Damage mechanisms in elastomeric foam composites: Multiscale X-ray computed tomography and finite element analyses

To understand the mechanisms of damage initiation and propagation in glass microballoon (GMB)/silicone elastomer matrix syntactic foam composites, multiscale X-ray computed tomography images obtained during in situ compression were analyzed using quantitative image processing and digital volume correlation (DVC) techniques. High-resolution tomograms revealed that both the initiation and propagation of GMB collapse depended on the local clustering of GMBs, leading to the formation of pseudo-crush bands in the composite. This resulted in prominent bands of axial strain variation that grew to several millimeters in length as revealed by DVC. A new mechanism based on stress redistribution around collapsed GMBs is proposed to explain the damage propagation, which is supported by finite element analysis and successfully captures the effects of cluster or ientation on the observed damage.