CN-121980122-A - Structural damage identification method based on curvature modal characteristic factor chromatography idea

CN121980122ACN 121980122 ACN121980122 ACN 121980122ACN-121980122-A

Abstract

The invention discloses a structural damage identification method based on a curvature modal characteristic factor chromatographic concept, which comprises the steps of setting curvature modal characteristic factor measuring points at all grid nodes of the peripheral boundary of a composite material wallboard structure, constructing a curvature modal characteristic factor sensing array, obtaining a plurality of groups of parallel virtual rays and curvature modal characteristic factor difference values corresponding to each group of rays, reconstructing a central curvature modal characteristic factor of a composite material wallboard unit about a X, Y direction change rate matrix, obtaining curvature modal factor distribution characteristics representing damage characteristics, realizing damage positioning, imaging and damage scale identification of the composite material wallboard, and measuring the curvature mode of the composite material wallboard according to actual application requirements. When the method is used for the damage of the interior of the composite material wallboard, the strain mode at the damaged part is utilized to generate mutation, the relevance between the strain change and the strain mode change in position coordinates is established, the damage identification and imaging are carried out, and the complexity of a monitoring system is effectively reduced.

Inventors

ZENG JIE
ZHANG BOXIANG
ZHU LINFENG
CHENG BO
ZHOU YANWEI
WEN XINGYU
WANG YUXUN

Assignees

南京航空航天大学
中国航空工业集团公司成都飞机设计研究所

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (8)

1. The structural damage identification method based on the curvature modal characteristic factor chromatography idea is characterized by comprising the following steps of: Step 1, setting curvature modal characteristic factor measuring points on all grid nodes on four boundaries of the periphery of a composite material wallboard structure, and constructing a curvature modal characteristic factor sensing array; Step 2, obtaining a plurality of groups of parallel virtual rays and curvature modal characteristic factor difference values corresponding to each group of parallel virtual rays, and reconstructing a central curvature modal characteristic factor of the composite material wallboard unit grid about X, Y direction change rate matrix; Step 3, obtaining curvature modal factor distribution characteristics representing damage characteristics through reconstruction, and carrying out damage positioning, imaging and damage scale identification on the composite material wallboard; and 4, measuring the curvature mode of the composite material wallboard according to actual application requirements, and obtaining the strain mode corresponding to the preset order of the composite material wallboard and the curvature mode corresponding to the preset order of the composite material wallboard.
2. The method of claim 1, wherein step 1 comprises: acquiring curvature mode characteristic factors of a composite material wallboard structure, and defining the strain mode of the No-damage composite material wallboard in the X direction of the (r) th order as The strain mode of the (r) th order of the wall plate made of the composite material containing the damage along the X direction is that Defining the strain mode of the (r) th order of the non-damaged composite material wallboard along the Y direction as The strain mode of the (r) th order of the wall plate made of the composite material containing the damage along the Y direction is that ; Defining the mode of the r-order synthetic curvature of the non-damaged and damaged composite material wall plate along the X, Y direction: ; In the formula, In order to damage the composite material wall plate in the mode of the r-order synthesized curvature, The mode of the r-th order synthesized curvature of the wall plate made of the composite material containing the damage is adopted; Calculating the first wall board of the composite material without damage and containing damage The difference value of the mode of the synthesized curvature of the r-th order measured by each measuring point : ; In the formula, 、 Is a non-damaged or damaged composite material wallboard The r-th order synthesized curvature mode measured by each measuring point; normalizing the synthesized curvature modes measured by the same measuring point at the natural frequencies of all orders to obtain curvature mode characteristic factors : ; In the formula, Representing composite wallboard commonality The order natural frequency; rate of change of curvature modal characteristic factor with respect to X, Y direction 、 The method comprises the following steps: ; In the formula, As a characteristic factor of the mode of curvature, 、 The coordinate position corresponding to the X, Y direction.
3. The method of claim 2, wherein step 1 further comprises: For a rectangular composite material wallboard structure, the center of the wallboard is set as an origin, an X axis and a Y axis are respectively established along the horizontal direction and the vertical direction, and the wallboard is uniformly divided into the X axis direction and the Y axis direction Segment, generate A grid of cells; setting curvature modal characteristic factor measuring points on all grid nodes on four boundaries on the periphery of the wall plate, constructing a curvature modal characteristic factor sensing array, taking the measuring point at the lower left corner of the wall plate as a first measuring point, numbering the measuring points along the anticlockwise direction, and carrying out the operation of The curvature modal characteristic factor data perceived at each measuring point is , ; Selecting curvature modal feature factors with respect to X, Y direction change rates 、 For the quantity to be reconstructed, constructing a matrix to be reconstructed of central curvature modal characteristic factors of each unit grid of the composite material wallboard with respect to X, Y direction change rates 、 : ; In the formula, To the point of 、 To the point of The curvature modal characteristic factor of each unit grid center along X, Y directions is respectively.
4. A method of identifying structural damage according to claim 3, wherein step 2 comprises: For the matrix to be reconstructed 、 Reconstructing the two-dimensional function Integrating along straight lines of different angles to obtain projection data: ; In the formula, For projection data of different angles, For the projection angle of the projection beam, For the projection distance, Is a dirac function; generating a virtual ray between any two measuring points A and B in the curvature modal characteristic factor perception array, and rewriting projection data into: ; The curvature modal characteristic factor difference value measured by the measuring points A and B As the degree of the attenuation of the virtual rays from the curvature mode characteristic factor measured at the point A to the point B, for the curvature mode characteristic factor field The projection integration is performed along different angles, and the expression is: ; In the formula, 、 For the curvature modal characteristic factor values measured at station A, B, Is a factor field Is a projection data of the image sensor; Matrix to be reconstructed by combining X, Y direction change rates 、 Will be The expression is rewritten as: ; ; And obtaining a plurality of groups of parallel virtual rays and curvature modal characteristic factor difference values corresponding to each group of parallel virtual rays.
5. The method of claim 4, wherein step 2 further comprises: Matrix to be reconstructed for X, Y direction change rate based on center slice theorem 、 Reconstruction is performed based on a matrix And carrying out one-dimensional Fourier transform on each group of parallel virtual rays and the corresponding synthesized curvature difference value between each group of parallel virtual rays: ; In the formula, Is a fourier transform of the signal, Is the angular frequency of the wave form, Is the difference value of curvature modal characteristic factors after Fourier transformation; multiplying the difference value of the curvature modal characteristic factors after Fourier transformation by a slope filter Filtering: ; For the filtered result Performing one-dimensional inverse Fourier transform to obtain filtered projection : ; In the formula, The function is inverse fourier transform; according to the convolution theorem of action, the product of the frequency domain equals the convolution of the space domain, projection Equivalent to: ; In the formula, Is a ramp filter Is the spatial domain form of (a); By windowing functions Make the slope filter Becomes an achievable filter: ; Integrating the projections filtered from all angles of 0-pi to obtain a rate of change matrix along the X direction : 。
6. The method of claim 5, wherein the center slice theorem uses a two-dimensional function At an angle of Lower projection Corresponding one-dimensional fourier transform Equal to a two-dimensional function The two-dimensional Fourier transform F is angular in the frequency plane One slice of the direction passing through the origin, the formula is: 。
7. The method of claim 5, wherein step 3 comprises: the resulting matrix will be reconstructed 、 Integrating along X, Y direction to obtain curvature modal characteristic factor field of composite material wallboard : ; Carrying out damage positioning, imaging and damage scale identification on the composite material wallboard, and defining the coordinate of the maximum damage factor of the composite material wallboard as the damage center position: ; In the formula, Is the position coordinate of the damage center of the composite material wallboard, Is the position coordinate of the position with the largest curvature modal characteristic factor, when the characteristic factor corresponding to a certain position is more than or equal to a preset damage discrimination threshold value And judging that the position is in the damaged area of the composite material wallboard.
8. The method of claim 7, wherein step 4 comprises: Measuring strain modal response at each node of structure to be measured, and calculating response variable frequency function As each element of the wall plate When the point is excited, at the first Strain response induced by individual site locations: ; In the formula, Is the first The modality participation factor of the order modality, Is a composite material wall board The measured r-th order displacement mode of the point, Is the first composite material wallboard The r-th order strain mode measured by the measuring points; evolving the response frequency conversion function as: ; In the formula, Is shown in The excitation frequency of the point input is chosen, Is the natural frequency of the order r, Is the modal damping ratio of the order r, Is the r-th order stiffness; When exciting force is applied to the position p of the random position measuring point on the surface of the composite material wallboard, and the frequency is equal to the natural frequency corresponding to the t-th order mode of the structure to be measured, the response frequency conversion function is rewritten as follows: ; aiming at the non-compact mode condition, the t-th order mode plays a dominant response role: ; Wherein w t is the natural frequency of the t th order, Is the modal damping ratio of the t-th order, Is the stiffness of the t-th order, Is the first The response amplitude of the individual stations at frequency w t , Is the excitation amplitude of the point P at the frequency w t , The t-th displacement mode measured by the measuring point P; is the t-th order strain mode of the composite material wallboard measuring point P: ; exciting a measuring point p fixed on the structure at a natural frequency of a t th order, wherein when the exciting force is fixed as a constant, the modal parameters of the structure are all constant, and the constant part is expressed as : ; Will be The writing is as follows: ; applying natural frequency excitation of preset order through a composite material wallboard, normalizing strain modal response amplitude values obtained by the fiber bragg grating sensor at different nodes, and substituting the strain modal response amplitude values into the fiber bragg grating sensor And obtaining a strain mode corresponding to the composite material wallboard at a preset order, and calculating a curvature mode corresponding to the composite material wallboard at the preset order.

Description

Structural damage identification method based on curvature modal characteristic factor chromatography idea Technical Field The invention relates to the field of structural health monitoring, in particular to a structural damage identification method based on a curvature modal characteristic factor chromatography idea. Background The composite material structure is in long-term service in a thermal coupling environment, and damages such as matrix damage, fiber debonding or fracture, interlayer cracking and the like are easy to occur due to the performance difference and interface effect of the matrix and the reinforced fiber, and the strength and damage mode analysis of the composite material connection structure are difficult due to the specificity of the composite material structure and complex nonlinear coupling factors existing in the composite material connection structure. The damage of the composite material is hidden, and the damage conditions such as layering damage caused by impact, internal microcracks and the like cannot be judged and analyzed in an external observation mode, so that the safe operation of the aerospace structure is seriously influenced. In the actual service process, the composite material structure is easy to damage in the face of complex severe environment and load, and the damage is difficult to effectively detect in an early stage. Conventional damage identification methods often require dense placement of sensors on or within the composite structure. Such "intrusive" arrangements not only add additional weight to the structure, affect aerodynamic performance, but the leads, adhesives, etc. are more likely to be new sources of stress concentrations or potential damage. Therefore, a real-time online damage monitoring research based on a non-invasive mode (i.e. no sensor is arranged in a monitoring area) is carried out on the composite material structure of the aircraft, a basis can be provided for making scientific maintenance decisions, and the adaptability and the resistance of the aircraft to various risks in the whole service process are obviously enhanced. Disclosure of Invention The structural damage identification method based on the curvature modal characteristic factor chromatographic concept is used for overcoming the limitation that a sensor needs to be arranged in a structural monitoring area in the conventional damage identification method and reducing the complexity of a monitoring system by constructing a curvature modal factor observation array based on the chromatographic concept, solving the problems that the conventional method can only damage and locate, but cannot quantify damage scale and contour characteristics and the like, and providing important help for further evaluating the damage degree of a composite material structure, predicting residual strength and formulating a maintenance strategy. The structural damage identification method based on curvature modal characteristic factor chromatography thought comprises the following steps: Step 1, setting curvature modal characteristic factor measuring points on all grid nodes on four boundaries of the periphery of a composite material wallboard structure, and constructing a curvature modal characteristic factor sensing array; Step 2, obtaining a plurality of groups of parallel virtual rays and curvature modal characteristic factor difference values corresponding to each group of parallel virtual rays, and reconstructing a central curvature modal characteristic factor of the composite material wallboard unit grid about X, Y direction change rate matrix; Step 3, obtaining curvature modal factor distribution characteristics representing damage characteristics through reconstruction, and carrying out damage positioning, imaging and damage scale identification on the composite material wallboard; and 4, measuring the curvature mode of the composite material wallboard according to actual application requirements, and obtaining the strain mode corresponding to the preset order of the composite material wallboard and the curvature mode corresponding to the preset order of the composite material wallboard. Preferably, step 1 includes: Firstly, obtaining curvature mode characteristic factors of a composite material structure, and defining the strain mode of the r-th order of a non-damaged composite material wallboard along the X direction as The strain mode of the (r) th order of the wall plate made of the composite material containing the damage along the X direction is thatDefining the strain mode of the (r) th order of the non-damaged composite material wallboard along the Y direction asThe strain mode of the (r) th order of the wall plate made of the composite material containing the damage along the Y direction is that; Then defining the mode of the r-order synthetic curvature of the non-damaged and damaged composite material wall plate along the X, Y direction: ; In the formula, In order to damage the composi