Abstract
In the present work, a theoretical model of three-dimensional (3D) transient temperature field for Al alloy brake discs with Al2O3-SiC(3D)/Al alloy wear-resisting surface layer was established. 3D transient thermo-stress coupling finite element (FE) and computational fluid dynamic (CFD) models of the brake discs was presented. The variation regularities of transient temperature and internal temperature gradient of the brake discs under different emergency braking conditions were obtained. The effects of initial braking velocity (IBV) and thickness of Al2O3-SiC(3D)/Al alloy composite wear-resisting layer on the maximum friction temperature evolution of the disc were discussed. The results indicated the lower temperature and thermal stress distributed uniformly on the wear-resisting surface, which was dominated by high conductivity and cooling ability of the Al alloy brake disc. The maximum friction temperature was not obviously affected by the thickness of the wear-resisting layer. The maximum friction temperature of the brake discs increased with the increase of the IBV, the maximum friction temperature and thermal stress of the brake discs is about 517 °C and 192 MPa at IBV = 97 m/s considering air cooling, respectively. The lower thermal stress and fewer thermal cracks are produced during the braking process, which relatively decrease the damage. The friction behavior of the tribo-couple predicted using FE method correlated well with the experimental results obtained by sub-scale testing.
Highlights
The brake system is a key component for high-speed trains
3-3 interpenetrating composites (IPC), which are whichintegrity are alsoand called co-continuous composites, consisting of three-dimensionally continuous called co-continuous composites, consisting of three-dimensionally discrete matrices of discrete metal and ceramic phases may provide novel continuous advantages matrices for wearofresistance metal and ceramic advantages for wear resistance applications as they applications as theyphases could may offer provide a higher novel load bearing capacity than the conventional could a higher[7,8,9]
The high-speed rotation of the brake disc with symmetrical ribs can drive the rotation of the surrounding high-speed rotation of the brake disc with symmetrical ribs can drive the rotation of the surrounding air flow flow (Figure (Figure 10)
Summary
The brake system is a key component for high-speed trains. To guarantee a safe, steady, and durable brake system, brake disc and pad materials generally should maintain a stable and reliable coefficient of friction (COF), irrespective of braking conditions, ambient temperatures, and humidity [1,2,3]. Unsprung weight can be reduced effectively by using an Al metal matrix composite (Al-MMC) brake disc [4]. The presence of hard structure with wear-resisting SiC3D/Al friction surface layers [13]. To delay the transition from mild to severe wear,toand improve improve high-temperature capabilities under different emergency braking conditions [14,15]. RPC in inthe thecomposites composites order to reduce the wear losses the friction pads, make whichtribo-couples make triboshow better matching friction friction and wear performance. Brake discs are emergency braking conditions duedue to the the temperature gradient, which to thermal crack, and bearing failure [16].
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