阅读说明：本技术 填充柔性材料的管形结构 (Tubular structure filled with flexible material ) 是由 高岳 邵飞 范鹏贤 徐倩 于 2020-12-02 设计创作，主要内容包括：填充柔性材料的管形结构,涉及用作建筑结构的管形结构。填充柔性材料的管形结构,包括管形部件,所述管形部件内填充有增强受拉作用的柔性材料棒材。柔性材料棒材的弹性模量为20MPa—2GPa。柔性材料棒材为聚氨酯、聚四氟乙烯、ABS工程塑料中的一种。本发明提出了一种“管材+柔性内部支撑”的方法,对于管材的拉伸极限力学性能和断裂韧性提升显著,且装配便捷,重量和成本增加不多,非常适合装配式钢管组合结构,具有高韧性、简捷性、轻量化、经济性等特点。(A tubular structure filled with flexible material relates to a tubular structure used as a building structure. A tubular structure filled with flexible material comprising tubular members filled with a rod of flexible material which enhances the tension. The elastic modulus of the flexible material bar is 20 MPa-2 GPa. The flexible material bar is one of polyurethane, polytetrafluoroethylene and ABS engineering plastics. The invention provides a method of 'pipe and flexible internal support', which has the advantages of remarkable improvement on the tensile limit mechanical property and the fracture toughness of the pipe, convenient and fast assembly, small increase in weight and cost, suitability for an assembled steel pipe combined structure, high toughness, simplicity, light weight, economy and the like.)

1. Tubular structure filled with flexible material, characterized in that it comprises a tubular member (1), said tubular member (1) being filled with a bar (2) of flexible material which enhances the tensile action.

2. A tube structure filled with flexible material according to claim 1, characterized in that said rod (2) of flexible material has an elastic modulus of between 20MPa and 2 GPa.

3. The flexible material filled tubular structure of claim 6, wherein said flexible material rod is one of polyurethane, teflon, and ABS engineering plastic.

4. A tubular structure filled with flexible material according to claim 1, characterized in that the surface of said rod (2) of flexible material is coated with a thermal barrier coating.

Technical Field

The present invention relates to tubular structures for use as building structures, and more particularly to tubular structures with fillers inside.

Background

The pipe member has wide application in the fields of aerospace, ocean platforms, power transmission facilities, energy chemical engineering, transportation and the like, and higher requirements are provided for the technical indexes of the pipe along with the more and more wide application of the pipe member in the engineering field. In a composite structure, tension is a common stress state of a steel pipe. In the service process of the structural pipe, when the structural pipe meets extreme working conditions such as earthquake, explosion, impact, ice and snow disasters, the strength of the structural pipe fails due to the fact that the structural pipe bears overlarge tensile load, and the damage process of the structural pipe is often a complex deformation damage process. Therefore, research on the ultimate mechanical properties of the pipe under specific working conditions becomes an important issue concerned by engineering designers.

Due to the special hollow structure of the hollow pipe, the hollow pipe can generate obvious transverse necking when being stretched longitudinally; the transverse necking in the middle of the pipe aggravates the stress concentration phenomenon at the necking part, thereby accelerating the breakage of the pipe in the middle and causing that the mechanical properties of other parts of the pipe are not fully exerted. The research on the tensile mechanical property of the hollow pipe is a mature field; the research on the pipe with the filling inside mainly focuses on the research on the compression limit bearing capacity of the steel pipe concrete and the energy absorption characteristic of the foam metal filled thin-walled pipe. The research on the tensile property of the pipe internally preset with the filling material is relatively less, and the research is mainly focused on the tensile property research of the concrete filled steel tube.

Although the ultimate bearing capacity of the concrete filled steel tube is improved to a certain extent, the elongation rate of the concrete filled steel tube tends to be lower than that of the concrete filled empty tube. The steel pipe concrete tension member has higher requirements on the construction process, longer concrete curing time, higher requirements on fields and equipment and higher comprehensive cost; the self weight of the steel pipe concrete tension member is also large. At present, no research is carried out on the extreme mechanical performances such as the ultimate tensile strength, the elongation, the fracture energy and the like of the pipe filled with the flexible supporting material.

Disclosure of Invention

The invention provides a method of 'pipe and flexible internal support', which has the advantages of remarkable improvement on the tensile limit mechanical property and the fracture toughness of the pipe, convenient and fast assembly, small increase in weight and cost, suitability for an assembled steel pipe combined structure, high toughness, simplicity, light weight, economy and the like.

A tubular structure filled with flexible material comprising tubular members filled with a rod of flexible material which enhances the tension.

Preferably, the elastic modulus of the flexible material bar of the invention is 20 MPa-2 GPa.

Preferably, the flexible material bar is one of polyurethane, polytetrafluoroethylene and ABS engineering plastics.

Preferably, the surface of the flexible material bar of the present invention is coated with a thermal barrier coating to enhance fire resistance.

By adopting the technical scheme, compared with the prior art, the invention has the following advantages:

1. from the aspect of weight, the flexible material is lower in density than concrete, and the lightweight design of the structure is facilitated.

2. From the aspect of construction process, the flexible material is simple and convenient to fill and operate, does not need maintenance, and is suitable for assembled steel pipe combined structures; the steel pipe concrete structure has a long curing age and is complex to process and manufacture.

3. From the aspect of comprehensive cost, the flexible material is filled and is plug-and-play, so that the comprehensive cost is low; and the steel pipe concrete tension tubular member has higher requirements on fields and equipment and higher comprehensive cost.

4. When the flexible material is used as an internal filling material, the ultimate tensile strength, elongation and fracture energy of the tension pipe member can be obviously improved, and the elongation of the tension pipe member is negatively amplified by concrete.

5. The method of 'pipe material + flexible internal support' provided by the invention has the advantages that the tensile limit mechanical property and the fracture toughness of the pipe material are obviously improved, the assembly is convenient, the weight and the cost are not increased much, the method is very suitable for an assembled steel pipe combined structure, and the method has the characteristics of high toughness, simplicity, light weight, economy and the like. A new technical path is provided for improving the comprehensive performance of the steel pipe composite structure in the extreme state, and the method has important significance for improving the structural design safety and saving the engineering construction cost.

Drawings

FIG. 1 is a schematic view of the structure of the present invention in the longitudinal direction.

Fig. 2 is a schematic view of the end structure of the present invention.

Fig. 3 is a graphical representation of the yield function of the tubular structure of the present invention.

FIG. 4 is a graph showing the increase in ultimate tensile strength according to the present invention.

FIG. 5 is a graph showing the increase in elongation according to the present invention.

FIG. 6 is a graph showing the variation of the energy increase of fracture according to the present invention.

Detailed Description

As shown in fig. 1 and 2, the tubular structure filled with flexible material of the present invention comprises a tubular member 1, wherein the tubular member 1 is filled with a bar 2 of flexible material for enhancing the tensile effect.

The elastic modulus of the flexible material bar 2 is 20 MPa-2 GPa.

The flexible material is one of polyurethane, polytetrafluoroethylene and ABS engineering plastics.

The surface of the flexible material bar 2 is sprayed with a layer of heat insulation coating.

Due to the supporting effect of the internal filling material, the transverse necking of the round pipe to the symmetry axis during stretching is limited, and the ultimate tensile bearing capacity, the elongation and the fracture energy of the tested piece are obviously improved. The flexible internal support and the thin-walled tension tube form an efficient combined structure.

Taking the classical Mises tensile pipe as an example, the following theoretical analysis was performed. When the material meets a certain stress condition, the material enters into yield, the condition is the yield condition, and the yield function is usually used for expressing. Wherein the Mises yield condition is one of the most widely applied yield conditions, and the physical meaning is as follows: when the distortion corresponding to the stress state of a certain point in the object can reach a certain value C, the material at the point yields. When the material yields, the three main stresses satisfy the following relationship:

J₂is a second invariant of bias stress, σ₁、σ₂、σ₃Is three principal stresses, σ_sIs the yield stress.

Experimental studies show that for metal materials with better ductility, the Mises yield condition can better describe the yield behavior of the materials. If the material constant is calibrated by the uniaxial tensile test of the thin-wall round pipe, the following are obtained:

in the principal stress space, the Mises yield surface appears as a cylindrical surface parallel to the hydrostatic pressure axis (as shown in fig. 3 a); the yield surface and sigma₁-σ₂The intersection of the planes is an ellipse (as shown in fig. 3 b), and the equation is:

from fig. 3 b: when the material is in a plane stress state, as the stress in one direction increases, the yield stress in the other direction increases and then decreases. By simply converting equation (3), we can obtain:

if only the two-way tension (first quadrant) is considered and the two-way stresses are independent of each other, the pair of equation (4)Derivation, namely, the following steps are obtained: in thatWhen the temperature of the water is higher than the set temperature,taking the maximum valueThat is, under bi-directional tension conditions, the yield stress of the material in the direction of maximum tension can be increased by about 15.5%.

The above analysis is an analysis of the increase in yield strength of the pipe by the internal support effect. According to the generalized Hooke's law and the principle that the plastic deformation volume is unchanged, the steel pipe under the action of the flexible internal support can keep a larger cross-sectional area than the steel pipe under the action of the rigid internal support under the same tension condition through strict mathematical derivation. Namely: from the analysis of the material deformation, the tensile mechanical property of the steel pipe is improved better by the flexible internal support than by the rigid support. The stress analysis and the deformation analysis are combined, the two parts are coupled, and the maximum increase of the yield strength of the steel pipe under the action of the flexible internal support reaches 18 percent (theoretical calculation value).

When the analysis is popularized to the limit state of the tension pipe, the ultimate tensile strength of the pipe is also improved.

The influence of the internal support material on the increase of the ultimate tensile mechanical property of the steel pipe is comprehensively considered, the improvement of the ultimate tensile mechanical property of the pipe by the flexible support material is better than that of the rigid support material, the harder the internal support material is, the better the internal support material is, and a proper elastic modulus range (20 MPa-2 GPa) exists.

As shown in FIG. 4, FIG. 5 and FIG. 6, the outer tube is a 304 stainless steel (0Cr18Ni9) thin-walled circular tube with an outer diameter of 30mm, an inner diameter of 25.7mm, a total length of 215mm, a clamping length of 60mm and a parallel length of 95 mm. The chock plug is Q235 round steel, the external diameter is 25.5mm, and the length is 60 mm.

In order to improve the pressure resistance of the end of the tubular part to the pressure part during the test, plugs are respectively arranged at the two ends of the tubular part 1 in the length direction. The plug is Q235 round steel, and the metal adhesive is filled between the inner wall of the plug and the outer wall of the Q235 round steel. The rod 2 of flexible material inside the tubular member 1 has a diameter of 25mm and a length of 95 mm.

When the internal filling material is polyurethane and the axial tensile loading rate is 15mm/min, the maximum increase of the nominal ultimate tensile strength is 8.12%, the maximum increase of the elongation is 18.78% and the maximum increase of the fracture energy is 26.01% compared with the stretching of an empty pipe.

When the inner filling material is polytetrafluoroethylene and the axial stretching loading rate is 15mm/min, the maximum increase of the nominal ultimate tensile strength is 10.81 percent, the maximum increase of the elongation is 23.30 percent and the maximum increase of the fracture energy is 35.94 percent compared with the stretching of an empty pipe.

When the internal filling material is ABS engineering plastic and the axial tensile loading rate is 15mm/min, the maximum increase of the nominal ultimate tensile strength is 8.51 percent, the maximum increase of the elongation is 24.56 percent and the maximum increase of the fracture energy is 35.84 percent compared with the stretching of an empty pipe.