Performance Advancement in Synthetic Brake Shoes: Tri-Matrix Formulation Optimization for Enhanced Mechanical Strength and Thermal Crack Resistance

In modern railway operations, maintaining thermal integrity and consistent friction performance under demanding drag braking and emergency stops is essential. Synthetic matrix composition plays a decisive role in energy absorption and interfacial wear behavior. Recent material research demonstrates that precisely balancing steel fibers, glass fibers, and synthetic graphite yields significant improvements in structural shear resistance and thermal stability.

To evaluate these matrix modifications, full-scale dynamometer testing was performed on the ZYDM-GH08 composite material block using a Link 7200 1:1 rail brake testing rig under standardized axle loads and speeds.

Tri-Fiber Matrix Design and Railroad Friction Dynamics

Achieving stable railroad friction requires controlling the friction film formed at the contact surface between the shoe and the cast steel wheel. Uncontrolled thermal spikes during high-energy braking cause binder degradation, micro-cracking, and erratic friction fluctuations.

• Steel Fibers: Provide structural reinforcement and rapid heat dissipation away from the contact boundary layer.
• Glass Fibers: Enhance mechanical shear strength at elevated temperatures and resist abrasive wear under wet and dry conditions.
• Graphite Lubricators: Regulate peak friction coefficients, reducing thermal stress on the wheel tread and suppressing noise.

Dynamometer Evaluation of Brakes in Train Operating Conditions

Simulating operational demands of brakes in train service, tests were executed using a 1050 mm diameter cast steel wheel under a 7.5-ton wheel load (11.8-ton brake mass equivalence). The ZYDM-GH08 prototype underwent bedding-in cycles until contact area exceeded 80%, followed by full drag and stop brake schedules under dry, slope, and static states.

Table 1: Synthetic Brake Shoe Mass Loss and Specific Wear Rate (JL Test Schedule)

Full Schedule Dynamometer Friction Characteristics

The modified formulation demonstrates smooth torque buildup without aggressive friction spikes at low speeds. Across 36 test sequences comprising high-speed emergency stops and prolonged slope drag braking, average friction coefficients remain highly stable while keeping wheel temperatures safely below critical stress thresholds.

Table 2: Complete Dynamometer Test Data across Speed and Pressure Regimes

Summary and Engineering Conclusions

By optimizing the proportion of metallic reinforcement, high-modulus glass fibers, and solid graphite lubricators, synthetic brake shoes achieve an exceptional balance between wear longevity and wheel tread protection. The low specific wear rate (δ = 0.029 cm³/MJ) coupled with controlled peak temperatures prevents heat-checking and thermal cracking, offering reliable performance across freight and passenger railway applications.