Fatigue mechanisms of a closed cell elastomeric foam: A mechanical and microstructural study using ex situ X-ray microtomography

Abstract

The degradation of mechanical properties of closed-cell elastomeric foams in fatigue and its link with the cellular structure is still poorly understood. To clarify this, we performed interrupted and continuous cyclic compression tests on EVA closed-cell foams used in running shoes. The 3D cellular structures of tested samples was analyzed before, during and after fatigue tests using X-ray microtomography and digital volume correlation. Interrupting the cycling allows the observation of the cell flattening along the compression axis with both plastic bending and an increase of tears/holes of cell walls. These two fatigue-induced defects are suspected to play a strong contribution on the fatigue properties of the foam at the sample scale and may explain the partial recovery of the initial mechanical property of foams while restarting cycling.

Keywords

• Closed cell elastomeric foams
• Fatigue
• Compression test
• Damage mechanisms
• X-ray microtomography
• Memory effects