This presentation was made at the NAFEMS Americas "Creating the Next Generation Vehicle" held on the 14th of November in Troy.

The automotive engineering community is now confronting the largest technology transformation since its inception. This includes the electrification of powertrains for more efficient consumption and cleaner emissions, the reinvention of the battery with fast wireless charging capabilities and finally the advent of a fully autonomous vehicle. Compounding to these technology changes, the automotive companies design verification process is moving away from a major reliance on physical testing to almost a full virtual simulation product verification process.

The automotive engineering community is now confronting the largest technology transformation since its inception. This includes the electrification of powertrains for more efficient consumption and cleaner emissions, the reinvention of the battery with fast wireless charging capabilities and finally the advent of a fully autonomous vehicle. Compounding to these technology changes, the automotive companies design verification process is moving away from a major reliance on physical testing to almost a full virtual simulation product verification process.

Resource Abstract

A numerical method was developed in this study to effectively account for the clutch nonlinear behaviour in steady state dynamic analysis for transmission NVH performance using nonlinear finite element analysis (FEA). Nonlinearities, such as the friction contact between the clutch components and the nonlinear properties of the friction lining material, were considered in the preloading procedure prior to the subsequent frequency domain vibration and acoustic analysis for the NVH evaluation. The paper-based friction material was modelled as hyperelastic by directly using compression stress and stretch curves obtained from material test. As a result, the material behaviour accuracy was ensured with perfect correlation with the test. The clutch stiffness calculated in the preload stage with nonlinearity considered was then imported into the transmission analysis model built with a special-purposed gear design and analysis code to calculate the Transmission Error (TE) and the bearing / connecting forces. The latter was subsequently used as the excitation input to an entire CAE transmission model to predict the radiated acoustic pressure through the housing vibration. With these nonlinear characteristics of the clutch being considered, improved agreement can be reached between the CAE prediction and the test measurements of transmission NVH performance such as gear whine and motor whine for hybrid transmission, and thus the design verification (DV) efficiency could be improved significantly as well.