MICRO/MACROMECHANICAL PLASTIC LIMIT ANALYSES OF COMPOSITE MATERIALS AND STRUCTURES

The load-bearing capacities of duclile composite materials and structures are studied bymeans of a combined micro/macromechanics approach.Firstly,on the microscopic scale,the aim is to getthe macroscopic strength domains by means of the homogenization theory of micromechanics.A representativevolume element(RVE)is selected to reflect the microstructures of the composite materials.By introducingthe homogenization theory into the kinematic limit theorem of plastic limit analysis,an optimization formal todirectly calculate the limit loads of the RVE is obtained.And the macroscopic yield criterion can be deter-mined according to the relation between macroscopic and microscopic fields.Secondly,on the macroscopicscale,by introducing the Hill’s yield criterion into the kinematic limit theorem,the limit loads of orthotropicstructures such as unidirectional fiber-reinforced composite structures are worked out.The finite elementmodeling of the kinematic limit analysis is deduced into a nonlinear mathematical programming with equality-constraint conditions that can be solved by means of a direct iterative algorithm.Finally,some examples areillustrated to show the application of the present approach.