Interfacial crack propagation between a rigid fiber and a hyperelastic elastomer: Experiments and modeling

The interfacial adhesion between a metal fiber and an elastomer plays a key role in maintaining the structural integrity of stretchable interconnect composites under large strains, but their interfacial adhesion mechanisms have remained elusive. To this end, the interfacial debonding behavior and physical mechanisms between a rigid metal fiber and hyperelastic elastomer matrix are investigated by means of fiber pullout tests and numerical modeling. An improved cylindrical specimen is adopted for a copper fiber pulling out from polydimethylsiloxane (PDMS). A numerical model is developed to simulate the interfacial cracking using the Yeoh hyperelastic model and cohesive damage model. We report a first-of-its-kind experimental observation on the pullout process of a rigid fiber from elastomers. The results demonstrate that there exist three stages in the fiber pullout process: elastic deformation, interfacial debonding and interfacial friction. The interfacial shear strength between the rigid fiber and the PDMS is proportional to the reciprocal of the mixing ratio of the PDMS, and the interfacial friction stress varies inversely with the 1.25 power of the mixing ratio. Enhancing the mixing ratio of the PDMS decreases the strength of both the PDMS and the interface between the PDMS and the metallic materials while increasing their ultimate stretch due to a decrease of chemical crosslinking degree within the PDMS and at the interface between the PDMS and the metallic materials. The results obtained from the numerical model agree well with the experimental data. This work can aid in the design of advanced stretchable interconnect composites. (C) 2019 Elsevier Ltd. All rights reserved.