-05 设计创作，主要内容包括：提供了制品和涉及采用应力预测分析的玻璃层叠体制品的冷成形方法。基于玻璃层叠体制品的玻璃层的多个几何参数,计算冷成形估算量(CFE)值,其与玻璃层叠体的玻璃片在冷成形过程中所经受的应力相关。将计算得到的CFE值与冷成形阈值进行对比,所述冷成形阈值与冷成形过程中复杂弯曲玻璃层叠体制品中形成缺陷的可能性相关。还提供了具有几何参数从而使得CFE值低于冷成形阈值的冷成形玻璃层叠体制品。(Articles and methods of cold forming glass laminate articles using stress prediction analysis are provided. Based on a plurality of geometric parameters of the glass layers of the glass laminate article, a Cold Forming Estimate (CFE) value is calculated that correlates to a stress experienced by the glass sheets of the glass laminate during cold forming. The calculated CFE value is compared to a cold forming threshold that correlates to a likelihood of forming defects in the complex curved glass laminate article during cold forming. Cold-formed glass laminate articles having geometric parameters such that the CFE value is below a cold-forming threshold are also provided.)

1. A method of estimating cold formability of a complexly curved glass laminate article comprising a first glass sheet and a second glass sheet, the method comprising:

obtaining a first geometric parameter (G1) and a second geometric parameter (G2) of a complexly curved first glass sheet of a glass laminate article;

calculating a Cold Forming Estimate (CFE) value that correlates to the stress experienced by the first glass sheet during cold forming, wherein the CFE value comprises B1G 1+ B2G 2, wherein B1 and B2 are coefficients calculated to correlate G1 and G2 to the CFE value; and

the calculated CFE value is compared to a cold forming threshold that correlates to a likelihood of forming defects in the complex curved glass laminate article during cold forming.

2. The method of claim 1, further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than a cold forming threshold.

3. The method of claim 1 or 2, wherein the first glass sheet has an average thickness greater than an average thickness of the second glass sheet, and the first glass sheet is formed from a first glass composition that is different from a second glass composition of the second glass sheet.

4. The method of claim 3, wherein B1, B2, and the cold forming threshold are a function of the first glass composition.

5. The method of claim 3, wherein the first glass composition is a soda lime glass.

6. The method of claim 5, wherein the first glass sheet is an unreinforced glass sheet and the cold forming threshold is 20MPa, and further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than 20 MPa.

7. The method of claim 5, wherein the first glass sheet is a thermally strengthened glass sheet and the cold forming threshold is 50MPa, and further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than 50 MPa.

8. The method of any of claims 2-7, wherein the second glass composition is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

9. The method of any one of claims 2-8, further comprising determining B1 and B2 by multiple linear regression analysis of finite element analysis determined stresses for a plurality of complex curved glass laminate articles.

10. The method of any of claims 1-9, wherein the cold forming threshold is a maximum allowable stress of the first glass sheet determined by comparing the laminated test sample to a stress level predicted using finite element analysis.

11. The method of any one of claims 1-10, wherein the first glass sheet comprises: length L, width W and chord height, where G1 equals L/W, G2 equals chord height, B1 equals 1 and B2 equals 0.5.

12. The method of any one of claims 1-10, wherein the first glass sheet further comprises:

an inner surface;

an outer surface opposite the inner surface;

a width W;

a length L;

average thickness T1;

wherein the complex curved shape has: chordal height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, and maximum Gaussian curvature GC;

wherein the second glass layer further comprises:

an inner surface;

an outer surface; and

average thickness T2;

wherein (0.05673 × W-0.1035 × L-0.0031 × CH +6.99003 × CH +0.1855 × R1+0.00115 × R2+4.633988 × GC-0.1836 × T1-101.95 × T2) is less than the cold forming threshold.

13. A method of cold forming a complexly curved glass laminate article, comprising:

supporting a first glass sheet, the first glass material sheet having a complex curved shape, a first major surface and a second major surface;

supporting a second glass sheet on the first glass sheet, wherein the second glass sheet has a first major surface, a second major surface, and a shape that is different from the complex curved shape;

placing a polymeric interlayer material between the second major surface of the first glass sheet and the first major surface of the second glass sheet;

bending a second sheet of glass material into a complex curved shape conforming to the first sheet of glass material, wherein during bending the maximum temperature of the first sheet of glass is less than the glass transition temperature of the glass material of the first sheet of glass, wherein the maximum temperature of the second sheet of glass is less than the glass transition temperature of the glass material of the second sheet of glass;

wherein the complex curved shape has a first geometric parameter (G1) and a second geometric parameter (G2), wherein a first principal stress experienced by the first glass sheet during bending is less than or equal to an estimated stress value of (B1G 1+ B2G 2), wherein B1 and B2 are coefficients determined to correlate G1 and G2 with a stress experienced by the first glass sheet during bending.

14. The method of claim 13, wherein the first glass sheet has an average thickness greater than an average thickness of the second glass sheet, and the glass material of the first glass sheet is different than the glass material of the second glass sheet.

15. The method of claim 13 or 14, wherein the first glass sheet is an unreinforced glass sheet and the estimated stress value is less than 20 MPa.

16. The method of claim 13 or 14, wherein the first glass sheet is a thermally strengthened glass sheet and the estimated stress value is 50 MPa.

17. The method of any of claims 13-16, wherein the glass material of the second glass sheet is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda lime glass composition.

18. A cold-formed glass laminate article comprising:

a first glass layer comprising:

an inner surface;

an outer surface opposite the inner surface;

a width W;

a length L;

a complex curved shape with a chordal height CH, wherein-0.14 < L/W-0.05 x (CH) < 0.223; and

a second glass layer comprising:

an inner surface;

an outer surface;

a polymer interlayer disposed between the inner surface of the first glass layer and the inner surface of the second glass layer.

19. The cold-formed glass laminate article of claim 18, wherein the average thickness T1 of the first glass layer is greater than the average thickness T2 of the second glass layer.

20. The cold-formed glass laminate article of claim 19, wherein T1 is 1mm to 4mm and T2 is.3 mm to 1 mm.

21. The cold-formed glass laminate article of any of claims 18-20, wherein W is 300mm to 1800mm, L is 230mm to 1600mm, and CH is 1mm to 45 mm.

22. The cold-formed glass laminate article of any of claims 18 to 21, wherein the glass material of the first glass layer is different from the glass material of the second glass layer.

23. The cold-formed glass laminate article of claim 22, wherein the glass material of the second glass layer is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda lime glass composition.

24. The cold-formed glass laminate article of any of claims 18 to 23, wherein the second glass layer is a chemically-strengthened glass material.

25. A cold-formed glass laminate article comprising:

a first glass layer comprising:

an inner surface;

an outer surface opposite the inner surface;

a width W;

a length L;

average thickness T1;

a complex curved shape having: chordal height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, and maximum Gaussian curvature GC;

a second glass layer comprising:

an inner surface;

an outer surface; and

average thickness T2; and

an intermediate layer disposed between an inner surface of the first glass layer and an inner surface of the second glass layer;

wherein (0.05673W-0.1035L-0.0031 CH +6.99003 CH + 0.1855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2) is less than 80 MPa.

26. The cold-formed glass laminate article of claim 25, wherein T1 is greater than T2.

27. The cold-formed glass laminate article of claim 25 or 26, wherein T1 is 1mm to 4mm and T2 is.3 mm to 1 mm.

28. The cold-formed glass laminate article of any of claims 25 to 27, wherein W is 300mm to 1800mm, L is 230mm to 1600mm, CH is 1mm to 45mm, DOB is 5mm to 210mm, R1 is 40mm to 5000mm, R2 is 740mm to 32500mm, and GC is 0.14 e-71/mm²To 15 e-71/mm²。

29. The cold-formed glass laminate article of any of claims 25 to 28, wherein the glass material of the first glass layer is different from the glass material of the second glass layer.

30. The cold-formed glass laminate article of claim 29, wherein the glass material of the second glass layer is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda lime glass composition.

31. The cold-formed glass laminate article of any of claims 25 to 30, wherein the second glass layer is a chemically-strengthened glass material.

Background

The present disclosure relates to cold-formed glass laminate articles, and more particularly, to articles and methods of cold-forming glass laminate articles using stress prediction analysis. In particular embodiments, such articles may be used in vehicle applications (e.g., automotive glazing) as well as architectural applications.

Curved laminates are used in a variety of applications, including automotive glazing and architectural windows. For such applications, the glass sheet is precisely bent to define a shape and/or curvature determined by the configuration and size of the opening into which the glass is to be installed, as well as the vehicle type or architectural aesthetics. Such curved laminates are typically manufactured by: a flat glass sheet is heated to a suitable temperature for shaping, a force is applied to the sheet to change the shape, and then two curved sheets are laminated together. This process is commonly referred to as a "thermal bending" process.

Disclosure of Invention

A first aspect of the present disclosure pertains to a method of evaluating cold formability of a complexly curved glass laminate article comprising a first glass sheet and a second glass sheet. The method comprises the following steps: a first geometric parameter (G1) and a second geometric parameter (G2) of a complexly curved first glass sheet of the glass laminate article are obtained. The method comprises the following steps: a Cold Forming Estimate (CFE) value is calculated that is related to the stress experienced by the first glass sheet during cold forming. The CFE values include B1G 1+ B2G 2, where B1 and B2 are coefficients calculated to correlate G1 and G2 with the CFE values. The method includes comparing the calculated CFE value to a cold forming threshold associated with a likelihood of forming a defect in the complex curved glass laminate article during cold forming.

A second aspect of the present disclosure pertains to a method of cold forming a complex curved glass laminate article. The method includes supporting a first glass sheet, and the first glass material sheet has a complex curved shape, a first major surface, and a second major surface. The method includes supporting a second glass sheet on the first glass sheet, and the second glass sheet has a first major surface, a second major surface, and a shape different from the complex curved shape. The method includes placing a polymeric interlayer material between the second major surface of the first glass sheet and the first major surface of the second glass sheet. The method includes bending the second sheet of glass material to conform to the complex curved shape of the first sheet of glass material. During bending, the maximum temperature of the first glass sheet is less than the glass transition temperature of the glass material of the first glass sheet, and the maximum temperature of the second glass sheet is less than the glass transition temperature of the glass material of the second glass sheet. The complex curved shape has a first geometric parameter (G1) and a second geometric parameter (G2), and a first primary stress (primary stress) experienced by the first glass sheet during bending is less than or equal to an estimated stress value of (B1G 1+ B2G 2), wherein B1 and B2 are coefficients determined to correlate G1 and G2 with the stress experienced by the first glass sheet during bending.

Another aspect of the present disclosure pertains to a cold-formed glass laminate article. The glass laminate article includes a first glass layer and a second glass layer. The first glass layer includes: an inner surface, an outer surface opposite the inner surface, a width W, a length L, and a complex curved shape having a chord height CH, wherein-0.14 < L/W-0.05 x (CH) < 0.223. The second glass layer includes an inner surface and an outer surface. The glass laminate article includes a polymer interlayer disposed between an inner surface of the first glass layer and an inner surface of the second glass layer.

Another aspect of the present disclosure pertains to a cold-formed glass laminate article. The glass laminate article includes a first glass layer and a second glass layer. The first glass layer includes: an inner surface, an outer surface opposite the inner surface, a width W, a length L, and an average thickness T1. The first glass layer includes a complex curved shape having: chordal height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, and maximum Gaussian curvature GC. The second glass layer includes an inner surface, an outer surface, and an average thickness T2. The glass laminate article includes an interlayer disposed between an inner surface of the first glass layer and an inner surface of the second glass layer. The dimensions of the glass laminate article are such that: (0.05673W-0.1035L-0.0031 CH +6.99003 CH + 0.1855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2) is less than 80 MPa.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the various embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the description, serve to explain the principles and operations of the various embodiments.

Drawings

Fig. 1 is a cross-sectional view of a flat glass layer, a curved glass layer, and an intervening film layer prior to forming, according to an example embodiment.

FIG. 2 is a cross-sectional view of a glass laminate article formed into a curved shape from the layers shown in FIG. 1, according to an exemplary embodiment.

FIG. 3 is a perspective view of a glass laminate article formed into a windshield according to an exemplary embodiment.

Fig. 4 is a top plan view of the glass laminate article of fig. 3.

FIG. 5 is a perspective view of a glass laminate article formed into a ceiling, according to an exemplary embodiment.

Fig. 6 is a top plan view of the glass laminate article of fig. 5.

FIG. 7 is a perspective view of a glass laminate article formed as a side window according to an exemplary embodiment.

Fig. 8 is a top plan view of the glass laminate article of fig. 7.

FIG. 9 shows a process for evaluating cold formability of a complex curved glass laminate article, according to an example embodiment.

Fig. 10 shows a comparison of the CFE values calculated using equation 3 versus the stress values calculated for the corresponding FEA for 29 different designs of glass laminate article 50.

11A and 11B are 2D plots of the data of FIG. 10 showing the relationship between selected geometric parameters and cold forming thresholds.

12A-12C are 2D plots of data for the glass laminate article of FIG. 10 designed for a windshield.

Fig. 13A-13C are 2D graphs of data for the glass laminate article of fig. 10 designed for use in a ceiling tile.

Fig. 14A-14C are 2D graphs of data for the glass laminate article of fig. 10 designed for a side window (e.g., side light).

FIG. 15 is a vehicle equipped with one or more of the glass laminate articles discussed herein.

Detailed Description

Referring generally to the figures, various methods involve cold forming of complex curved glass laminate articles. In general, applicants have determined that the stress (e.g., the first principal stress) to which one or more of the glass layers of the glass laminate is subjected during cold bending is a good indicator of the likelihood of forming defects during cold bending. For example, applicants have found that if the cold bending stress experienced during cold bending is too high, defects such as wrinkles or cracks may occur. However, standard processes (e.g., finite element analysis) for accurately calculating the stresses to which a glass laminate article may be subjected during a cold bending process are complex and require a significant amount of computational time and energy.

Thus, the present application is directed to a process for determining the cold formability of a glass laminate article by calculating a Cold Forming Estimate (CFE) value that is related to the stress to which the glass sheet is expected to be subjected during cold forming. The CFE value is then compared to a cold forming threshold that correlates with a likelihood that defects will form in the complex curved glass laminate article during cold forming. The CFE value is based on a sum of at least two geometric parameters indicative of the geometry of the glass laminate article, each multiplied by a statistically calculated coefficient. The cold forming threshold may be determined by: different laminate structures were tested to determine a threshold value associated with the maximum acceptable stress that the glass laminate article can withstand during cold bending without forming undesirable levels of defects.

With the method discussed above, once the CFE coefficients are determined and the cold forming threshold is determined, the formation of defects during cold forming can be accurately predicted simply by calculating CFE values based on readily measurable geometric parameters of the glass laminate article. Thus, the methods discussed herein eliminate the need to run complex mathematical analyses (e.g., finite element analysis) or perform prototyping/testing to determine whether a new complex curved glass laminate article design can be cold-formed without unacceptable defect formation. Thus, in this manner, the process of cold forming a new complex curved glass laminate article may be simplified.

Referring to fig. 1 and 2, a cold-formed glass laminate article and forming process according to an exemplary embodiment is shown. As shown in fig. 1, the laminate stack 10 includes a first glass layer 12 having a complex curved shape. The first glass layer 12 includes: an outer surface 14 comprising at least one segment having a convex shape; and an inner surface 16 opposite the outer surface 14 and including at least one segment having a concave shape. A thickness, such as an average thickness T1, is defined between the outer surface 14 and the inner surface 16.

The laminate stack 10 also includes a second glass layer 20. Glass layer 20 includes an outer surface 22 and an inner surface 24 opposite outer surface 22. A thickness, such as an average thickness T2, is defined between the outer surface 22 and the inner surface 24. In some embodiments, glass layer 20 is thinner than glass layer 12 such that T1> T2; and in particular embodiments, the glass material composition of glass layer 12 is different than the glass material composition of glass layer 20. In various embodiments, T1 is at least as great as 2.5 times T2, and in other embodiments, T2 is at least as great as 2.5 times T1. In a specific embodiment, T1 is 1.5mm to 4mm and T2 is 0.3mm to 1mm, and in an even more specific embodiment, T2 is less than 0.6 mm. In a specific embodiment, T1 is 1.6mm and T2 is.55 mm; t1 is 2.1mm and T2 is.55 mm; t1 is 2.1mm and T2 is 0.7 mm; t1 is 2.1mm and T2 is 0.5 mm; t1 is 2.5mm and T2 is 0.7 mm.

The laminate stack 10 includes an interlayer 30 between the first glass layer 12 and the second glass layer 20. In this arrangement, interlayer 30 is located between inner surface 16 of first glass ply 12 and inner surface 24 of second glass ply 20. In particular embodiments, interlayer 30 is secured to at least one of inner surface 16 of first glass ply 12 and inner surface 24 of second glass ply 20 and functions to hold laminate 50 together after formation (as shown in FIG. 2). The interlayer 30 can be a polymer interlayer, such as a polyvinyl butyral layer.

Fig. 1 shows a cross-sectional view of the laminate stack 10 prior to cold forming, and fig. 2 shows a glass laminate article (laminate 50) formed from the laminate stack 10 via cold forming. As shown in fig. 1, the first glass layer 12 is supported on (e.g., on a frame), and the second glass layer 20 is positioned to be supported on the first glass layer 12. The polymer interlayer 30 is placed between the first glass layer 12 and the second glass layer 20.

As shown in fig. 1, prior to beginning the cold forming process, the first glass layer 12 is formed into a curved shape, while the second glass layer 20 is flat prior to the forming process. During the cold forming process of fig. 1, pressure (shown as arrow P) is applied to the stack, thereby pressing the second glass layer 20, the interlayer 30, and the first glass layer 12 together. Under pressure P, second glass layer 20 deforms to take the curved shape of first glass layer 12, and once second glass layer 20 is shaped to match the shape of first glass layer 12, first glass layer 12 and second glass layer 20 are bonded together by interlayer 30 to form a complex curved article 50 as shown in fig. 2.

As can be seen in fig. 2, after shaping, second glass layer 20 also has a curved shape such that outer surface 22 includes at least one segment having a concave shape and inner surface 24 includes at least one segment having a convex shape. The forming process shown ensures that the shape and curvature of second glass layer 20 closely matches the shape and curvature of first glass layer 12. Thus, in this arrangement, the second glass layer 20 is bent to conform to the complex curved shape of the first glass layer 12 by the pressure P without raising the temperature above the glass transition temperature of the glass material of the second glass layer 20 and/or the glass material of the first glass layer 12.

In various embodiments, the forming pressure, represented by arrow P, may be about 1 atmosphere or greater. The forming pressure may be air pressure and/or pressure applied by a press or die.

In various embodiments, first glass layer 12 is shaped into its complex curved shape via a hot forming process and then cooled prior to the cold forming process, as shown in fig. 1. In particular embodiments, the thermoforming of first glass layer 12 may include: it is heated to a temperature close to the softening point of the glass material of the first glass layer 12 and then bent into a complex curved shape.

During the forming process shown in fig. 1, the complexly curved first glass layer 12 and the flat second glass layer 20 are cold formed into a curved laminate 50 at a temperature well below the softening point of the glass material of the second glass layer 20 and/or the glass material of the first glass layer 12. In various embodiments, the cold forming process of fig. 1 occurs at a temperature that is 200 degrees celsius or more below the softening point of the glass material of second glass layer 20 and/or the glass material of first glass layer 12. The softening point refers to the temperature at which the glass will deform under its own weight. In one or more specific embodiments, the temperature during the cold forming process is less than about 400 degrees celsius, less than about 350 degrees celsius, or less than about 300 degrees celsius. In one embodiment, the cold forming process is from room temperature to about 140 degrees celsius. Room temperature may be considered the ambient temperature at which the flooring is produced (e.g., 16 degrees celsius to about 35 degrees celsius).

As shown in fig. 1, during cold forming, the interlayer 30 is positioned between the glass layers 12 and 20. In some such embodiments, the interlayer 30 serves to bond the glass layers 12 and 20 together prior to or during cold forming. In some such embodiments, during application of the pressure P, the stack 10 is heated to a temperature of about 100 degrees celsius to about 140 degrees celsius, thereby forming a bond between the interlayer 30 and the glass layers 12 and 20.

As shown in fig. 3-8, in various embodiments, the laminate 50 is shown as being formed into various complex curved shapes, thereby illustrating various geometric parameters that may be used to determine CFE values. As shown in fig. 3-8, the geometric parameters of first glass layer 12 that may be used to calculate CFE values may include: width W, length L, chord height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, and maximum gaussian curvature GC. In particular embodiments, the determination of the CFE value may also include additional geometric parameters, such as a thickness T1 of first glass layer 12 and a thickness T2 of second glass layer 20.

As shown in fig. 3-8, the glass laminate article 50 can be formed into various shapes for a wide variety of applications. For example, fig. 3-4 show a glass laminate article 50 shaped to form an automotive windshield, according to an exemplary embodiment. Fig. 5-6 show a glass laminate article 50 shaped to form an automotive ceiling/sun visor/moon roof (moon roof) according to an exemplary embodiment. Fig. 7-8 show a glass laminate article 50 shaped to form an automotive sidelight (e.g., sidelight), according to an exemplary embodiment.

As can be seen in fig. 3-8, it may be desirable for the glass laminate article 50 to be formed into a wide variety of complex curved shapes as may be desired for a particular application, vehicle body design, and the like. Generally, to determine whether a particular glass laminate article design is suitable for cold forming, a complex and computationally intensive Finite Element Analysis (FEA) may be required to determine whether the stresses in the glass layers during cold bending may be too high and thus cause defects. Due to the large number of potential article shapes and designs and the need for rapid production, applicants have developed methods that employ relatively simple calculations to predict when a glass laminate article shape will be cold formed, which do not rely on FEA or other computer modeling techniques.

3-8 show different geometric parameters that may be used to calculate CFE values as discussed herein. As shown in fig. 3-8, the glass laminate article 50 (or one of the glass layers of the article 50) includes: width W, length L, chord height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, and maximum gaussian curvature GC. As shown in fig. 1, glass layers 12 and 20 also have average thicknesses T1 and T2. In the specific embodiments discussed herein, these dimensions are defined as follows: width WI is the width of the smallest bounding box containing the glass laminate article 50; length L1 is the length of the smallest bounding box containing the glass laminate article 50; the depth of curvature DOB is the maximum depth of the glass laminate article 50 from the projection plane; the chord height CH is the maximum perpendicular distance between the arc of the glass surface of the glass laminate article 50 and the centerline chord; the minimum first radius of curvature R1 is the minimum radius along the first direction of curvature of the bend; the second minimum radius of curvature R2 is the minimum radius along the transverse bending curvature direction (cross bending curvature direction); gaussian curvature is the product of the principal curvatures at a point, where principal curvatures are the minimum and maximum normal curvatures at a point, and normal curvature is the curvature on a surface lying on a plane containing the tangent vector at a given point.

As discussed in more detail below, various combinations of these geometric parameters are used for various CFE values.

In general, referring to fig. 9, the present disclosure provides a method 100 for evaluating cold formability of a complex curved glass laminate article (e.g., article 50). At step 102, a plurality of geometric parameters, such as a first geometric parameter (G1) and a second geometric parameter (G2), of a complexly curved first glass sheet of a glass laminate article are obtained. As discussed below, in various embodiments, more than two geometric parameters may be used in the cold formability evaluation methods discussed herein. At step 104, a Cold Forming Estimate (CFE) value is calculated that relates to the stress experienced by the first glass sheet during cold forming. At step 106, the calculated CFE value is compared to a cold forming threshold associated with a likelihood that defects will form in the complex curved glass laminate article during cold forming.

Generally speaking, the comparison of step 106 is then used to determine whether a particular design of the complex curved article 50 is suitable for cold forming. In particular embodiments, if the CFE value is less than the cold forming threshold, a cold forming method, such as the one discussed above with respect to fig. 1, is performed. Due to the correlation between the various CFE values discussed herein and the first principal stress experienced by the first glass layer during cold forming, when cold forming is performed on a glass laminate article having a CFE value less than the cold forming threshold, the stress within the glass laminate article 50 remains at a level that causes defects during cold forming.

Generally, the CFE value is the sum of two or more geometric parameters associated with the glass laminate article 50 (multiplied by the calculated coefficients discussed herein), for which applicants have determined that it provides a high level of correlation with the stresses experienced during cold forming. Thus, by calculating CFE values as discussed herein, the cold formability of a particular glass laminate design can be determined without the need for FEA or prototyping and testing of the particular design. Thus, while the CFE values may be calculated in various ways, as discussed herein, in one embodiment the CFE values are B1G 1+ B2G 2, where B1 and B2 are statistically calculated coefficients that relate G1 and G2 to glass laminate articles suitable for cold forming.

Generally, the coefficients B1 and B2 (as well as coefficients for any other geometric parameters that may be used to calculate CFE values) are determined by multiple linear regression analysis of the stress determined by finite element analysis of a plurality of complex curved glass laminate articles. Thus, by calculating a linear regression analysis of the data set of FEA-determined stresses for a plurality of complex curved articles, the effect or correlation of G1 and G2 (and other geometric parameters discussed below) on the stresses experienced during cold forming can be determined. This analysis provides a numerical value for the coefficients B1 and B2 to be determined. Once the B1 and B2 (and coefficients for any other geometric parameters that may be used to calculate the CFE value) are determined, the CFE value may be calculated as the sum of the desired set of geometric parameters multiplied by the coefficients without running the FEA for each new design evaluation.

Applicants believe that the coefficients (e.g., B1 and B2) are a function of the glass materials of the first glass layer 12 and the second glass layer 20. Thus, for the material type of the glass layers of a particular glass laminate article, B1 and B2 (and coefficients for any other geometric parameters that may be used to calculate CFE values) will be determined by linear regression analysis, and may then be used to calculate CFE values for different sizes, shapes, curvatures, etc. of different laminate designs, without the need for FEA for each new design.

In addition, it is believed that the cold forming threshold is also a function of the glass materials of the first glass layer 12 and the second glass layer 20. In various embodiments, the cold forming threshold is related to the maximum allowable stress that the first glass sheet 12 can withstand without forming defects. In a particular embodiment, the cold forming threshold is determined by: the presence or absence of defects in various sizes and shapes of laminated test specimens is evaluated and then correlated to the stress level expected during cold bending calculated using finite element analysis or measured. Further, applicants believe that the cold forming threshold is a function of the material strength of layers 12 and 20.

In a specific embodiment, the first geometric parameter G1 is L/W, the second geometric parameter G2 is chord height CH, B1 is 1 and B2 is 0.5. Thus, in such embodiments, the CFE value is determined as follows:

equation 1: CFE ═ L/W +0.5CH)

When the value of equation 1 is less than the determined cold forming threshold, the glass laminate article having L, W and CH is determined to be cold formable. In particular embodiments, when-0.14 < (L/W +0.5CH) <0.223, it is determined that a glass article having L, W and CH can be cold formed, and in such embodiments, a laminated glass article 50 can be formed having a shape and size such that-0.14 < L/W-0.05 (CH) < 0.223. In some such embodiments, first glass layer 12 is formed from a soda lime glass material and second glass layer 20 is formed from an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

In another embodiment, G1 is chord high CH, G2 is the maximum gaussian curvature GC, B1 is 1 and B2 is 1. Thus, in such embodiments, CFE ═ (CH + GC), and when this value is less than the determined cold forming threshold, it is determined that the glass article having GC and CH is cold formable. In a specific embodiment, when 8< (GC + CH) <20, it is determined that the glass article having GC and CH is cold formable. In some such embodiments, first glass layer 12 is formed from a soda lime glass material and second glass layer 20 is formed from an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

In another embodiment, first glass layer 12 comprises: width W, length L, chord height CH, depth of curvature (DOB), minimum first radius of curvature R1, second minimum radius of curvature R2, average thickness T1, and maximum gaussian curvature GC. In addition, second glass layer 20 includes a thickness T2. In such embodiments, the CFE value is a predicted stress value, and its determination is as follows:

equation 2: CFE ═ B0+ B1 × W + B2 × L + B3 × DOB + B4 × CH + B5 × R1+ B6 × R2+ B7 × GC + B8 ═ T1+ B9 × T2)

In this embodiment, the units of the 9 geometric parameters are as follows: w (mm), L (mm), DOB (mm), CH (mm), R1(mm), R2(mm), maximum GC (10)^-7)(1/mm²) T1(mm) and T2 (mm). Determining each geometric parameter from FEA data sets for glass laminate articles 50 having different geometric parameters but formed from the same materialConstant coefficients B0-B9.

In a specific embodiment, B0-B9 were calculated from the data set for the FEA determined stress for 29 different glass laminate article designs and are shown in table 1.

TABLE 1

With this data, equation 2 becomes:

equation 3: CFE-0.05673W-0.1035L-0.0031 DOB +6.99003 CH + 0.01855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2

The value of equation 3 is then further compared to a cold forming threshold to determine cold formability for a given design of glass laminate article 50. In particular embodiments, using this equation, the cold forming threshold is 80MPa, 50MPa, or 20 MPa. Thus, in such embodiments, the laminate glass article 50 formed has a shape and dimensions such that (0.05673W-0.1035L-0.0031 DOB +6.99003 CH + 0.01855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2) <80 MPa.

It will be appreciated that in this embodiment, W, L, CH, DOB, R1, R2, T1 and GC are all geometric parameters of the first layer 12, while T2 is a geometric parameter of the second glass layer 20. As described above, the coefficients shown in equation 3 are determined using linear regression analysis. In some such embodiments, first glass layer 12 is formed from a soda lime glass material and second glass layer 20 is formed from an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

In a particular embodiment, the first glass layer 12 is formed from an unreinforced glass sheet and the cold forming threshold is determined to be 20 MPa. In this embodiment, the CFE value is a predicted stress value, and is obtained by equation 3. In such embodiments, the method of predicting cold formability comprises: when the calculated CFE value of equation 30 is less than 20MPa, the particular design of the glass laminate article 50 is determined to be suitable for cold forming.

In another embodiment, first glass layer 12 is formed from a strengthened glass sheet (e.g., a thermally strengthened glass material, a chemically strengthened glass sheet, etc.), and the cold forming threshold is determined to be 50 MPa. In this embodiment, the CFE value is a predicted stress value, and is obtained by equation 3. In such embodiments, the method of predicting cold formability comprises: when the calculated CFE value of equation 3 is less than 50MPa, the particular design of the glass laminate article 50 is determined to be suitable for cold forming.

In various embodiments, first glass layer 12 is formed from a soda lime glass material and second glass layer 20 is formed from an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition. In some such embodiments, glass layer 20 is chemically strengthened by ion exchange. In some embodiments, first glass layer 12 may be annealed. In some embodiments, both layers 12 and 20 are formed from soda lime glass. In other embodiments, both layers 12 and 20 are formed from an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

In various embodiments, W is 300mm to 1800mm, L is 230mm to 1600mm, CH is 1mm to 45mm, DOB is 5mm to 210mm, R1 is 40mm to 5000mm, R2 is 740mm to 32500mm, GC is 0.14 e-71/mm²To 15 e-71/mm²T1 is 1mm to 4mm, and T2 is.3 mm to 1 mm.

To provide further examples, the data plots shown in FIGS. 10-14C show the relationship between various CFE values and various cold forming thresholds. Fig. 10 shows the CFE values calculated using equation 3 versus the designed FEA calculated stress for 29 different designs of glass laminate article 50. As can be seen from fig. 10, when the CFE value calculated using equation 3 is below the cold forming threshold 120, the FEA-determined stress is also less than the cold forming threshold 120 for a particular glass article design, and this relationship indicates that the article is cold formable. In this embodiment, the cold forming threshold 120 is 20 MPa.

As shown in fig. 10, an upper limit of the cold forming threshold 130 may also be determined. As can be seen from fig. 10, when the CFE value calculated using equation 3 is above the cold forming threshold 130, the FEA-determined stress is also above the cold forming threshold 130 for a particular glass article design, and this indicates that the article is not cold formable. If the CFE value calculated using equation 3 is between the threshold values 120 and 130, there is a low correlation between the calculated CFE value and the FEA stress value, and thus within this range, the FEA stress should be calculated to determine whether a particular glass laminate design within this range is cold formable because the predicted value of the CFE value is low. In a particular embodiment, the threshold 130 is a B10 value for the material of the first glass layer 12 (in the particular embodiment shown, soda lime glass) based on a weibull distribution, and the threshold 120 is determined to be below that threshold with an acceptably low probability of forming the wrinkled layer 20. Illustratively, during the cold forming process, stress builds up on both layers of the glass laminate article. Typically, one layer (e.g., a soda lime glass layer) has a much lower strength than another layer (e.g., a chemically strengthened layer). Thus, the weaker one is used to determine the intensity threshold during bending.

11A and 11B are 2D plots of the data of FIG. 10 showing the relationship between selected geometric parameters and cold forming thresholds 120 and 130. FIG. 11A is a 2D map generated using maximum GC and chordal height, while FIG. 11B is a 2D map generated using chordal height CH and L/W. Both maps in fig. 11A and 11B are divided into 3 regions by cold forming thresholds 120 and 130, respectively. With some exceptions, most of the data points are within the desired region. Fig. 11A shows the clear correlation between these two parameters (max GC and CH): as the chord height increases, the maximum GC should be reduced to ensure that the laminate article is cold formable. Similarly, fig. 11B shows the clear correlation between these two parameters (L/W and chordal height CH): as the chord height increases, the L/W needs to be increased so that the glass laminate article is cold formable.

Fig. 12A-12C are 2D views of the glass laminate article of fig. 10 designed for a windshield. As shown in FIG. 12B, the L/W values for the windshield design are distributed primarily over the range of 0-0.8. The windshield data has cold forming thresholds 120 and 130, which are similar to the overall data in the maximum GC-chord height map (fig. 11A) and the L/W-chord height map (fig. 11B).

Fig. 13A-13C are 2D views of the glass laminate article of fig. 10 designed for use in a ceiling tile. As shown in FIG. 13B, the L/W values are mainly distributed over the range of 0-1.0. As shown, the ceiling data has a wider area between thresholds 120 and 130 than the overall data (fig. 11A and 11B).

Fig. 14A-14C are 2D views of the glass laminate article of fig. 10 designed for use in a sidelight (e.g., sidelight). As shown in FIG. 14B, the L/W values are mainly distributed over the range of 0 to 0.7.

Referring to fig. 15, a glass laminate article 50 is shown for use as part of a vehicle window, ceiling or side window. As shown, the vehicle 200 includes one or more side windows 202, a ceiling 204, a rear window 206, and/or a windshield 208. Generally speaking, any of the embodiments of the glass laminate article 50 discussed herein may be used for one or more of the side windows 202, the ceiling 204, the back window 206, and/or the windshield 208. Generally speaking, one or more side windows 202, ceiling 204, backlight 206, and/or windshield 208 are supported within an opening defined by a vehicle frame or body 210 such that the exterior surface 22 (see fig. 1) of the second ply of glass 20 faces toward a vehicle interior 212. In this arrangement, the outer surface 14 (see fig. 1) of the first glass layer 12 faces toward the exterior of the vehicle 200 and may define the outermost surface of the vehicle 200 at the location of the glazing. As used herein, a vehicle may include: vehicles, locomotives, trains, boats, ships, airplanes, helicopters, drones, and spacecraft, among others. In other embodiments, the glass laminate article 50 may be used in a variety of other applications where thin, curved glass laminate articles may be advantageous, such as for architectural glass, and the like.

As used herein, "complex curvature" or "complex curved" means a non-flat shape having curvature along two mutually different orthogonal axes. Examples of complex curved shapes include shapes with simple or compound curvatures, also referred to as non-deployable (non-deployable) shapes, including but not limited to spherical, non-spherical, and toroidal. Complex curved laminates according to embodiments may also include sections or portions of such surfaces, or may include combinations of such curves and surfaces. In one or more embodiments, the laminate may have a compound curvature including a major radius and a transverse curvature (cross curvature). According to embodiments, the complex curved laminate may have different radii of curvature in the two independent directions. Thus, according to one or more embodiments, a complex curved stack can be characterized as having a "lateral curvature," where the stack is curved along one axis parallel to a given dimension (i.e., a first axis) and also curved along one axis perpendicular to the same dimension (i.e., a second axis). The curvature of the stack can be even more complex when a significant minimum radius is combined with a significant lateral curvature and/or depth of curvature.

Some laminates may also include bends along axes that are not perpendicular to each other. By way of non-limiting example, a complex curved laminate may have length and width dimensions of 0.5m by 1.0m, with a radius of curvature along the minor axis of 2 to 2.5m and a radius of curvature along the major axis of 4 to 5 m. In one or more embodiments, the complex curved laminate can have a radius of curvature along at least one axis of 5m or less. In one or more embodiments, the complex curved laminate may have a radius of curvature of 5m or less at least along a first axis and along a second axis perpendicular to the first axis. In one or more embodiments, the complex curved laminate can have a radius of curvature of 5m or less at least along a first axis and along a second axis that is not perpendicular to the first axis.

Glass layers 12 and/or 20 may be formed from a variety of materials. In particular embodiments, glass layer 20 is formed from a chemically strengthened alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and glass layer 12 is formed from a Soda Lime Glass (SLG) composition. In particular embodiments, glass layers 12 and/or 20 are formed from a chemically strengthened material, such as an alkali aluminosilicate glass material or an alkali aluminoborosilicate glass composition, having a chemically strengthened compressive layer with a depth of compression (DOC) of from about 30 μm to about 90 μm, and a compressive stress on at least one major surface of the sheet of from 300MPa to 1000 MPa. In some embodiments, the chemically strengthened glass is strengthened by ion exchange.

Examples and Properties of glass materials

In various embodiments, glass layers 12 and/or 20 may be formed from any of a variety of glass compositions. Examples of glasses that may be used for glass layers 12 and/or 20 described herein may include: a soda lime silicate glass composition, an aluminosilicate glass composition, an alkali aluminosilicate glass composition, or an alkali aluminoborosilicate glass composition, although other glass compositions are also contemplated. In one or more embodiments, suitable glass compositions can be characterized as being ion-exchangeable. As used herein, "ion-exchangeable" means that the layer comprises a composition that enables the exchange of larger or smaller sized homovalent cations with cations located at or near the surface of the glass layer. In one exemplary embodiment, the glass composition of glass 12 and/or 20 comprises: SiO 2₂、B₂O₃And Na₂O, wherein (SiO)₂+B₂O₃) Not less than 66 mol% and Na₂O is more than or equal to 9 mol percent. In some embodiments, suitable glass compositions for glass layers 12 and/or 20 further comprise K₂O, MgO and CaO. In particular embodiments, the glass composition for glass layers 12 and/or 20 may comprise: 61-75 mol% SiO₂(ii) a 7-15 mol% Al₂O₃(ii) a 0-12 mol% of B₂O₃(ii) a 9-21 mol% of Na₂O; 0-4 mol% of K₂O; 0-7 mol% MgO; and 0-3 mol% CaO.

Another example of a suitable glass composition for glass layers 12 and/or 20 includes: 60-70 mol% SiO₂(ii) a 6-14 mol% Al₂O₃(ii) a 0-15 mol% of B₂O₃(ii) a 0-15 mol% Li₂O; 0-20 mol% Na₂O; 0-10 mol% of K₂O; 0-8 mol% MgO; 0-10 mol% CaO; 0-5 mol% of ZrO₂(ii) a 0-1 mol% of SnO₂(ii) a 0-1 mol% of CeO₂(ii) a Less than 50ppm of As₂O₃(ii) a And less than 50ppm Sb₂O₃(ii) a Wherein 12 mol% is less than or equal to(Li₂O+Na₂O+K₂O) is less than or equal to 20 mol percent, and (MgO + CaO) is less than or equal to 0 mol percent and less than or equal to 10 mol percent.

Even further, another example of a suitable glass composition for glass layers 12 and/or 20 comprises: 63.5-66.5 mol% SiO₂(ii) a 8-12 mol% Al₂O₃(ii) a 0-3 mol% of B₂O₃(ii) a 0-5 mol% Li₂O; 8-18 mol% Na₂O; 0-5 mol% of K₂O; 1-7 mol% MgO; 0-2.5 mol% CaO; 0-3 mol% of ZrO₂(ii) a 0.05-0.25 mol% SnO₂(ii) a 0.05-0.5 mol% of CeO₂(ii) a Less than 50ppm of As₂O₃(ii) a And less than 50ppm Sb₂O₃(ii) a Wherein 14 mol percent is less than or equal to (Li)₂O+Na₂O+K₂O) is less than or equal to 18 mol percent, and 2 mol percent is less than or equal to (MgO + CaO) is less than or equal to 7 mol percent.

In particular embodiments, suitable alkali aluminosilicate glass compositions for glass layers 12 and/or 20 include: alumina; at least one alkali metal; and in some embodiments greater than 50 mole% SiO₂And in other embodiments at least 58 mole% SiO₂And in other embodiments at least 60 mole% SiO₂(ii) a Wherein, the ratio ((Al)₂O₃+B₂O₃) /∑ modifier>1, wherein the proportions of the components are in mole% and the modifier is an alkali metal oxide. In certain embodiments, such glass compositions comprise: 58-72 mol% SiO₂9-17 mol% of Al₂O₃2-12 mol% of B₂O₃8-16 mol% of Na₂O and 0-4 mol% of K₂O, wherein, the ratio ((Al)₂O₃+B₂O₃) /∑ modifier>1。

In another embodiment, glass layers 12 and/or 20 may comprise an alkali aluminosilicate glass composition comprising: 64-68 mol% SiO₂(ii) a 12-16 mol% Na₂O; 8-12 mol% Al₂O₃(ii) a 0-3 mol% of B₂O₃(ii) a 2-5 mol% ofK₂O; 4-6 mol% MgO; and 0-5 mol% of CaO, wherein SiO is more than or equal to 66 mol%₂+B₂O₃CaO is less than or equal to 69 mol%; na (Na)₂O+K₂O+B₂O₃+MgO+CaO+SrO>10 mol%; MgO, CaO and SrO are more than or equal to 5 mol% and less than or equal to 8 mol%; (Na)₂O+B₂O₃)-Al₂O₃Less than or equal to 2 mol percent; na is not more than 2 mol percent₂O-Al₂O₃Less than or equal to 6 mol percent; and 4 mol% is less than or equal to (Na)₂O+K₂O)-Al₂O₃Less than or equal to 10 mol percent.

In alternative embodiments, glass layers 12 and/or 20 may include an alkali aluminosilicate glass composition comprising: 2 mol% or more of Al₂O₃And/or ZrO₂Or 4 mol% or more of Al₂O₃And/or ZrO₂. In one or more embodiments, glass layers 12 and/or 20 include a glass composition comprising: SiO 2₂In an amount of about 67 to about 80 mole%, Al₂O₃In an amount of about 5 to about 11 mole%, an alkali metal oxide (R)₂O) is greater than about 5 mol% (e.g., about 5 mol% to about 27 mol%). In one or more embodiments, R₂The amount of O includes: li₂The amount of O is from about 0.25 mole% to about 4 mole%, and K₂The amount of O is equal to or less than 3 mol%. In one or more embodiments, the glass composition includes a non-zero amount of MgO and a non-zero amount of ZnO.

In other embodiments, glass layers 12 and/or 20 are formed from glass compositions exhibiting: SiO 2₂In an amount of about 67 to about 80 mole%, Al₂O₃In an amount of about 5 to about 11 mole%, an alkali metal oxide (R)₂O) is greater than about 5 mol% (e.g., about 5 mol% to about 27 mol%), wherein the glass composition is substantially free of Li₂O, and a non-zero amount of MgO; and a non-zero amount of ZnO.

In other embodiments, glass layers 12 and/or 20 are aluminosilicate glass articles including a glass composition comprising: SiO 2₂The amount of (a) is about 67 mole% or greater; and the sag temperature is about 600 ℃ to about 710 ℃. In other embodiments, glass layers 12 and/or 20 are formed from aluminosilicate glass articles, including glass compositions, comprising: SiO 2₂The amount of (a) is about 68 mole% or greater; and a sag temperature of from about 600 ℃ to about 710 ℃ (as defined herein).

In some embodiments, glass layers 12 and/or 20 are formed from mutually different glass materials that differ in any one or more of composition, thickness, level of strengthening, and method of forming (e.g., float forming rather than melt forming). In one or more embodiments, glass layers 12 and/or 20 described herein have a sag temperature of about 710 ℃ or less or about 700 ℃ or less. In one or more embodiments, one of the glass layers 12 and 20 is a soda-lime glass sheet and the other of the glass layers 12 and 20 is any of the non-soda-lime glass materials discussed herein. In one or more embodiments, glass layers 12 and/or 20 comprise a glass composition comprising: SiO 2₂In an amount of about 68 mol% to about 80 mol%, Al₂O₃In an amount of about 7 to about 15 mole%, B₂O₃The amount of (a) is about 0.9 molar% to about 15 molar%; non-zero amount of P₂O₅Up to and including about 7.5 mol%, Li₂The amount of O is about 0.5 mol% to about 12 mol%, and Na₂The amount of O is from about 6 mol% to about 15 mol%.

In some embodiments, the glass composition of glass layers 12 and/or 20 may include an oxide that imparts a color or tint to the glass article. In some embodiments, the glass composition of glass layers 12 and/or 20 comprises an oxide that prevents discoloration of the glass article when the glass article is exposed to ultraviolet radiation. Examples of such oxides include, but are not limited to, oxides of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, W, and Mo.

Glass layers 12 and/or 20 may have a refractive index of about 1.45 to about 1.55. As used herein, refractive index values are relative to a wavelength of 550 nm. Glass layers 12 and/or 20 may be characterized by the manner in which they are formed. For example, glass layers 12 and/or 20 may be characterized as float formable (i.e., formed by a float process), down drawable, specifically, fusion formable, or slot drawable (i.e., formed by a down draw process such as a fusion draw process or a slot draw process). In one or more embodiments, the glass layers 12 and/or 20 described herein may exhibit an amorphous microstructure, and may be substantially free of crystals or crystallites. In other words, in such embodiments, the glass article excludes a glass-ceramic material.

In one or more embodiments, when the thickness of the glass layers 12 and/or 20 is 0.7mm, the glass layers 12 and/or 20 exhibit an average total solar transmittance of about 88% or less over a wavelength range of about 300nm to about 2500 nm. For example, glass layers 12 and/or 20 exhibit an average total solar transmittance at: about 60% to about 88%, about 62% to about 88%, about 64% to about 88%, about 65% to about 88%, about 66% to about 88%, about 68% to about 88%, about 70% to about 88%, about 72% to about 88%, about 60% to about 86%, about 60% to about 85%, about 60% to about 84%, about 60% to about 82%, about 60% to about 80%, about 60% to about 78%, about 60% to about 76%, about 60% to about 75%, about 60% to about 74%, or about 60% to about 72%.

In one or more embodiments, glass layers 12 and/or 20 exhibit an average transmission of about 75% to about 85% for a thickness of 0.7mm or 1mm over a wavelength range of about 380nm to about 780 nm. In some embodiments, the average transmission over this thickness and this wavelength range may be in the following ranges: about 75% to about 84%, about 75% to about 83%, about 75% to about 82%, about 75% to about 81%, about 75% to about 80%, about 76% to about 85%, about 77% to about 85%, about 78% to about 85%, about 79% to about 85%, or about 80% to about 85%. In one or more embodiments, glass layers 12 and/or 20 exhibit a T of 50% or less for a thickness of 0.7mm or 1mm over a wavelength range of about 300nm to about 400nm_uv-380Or T_uv-400(e.g., 49% or less, 48% or less, 45% or less, 40% or less, 30% or less, 25% or moreSmall, 23% or less, 20% or less, or 15% or less).

In one or more embodiments, glass layers 12 and/or 20 may be strengthened to include a compressive stress extending from the surface to a depth of compression (DOC). The compressive stress region is balanced by a central portion exhibiting tensile stress. At the DOC, the stress is converted from positive (compressive) stress to negative (tensile) stress.

In one or more embodiments, the glass layers 12 and/or 20 may be mechanically strengthened by utilizing mismatches in the coefficient of thermal expansion between portions of the article to create regions of compressive stress and central regions exhibiting tensile stress. In some embodiments, the glass article may be heat strengthened by heating the glass to a temperature below the glass transition point and then rapidly quenching.

In one or more embodiments, glass layers 12 and/or 20 may be chemically strengthened by ion exchange. During the ion exchange process, larger ions having the same valence or oxidation state are substituted or exchanged for ions at or near the surface of glass layers 12 and/or 20. In those embodiments where glass layers 12 and/or 20 comprise alkali aluminosilicate glasses, the ions in the surface layers of the article, as well as larger ions, are monovalent alkali cations, such as Li⁺、Na⁺、K⁺、Rb⁺And Cs⁺. Alternatively, monovalent cations other than alkali metal cations, such as Ag, may be used as the monovalent cations in the surface layer⁺And so on. In such embodiments, the monovalent ions (or cations) exchanged into glass layers 12 and/or 20 create stress.

Aspect (1) of the present disclosure pertains to a method of evaluating cold formability of a complexly curved glass laminate article comprising a first glass sheet and a second glass sheet, the method comprising: obtaining a first geometric parameter (G1) and a second geometric parameter (G2) of a complexly curved first glass sheet of a glass laminate article; calculating Cold Forming Estimate (CFE) values relating to the stress experienced by the first glass sheet during cold forming, wherein the CFE values include B1G 1+ B2G 2, wherein B1 and B2 are coefficients calculated to correlate G1 and G2 to the CFE values; and comparing the calculated CFE value to a cold forming threshold associated with a likelihood of forming a defect in the complex curved glass laminate article during cold forming.

Aspect (2) pertains to the method of aspect (1), further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than the cold forming threshold.

Aspect (3) is the method of aspect (1) or aspect (2), wherein the first glass sheet has an average thickness that is greater than an average thickness of the second glass sheet, and the first glass sheet is formed from a first glass composition that is different from a second glass composition of the second glass sheet.

Aspect (4) pertains to the method of aspect (3), wherein B1, B2, and the cold forming threshold are a function of the first glass composition.

Aspect (5) pertains to the method of aspect (3), wherein the first glass composition is a soda lime glass.

Aspect (6) pertains to the method of aspect (5), wherein the first glass sheet is an unreinforced glass sheet and the cold forming threshold is 20MPa, and further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than 20 MPa.

Aspect (7) pertains to the method of aspect (5), wherein the first glass sheet is a thermally strengthened glass sheet and the cold forming threshold is 50MPa, and further comprising determining that the bent glass laminate article is suitable for cold forming when the calculated CFE value is less than 50 MPa.

Aspect (8) pertains to the method of any one of aspects (2) to (7), wherein the second glass composition is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition.

Aspect (9) pertains to the method of any one of aspects (2) to (8), further comprising determining B1 and B2 by multiple linear regression analysis of finite element analysis determined stresses for a plurality of complex curved glass laminate articles.

Aspect (10) pertains to the method of any one of aspects (1) through (9), wherein the cold forming threshold is a maximum allowable stress of the first glass sheet determined by comparing the laminated test sample to a stress level predicted using finite element analysis.

Aspect (11) pertains to the method of any one of aspects (1) to (10), wherein the first glass sheet comprises: length L, width W and chord height, where G1 equals L/W, G2 equals chord height, B1 equals 1 and B2 equals 0.5.

Aspect (12) pertains to the method of any one of aspects (1) to (10), wherein the first glass sheet further comprises: an inner surface, an outer surface opposite the inner surface, a width W, a length L, an average thickness T1, wherein the complex curved shape has a chord height CH, a depth of curvature (DOB), a minimum first radius of curvature R1, a second minimum radius of curvature R2, and a maximum gaussian curvature GC, wherein the second glass layer further comprises: inner surface, outer surface and average thickness T2, wherein (0.05673W-0.1035L-0.0031 CH +6.99003 CH + 0.1855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2) is less than the cold forming threshold.

Aspect (13) pertains to a method of cold forming a complex curved glass laminate article comprising: supporting a first glass sheet having a complex curved shape, a first major surface, and a second major surface; supporting a second glass sheet on the first glass sheet, wherein the second glass sheet has a first major surface, a second major surface, and a shape that is different from the complex curved shape; placing a polymeric interlayer material between the second major surface of the first glass sheet and the first major surface of the second glass sheet; bending a second glass sheet material into a complex curved shape conforming to the first glass sheet material, wherein during the bending process the maximum temperature of the first glass sheet is less than the glass transition temperature of the glass material of the first glass sheet, wherein the maximum temperature of the second glass sheet is less than the glass transition temperature of the glass material of the second glass sheet; wherein the complex curved shape has a first geometric parameter (G1) and a second geometric parameter (G2), wherein a first principal stress experienced by the first glass sheet during bending is less than or equal to an estimated stress value (B1G 1+ B2G 2), wherein B1 and B2 are coefficients determined to correlate G1 and G2 with a stress experienced by the first glass sheet during bending.

Aspect (14) pertains to the method of aspect (13), wherein the first glass sheet has an average thickness that is greater than an average thickness of the second glass sheet, and the glass material of the first glass sheet is different from the glass material of the second glass sheet.

Aspect (15) is the method of aspect (13) or aspect (14), wherein the first glass sheet is an unreinforced glass sheet, and the estimated stress value is less than 20 MPa.

Aspect (16) pertains to the method of aspect (13) or aspect (14), wherein the first glass sheet is a thermally strengthened glass sheet, and the estimated stress value is 50 MPa.

Aspect (17) is the method of any one of aspects (13) to (16), wherein the glass material of the second glass sheet is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda lime glass composition.

Aspect (18) pertains to a cold-formed glass laminate article comprising: a first glass layer comprising: an inner surface, an outer surface opposite the inner surface, a width W, a length L, a complex curved shape having a chordal height CH, wherein-0.14 < L/W-0.05 x (CH) < 0.223; and a second glass layer comprising: an inner surface, an outer surface; a polymer interlayer disposed between the inner surface of the first glass layer and the inner surface of the second glass layer.

Aspect (19) is the cold-formed glass laminate article of aspect (18), wherein the average thickness T1 of the first glass layer is greater than the average thickness T2 of the second glass layer.

Aspect (20) is the cold-formed glass laminate article of aspect (19), wherein T1 is 1mm to 4mm and T2 is.3 mm to 1 mm.

Aspect (21) pertains to the cold-formed glass laminate article of any of aspects (18) to (20), wherein W is 300mm to 1800mm, L is 230mm to 1600mm, and CH is 1mm to 45 mm.

Aspect (22) pertains to the cold-formed glass laminate article of any of aspects (18) to (21), wherein the glass material of the first glass layer is different from the glass material of the second glass layer.

Aspect (23) pertains to the cold-formed glass laminate article of aspect (22), wherein the glass material of the second glass layer is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda-lime glass composition.

Aspect (24) pertains to the cold-formed glass laminate article of any of aspects (18) to (23), wherein the second glass layer is a chemically-strengthened glass material.

Aspect (25) pertains to a cold-formed glass laminate article comprising: a first glass layer comprising: an inner surface, an outer surface opposite the inner surface, a width W, a length L, an average thickness T1, a complex curved shape having a chord height CH, a depth of curvature (DOB), a minimum first radius of curvature R1, a second minimum radius of curvature R2, and a maximum gaussian curvature GC; a second glass layer comprising: an inner surface, an outer surface, and an average thickness T2; and an interlayer disposed between the inner surface of the first glass layer and the inner surface of the second glass layer, wherein (0.05673W-0.1035L-0.0031 CH +6.99003 CH + 0.1855R 1+ 0.00115R 2+4.633988 GC-0.1836T 1-101.95T 2) is less than 80 MPa.

Aspect (26) is the cold-formed glass laminate article of aspect (25), wherein T1 is greater than T2.

Aspect (27) is the cold-formed glass laminate article of aspect (25) or aspect (26), wherein T1 is 1mm to 4mm and T2 is.3 mm to 1 mm.

Aspect (28) is the cold-formed glass laminate article of any of aspects (25) to (27), wherein W is 300mm to 1800mm, L is 230mm to 1600mm, CH is 1mm to 45mm, DOB is 5mm to 210mm, R1 is 40mm to 5000mm, R2 is 740mm to 32500mm, and GC is 0.14 e-71/mm²To 15 e-71/mm²。

Aspect (29) pertains to the cold-formed glass laminate article of any of aspects (25) through (28), wherein the glass material of the first glass layer is different from the glass material of the second glass layer.

Aspect (30) pertains to the cold-formed glass laminate article of aspect (29), wherein the glass material of the second glass layer is an alkali aluminosilicate glass composition or an alkali aluminoborosilicate glass composition, and the glass material of the first glass sheet is a soda lime glass composition.

Aspect (31) pertains to the cold-formed glass laminate article of any of aspects (25) to (30), wherein the second glass layer is a chemically-strengthened glass material.

Unless otherwise stated, it is not intended that any method described herein be construed as requiring that its steps be performed in a particular order. Thus, where a method claim does not actually recite an order to be followed by its steps or it does not otherwise specifically imply that the steps are to be limited to a specific order in the claims or specification, it is not intended that any particular order be implied. In addition, the articles "a" and "an" as used herein are intended to include one or more than one component or element, and are not intended to be construed as meaning only one.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the illustrated embodiments. Since numerous modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments are to be considered as including all equivalents thereof within the scope of the appended claims.