Design-Oriented Degradation Mapping and Hyperelastic Model-Switch Guidelines for Nitrile-Butadiene Rubber Seals

Nitrile-butadiene rubber (NBR) seals used in automotive and energy equipment undergo pronounced mechanical degradation at elevated temperatures, yet a quantitative rule for switching between hyperelastic models remains unclear. Here, accelerated thermal aging tests were linked to service conditions by estimating the activation energy via Flynn-Wall-Ozawa analysis and applying an Arrhenius-based equivalence. Tensile testing, dynamic mechanical analysis, and thermogravimetric analysis were combined to track embrittlement and crosslinking, and finite element simulations were benchmarked against experiments using an L2-norm metric. The outcome is a degradation map with a model-switching guideline. The Neo-Hookean model is preferred in the less-embrittled regime, whereas the five-parameter Mooney-Rivlin model is recommended as embrittlement progresses. This framework improves stress-prediction fidelity while keeping model complexity commensurate with the aging state, enabling faster and more reliable design of NBR seals for high-temperature automotive and renewable-energy applications.