Impact on low fibre-volume, glass/polyester rectangular plates

Impact tests on composite plates were performed using an instrumented drop-weight machine. Orthophthalic and isophthalic resin, and different woven-roving reinforcements were considered. Degree of fibre-crimp was more influential than the type of polyester resin. Multiple, complex and interacting damage mechanisms occurred even at very low incident energies. Three main stages of damage were seen, `undelaminatedʹ, `delaminatedʹ and `fibre damageʹ. Delamination gave a bi-linear force–deflection response for thicker laminates. Low fibre-crimp thinner laminates exhibited membrane stiffening, but for other thin laminates this was preceded by fibre damage. A bending and shear deflection dominated model facilitated identification and interpretation of the complex impact behaviour. For thin and undelaminated thicker laminates bending was significant. For thicker delaminated specimens shear deflection dominated. An energy balance approach successfully related impact response to impact severity. Delamination controlled almost all of the impact response of thicker laminates until fibre damage occurred.