Test method for poisson ratio of continuous fiber enhanced resin-based composite material

Abstract

The invention discloses a test method for a poisson ratio of a continuous fiber enhanced resin-based composite material. The test method has the advantages that (1) the shortcomings of the existing composite material poisson ratio test technology are overcome, and a novel FBG test method for the poisson ratio of the composite material is provided based on a fiber Bragg grating string technology; (2) the problem that a test piece is low in surface quality, non-uniform in thickness, non-uniform in width, low in parallelism and the like caused by the conventional composite material test piece vacuum bag and thermal pressing tank manufacturing technology is solved, a manufacturing technology for a continuous fiber enhanced resin-based composite material standard test piece is provided based on a closed type thermal die pressing technology, and the problem of separation of the composite material standard test piece with the built-in fiber Bragg grating string from a rigid closed type die is focused to be solved, and convenient, precise and effective test on the poisson ratio of the composite material is realized.

Description

Technical field [0001] The invention relates to a method for testing Poisson ratio of a material, in particular to a method for testing Poisson ratio of a continuous fiber reinforced resin-based composite material. Background technique [0002] Fiber-reinforced resin-based composite materials are widely used in aerospace, automobiles, ships, construction and other fields due to their high specific strength and specific modulus, good chemical resistance, and strong designability. Among them, the density of carbon fiber reinforced resin matrix composites is only about 1.6g / cm 3 , Superior performance, is expected to become one of the main materials for new energy vehicles and airplanes. [0003] To carry out research on composite material structure mechanics, the first problem to be solved is to accurately test the engineering elastic constants of composite materials such as Poisson’s ratio and modulus; when using classical laminate theory to analyze and evaluate composite material s...

AI Technical Summary

Problems solved by technology

However, there are a series of key core problems in the method of using a single longitudinal and transverse FBG sensor to test the Poisson's ratio of composite materials. Take the "Fiber Bragg Grating of Composite Laminate Engineering Constants" paper by Wang Kaige and Mei Zhiyuan "Test and Analysis" as an example is as follows: (1) The distance between the bending position of the fiber in the transverse direction (90° direction of the fiber) and the grating area is too close, which may easily cause the deformation of the grating area to generate chirp signals, and the optical signal intensity attenuation is serious, resulting in lateral The accuracy of the strain test is greatly reduced; (2) The position of the lead wire conflicts with the position of the fixture of the universal material testing machine. When the optical fiber is led out from the fixture of the testing machine, it needs to be bent significantly, resulting in attenuation of the optical signal intensity and a decrease in test accuracy; (3) Transverse grating No protective measures are added during laying, which will easily cause the grating to be sheared and damaged by the uneven reinforcing fibers perpendicular to it; (4) only one grating area is used to measure the micro-strain of the composite material standard specimen in the horizontal and vertical directions, so that it cannot Averaging the uneven spatial distribution of the Poisson's ratio of the material in the same sample will bring large errors to the experimental results

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