阅读说明：本技术 一种t型复合结构的超声无损检测装置及方法和r区检测方法及装置 (Ultrasonic nondestructive testing device and method for T-shaped composite structure and R-region testing method and device ) 是由 阚艳 范鑫 张平 程宗辉 朱萌 史维佳 李佳鑫 于 2021-09-10 设计创作，主要内容包括：一种T型复合结构的超声无损检测装置及方法和R区检测方法及装置,涉及无损检测领域。现有的T型复合结构缺陷检测精度低,没有一种能够准确检测R区的缺陷的方法。针对上述问题,本申请采用的技术方案为：标定超声波在被测复合材料内部沿各个方向的传播速度,采集超声波在材料内部传播时产生的反射回波进行成像；获取两种材料交界面处的反射回波强度,进行成像；从R区的背面进行检测；根据检测结果和成像结果判断。本申请采用逐层扫描的方式对T型复合结构进行在役超声无损检测,有效提高了T型复合结构的缺陷检测精度,同时利用从R区背面发射聚焦超声波的方法简化了R区检测的难点。可应用在航空航天领域中对T型复合结构检测的工作中。(An ultrasonic nondestructive testing device and method for a T-shaped composite structure and an R region testing method and device relate to the field of nondestructive testing. The existing T-shaped composite structure has low defect detection precision, and no method for accurately detecting the defects of the R area exists. In order to solve the above problems, the technical scheme adopted by the application is as follows: calibrating the propagation speed of ultrasonic waves in each direction in the tested composite material, and collecting reflection echoes generated when the ultrasonic waves propagate in the material for imaging; acquiring the intensity of reflected echoes at the interface of the two materials for imaging; detecting from the back of the R region; and judging according to the detection result and the imaging result. According to the method, the T-shaped composite structure is subjected to in-service ultrasonic nondestructive testing in a layer-by-layer scanning mode, the defect detection precision of the T-shaped composite structure is effectively improved, and meanwhile, the difficulty of R-region detection is simplified by a method of transmitting focused ultrasonic waves from the back of the R region. The method can be applied to the detection of the T-shaped composite structure in the field of aerospace.)

1. A back detection method for R region defects of a T-shaped composite structure is characterized by comprising the following steps:

and transmitting ultrasonic signals from the back of the R area and the outer side of the top composite material layer, collecting echo signals, obtaining whether the R area to be detected has defects or not according to the echo signals, and determining the position coordinates of the defects.

2. A method for detecting the back surface of an R region defect of a T-shaped composite structure is characterized by comprising the following steps:

calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be tested;

carrying out meshing division on a target area to be detected to obtain a plurality of grid points, and detecting each grid point one by one from the back of an R area by adopting an ultrasonic phased array:

aiming at the ith array element of the ultrasonic phased array, acquiring the coordinate (x) of the ultrasonic phased array according to the Fermat principle_i,z_i) The propagation time T of the ith array element transmitting ultrasonic waves to reach a focus point P through two layers of media_i：

Wherein, c₁Represents the ultrasonic wave propagation speed of the first layer medium of the T-shaped composite structure, c₂Showing the ultrasonic propagation velocity of the second layer medium of the T-shaped composite structure, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) The coordinate of a point focused in the R area is shown, H represents the thickness of the top layer composite material layer of the tested T-shaped composite structure, L represents the length of the short side of the top layer composite material layer, and theta_iRepresenting the propagation direction of the ultrasonic wave inside the first layer medium;

obtaining x by prior art optimization algorithms_sAnd z_sA value of (d);

traversing each array element of the ultrasonic phased array to obtain the propagation time of each array element, and screening out the maximum propagation time T_max；

Obtaining the excitation delay time of each array element, the ith array elementExcitation delay time T_j＝T_max-T_i；

Transmitting ultrasonic waves through an ultrasonic phased array, collecting reflected echo signals of focused beams, and superposing corresponding receiving delay time on the reflection time of the reflected echo signals of the ith array element, wherein the receiving delay time and the excitation delay time T of the ith array element_jEqual;

calculating corresponding zero delay array elements of all array elements, returning echo signals of the propagation time of the zero delay array elements after transmitting ultrasonic waves to a focus point, superposing and imaging, if an imaging result has a relative bright point, indicating that a defect exists at the corresponding position of the array elements, and otherwise, indicating that no defect exists at the position of the focus point; the zero delay array element is as follows: the excitation signal has no delay time array element.

3. A back side ultrasonic non-destructive inspection apparatus for R-zone defects of a T-shaped composite structure, the apparatus comprising:

propagation time T_iAn obtaining module for obtaining coordinates (x) of the phased array according to Fermat's principle_i,z_i) The propagation time T of the ith array element from the upper part of the T-shaped composite structure to the focus point P by transmitting ultrasonic waves through two layers of media_i：

In the formula, c₁Represents the propagation velocity of the ultrasonic wave of the first layer medium, c₂Showing the propagation velocity of the ultrasonic wave of the second layer medium, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) The coordinate of a focusing point for transmitting ultrasonic waves is represented, H represents the thickness of the top layer composite material layer of the tested T-shaped composite structure, L represents the length of the short side of the top layer composite material layer, and theta_iRepresenting the propagation direction of the transmitted ultrasonic wave inside the first layer medium;

coordinate (x)_s,z_s) An optimization acquisition module: for obtaining x by an optimization algorithm_sAnd z_sA value of (d);

a maximum propagation time acquisition module: for comparing the propagation times of all array elements to obtain the maximum propagation time T_max；

An excitation delay time acquisition module: for according to T_j＝T_max-T_iObtaining the excitation delay time of each array element;

echo signal delay processing module: the method is used for superposing the corresponding receiving delay time on the reflected echo signal of the collected focused beam to obtain a delayed echo signal, namely: superposing the receiving delay time of the array element on the reflection time of the reflected echo signal of the ith array element, wherein the receiving delay time and the excitation delay time T of the array element_jEqual;

the echo signal superposition module is used for calculating echo signals corresponding to the zero delay array elements from the transmission of ultrasonic waves to a focus point and then returning the propagation time of the zero delay array elements for superposition and imaging to obtain an imaging result; the defect judging module is used for judging whether a defect exists according to the imaging result;

and the defect position determining module is used for determining the array element corresponding to the defect according to the array element corresponding to the defect and the relative bright spot in the imaging result.

4. A T-shaped composite structure defect ultrasonic nondestructive detection method is characterized by comprising the following steps:

the top composite material layer defect detection method specifically comprises the following steps: calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be detected, collecting reflection echoes generated when the ultrasonic waves propagate in the material, imaging, and judging whether the top layer composite material to be detected has defects or not according to the imaging brightness;

the material interface defect detection method specifically comprises the following steps: acquiring the intensity of reflected echoes at the interface of the two materials, imaging the reflected echoes at the interface of the two materials, and judging whether the boundary of the two materials has defects or not according to the imaging brightness;

the R region defect detection method is specifically the detection method of the R region defect of the T-shaped composite structure in claim 1.

5. A method for ultrasonic nondestructive testing of defects of a T-shaped composite structure, the method comprising:

a step of defect detection of the top composite layer, the step further comprising:

acquiring a reflection echo of ultrasonic waves in the composite material in a full-matrix capture mode according to a phased array acquisition system;

imaging the reflected echo by combining a speed-corrected full-focusing algorithm;

judging whether the detected top layer composite material has defects according to the imaging brightness, wherein the array element position corresponding to the pixel point with high relative brightness in the imaging result has defects;

a step of material interface defect detection, the step further comprising:

meshing the interface of the two materials or a plurality of grid points;

determining the detection position of the corresponding array element according to the position of each grid point;

detecting each grid point, specifically:

acquiring the propagation time t from the ith array element to the jth grid point in the phased array_ij；

According to

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)

Obtaining the delay time delta t of the ith array element_i(ii) a Wherein, t_iRepresenting the excitation time of the ith array element;

exciting each array element of the phased array by adopting a delay excitation mode, wherein the delay excitation mode refers to delaying the excitation time of the ith array element by delta t_iThe excitation mode of (1);

collecting all echo signals;

imaging all the collected echo signals, judging whether a defect exists in an interface of a detected material according to the imaging brightness, and detecting the defect of an R region at the position of an array element corresponding to a pixel point with high relative brightness in the imaging result, wherein the step is the detection method of the R region defect of the T-shaped composite structure as claimed in claim 1.

6. The method of claim 5, wherein the step of imaging the reflected echoes in combination with the velocity corrected full focus algorithm comprises:

collecting the propagation distance from the ith array element to a to-be-detected focus point in a to-be-seen area;

collecting a deflection angle between the ith array element and the focusing point along the vertical direction;

solving sound velocity according to a sound velocity fitting formula, wherein the sound velocity is the sound velocity in the direction of the reflected echo to be collected;

collecting echo signals of pixel points corresponding to signals according to a linear interpolation algorithm by combining the signals received by a transducer in the prior art; the transducer is used for converting the electric signal into an ultrasonic signal.

And imaging the echo signals of all the pixel points.

7. The ultrasonic defect detection method for T-shaped composite structures according to claim 5, wherein in the step of detecting the defects of the material interface, the method for imaging all the acquired echo signals comprises the following steps:

imaging the collected reflection echo by adopting a logarithmic compression mode, wherein the logarithmic compression mode is specifically realized by the following formula:

g＝c×log₁₀(1+f)，

where c is a constant, f represents the amplitude of each point pixel of the original image, and g represents the amplitude of each point pixel after log compression.

8. The in-service ultrasonic defect detection method for the T-shaped composite structure according to claim 6 or 7, wherein the method for calibrating the propagation speed of the ultrasonic wave in each direction in the tested composite material comprises the following steps:

measuring the propagation velocity of ultrasonic waves in the partial direction of the composite material to be measured by using an ultrasonic liquid immersion back reflection method, then obtaining the functional relation between the propagation velocity and the propagation direction of the ultrasonic waves in the composite material by using a polynomial linear fitting mode, and giving test data p_i，q_iWhere i is 1,2, … M, p_iDenotes the propagation direction of the ultrasonic wave, q_iRepresenting the propagation velocity of the ultrasonic wave so that a curve is fittedThe deviation from the given test data is minimal and is represented in matrix form as:

solving the matrix equation to obtain all coefficients of the polynomial, obtaining a fitting curve, and determining the propagation speed of the ultrasonic wave in any direction in the composite material.

9. The method for detecting the defect of the T-shaped composite structure in an ultrasonic in-service mode according to claim 8, wherein the method for acquiring the reflected echo comprises the following steps: the detection is carried out by utilizing a C scanning mode, which specifically comprises the following steps:

performing grid division on the bonding interface, determining the detection position of the ultrasonic phased array probe according to the positions of grid points of the bonding interface, and then calculating the propagation time t from all array elements of the phased array to the grid points to be detected_ijSaid t is_ijRepresenting the propagation time from the ith array element to the jth grid point of the phased array, and acquiring the excitation delay time t of each array element of the phased array according to the propagation time difference_iThe excitation delay time is obtained by the following formula:

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)，

the reflected echoes at the interface are acquired by a phased array.

10. An ultrasonic nondestructive inspection apparatus for defects of a T-shaped composite structure, the apparatus comprising:

the top composite material layer defect detection module is used for calibrating the propagation speed of ultrasonic waves in each direction in the detected top composite material, collecting reflection echoes generated when the ultrasonic waves propagate in the material for imaging, and judging whether the detected top composite material has defects according to the imaging brightness;

the material interface defect detection module is used for acquiring the intensity of the reflected echo at the interface of the two materials, imaging the reflected echo at the interface of the two materials and judging whether a defect exists at the junction of the two materials according to the imaging brightness;

an R-region defect detection module, in particular to an R-region defect detection device of a T-shaped composite structure as claimed in claim 3.

Technical Field

The application relates to the technical field of nondestructive testing, in particular to the technical field of nondestructive testing of T-shaped composite structures.

Background

A T-shaped composite structure formed by bonding a composite material and a metal material is widely applied to the field of aerospace, the composite material is easy to generate delamination defect inside, the bearing capacity and the service life of a structural member can be seriously influenced, and the original performance of the structure is influenced because the bonding exists at the interface of the two materials and the debonding defect is easy to generate. In addition to the two defects, an R angle generally exists in a T-shaped structure and is limited by the space size and the shape, the curvature radius of an R angle area is generally small, the cross section geometry of a part is suddenly changed, the local stress is far larger than the nominal stress, and the stress concentration phenomenon occurs in the R angle area, so that the defects such as cracks and the like are easily generated in the R area. Therefore, the high-precision in-service nondestructive testing of the T-shaped composite structure has great significance for guaranteeing the quality of the structure, and the flexible and controllable synthetic beam mode of the ultrasonic phased array has great application potential in the aspect of defect detection of complex components.

Boeing company proposes a METHOD and a system for testing a laminated material (LAMINATE MATERIAL TESTING METHOD AND SYSTEMS, European patent publication: EP1759195B1), which utilizes a certain prior condition to perform detection, namely firstly, echo data of a perfect flat plate with the same size as that of a flat plate to be tested is obtained as reference data, and then, the actually measured data is compared with the reference data to judge whether a defect exists in the flat plate to be tested.

The south China university of China proposed a phased array ultrasonic detection method for debonding of a composite material interface (phased array ultrasonic detection for debonding of a composite material interface, publication number: CN 103901108). when ultrasonic waves are transmitted in a composite material, reflection occurs at the debonding interface of the composite material, and the occurrence of defects can be judged after data processing is performed on generated echo signals. The method has problems that: the ultrasonic detection image when the interface bonding of the composite material is good and the ultrasonic detection image when the interface debonding possibly occurs need to be compared to judge whether the debonding defect exists in the composite material.

The technical research center of Beijing civil aircraft of Chinese commercial aircraft Limited liability company proposes an ultrasonic phased array detection device for a composite material R area (an ultrasonic phased array detection device for a composite material R area, publication number: CN107014900B), referring to fig. 5 and 6, the device uses a water bag as a flexible ultrasonic coupling module to realize the coupling between an ultrasonic probe and the R area to be detected, namely: the space between the ultrasonic probe and the R area to be detected is filled, the coupling of the phased array and the object to be detected is realized without a liquid coupling agent, and the flexible coupling module can be applied to ultrasonic detection of the R areas with different curvature radiuses due to the self-adaptability. The method has problems that: when the R region is located inside the structural member, i.e., a position that cannot be reached by the detection device, the detection of the R region defect cannot be realized.

The middle aviation composite material company with limited liability proposes a composite material T-shaped connecting area liquid self-coupling transducer and a detection method (composite material T-shaped connecting area liquid self-coupling ultrasonic transducer and detection method, publication number: CN106770683B), and referring to fig. 7, the method is based on a broadband narrow pulse reflection detection principle, and the acoustic coupling effect and detection signal stability of the ultrasonic transducer and the T-shaped connecting area surface of the detected composite material structure are obviously improved through liquid self-coupling. The method has problems that: the coverage detection of the T-shaped connecting area of the composite material structure can be realized only by using a manual or mechanical automatic scanning mode.

Disclosure of Invention

The problem that this application was solved does: the existing method has the problems of poor detection effect due to poor acoustic coupling effect and poor detection effect of R regions of the T-shaped composite structure, and has the problems of complex measurement process and high measurement cost because different devices are required to detect different layers of the T-shaped composite structure.

The scheme adopted by the application is as follows:

a back detection method for R region defects of a T-shaped composite structure comprises the following steps:

and transmitting ultrasonic signals from the back of the R area and the outer side of the top composite material layer, collecting echo signals, obtaining whether the R area to be detected has defects or not according to the echo signals, and determining the position coordinates of the defects.

A method for backside detection of R-region defects of a T-shaped composite structure, the method comprising:

calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be tested;

carrying out meshing division on a target area to be detected to obtain a plurality of grid points, and detecting each grid point one by one from the back of an R area by adopting an ultrasonic phased array:

aiming at the ith array element of the ultrasonic phased array, acquiring the coordinate (x) of the ultrasonic phased array according to the Fermat principle_i,z_i) The propagation time T of the ith array element transmitting ultrasonic waves to reach a focus point P through two layers of media_i：

Wherein, c₁Represents the ultrasonic wave propagation speed of the first layer medium of the T-shaped composite structure, c₂Showing the ultrasonic propagation velocity of the second layer medium of the T-shaped composite structure, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) The coordinate of a point focused in the R area is shown, H represents the thickness of the top layer composite material layer of the tested T-shaped composite structure, L represents the length of the short side of the top layer composite material layer, and theta_iRepresenting the propagation direction of the ultrasonic wave inside the first layer medium;

by means of prior artOptimization algorithm in the art obtains x_sAnd z_sA value of (d);

traversing each array element of the ultrasonic phased array to obtain the propagation time of each array element, and screening out the maximum propagation time T_max；

Obtaining the excitation delay time of each array element, the excitation delay time T of the ith array element_j＝T_max-T_i；

Transmitting ultrasonic waves through an ultrasonic phased array, collecting reflected echo signals of focused beams, and superposing corresponding receiving delay time on the reflection time of the reflected echo signals of the ith array element, wherein the receiving delay time and the excitation delay time T of the ith array element_jEqual;

calculating corresponding zero delay array elements of all array elements, returning echo signals of the propagation time of the zero delay array elements after transmitting ultrasonic waves to a focus point, superposing and imaging, if an imaging result has a relative bright point, indicating that a defect exists at the corresponding position of the array elements, and otherwise, indicating that no defect exists at the position of the focus point; the zero delay array element is as follows: the excitation signal has no delay time array element.

A device for back side ultrasonic non-destructive inspection of R-zone defects of a T-shaped composite structure, the device comprising:

propagation time T_iAn obtaining module for obtaining coordinates (x) of the phased array according to Fermat's principle_i,z_i) The propagation time T of the ith array element from the upper part of the T-shaped composite structure to the focus point P by transmitting ultrasonic waves through two layers of media_i：

In the formula, c₁Represents the propagation velocity of the ultrasonic wave of the first layer medium, c₂Showing the propagation velocity of the ultrasonic wave of the second layer medium, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) Coordinates of a focus point for transmitting ultrasonic waves, and H represents a T-shaped composite junction to be measuredThe thickness of the top layer of the top composite layer of the structure, L represents the length of the short side of the top composite layer, theta_iRepresenting the propagation direction of the transmitted ultrasonic wave inside the first layer medium;

coordinate (x)_s,z_s) An optimization acquisition module: for obtaining x by an optimization algorithm_sAnd z_sA value of (d);

a maximum propagation time acquisition module: for comparing the propagation times of all array elements to obtain the maximum propagation time T_max；

An excitation delay time acquisition module: for according to T_j＝T_max-T_iObtaining the excitation delay time of each array element;

echo signal delay processing module: the method is used for superposing the corresponding receiving delay time on the reflected echo signal of the collected focused beam to obtain a delayed echo signal, namely: superposing the receiving delay time of the array element on the reflection time of the reflected echo signal of the ith array element, wherein the receiving delay time and the excitation delay time T of the array element_jEqual;

the echo signal superposition module is used for calculating echo signals corresponding to the zero delay array elements from the transmission of ultrasonic waves to a focus point and then returning the propagation time of the zero delay array elements for superposition and imaging to obtain an imaging result; the defect judging module is used for judging whether a defect exists according to the imaging result;

and the defect position determining module is used for determining the array element corresponding to the defect according to the array element corresponding to the defect and the relative bright spot in the imaging result.

A T-shaped composite structure defect ultrasonic nondestructive detection method comprises the following steps:

the top composite material layer defect detection method specifically comprises the following steps: calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be detected, collecting reflection echoes generated when the ultrasonic waves propagate in the material, imaging, and judging whether the top layer composite material to be detected has defects or not according to the imaging brightness;

the material interface defect detection method specifically comprises the following steps: acquiring the intensity of reflected echoes at the interface of the two materials, imaging the reflected echoes at the interface of the two materials, and judging whether the boundary of the two materials has defects or not according to the imaging brightness;

the R region defect detection method is specifically the detection method of the R region defect of the T-shaped composite structure in claim 1.

A method of ultrasonic non-destructive inspection of defects in a T-shaped composite structure, the method comprising:

a step of defect detection of the top composite layer, the step further comprising:

acquiring a reflection echo of ultrasonic waves in the composite material in a full-matrix capture mode according to a phased array acquisition system;

imaging the reflected echo by combining a speed-corrected full-focusing algorithm;

judging whether the detected top layer composite material has defects according to the imaging brightness, wherein the array element position corresponding to the pixel point with high relative brightness in the imaging result has defects;

a step of material interface defect detection, the step further comprising:

meshing the interface of the two materials or a plurality of grid points;

determining the detection position of the corresponding array element according to the position of each grid point;

detecting each grid point, specifically:

acquiring the propagation time t from the ith array element to the jth grid point in the phased array_ij；

According to

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)

Obtaining the delay time delta t of the ith array element_i(ii) a Wherein, t_iRepresenting the excitation time of the ith array element;

exciting each array element of the phased array by adopting a delay excitation mode, wherein the delay excitation mode refers to delaying the excitation time of the ith array element by delta t_iThe excitation mode of (1);

collecting all echo signals;

imaging all the collected echo signals, judging whether a defect exists in an interface of a detected material according to the imaging brightness, and detecting the defect of an R region at the position of an array element corresponding to a pixel point with high relative brightness in the imaging result, wherein the step is the detection method of the R region defect of the T-shaped composite structure as claimed in claim 1.

Further, the step of imaging the reflected echo in combination with the velocity corrected full focus algorithm comprises:

collecting the propagation distance from the ith array element to a to-be-detected focus point in a to-be-seen area;

collecting a deflection angle between the ith array element and the focusing point along the vertical direction;

solving sound velocity according to a sound velocity fitting formula, wherein the sound velocity is the sound velocity in the direction of the reflected echo to be collected;

collecting echo signals of pixel points corresponding to signals according to a linear interpolation algorithm by combining the signals received by a transducer in the prior art; the transducer is used for converting the electric signal into an ultrasonic signal.

And imaging the echo signals of all the pixel points.

Further, in the step of detecting the material interface defect, the method for imaging all the acquired echo signals includes:

imaging the collected reflection echo by adopting a logarithmic compression mode, wherein the logarithmic compression mode is specifically realized by the following formula:

g＝c×log₁₀(1+f)，

where c is a constant, f represents the amplitude of each point pixel of the original image, and g represents the amplitude of each point pixel after log compression.

Further, the method for calibrating the propagation speed of the ultrasonic wave in each direction in the tested composite material comprises the following steps:

ultrasonic wave is measured in the direction of part of the tested composite material by using an ultrasonic liquid immersion back reflection methodThen obtaining the functional relation between the ultrasonic propagation speed and the propagation direction in the composite material by utilizing a polynomial linear fitting mode, and giving test data p_i，q_iWhere i is 1,2, … M, pi denotes the propagation direction of the ultrasonic wave, qi denotes the propagation velocity of the ultrasonic wave, such that a curve is fittedThe deviation from the given test data is minimal and is represented in matrix form as:

solving the matrix equation to obtain all coefficients of the polynomial, obtaining a fitting curve, and determining the propagation speed of the ultrasonic wave in any direction in the composite material.

Further, the method for acquiring the reflected echo comprises the following steps:

the detection is carried out by utilizing a C scanning mode, which specifically comprises the following steps:

performing grid division on the bonding interface, determining the detection position of the ultrasonic phased array probe according to the positions of grid points of the bonding interface, and then calculating the propagation time t from all array elements of the phased array to the grid points to be detected_ijSaid t is_ijRepresenting the propagation time from the ith array element to the jth grid point of the phased array, and acquiring the excitation delay time t of each array element of the phased array according to the propagation time difference_iThe excitation delay time is obtained by the following formula:

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)，

the reflected echoes at the interface are acquired by a phased array.

An ultrasonic nondestructive inspection apparatus for defects of a T-shaped composite structure, the apparatus comprising:

the top composite material layer defect detection module is used for calibrating the propagation speed of ultrasonic waves in each direction in the detected top composite material, collecting reflection echoes generated when the ultrasonic waves propagate in the material for imaging, and judging whether the detected top composite material has defects according to the imaging brightness;

the material interface defect detection module is used for acquiring the intensity of the reflected echo at the interface of the two materials, imaging the reflected echo at the interface of the two materials and judging whether a defect exists at the junction of the two materials according to the imaging brightness;

an R-region defect detection module, in particular to an R-region defect detection device of a T-shaped composite structure as claimed in claim 3.

The application has the advantages that:

the invention adopts a back detection method aiming at the detection of the R area, and has the advantages compared with the prior method that:

in order to solve the problem of acoustic coupling between the ultrasonic transducer and the R region to be detected, the prior art adopts a technical means of how to arrange a coupling material between the ultrasonic transducer and the R region to be detected, such as: in patent document CN107014900B, a detection device is designed, a water bag is arranged between an ultrasonic transducer and an R region as a coupling module, and in order to adapt to angles of different R regions, see fig. 5 and 6, a corresponding support structure is designed to adapt to different R region included angles, so that the water bag is in full surface contact with the R region, and the acoustic coupling effect and the detection signal stability effect between the ultrasonic transducer and the R region to be detected are improved. Patent document CN106770683B is to improve the structure of the ultrasonic transducer, and a coupling cavity 1C is designed between the ultrasonic sensor 1A and the region R to be detected, where this coupling cavity 1C is used to accommodate a liquid coupling agent, so as to realize that the region R to be detected of the ultrasonic sensor is filled with the liquid coupling agent during the detection process, thereby achieving the effect of improving the acoustic coupling effect and the stability of the detection signal. In summary, in the technical field of R-region nondestructive testing for T-type composite structures, in order to solve the problems of acoustic coupling effect and detection signal stability between the ultrasonic transducer and the R region to be detected due to the special shape of the R region, the technical means adopted is a design idea how to fill the coupling agent between the ultrasonic transducer and the R region to ensure the acoustic coupling effect.

This application the detection technology in R district abandon the thinking of above-mentioned solution problem completely, overcome prior art's prejudice, adopt brand-new design thinking, do not consider the problem of how to design couplant or coupling material completely, and do not consider the problem of the contained angle size in R district. This application has adopted the design thinking of complete difference, promptly: in the detection process, the ultrasonic transducer is designed on the top composite material layer of the T-shaped structure, ultrasonic waves are emitted from the back of the R area to realize nondestructive detection, and referring to fig. 4, the direction indicated by B is the incident direction of the ultrasonic detection. According to the method, the problem of a coupling agent or a coupling material does not need to be considered, ultrasonic waves are incident to the R region through the T-shaped structure top layer composite material layer, and nondestructive testing is achieved. Compared with the prior art, the method has the following advantages: 1. the problem of the size of an included angle of the R area does not need to be considered; 2. without the use of a coupling agent or coupling material; 3. the detection equipment for detecting the T-shaped composite material layer is used, and special detection equipment is not needed.

The nondestructive detection method based on the R region is simpler for the detection method of the T-shaped composite material, the defects at different positions in the T-shaped composite material can be detected only by one set of equipment, the defect detection efficiency of the T-shaped composite structure and the stability of a detection signal are effectively improved, and the detection precision is further improved; and judging the detection result according to whether the imaging result has a highlight point or not without comparing standard parts.

The R-removing detection technology of the T-shaped composite structure and the detection technology aiming at the whole T-shaped composite structure can realize nondestructive detection without considering the detection space problem, are suitable for performing nondestructive detection on the in-service T-shaped composite structure, do not need to disassemble devices, and can effectively improve the working efficiency.

Drawings

FIG. 1 is a schematic structural view of a T-shaped composite material;

FIG. 2 is a flow chart of the ultrasonic testing proposed in the present application;

FIG. 3 is a schematic diagram of the 5C scan test of the bonding interface proposed by the present application;

FIG. 4 is a schematic diagram of acoustic beam propagation through a multilayer medium of the present application;

wherein, 1 is a top layer composite material, 2 is a bottom layer metal material, 3 is an R area, 4 is a phased array probe, 5 is an adhesive interface, 6 is an acoustic beam focusing point, and B is an ultrasonic wave incidence direction when detecting the R area and is on the back of the R area.

Fig. 5 and 6 are schematic diagrams of the detection device for the R region of the composite material disclosed in conventional patent document CN107014900B (an ultrasonic phased array detection device for the R region of the composite material), where fig. 5 is a schematic diagram of a detection state when the R region angle of the workpiece is 90 °, and fig. 6 is a schematic diagram of a detection state when the R region angle of the workpiece is an obtuse angle.

Fig. 7 is a schematic diagram of the detection principle of CN106770683B (a composite material T-shaped connection region liquid self-coupling transducer and detection method).

Detailed Description

The invention will be further explained with reference to the drawings.

In one embodiment, the present invention provides a method for detecting a back surface of an R-region defect of a T-type composite structure, the method comprising:

and transmitting ultrasonic signals from the back of the R area and the outer side of the top composite material layer, collecting echo signals, obtaining whether the R area to be detected has defects or not according to the echo signals, and determining the position coordinates of the defects.

In a second embodiment, the present embodiment is described with reference to fig. 1 and 4, and the present embodiment further defines the method for detecting the back surface of the R region defect of the T-shaped composite structure proposed in the first embodiment, wherein the method comprises:

calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be tested;

carrying out meshing division on a target area to be detected to obtain a plurality of grid points, and detecting each grid point one by one from the back of an R area by adopting an ultrasonic phased array:

aiming at the ith array element of the ultrasonic phased array, acquiring the coordinate (x) of the ultrasonic phased array according to the Fermat principle_i,z_i) The ith array element transmits ultrasonic waves through twoPropagation time T of the layer medium to the focal point P_i：

Wherein, c₁Represents the ultrasonic wave propagation speed of the first layer medium of the T-shaped composite structure, c₂Showing the ultrasonic propagation velocity of the second layer medium of the T-shaped composite structure, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) The coordinate of a point focused in the R area is shown, H represents the thickness of the top layer composite material layer of the tested T-shaped composite structure, L represents the length of the short side of the top layer composite material layer, and theta_iRepresenting the propagation direction of the ultrasonic wave inside the first layer medium;

obtaining x by prior art optimization algorithms_sAnd z_sA value of (d);

traversing each array element of the ultrasonic phased array to obtain the propagation time of each array element, and screening out the maximum propagation time T_max；

Obtaining the excitation delay time of each array element, the excitation delay time T of the ith array element_j＝T_max-T_i；

Transmitting ultrasonic waves through an ultrasonic phased array, collecting reflected echo signals of focused beams, and superposing corresponding receiving delay time on the reflection time of the reflected echo signals of the ith array element, wherein the receiving delay time and the excitation delay time T of the ith array element_jEqual;

calculating corresponding zero delay array elements of all array elements, returning echo signals of the propagation time of the zero delay array elements after transmitting ultrasonic waves to a focus point, superposing and imaging, if an imaging result has a relative bright point, indicating that a defect exists at the corresponding position of the array elements, and otherwise, indicating that no defect exists at the position of the focus point; the zero delay array element is as follows: the excitation signal has no delay time array element.

The beneficial effects of the embodiment are as follows: in the detection process, the ultrasonic transducer is designed on the top composite material layer of the T-shaped structure, ultrasonic waves are emitted from the back of the R area to realize nondestructive detection, and referring to fig. 4, the direction indicated by B is the incident direction of the ultrasonic detection. According to the method, the problem of a coupling agent or a coupling material does not need to be considered, ultrasonic waves are incident to the R region through the T-shaped structure top layer composite material layer, and nondestructive testing is achieved. Compared with the prior art, the method has the following advantages: 1. the problem of the size of an included angle of the R area does not need to be considered; 2. without the use of a coupling agent or coupling material; 3. the detection equipment for detecting the T-shaped composite material layer is used, and special detection equipment is not needed. The novel design idea different from the prior art is adopted, the problem of 'how to design the couplant' or 'how to select the coupling material' which needs to be considered in the prior art is not considered at all, and the prejudice of the prior art is overcome.

In a third embodiment, the present invention provides an apparatus for ultrasonic non-destructive inspection of a back surface of an R-region defect of a T-shaped composite structure, the apparatus comprising:

propagation time T_iAn obtaining module for obtaining coordinates (x) of the phased array according to Fermat's principle_i,z_i) The propagation time T of the ith array element from the upper part of the T-shaped composite structure to the focus point P by transmitting ultrasonic waves through two layers of media_i：

In the formula, c₁Represents the propagation velocity of the ultrasonic wave of the first layer medium, c₂Showing the propagation velocity of the ultrasonic wave of the second layer medium, (x)_s,z_s) Representing the coordinates of the incident point of the ultrasonic wave from the first medium to the second medium, (x)₀,z₀) The coordinate of a focusing point for transmitting ultrasonic waves is represented, H represents the thickness of the top layer composite material layer of the tested T-shaped composite structure, L represents the length of the short side of the top layer composite material layer, and theta_iRepresenting the propagation direction of the transmitted ultrasonic wave inside the first layer medium;

coordinate (x)_s,z_s) An optimization acquisition module: for calculating by optimizationMethod of obtaining x_sAnd z_sA value of (d);

a maximum propagation time acquisition module: for comparing the propagation times of all array elements to obtain the maximum propagation time T_max；

An excitation delay time acquisition module: for according to T_j＝T_max-T_iObtaining the excitation delay time of each array element;

echo signal delay processing module: the method is used for superposing the corresponding receiving delay time on the reflected echo signal of the collected focused beam to obtain a delayed echo signal, namely: superposing the receiving delay time of the array element on the reflection time of the reflected echo signal of the ith array element, wherein the receiving delay time and the excitation delay time T of the array element_jEqual;

the echo signal superposition module is used for calculating echo signals corresponding to the zero delay array elements from the transmission of ultrasonic waves to a focus point and then returning the propagation time of the zero delay array elements for superposition and imaging to obtain an imaging result; the defect judging module is used for judging whether a defect exists according to the imaging result;

and the defect position determining module is used for determining the array element corresponding to the defect according to the array element corresponding to the defect and the relative bright spot in the imaging result.

The beneficial effects of the embodiment are as follows: in the detection method provided by the first embodiment, a data processing device implemented by computer software is designed as a data processing part, and the data processing device can be stored in a computer readable medium and is convenient for a user to use.

The fourth embodiment is described with reference to fig. 1 to 4, and the fourth embodiment proposes a method for ultrasonic nondestructive testing of defects of a T-shaped composite structure, the method comprising:

the top composite material layer defect detection method specifically comprises the following steps: calibrating the propagation speed of ultrasonic waves in all directions in the top layer composite material to be detected, collecting reflection echoes generated when the ultrasonic waves propagate in the material, imaging, and judging whether the top layer composite material to be detected has defects or not according to the imaging brightness;

the material interface defect detection method specifically comprises the following steps: acquiring the intensity of reflected echoes at the interface of the two materials, imaging the reflected echoes at the interface of the two materials, and judging whether the boundary of the two materials has defects or not according to the imaging brightness;

the R region defect detection method is specifically the detection method of the R region defect of the T-shaped composite structure in claim 1.

Fifth, the present embodiment is described with reference to fig. 1 to 4, and the present embodiment is further limited to the method for ultrasonic nondestructive testing of defects of a T-shaped composite structure, which is set forth in the fourth embodiment, and the method includes:

a step of defect detection of the top composite layer, the step further comprising:

acquiring a reflection echo of ultrasonic waves in the composite material in a full-matrix capture mode according to a phased array acquisition system;

imaging the reflected echo by combining a speed-corrected full-focusing algorithm;

judging whether the detected top layer composite material has defects according to the imaging brightness, wherein the array element position corresponding to the pixel point with high relative brightness in the imaging result has defects;

a step of material interface defect detection, the step further comprising:

meshing the interface of the two materials or a plurality of grid points;

determining the detection position of the corresponding array element according to the position of each grid point;

detecting each grid point, specifically:

acquiring the propagation time t from the ith array element to the jth grid point in the phased array_ij；

According to

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)

Obtaining the delay time delta t of the ith array element_i(ii) a Wherein, t_iRepresenting the excitation time of the ith array element;

exciting each array element of the phased array by adopting a delay excitation mode, wherein the delay excitation mode refers to delaying the excitation time of the ith array element by delta t_iThe excitation mode of (1);

collecting all echo signals;

imaging all the acquired echo signals, judging whether a defect exists in an interface of the detected material according to the imaging brightness, and detecting the defect of the R area at the position of the array element corresponding to the pixel point with high relative brightness in the imaging result.

In a sixth aspect, the present invention is further limited to the method for ultrasonic nondestructive testing of defects of a T-shaped composite structure as set forth in the fifth aspect, wherein the step of imaging the reflected echo in combination with a velocity-corrected full-focus algorithm includes:

collecting the propagation distance from the ith array element to a to-be-detected focus point in a to-be-seen area;

collecting a deflection angle between the ith array element and the focusing point along the vertical direction;

solving sound velocity according to a sound velocity fitting formula, wherein the sound velocity is the sound velocity in the direction of the reflected echo to be collected;

collecting echo signals of pixel points corresponding to signals according to a linear interpolation algorithm by combining the signals received by a transducer in the prior art; the transducer is used for converting the electric signal into an ultrasonic signal.

And imaging the echo signals of all the pixel points.

In a seventh embodiment, the method for ultrasonic testing of defects of a T-shaped composite structure according to the fifth embodiment is further defined, wherein in the step of testing the defects of the material interface, the method for imaging all the acquired echo signals includes:

imaging the collected reflection echo by adopting a logarithmic compression mode, wherein the logarithmic compression mode is specifically realized by the following formula:

g＝c×log₁₀(1+f)，

where c is a constant, f represents the amplitude of each point pixel of the original image, and g represents the amplitude of each point pixel after log compression.

In an eighth embodiment, the present embodiment is further limited to the method for detecting defects of a T-shaped composite structure in service according to the sixth or seventh embodiment, where the method for calibrating the propagation speed of ultrasonic waves in each direction inside the composite material to be detected includes:

measuring the propagation velocity of ultrasonic waves in the partial direction of the composite material to be measured by using an ultrasonic liquid immersion back reflection method, then obtaining the functional relation between the propagation velocity and the propagation direction of the ultrasonic waves in the composite material by using a polynomial linear fitting mode, and giving test data p_i，q_iWhere i is 1,2, … M, pi denotes the propagation direction of the ultrasonic wave, qi denotes the propagation velocity of the ultrasonic wave, such that a curve is fittedThe deviation from the given test data is minimal and is represented in matrix form as:

solving the matrix equation to obtain all coefficients of the polynomial, obtaining a fitting curve, and determining the propagation speed of the ultrasonic wave in any direction in the composite material.

In a ninth embodiment, the present embodiment is further limited to the in-service ultrasonic flaw detection method for a T-shaped composite structure, which is provided in the eighth embodiment, and the method for acquiring the reflected echo includes: the detection is carried out by utilizing a C scanning mode, which specifically comprises the following steps:

performing grid division on the bonding interface, determining the detection position of the ultrasonic phased array probe according to the positions of grid points of the bonding interface, and then calculating the propagation time t from all array elements of the phased array to the grid points to be detected_ijSaid t is_ijRepresenting the propagation time from the ith array element to the jth grid point of the phased arrayAcquiring the excitation delay time t of each array element of the phased array according to the propagation time difference_iThe excitation delay time is obtained by the following formula:

Δt_i＝max(t₁,t₂,K,t_N)-t_i(i＝1,2,K N)，

the reflected echoes at the interface are acquired by a phased array.

The beneficial effects of the embodiment are as follows: only one set of equipment is needed, the defects at different positions in the T-shaped composite material can be detected, the defect detection efficiency of the T-shaped composite structure and the stability of detection signals are effectively improved, and the detection precision is further improved.

Embodiment ten, a defect ultrasonic nondestructive testing device of T type composite construction, characterized in that, the device includes:

the top composite material layer defect detection module is used for calibrating the propagation speed of ultrasonic waves in each direction in the detected top composite material, collecting reflection echoes generated when the ultrasonic waves propagate in the material for imaging, and judging whether the detected top composite material has defects according to the imaging brightness;

the material interface defect detection module is used for acquiring the intensity of the reflected echo at the interface of the two materials, imaging the reflected echo at the interface of the two materials and judging whether a defect exists at the junction of the two materials according to the imaging brightness;

an R-region defect detection module, in particular to an R-region defect detection device of a T-shaped composite structure as claimed in claim 3.

The embodiments described above are merely illustrative of the technical aspects claimed in the present invention, and the technical aspects claimed in the present invention are not limited to the specific aspects described in the embodiments described above, and may be a reasonable combination of the technical features described in the embodiments described above.