Surface strain maps produced using digital image correlation (DIC) provide insight into the evolution of localized compaction in closed cell Cymat aluminum foam under uniaxial compression. This foam displays stress – axial strain curves characteristic of cellular solids: a semi-linear region ending in a peak stress, and subsequent stress drop followed by reloading to a near constant stress plateau. Surface strain maps are used to relate the microstructural deformation process to the macroscopic stress strain behavior. Prior to peak stress, specimens exhibit pockets of concentrated axial compaction under semi-linear, but inelastic loading conditions. Near peak stress one of the largest pockets evolves into a band of axial compaction, thereby triggering an inelastic collapse event immediately following the peak load. At the peak load, variable stresses occur at an average strain of -0.009 mm/mm when measured from the load frame and through DIC. A stress reduction of 40-55% of the peak load characterizes the stress drop, with termination always at an average strain of -0.0165 mm/mm. During the collapse event the compaction band represents the primary area of deformation while the strain levels outside this region stabilize. This trend continues into the reloading region of the stress strain curve where the band thickens and DIC breaks down. The load and strain data obtained provide valuable insight into the bulk material properties and the localization behavior of this non-uniform material.
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