Engine Roll and Its Impact on Powertrain Battery Cable Structural Design

Powertrain wiring cable is a backbone of the electrical architecture in any vehicle electrical system design. The weight of a wiring cable is increasing year by year because of the recent development on high-voltage wiring systems, hybrid electric vehicles (HEVs) and electric vehicles (EVs). Clip failure, loosening clip and terminal breakage under engine roll condition is a common issue in powertrain electric cable (or body harness routing) development cycle in automotive industry. Usage of more number of clips in cable routing results in the powertrain design being more complex and it increases manufacturing cost. The standard procedure practiced to develop any dynamic envelope is by using CAD software tools and performing rigid body movements with the help of the motion file. However, the limitation of this procedure is that it could not be applied to cables, hoses or any component that experiences partial movement (i.e. components connected between body/frame and engine/other moving components). This limitation of the existing method makes it unusable for the wiring harness and cables routing study. To overcome the existing limitation, a new method was developed with the help of CAE software employing finite element methods where any study of deformable bodies could be performed. Finite element analysis enables upfront design improvement to decide number of clips required for cable routing and optimum distance between clips required. The root cause for Cable terminal failure and solution for improving design addressed in the design development cycle. Modeling of individual strands and the importance of strands modeling for FE simulation is another challenging topic that is discussed in this paper. It should be also used as an opportunity to optimize the design from cost, serviceability and assembly point of view. Input load value for this study is calculated from drive unit power train movement in different scenarios. There are 24-engine movement scenarios that are identified as the worst case for load calculation. The objective of this paper is to present the virtual validation process for powertrain mounted electric cable, which encountered a structural problem in physical validation under Engine roll conditions. Correlation of simulation results with the physical validation and design improvement through virtual validation discussed in this paper.