In situ deformation characterization of density-graded foams in quasi-static and impact loading conditions

• Full-field deformation response of density-graded foams is investigated by DIC. Effects density gradient are in-situ strain/stress measurements. Mechanisms associated with formation and propagation stress wave discussed. Double shock mechanism observed for graded negative gradients. Positive gradients show a unidirectional (single) compaction wave. Digital image correlation utilized to characterize strain fields developed within the layers multilayered foam structures subjected uniaxial quasi-static dynamic compression. Three-layered fabricated from rigid polyurethane nominal densities 160, 240, 320 kg/m 3 loading. The measurements that, irrespective loading direction, densification initiated in lowest layer propagates into other later once first fully densified. mechanisms different case conditions than In loading, depends on sample orientation relative direction applied load. cases where higher impacted, elastic waves leads partial layer. Sample continues all upon reflection distal end sample. A completely oriented towards impact face. detailed full-field analysis performed. samples'