Transverse compression failure of unidirectional composites

The mechanical response of unidirectional composites subject to uniaxial transverse compressive loads was measured and analyzed by finite element simulation. Consistency in failure plane orientation was observed when comparing simulated matrix shear band angle to measured crack angle. A model based on hexagonal packing of fibers was proposed and the shear band angle was shown to depend on the fiber volume fraction. The effects of strong and weak fiber–matrix interfaces were considered using models with randomly distributed fibers for a valid statistical analysis. The results of these models showed that the composite compressive strength increased with the fiber loading for the strong interface case, while the strength was independent of the fiber loading for the weak interface case because of interface debonding. POLYM. COMPOS., 36:756–766, 2015. © 2014 Society of Plastics Engineers