Effect of Temperature on Interface Pressure Between Cable and Accessory

The interface pressure between cable and accessory is key to ensuring the safe operation of the cable terminal of electric locomotives, and temperature is the main cause of changes in interface pressure. This article studies the effect of temperature on the silicone rubber (SiR) used in cable accessories and then on the interface pressure between cable and accessory using the operation temperature range of the electric locomotive cable terminal. First, the low-temperature crystallization behavior of the SiR insulation is analyzed using differential scanning calorimetry (DSC) analysis and dynamic mechanical analysis (DMA). Second, the mechanical behavior of SiR at variable temperatures is analyzed using uniaxial mechanical tensile tests and stress relaxation tests. Finally, the changes in interface pressure between the cable and the flexible accessory in a wide temperature range are measured by building a thin-film piezoresistive measurement system. The results show that interface pressure between cable and accessory positively correlates with temperature. When the temperature rises from $25~^{\circ }$ C to $90~^{\circ }$ C, the interface pressure increases from 0.220 to 0.333 MPa, while the temperature drops to $- 20~^{\circ }$ C, the interface pressure decreases to 0.195 MPa. The results indicate that the interface pressure between cable and accessory cannot be simply simulated by building the SiR material elastic mechanics equations, which are obtained through uniaxial stress-strain curves of SiR at variable temperatures. The changes in interface pressure under variable temperatures are caused by the combined effects of thermal expansion, entropy elasticity, and stress relaxation. The strain-induced crystallization (SIC) effect of SiR at low temperatures also decreases interface pressure.