Thermal Contact Characteristics of Magneto-Electro-Elastic Composite

Smart materials made of Magneto-Electro-Elastic (MEE) composites are frequently used in frictional contact environment, and complex multi-physics responses of thermal-stress, thermo-electricity and thermo-magnet for these materials may be activated by contact thermal loads. Base on the constitutive equation, equilibrium equation, Maxwell’s equation and heat transfer equation, Frequency Response Functions (FRFs) associating unit concentrated normal force, tangential force, electric charge, magnetic charge and temperature rise with their induced physical fields were derived, which were converted into exact expressions of the influence coefficients (ICs) in a form of continuous Fourier transform. Further, these ICs were used to establish a thermal contact model for MEE composites based on a Semi-Analytical Method (SAM) and electric potential, magnetic potential and stress generated in contact body were calculated. In this model, the electric and magnetic charge were assumed to be uniformly distributed on the contact surface, and contact pressure could be obtained by the load-displacement equilibrium equation. Moreover, based on the hypothesis of equivalent temperature on the surfaces of two contact bodies, frictional heat was partitioned. Then, temperature rise produced by frictional heat was obtained by introducing influence coefficients relating heat flux to temperature rise of transversely isotropic MEE material. Besides, during the whole calculation process of thermal contact, a Discrete-Convolution and Fast Fourier Transform (DC-FFT) algorithm and a Conjugate Gradient Method (CGM) were adopted to enhance the computation efficiency in this model. Additionally, effectiveness of this model was validated by comparing piezoelectric and thermoelastic results with those from the Finite Element Method (FEM). Effects, further, of frictional heat during the contact process on multi-physics responses were explored by the proposed model, and results showed that changes in sliding velocity, coefficient of friction and surface topography had an influence on frictional heat distribution. An augment in the sliding speed and coefficient of friction leaded to an increase in temperature rise, while a decrease first and then increase in stress, and location of the maximum stress was shifted horizontally. The electric potential decreased gradually considering influence of frictional heat, but the magnetic potential increased slightly. When it came to thermal contact for rough surface, contact pressure was concentrated around asperities, thus resulting in higher temperature rise near them, which imposed a corresponding impact on magnitude, distribution of stress, electric potential and magnetic potential. In addition, sensitivities of elastic field, electric field and magnetic field to temperature rise were investigated. The elastic and electric fields were negatively correlated with surface temperature rise introduced by friction, while magnetic field was positively correlated and elastic field was susceptible to temperature most, followed by electric field and magnetic field.