Highly sensitive and stable conductive elastomer composites for strain monitoring of seismic isolation bearings: Experiment and molecular simulation

Seismic isolation bearings are critical components for energy dissipation and seismic resistance in building structures. Real-time deformation monitoring during service can provide timely performance assessments, accurately evaluate damage, reduce maintenance costs, and enhance construction efficiency. Conductive elastomers, which exhibit a resistance/strain response, are effective sensing materials for such monitoring. However, they often suffer from a shoulder peak effect in their output monitoring signals, compromising monitoring stability and reliability. In this study, we endowed elastomer (VMQ) with conductive properties using multi-walled carbon nanotubes (MWCNT) and modified its cross-linking structure with Hydrogen silicone oil (TMS) and Hydrosilane (HSO) to eliminate the shoulder peak effect. Results showed that introducing dihydrogen structures reduced the resistive hysteresis area by 94.22% and eliminated the shoulder peak effect. The underlying mechanism was explored through a combination of experiments and molecular dynamics (MD) simulations. Additionally, the tensile strength and elongation at break of the conductive elastomer improved by 21.89% and 45.11%, respectively. The optimized conductive elastomer exhibited excellent strain-sensing properties, including high sensitivity (GF = 2918.524) and a fast response time (217 ms). Its resistance/strain response remained stable and free of shoulder peak effects across different strain levels, strain rates, and after 5000 loading-unloading cycles. When applied to seismic isolation bearings, the material maintained a stable monitoring signal under large deformations. These findings highlight the potential of this smart sensing composite for structural health monitoring in large-scale components.