The automobile sector has been distinguished by its significant innovations, sophistications, and intense competition that incorporates massive supply chains [1]. The direct annual growth rate of automotive industries is expected to be 1–2% [2]. Due to its massive size in terms of workforce employed and revenue generated, the industry is one of the major players in global climate change. The per capita carbon footprint of each automobile industry is huge due to its production and associated supply chain emissions. Thus, the united nations (UN) has stepped in to resolve the issue by proposing sustainable development goals (SDGs) [3, 4]. The role of additive manufacturing is crucial in implementing these SDG policies around the globe.
The topology optimization approach has the potential to reduce the material usage and energy for the production of automotive components without reducing their intended performance [5–9]. However, the traditional manufacturing routes has restricted the production of these optimized designs due to manufacturing constraints. Complex designs with interconnected pores and curvatures are either not possible or economically infeasible to manufacture [10]. These shortcomings can be overcome by the integration of topology optimization (TO) and additive manufacturing (AM) [6, 11, 12]. The conceptual design approach of weight restricted shape optimization has long been studied by various researchers worldwide [11, 13–16]. This strategy has paved the way to strategically distribute the material based on the locations of the component that witness intense stress [17].
In the current study, the topology optimization process is carried out on the flange fork that forms one of the crucial components in the transmission part of the automobile. Traditionally, the flange forks are fabricated through hot forging process. The hot metallic billet is transformed into a flange fork by applying stepwise pressure using a die through number of forging steps. Since the forging operation takes place at an elevated temperature, the forging dies often undergo extensive wear. Moreover, thermal fatigue cracks and high temperature deformation often leads to replacement of forging dies. This includes the overhead charges along with extensive energy requirements for maintaining high temperature. Lange et al. reported that 70% of the dies that are used in the hot-forging processes fail due to repeated cycle of wear [18]. Die wear results in the folding of the fabricated components with striations, lack of material filling in the sharp or intricate corners, and pre-forging die scrap [19]. Luo et al. reported the phenomenon of thermal softening of forging dies due to repeated heating and cooling cycles [20]. Moreover, the die geometry also plays an important role in the wear, thus restricting the design freedom [21]. Zheng et al. carried out the die wear analysis of the flange fork and reported that the forged component had worn surface due to adhesive, abrasive, and oxidative wears [19]. Such a surface defect reduces the life of the component and may increase the risk of failure under extreme operating conditions.
Thus, in the current study, the automotive flange fork is fabricated through powder bed fusion (PBF) additive manufacturing process. Inconel 718 material in the powder form is used to manufacture the component. Inconel 718 being the nickel superalloy, can sustain its high strength at extreme temperature fluctuations. Moreover, the material is also extensively used in hot-section of aero-engines. The CAD design of the automotive flange is prepared based on the description given by Zheng et al. [19]. The shape-based topology optimization is carried out in the Ntopology platform based on the constraints. Considering the volume and mass reduction as the criteria, two alternative designs are proposed. Finite element analysis is carried out on these alternate optimized designs to validate its load-bearing efficiency. The manuscript is organized into 4 major sections with the first section dedicated to highlighting the need for the implementation of sustainable development goals in automotive sector. Also, the shortcomings of manufacturing automotive flange forks through traditional hot forging are addressed. Section 2 deals with the materials and methods wherein, the optimization procedure, force analysis, finite element methodology, powder preparation, and fabrication are discussed. Section 3 deals with the detailed analysis of the results and discussions followed by conclusions and future scope of the study in section 4.