Mechanical behavior of unidirectional fiber-reinforced polymers under transverse compression: Microscopic mechanisms and modeling

The mechanical behavior of polymer–matrix composites unidirectionally reinforced with carbon or glass fibers subjected to compression perpendicular to the fibers was studied using computational micromechanics. The stress–strain curve was determined by the finite element analysis of a representative volume element of the microstructure idealized as a random dispersion of parallel fibers embedded in the polymeric matrix. The dominant damage mechanisms experimentally observed – interface decohesion and matrix plastic deformation – were included in the simulations, and a parametrical study was carried out to assess the influence of matrix and interface properties on the stress–strain curve, compressive strength, ductility and the corresponding failure modes. It was found that the composite properties under transverse compression were mainly controlled by interface strength and the matrix yield strength in uniaxial compression. Two different fracture modes were identified, depending on whether failure was controlled by the nucleation of interface cracks or by the formation of matrix shear bands. Other parameters, such as matrix friction angle, interface fracture energy or thermo-elastic residual stresses, played a secondary role in the composite mechanical behavior.