NONLINEAR COMPRESSION STRESS-STRAIN CURVE OF PITCH-BASED HIGH MODULUS CARBON-FIBER COMPOSITES AND STRUCTURAL RESPONSES

The longitudinal compression behaviour of unidirectional composites is studied to understand the role of the fibre compressive property. in deformation and failure by systematically varying the tensile modulus of reinforcing high modulus carbon fibre. As the composites deform, their softness increases with increasing compressive strain, and the loading path is traced back when the load is removed. The intensity of softening is correlated to the fibre's tensile modulus and possible softening mechanisms are discussed in conjunction with fibre and matrix properties. Further, it is investigated how the non-linear stress-strain relation affects the stress and strain distributions and deformation when plates fabricated from these fibres are tested by the three-point bending test.