Multiaxial Strength Analysis And Experimental Study Of Laminated Resin Composite

Laminated composites are widely used in aerospace,marine engineering,weaponry and automotive industries in terms of their high specific strength,high specific stiffness and ply-up designability.With the wide application of composite materials,composite material components in service usually operate under complex multi-axial loadings.Therefore,it is very important to study the multi-axial strength theory of composite materials.Therefore,in this paper,it is of great theoretical significance and engineering value to study the failure test and prediction method of the resin matrix composite tube structures under multi-axial loadings.The main research contents of this paper are as follows:1.Based on the properties of composites unidirectional laminate with the combination of three-dimensional progressive damage theory and the Maximum stress criterion and the Hashin criterion separately,the three-dimensional progressive cumulative damage strength prediction method of resin composite pipe under tensile/torsional multi-axial loadings was established.The prediction results were compared with the experimental results,and the comparative results showed that: the maximum prediction error of Hashin failure criteria was 7.0%,which was better than the maximum stress criterion,namely the Hashin failure criteria was more suitable for predicting the strength of laminated composite pipe under tensile/torsional multi-axial loadings.2.Tension/torsion multi-axial loading experiments of resin composite laminated pipe under four different stress ratios were conducted to obtain the axial strength,torsional strength,the torque-twist angle curve and the axial tensile load-axial displacement curve.The experimental results showed that the tensile strength increased with the increase of the stress ratio,while the torsional strength decreased with the increase of the stress ratio,and the torsional rigidity and tensile rigidity of the composite pipe were decreased with the increase of the stress ratio.3.Multi-axial loadings tests and theoretical prediction results showed that the stress ratios had certain influence on the initial damage modes and failure models of composites laminated pipes.In the case of low stress ratios,the initial damages of laminated tube were fiber compression and fiber matrix shear,and fiber compression,matrix compression and fiber matrix shear dominated in the final failure.In the case of high stress ratios,the initial damage was matrix cracking,and fiber breakage and matrix cracking was dominant in the final failure.4.A series of unidirectional lamina experiments which comprised longitudinal tensile and com-pression tests,transverse tensile and compression tests and in-plane shear test,were conducted on 17 samples to obtain the unidirectional mechanical properties of resin matrix composites to provide the basic performance parameters for progressive cumulative damage analysis method under different tensile/torsion combined loadings,including: longitudinal/transverse elastic modulus,shear modulus,Poisson's ratio,longitudinal tensile/compressive strength,transverse tensile/compressive strength and shear strength.