On failure mechanisms and load-parallel cracking in confined elastomeric layers

TL;DR

This paper investigates the failure mechanisms of confined elastomeric layers, focusing on load-parallel crack growth, through numerical analysis to understand the influence of material and geometric factors.

Contribution

It provides a detailed numerical explanation for load-parallel cavitation crack growth, a phenomenon less understood compared to traditional penny-shaped cracks.

Findings

Load-parallel crack growth depends on specific material and geometric parameters.

Cavitation can act as a fracture process leading to crack propagation.

Understanding these mechanisms aids in designing tougher soft films and adhesives.

Abstract

Thin layers of elastomers bonded to two rigid plates demonstrate unusual failure response. Historically, it has been believed that strongly-bonded layers fail by two distinct mechanisms: (i) internal/external penny-shaped crack nucleation and propagation, and (ii) cavitation, that is, cavity growth leading to fibrillation and then failure. However, recent work has demonstrated that cavitation itself is predominantly a fracture process. While the equations describing cavitation from a macroscopic or top-down view are now known and validated with experiments, several aspects of the cavitation crack growth need to be better understood. Notably, cavitation often involves through-thickness crack growth parallel to the loading direction, raising questions about when it initiates instead of the more typical penny-shaped cracks perpendicular to the load. Understanding and controlling the two vertical and horizontal crack growth is key to developing tougher soft films and adhesives. The purpose of this Letter is to provide an explanation for the load-parallel crack growth through a comprehensive numerical analysis and highlight the role of various material and geometrical parameters.