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Method for performing strain field measurement on inflatable structure by utilizing photogrammetric technology

A technology of inflatable structure and photogrammetry, which is applied in the field of strain testing, can solve the problems affecting measurement accuracy, difficult to remove, irrelevant speckle, etc., to achieve the effect of solving difficult measurement and expanding the scope of application

Inactive Publication Date: 2018-01-12
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional contact measurement method such as sticking strain gauges is a point-by-point measurement method, and the use of glue will cause the local stiffness of the skin of the inflatable structure to increase, which will affect the measurement accuracy; the use of digital image correlation technology (DIC) needs to be fabricated on the test surface Speckle that is difficult to remove; digital / electronic speckle interference technology requires stable optical conditions, and excessive deformation will cause speckle irrelevance, which limits the use of this technology in environments outside the laboratory; digital speckle Image technology (DSP) and digital speckle interferometry (ESPI) are based on the diffuse reflection of rough surfaces, requiring the sample surface to have sufficient roughness

Method used

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  • Method for performing strain field measurement on inflatable structure by utilizing photogrammetric technology
  • Method for performing strain field measurement on inflatable structure by utilizing photogrammetric technology
  • Method for performing strain field measurement on inflatable structure by utilizing photogrammetric technology

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specific Embodiment approach 1

[0021] Specific implementation mode one: as figure 1 As shown, this embodiment discloses a method for measuring the strain field of an inflatable structure using photogrammetry technology, and the steps of the method are as follows:

[0022] Step 1, obtaining the surface point cloud of the inflatable structure before and after deformation by photogrammetry technology;

[0023] Step 2, matching the same points before and after deformation, so that the points before and after deformation correspond one-to-one;

[0024] Step 3, using the Delaunay (Delaunay) triangulation algorithm to discretize the point cloud into triangular sets;

[0025] Step 4, establish a unit coordinate system for each triangular unit, and convert the overall coordinates of the corner points of the triangular unit to the unit coordinate system through the coordinate transformation matrix;

[0026] Step five, using the finite element method and the knowledge of elastic mechanics, calculate the strain of th...

specific Embodiment approach 2

[0028] Specific embodiment 2: This embodiment is a further description of specific implementation 1. The process of obtaining the surface point cloud of the inflatable structure before and after deformation through photogrammetry described in step 1 is specifically:

[0029] Paste the target points on the surface of the structure to be tested; calibrate the digital camera; take photos; import the photos into photogrammetry processing software; mark the target points in each photo; detect the coded marker points and reference rulers; identify the same points in different photos ; Calculate the three-dimensional space coordinates of the target point by beam adjustment, so as to obtain the point cloud of the target point on the surface of the structure to be measured.

specific Embodiment approach 3

[0030] Specific embodiment 3: This embodiment is a further description of specific embodiment 1. The process of matching the same points before and after deformation as described in step 2, so that the points before and after deformation correspond to each other is specifically as follows:

[0031] The coded mark points under different working conditions have the same number, and the target points are numbered by using the relative positions of the target point, the coded mark point and the reference bar, so that the same point numbers before and after deformation are the same.

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Abstract

The invention provides a method for performing strain field measurement on an inflatable structure by utilizing a photogrammetric technology. The method belongs to the field of strain testing technologies. The method comprises the steps of: acquiring surface point cloud before and after deformation of a measured structure by adopting the photogrammetric technology, so as to obtain coordinates of asurface object point of the measured structure before and after deformation; dispersing the point cloud into a triangle set by adopting a Delaunay triangularization method, calculating strain in triangles by using a finite element method, and converting the strain into a strain field of the whole structure through coordinate transformation. The method provided by the invention can realize the full-field strain measurement of the large-size three-dimensional curved surface inflatable structure, improves the efficiency of strain measurement compared with a non-contact strain testing method of adigital image correlation technology, can be used for strain measurement of a large curvature three-dimensional curved surface, does not need to perform unrecoverable surface treatment on the surfaceof the structure, and is suitable for applications in the engineering environment.

Description

technical field [0001] The invention relates to a method for measuring a strain field of an inflatable structure, belonging to the technical field of strain testing. Background technique [0002] Inflatable structures have a large number of applications in the aerospace field due to their light weight, softness, and foldability, such as airships, overpressure balloons, cushioning airbags, loading reducers, etc. Inflatable structures are usually closed three-dimensional curved surface structures, made of flexible fabrics Made of composite materials, the measurement of its strain field is a difficult point. The traditional contact measurement method such as sticking strain gauges is a point-by-point measurement method, and the use of glue will cause the local stiffness of the skin of the inflatable structure to increase, which will affect the measurement accuracy; the use of digital image correlation technology (DIC) needs to be fabricated on the test surface Speckle that is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16
Inventor 谭惠丰罗锡林林国昌连尹陈雪岩
Owner HARBIN INST OF TECH
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