A study of pre-stress effect on static and dynamic contact failure of brittle materials

Layered plates consisting of brittle glass and ductile aluminum layers were fabricated using room temperature and elevated temperature curing adhesives. Significant thermal residual stresses were induced in the layered plate bonded at an elevated temperature. Static indentation and dynamic impact tests were performed. The results indicate that thermal residual stresses can delay the onset of contact failure in the glass. However, the benefit of thermal residual stresses in protecting the structure from fracture failure seems to diminish once the projectile achieves substantial penetration into the layered target. The conoid cracking in the glass layer produced by static indentation was modeled using linear elastic fracture mechanics with very good result.