Thermal-Mechanical Instabilities in Brake Discs 2018-01-1894
It is well known that thermal buckling and TEI (Thermoelastic Instability) can cause material damage, vibration and noise in automotive brake and clutch systems. Recently, thermal buckling was investigated using the Fourier decomposition method. It was found that the radial variation of temperature considerably affects the critical buckling temperature. A linear or monotonic temperature profile always leads to a dominant coning mode. Whereas a temperature profile with the maximum temperature located in the middle leads to a dominant non-axisymmetric buckling mode, and the associated critical temperature is much higher than the typical operating speed. The numerical solutions for periodic variations of temperature with multiple waves in circumference were also obtained. Further, the coupling between thermal buckling and TEI was tentatively investigated using a finite element analysis. The temperature distributions were first obtained from the eigenmodes in a set of classical TEI analyses. The critical buckling temperatures along with the buckling deformation modes were subsequently computed from the prescribed temperature fields. It was concluded that there exists a strong coupling between TEI and thermal buckling, and that the TEI induced unstable modes can alter the input temperature profiles for thermal buckling, and thus the critical temperature values. Overall these research findings imply that thermal buckling and TEI exhibit similar mode patterns and that they could be coupled together in brake discs at a sufficiently high sliding speed.