Topology Driven Design of Under-hood Automotive Components for Optimal Weight and NVH Attributes
To be published on April 2, 2019 by SAE International in United States
Weight is a major factor during the development of Automotive Powertrains due to stringent fuel economy requirements. Light weighting constitutes a challenge to the engineering community when trying to deliver quieter powertrains to meet customer satisfaction. In particular, the NVH CAE engineers are trying to balance between the weight requirements and Noise Vibration Harshness aspects like radiated sound of the under hood components. Typical tools used by CAE engineers are complex and require significant computation effort. Computation of Equivalent Radiated Power (referred to as ERP) is a simplified method to assess maximum dynamic radiation of components for specific excitations in frequency response analysis which in turn affects radiated sound. Topology Optimization is a mathematical technique used to find the best material distribution for structural systems under clearly defined constraints and an objective. The paper will showcase the process adopted using Altair OptiStruct© to optimize the weight of an under-hood automotive component while maintaining the ERP performance across several one third octave bands. In order to address the large eigenvalue problem solved during the ERP loadcase, a multi-threaded approximate eigensolver called AMSES (Automatic Multi-level Sub-structuring Eigensolver Solution) within OptiStruct© solver is used. The paper will highlight the methodology and best practices identified during ERP analysis and topology optimization of the front cover of an inline gasoline engine. In order to obtain higher fidelity during the optimization process, the engine model was condensed to a modal super element model. ERP performance of residual model was validated to match the results of the complete model. Role of design optimization parameters in controlling manufacturability of topology driven concept design process will be illustrated with respect to the system under consideration. Techniques adopted to recover modified geometry resulting from a structural optimization, for further use in the design re-evaluation of the front cover is presented.