Thermal-Structure Coupling Analysis Of Wet Multi-Disc Brake

Wet multi-disc brake is widely used in engineering vehicles because of its stable working performance, long service life, large capacity of brake, etc. Thermal overload is increasingly prominent to cause wet multi-disc brake failure, along with the engineering vehicles developing larger day by day. The study is relying on the wet multi-disc brake of ZL-50loader. Based on the heat transfer and the thermal elastic mechanics theory, completed the physical field coupling analysis with the finite element method, and discussed its failure mechanism, tried to provide reference for brake designing in the future.Based on the theory of heat conduction in solids, The transient conduction-convection differential equation of two objects with relative sliding was derived. According to the actual size of wet multi-disc brake, Established its three-dimensional finite element model of transient temperature field and stress field analysis, and took into account the actual braking mode of the movement and the vary of dynamic parameters, convective heat transfer boundary conditions and the others. The variation of temperature and stress field in radial, circumferential and axial were Revealed, it was shown that radial temperature gradient is the major factor to cause axial stress and radial cracks.After obtaining the original pressure distribution on each friction surfaces, contrasted the different of the friction pairs’ temperature field and stress field, found that the distribution of the initial pressure exert a tremendous influence. The influence factors of two physical field distribution of wet multi-disc brake could be divided into structural factors and material factors, and the influence of different factors on the temperature and stress field were discussed.Based on the typical operating mode of loader and the cumulative effect of multiple, high frequency braking, the two-dimensional stress field and heat dissipation finite element model with120min cycle braking was established. To get the overall characteristics of the change of the temperature field and stress field, cycle braking was considered as continuous braking with equivalent transformation, Result of the simulation showed that the two physical fields were dominated by the rule of "uneven growth-equal amplitude growth-equal amplitude change along with the oil temperature". Regarded the overall distribution at the beginning of a braking as the initial conditions of instantaneous simulation could obtain the instantaneous characteristics of the temperature field and stress field, it was found that the two physical field follows a "fast and uneven growth-slow decline-the next time overall distribution characteristics".