Lightweight Design of a Rear Axle Connection Bracket for a Heavy Commercial Vehicle by Using Topology Optimisation: A Case Study

  • Mehmet Murat TOPAÇ Department of Mechanical Engineering, Dokuz Eylul University, Faculty of Engineering
  • Merve KARACA The Graduate School of Natural and Applied Sciences, Dokuz Eylül University
  • Birkan AKSOY Faculty of Engineering, Dokuz Eylül University
  • Uğur DERYAL BMC Otomotiv Sanayi ve Ticaret A.Ş., Pınarbaşı
  • Levent BİLAL Faculty of Engineering, Dokuz Eylül University
Keywords: Lightweight design, Mechanical design, Multibody dynam-ics (MBD), Topology optimisation, Finite element analysis (FEA), Response surface methodology (RSM), Heavy commercial vehicle


An important design challenge of modern vehicles is mass reduction. Hence in many cases, mechanical design of vehicle components covers different optimization processes. One important structural optimization technique which is highly utilised in weight reduction applications is the topology optimization. This paper contains a multi-stage optimization based on the topology and design optimizations. During this study, the mechanical design of a rear axle-chassis connection bracket is achieved. First of all, the design load of the bracket was determined through a multibody dynamics analysis. This load case was determined among various driving conditions and the most critical load case was indicated as the design load of the bracket. This process was executed by using Adams/Car™ software. Subsequently, a design volume for the bracket was decided, which specifies the domain of topology optimization that will be employed later on. The determination of the design domain was made by considering the structural position of the design component, the neighbor components of the rear axle and the chassis. In this manner, the basic shape and dimensions of the bracket were created. The unnecessary volume of the draft design, which is not properly loaded under the design conditions was determined and removed from the design by means of topology optimization. The topology optimization was run in topology optimization module of ANSYS® Workbench 18.2 finite element analysis (FEA) software package. In the light of the primary shape obtained from the topology optimization study, a producible initial design model was built. This model was then subjected to FE analysis under the same circumstances with the draft model, in order to perform strength and deformation assessments of the initial design. Correspondingly, the critical regions were determined where stress concentrations were observed. The model was updated in a way that the stress values were reduced in these regions through the response surface methodology (RSM). The comparisons between the result and the initial geometries reveal that the mass of the connection bracket was reduced by 63%. Besides, the total deformation which was dropped by the design optimization is 13% lower than the initial design that was generated with the influence of topology optimization result.

Author Biography

Mehmet Murat TOPAÇ, Department of Mechanical Engineering, Dokuz Eylul University, Faculty of Engineering
Assistant Professor, Dr.