Effects of seawater exposure on mode II fatigue delamination growth of a woven E-glass/bismaleimide composite

Abstract

The effects of seawater exposure on Mode II fatigue delamination growth of a woven E-glass Bismaleimide composite are investigated by end-notched flexure tests in this study. Dynamic mechanical analysis shows a strong plasticization effect of seawater immersion on the matrix material. Static tests of specimens after 2500 h of immersion in 50℃ seawater reveal that the critical strain energy release rate ([Formula: see text] is increased by 15.4%. This is mainly due to seawater effects of plasticization of the matrix, extension of the damage zone and enhancement of the ductility of the material. In fatigue tests, a practical formulation based on the Paris law is proposed to model the stable delamination growth rate for both dry and wet specimens. At a given normalized strain energy release rate, the delamination growth was found to be slower in wet specimens than in dry specimens. The examination on fracture surfaces by scanning electron micrographs also reveals evidence of the plasticization effect of seawater which improves the [Formula: see text] of wet specimens.