An electromechanical model for the temperature dependence of resistance and piezoresistance behavior in a CFRP unidirectional laminate

This paper describes a model for predicting the resistance and piezoresistance behavior in a carbon fibre reinforced plastics (CFRP) unidirectional laminate under the mechanical loading at various temperatures. A two-dimensional model including temperature effect is established to predict the change in the resistance due to both tensile loading and temperature change. The initial gage factor (IGF) and the temperature coefficient as functions of the off-axis angle are obtained from the model. In addition, macroscopic parameters regarding resistance and piezoresistance are related with microscopic ones on the basis of an equivalent circuit model. It is observed that the IGF shows temperature dependence at all the off-axis angles and becomes the maximum at an off-axis angle of 12° at all the temperatures. The temperature dependence of IGF is mainly attributed to temperature-dependent piezoresistivities and compliances. The temperature coefficient is negative at all the off-axis angles and shows the minimum at 17°. The negative temperature coefficient of the laminate is found to be ascribed to the temperature dependence of resistance of carbon fibre as well as contact resistance between fibres.