Blind hole method based residual stress distribution measurement method for composite material plate

A composite material and residual stress technology, applied in force/torque/work measuring instruments, measuring devices, analysis materials, etc., can solve problems such as error, single measurement stress direction, and large stress gap, so as to improve scientificity and accuracy , flexible and accurate measurement, the effect of precise measurement

CN111855057AInactive Publication Date: 2020-10-30DALIAN UNIV OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2020-10-30
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention belongs to the field of composite material residual stress measurement, and provides a blind hole method based residual stress distribution measurement method for a composite material plate. The method comprises the following steps: firstly, determining a measurement position and a measurement direction for the to-be-measured composite material plate, and adhering a plurality of strain gauges to corresponding positions; using a numerical control drilling machine for conducting stepping drilling on the back face of the position, where the strain gauges are pasted, of the plate, drilling the plate for multiple times with the fixed stepping amount, determining the drilling depth according to the measurement purpose, and after drilling is completed, obtaining strain values, changing along with the drilling depth, measured by the strain gauges at the blind hole positions; then, solving stress distribution at all strain gauge positions by utilizing a finite element model; and finally, correspondingly measuring other directions and position by changing the pasting direction of the strain gauges and the positions of the blind holes.
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Description

technical field

[0001] The invention belongs to the field of residual stress measurement of composite materials, and relates to a method for measuring residual stress distribution of composite material plates based on a blind hole method. Background technique

[0002] During the molding process of the composite material, due to the difference in the thermal expansion coefficient of the fiber and the matrix and the difference in the internal and external cooling rates, obvious residual stress will be generated during the cooling process. The generation of residual stress will cause the plate to warp and deform. There are many adverse effects in the use process. Therefore, in order to achieve the purpose of controlling the residual stress, the measurement of the residual stress of the composite material is particularly critical. At present, the commonly used residual stress measurement methods are mainly divided into two categories: non-destructive testing and destructive tes...

Examples

Embodiment Construction

[0043] The specific embodiments of the present invention will be described in detail below in conjunction with the technical solutions and accompanying drawings.

[0044] figure 1 It is a flowchart of the measurement and calculation of the residual stress of the composite material plate; Figure 4 is a schematic diagram of the residual stress measurement of a composite sheet based on the step drilling method.

[0045] (1) determine the area to be measured and the direction of the composite material plate 1, figure 2 and image 3 A common test scheme is shown, and 8 drilling positions are determined. The longitudinal stress is measured on one side of the plate and the transverse stress is measured on the other side. In addition, the drilling position and the direction of the strain gauge can be determined by oneself according to the requirements.

[0046](2) Grind the first drilling position I in the area to be tested with fine sandpaper in a direction 45° from the strain g...