Research On Damage Modeling And Acousto-optical Hybrid Calibration Method Of Composites

Carbon fiber braided composites are widely used in aerospace and automobile industries due to their advantages such as high specific strength,large specific modulus and corrosion resistance.Moreover,due to their diverse damage forms and interrelated coupling,two or more damage modes tend to occur at the same time.In order to reveal the damage evolution mechanism,In this paper,two-dimensional braided laminate composites are studied by combining experiment and numerical simulation.In the experiment,the load curve can reflect the mechanical properties to the material,the strain field can be used to analyze the local stress concentration and crack propagation on the surface of the material,and the acoustic emission signal is closely related to the occurrence and evolution of the internal damage of the material.If only the above single method is used,it is not conducive to a more comprehensive understanding of the damage mechanism of composites.Therefore,the acoustic and optical and mechanical methods are combined together in this paper.The damage failure process of composites is described from multiple dimensions.In the numerical simulation,the calibration method of elastic and damage constitutive parameters of composites is proposed,which lays a solid foundation for numerical simulation and progressive damage analysis of two-dimensional braided laminate composites.The main work of this paper is as follows:(1)Design and prepare tensile and three-point bending test specimens;Optical experiment platform is established based on 3D Didital Image Correlation.Acoustic experiment platform was built based on Acoustic Emission technology,and acoustic emission signal analysis method was proposed.(2)Tsai-Wu material failure criterion is introduced and the material stiffness reduction coefficient table is given.The transitional mesh modeling method is proposed,and the finite element macroscopic and mesoscopic model is established.By applying the boundary conditions to the finite element unit cell model,the macroscopic elastic parameters of composites are predicted.(3)The mechanical-optical hybrid calibration method of elastic constitutive parameters of composites was proposed.The gradient algorithm is used to calibrate the elastic constitutive parameters of composites by taking the residual difference between the measured strain\load curve and finite element calculation results as the objective function.(4)Damage pattern recognition and evolution analysis of composites were realized based on AE technology.The mechanical-acoustic hybrid calibration method was proposed to calibrate the composites damage constitutive parameters.The progressive damage analysis of composites was carried out based on the finite element mesoscopic model to reveal the damage evolution mechanism inside the materials.