An Integrated Approach for Instability Analysis of Lattice Brake System Using Contact Pressure Sensitivity

This paper presents an attempt to evaluate the sensitivity of lattice parameters on the contact pressure instability of newly lattice brake disc. The instability characteristics are investigated through theoretical representation, modal analysis experiments, and nonlinear finite element thermo-mechanical analysis. Lattice properties are defined concerning the lattice truss angle geometry in the unit cell and periodicity of the lattice cell on the lattice plate. Motion dynamics of lattice plate concern the principal coordinates on the rotating disc are presented to use in the braking system. The modal behaviour of vanned and lattice brake disc/pad systems are defined through experimental modal analysis at free-free boundary conditions, and results are used as inputs of nonlinear finite element models as it goes through a partial simulation of the SAE J2521 drag braking noise test. Subsequently, the dynamic instability analysis of the brake disc is detailed by using the complex eigenvalue extraction technique concerning the contact pressure and lattice parameters effect. The sensitivity analysis of the brake instability respected to the mass fraction factor and relative density of the lattice structure is presented by using the average standard deviations of the contact pressure force. The likelihood of instability occurrence is quantified by definition of a single indicator derived from the system eigenvalues. The analysis indicates that the higher relative density with lower mass fraction factor of lattice structure is led to a higher temperature at the disc and pad surface. Mutually, the higher mass fraction factor with lower relative density is led to the lower temperature. The maximum contact pressure is observed in the model with less mass fraction factor and more uniform pressure distributions are observed at higher values of the mass fraction factor. The instability analysis points out that high instability frequencies are predicted at lower mass fraction factor and higher relative density.