Effect of matrix properties on the fatigue damage initiation and its growth in plain woven carbon fabric vinylester composites

The influence of matrix properties including the fracture toughness and carbon fiber (CF)/vinylester (VE) adhesion on the static tensile properties and tension–tension fatigue properties of CF/VE composites has been investigated. An appropriate chemical modification of VE resin improved the tensile strength up to 37.3% and extended the fatigue life of CF/VE composites greatly by several ten times than that using regular VE resin as matrix. Under static loading different failure modes appeared and strain at failure changed due to chemical modification of VE altering the fracture toughness and CF/VE adhesion. Based on TSA (thermoelastic stress analysis) and SEM (scanning electron microscopy) observation, it was revealed that the fracture toughness of matrix dominated the initiation and growth of matrix cracks in CF/VE composites at fatigue initial stage. Transverse cracks formed by linkage of individual matrix crack occurred at interface or matrix that depended on CF/VE adhesive strength. At fatigue middle stage, local delamination tended to initiate early in composites fabricated by resin with lower fracture toughness. High CF/VE adhesive strength also brought a positive effect on the resistance to delamination growth resulting in remarkable extension in fatigue life of composites. The coupling effect of fracture toughness of matrix and CF/VE adhesion on the mechanical properties especially fatigue performance of CF/VE composites was investigated.