PSI - Issue 12

T. Novi et al. / Procedia Structural Integrity 12 (2018) 145–164

163

Author name / Structural Integrity Procedia 00 (2018) 000–000

19

Fig. 11. Thermal duty cycle

the minimum of approximately 2 ◦ C can be seen. The average temperature reached by the disc pack is approximately 40 ◦ C. At this temperature the properties of the materials remain the same and, therefore, the correct functioning of the device is guaranteed. For this reason, an external cooling system is not needed.

5. Conclusions

Many di ff erent aspects regarding the thermal behaviour of a semi-active di ff erential have been analysed in detail in this work. After having analysed the various heat sources and equations involved, the finite element model developed has been discussed. All the approximations, simplifications, hypothesis and techniques used to model the di ff erential in the FE environment have been described. From the results, it can be said that the temperature gradient in the disc pack increases with the increase of heat produced by the clutch and the temperature tends to increase particularly towards the middle of the disc pack. Thermal maps of both the temperature distributions and the temperature gradients have been created for various working conditions. This has also been done to evaluate how the temperature along each surface di ff ers in terms of surface temperature uniformity if compared to the average temperature of the entire clutch. This analysis, evaluated for a certain time lapse, is useful to evaluate the total friction coe ffi cient and, consequently, the total friction torque generated by the disc pack considering the temperature influence. In addition, a duty cycle simulating real working conditions has been run to evaluate the temperatures reached by the entire pack, represented by the hottest node, after a certain amount of cycles so that the temperature increment during the loading phase is the same as the temperature drop during the unloading phase.

References

Abdullah, O.I., Abd Al-Sahb, W., Al-Shabibi, A., 2015. Finite Element Analysis of Transient Thermoelastic Behavior in Multi-Disc Clutches. doi: 10.4271/2015-01-0676 . Bahrami, M., Yovanovich, M.M., Culham, J.R., 2005. Thermal contact resistance at low contact pressure: E ff ect of elastic deformation. International Journal of Heat and Mass Transfer 48, 3284–3293. Bergman, T.L., Incropera, F.P. (Eds.), 2011. Fundamentals of Heat and Mass Transfer. 7th ed ed., Wiley, Hoboken, NJ. Cui, J., Wang, C., Xie, F., Xuan, R., Shen, G., 2014. Numerical investigation on transient thermal behavior of multidisk friction pairs in hydro viscous drive. Applied Thermal Engineering 67, 409–422. Cze´l, B., Va´radi, K., Albers, A., Mitariu, M., 2009. Fe thermal analysis of a ceramic clutch. Tribology International 42, 714–723.