Modeling of the thermal elasto-plastic behavior for composite materials using the homogenization method

In this dissertation, the homogenization method is used to investigate the thermo-mechanical behavior of composite materials. Assuming the characteristic microstructure in a composite material is spatially repeating, the equivalent material properties in one unit cell are calculated. These equivalent material properties represent the microscopic information. Using this approach, three research topics, in particular, stationary heat conduction, thermoelasticity and thermal elasto-plasticity in composite materials are studied in order to determine the global behavior and the local response at the microscopic level.;For heat conduction in composite materials, the well-known homogenization method is used to solve for the homogenized conductivity and the local heat flux field. Two boundary value problems, one, a local problem, the other, a global problem, are derived in order to obtain the characteristic temperature field in the microstructure and the equivalent thermal conductivity. Overall and local thermal response of the composite material is then determined.;This rigorous method is extended to inquire into the stress mismatch in the microstructure and the effective stress field in macrostructure for the thermal stresses in composites. The global thermal expansion behavior as well as the microscopic thermal stress analysis is studied theoretically by employing the homogenization method. It is found that this method provides good results in comparison with other analytical theories. From the examples, it is interesting to note that the thermal effect causes severe stress concentrations at the interface between the constituents, due to the mismatch in their thermal expansion coefficients.;The homogenization method is not limited by its assumption of periodicity in the microstructure. It can be used to deal with both geometrically and materially nonlinear problems such as thermal elasto-plasticity in composite materials. In association with the total Lagrangian update scheme, the proposed method can be used to model both globally and locally the thermophysical behavior of composites undergoing plastic deformation.