# A Study on the Pantograph Slide Wear Model Based on Energy Dissipation
## 6 Discussion
The variations in pantograph-catenary current-carrying frictional energy dissipation under different contact pressures at a contact current of 150 A and a sliding speed of 100 km/h are shown in Figure 7.  
As shown in Figure 7, with the increase in contact pressure, the energy generated by frictional work increases, while the energy generated by electrical work decreases, with the rate of decrease gradually slowing. During high-speed relative sliding between the pantograph slide and the catenary wire, the contact surface is rough and uneven, and only a limited number of microscopic contact spots are in actual contact. According to Hertzian elastic contact theory [29], when the contact pressure increases, elastic deformation occurs in the contact region, leading to an increase in the radius of the contact spots and a reduction in contact resistance. As a result, the energy generated by electrical work decreases. When the contact pressure reaches a certain level, the radius of the contact spots no longer increases significantly, and the variation in contact resistance stabilizes within a certain range, causing the decrease in electrical energy dissipation to slow down. Since the frictional force is directly proportional to the contact pressure, an increase in contact pressure leads to a greater frictional force and thus higher frictional energy dissipation. As the contact pressure continues to rise, the contact performance between the pantograph and catenary improves, resulting in reduced electrical wear and increased mechanical wear. Consequently, the total wear of the pantograph slide increases, and the dominant wear mechanism transitions to mechanically enhanced wear driven by Joule heating. The variations in pantograph-catenary current-carrying frictional energy dissipation under different sliding speeds at a contact current of 200 A and a contact pressure of 90 N are shown in Figure 8.  
Figure 7: The variation law of the pantograph–catenary current-carrying friction dissipation energy under different contact pressure. As shown in Figure 8, both the energy generated by frictional work and the energy generated by electrical work gradually increase with rising sliding speeds. At a relatively high contact current, the electrical work causes a rapid temperature rise on the contact surface. Meanwhile, the increase in sliding speed enhances frictional heating, resulting in a further rise in frictional energy dissipation and an elevated surface temperature of the pantograph slide. The high temperature reduces the adhesive strength of the pantograph slide surface, thereby increasing adhesive wear. Additionally, as the sliding speed increases, the contact performance between the pantograph and catenary deteriorates, leading to higher inertial and aerodynamic forces induced by frictional vibrations. This increases the likelihood of multiple detachments between the pantograph slide and the contact wire. The resulting arc discharges during these detachments cause surface ablation, further intensifying the wear of the pantograph slide. With the simultaneous increase in energy from both frictional and electrical work, the surface temperature of the pantograph slide continues to rise. The combined effects of temperature elevation and arc ablation contribute to increased electrical wear. At this stage, the dominant wear mechanism transitions to electrical wear characterized primarily by mild arc ablation. The erosive effect of arcing on the surface material of the pantograph slide becomes more pronounced, accelerating the wear. Although the energy required to remove a unit mass of material remains constant, the prevailing wear mechanism changes as the wear process evolves. Different wear mechanisms involve different material removal modes, each requiring varying energy inputs. This shift in mechanism is a primary factor contributing to increased model prediction errors.