Rate-temperature coupled deformation mechanism and constitutive parameters of catenary copper-magnesium alloy materials for high-speed railway

With the increasing speed of trains, the impacts of mechanical shock, arc heat, and Joule heat on the high-speed railway catenary system have become increasingly significant. The coupling effect of high temperature and impact load has emerged as a key limiting factor for the safe operation of the pantograph-catenary system. This study focuses on copper-magnesium alloy materials used in the catenary system to address the challenges of dynamic impact and friction-induced heat generation in high-speed railways. To investigate the mechanical properties of the high-speed railway pantograph-catenary system under service conditions such as dynamic impact and frictional temperature rise, a DF14.205D electronic universal testing machine and a split Hopkinson pressure bar were employed. The uniaxial compression mechanical properties of the copper-magnesium alloy in the catenary were tested over a strain rate range of 0.001 s−1 to 3000 s−1 and a temperature range of 293 K to 873 K. The strain-rate effect and temperature sensitivity of the stress-strain response were carefully analyzed. The study also revealed the compression deformation mechanism and the evolution law of the alloy’s microstructure under the combined influence of strain rate and temperature. Furthermore, a dynamic constitutive model was established to accurately describe the plastic flow behavior of the material. The findings indicate that during compression, the copper-magnesium alloy materials exhibit significant strain-rate strengthening and temperature softening effects. These effects result from the combined action of work hardening, strain rate, and temperature softening. When the temperature exceeds 473 K, temperature softening becomes the dominant factor in material deformation, and the elevated temperature can stimulate dynamic recovery and dynamic recrystallization processes. The modified Johnson-Cook model was found to be capable of accurately predicting the plastic flow stress-strain response. These research outcomes provide valuable guidance and references for the safety design and evaluation of the high-speed train pantograph-catenary system during its service.