High Strain Rate Testing of Sandwich Core Materials

Mechanical response of a cellular sandwich core material, balsa wood, is investigated over its entire density spectrum from 55 to 380 kg/m^3. Specimens were compression loaded along the grain direction in both quasi-static and dynamic strain rates from 10^(−3) to 10^3 s^(−1). Results show that while the initial failure stress is very sensitive to the rate of loading, plateau (crushing) stress remains unaffected by the strain rate. Kinematics of deformation and micro inertial effects are suggested and discussed to explain this different behavior. Specific energy dissipation capacity of balsa wood was measured and determined to be comparable with those of fiber-reinforced polymers. As in quasi-static loading, buckling and kink band formation were identified to be two major failure modes in dynamic loading as well