Integrated design and validation of 3D radiant heater for electric vehicles: Thermo-Electrical finite element analysis considering strain-dependent resistance in thermo-forming

Abstract

An integrated forming-heating finite-element model was developed to evaluate the thermal performance of a 3D radiant film heater for electric-vehicle applications, with particular attention to strain-induced variation in electrical resistance. The electrical response of the carbon-nanotube (CNT) network embedded in the heater film was experimentally characterized by simultaneous measurements of mechanical strain and electrical resistance during uniaxial tension, yielding a ΔR/R<inf>0</inf>–ε relation. This relation was used in a thermoforming simulation of the CNT-patterned film to obtain strain distributions, which were subsequently mapped into a Joule heating analysis by prescribing strain-dependent electrical resistivity/conductivity for the CNT layer. Thermal predictions were validated against experiments. Incorporating strain-dependent resistance significantly improved the accuracy of the predicted temperature fields. Specifically, neglecting this coupling overestimated the maximum temperature by ≈12.3 %, driven by local resistance increases up to 36.6 % in highly strained regions. These results highlight the necessity of accounting for electromechanical coupling during forming to achieve reliable thermal predictions. The proposed framework offers a practical tool for optimizing high-efficiency radiant heaters in electric vehicles and is extendable to urban air mobility, electric trams, and building-integrated heating systems.