MDO approach for design synthesis of automotive interior components subjected to conflicting functional requirements

Light weighting has been one of the focus areas in automotive design, which has assumed greater importance for electric vehicles due to sensitivity of electric range to mass of the vehicle and increased cost of the battery packs to meet range target with increasing mass of vehicle. Mass of vehicle interior components have significant impact of overall vehicle mass due to cascading effect. Hence mass of such components must be minimized during design synthesis, where multiple design configurations may be explored with tradeoffs with regard to meeting functional requirements which are often conflicting. Assist handle bracket is one of such components in vehicle which needs to meet mandatory safety requirement of FMVSS 201U that requires the bracket to be soft. At the same time, the bracket needs to have adequate stiffness and strength to meet perceived quality and durability requirements. These are conflicting requirements which are often difficult to meet using manual design iterations which also takes longer time and may not lead to a minimum mass configuration. The traditional design process takes appreciable number of manual design iterations and remarkable effort from the CAE engineer to meet required performance, but often may not meet the contradictory loadcase requirements for full vehicle level analysis. Objective of this piece of the work is to establish application of Multi-Disciplinary Optimization (MDO) process to come up with balanced optimized bracket design which will meet both the requirements and will be of minimal mass for both component and full vehicle level analysis. Shape and gauge design variables are used in parametric design optimization. Relevant shape and gauge variables are considered for MDO which are sensitive to both the performance. Appropriate response surface methodology and optimization technique are used to get the optimized design. This MDO process meets three objectives: (a) mass minimization, (b) satisfying the conflicting requirement even when the initial design is deficient in performance and (c) enabling trade-off analysis. The in-house MDO tool works with actual analysis results for adaptive runs and hence the results are not approximate unlike other MDO tools, thus requiring no additional verification. This parametric shape and size MDO technique, demonstrated for assist handle bracket in this report, can also be applied to other vehicle components to obtain mass efficient designs in quick time while meeting conflicting performance requirements