Progressive Damage Analysis Of Laminated Composite Under Thermal-mechanical Coupling Load

The laminated composite plate has high strength-to-weight ratio and strength-to-stiffness ratio, compared to traditional material, it is widely used in aerospace field. The composite structures are susceptible to the effects of thermal-mechanical coupling load in service, composite exists thermal mismatch, since matrix and fiber belong to different material components. When the temperature changes from50℃to-50℃, thermal load may cause material internal damage and reduce the structural strength, finally lead to dangerous event in the composite joints. It is a concern question that how to analyze composite damage failure and strength prediction in the structural design. In order to take advantage of composite high strength, it is a great significance to study laminated composite damage law under the thermal-mechanical coupling load.According to the above problem, this paper established a three dimensional progressive damage analysis model and studied the influence of the variable temperature on the open-hole laminates plate strength. The method used the commercial finite element software ABAQUS user defined subroutines (UMAT) based on the classical laminated plate theory. The specific content includes:1. Deduced the thermal residual stress under the large thermal-mechanical coupling load. Using the classical laminated plate theory, this method concerned the thermal mismatch between fiber and matrix and gave the change rule in each lay.2. In order to precisely predict the composite element damage, this paper studied the composite damage criteria under the thermal-mechanical coupling load. Supposed the damage plane on the maximal shear stress, a improved Camanho criteria was raised in a unified expression.3. Using Shahid method of matrix crack density, calculated the Stiffness degradation of composite materials in the initial damage stage, damage material stiffness degradation modes were defined with a second order damage tensor. Based on damage mechanics theory, a damaged composite constitutive model was established.4. Developed progressive damage analysis program of laminated composite plates under the thermal-mechanical coupling load, used the commercial finite element software ABAQUS user defined subroutines in fortran language, then studied the influence of the variable temperature on the laminates plate strength under temperature and displacement load.