To enhance sustainability performance and reduce CO2 impact on our environment, demand for alternative energy sources for vehicles is increasing. Electric Vehicle (EV) is identified as an adequate alternative to fossil-based fuels. Additionally, EV technologies are under strong development and progress but for the next generation of electric vehicles with higher battery capacity, lightweight and more compact design with advanced thermal controlling systems and electronic components are required.
In most cases, the product must fulfill all safety regulations for vehicles and many other requirements, e.g., high battery capacity, complete life cycle, excellent energy performance, and low cost. The battery packs are typically placed in the car’s floor structure or located near the rear axle, which implies a higher stiffness level. Additionally, the crash protection requirements are set in these areas compared with the floor of the traditional cars.
Based on the sustainability perspective of future electric vehicles, the advanced multi-layer material Hybrix™ developed by Lamera AB, seeks to develop lightweight protective panels and housing for batteries with crashworthiness requirements considered. Both good formability and high stiffness properties are two essential elements for the product’s final performance and functionality.
CAE (Computer-Aided Engineering) techniques have been used within engineering applications for many decades. The technology is consistently improved and substituted “in many cases” the physical full-scale experimental validation. Nowadays, the use of the CAE tool has been an obvious choice for Engineers in the design process to develop reliable and cost-efficient products.
However, the engineer needs to have access to reliable experimental data to ensure the accuracy of the input parameters for the simulation software. Therefore, it is essential to establish straightforward and repeatable experimental procedures to evaluate the mechanical properties of the material.
Experimental investigation and material characterisation
Under the framework of FormPlanet project, Luleå University of Technology (LTU) has been involved in establishing a methodology to characterise the complex Hybrix™ core and perform experimental based CAE analyses. These analyses have been a reliable source for calibration and predication parameters for the damage model, see Figure 1.
Fig. 1: The obtained numerical response, including damage, is compared with the experimental data for two different load conditions tensile and shear.
To demonstrate the outstanding performance of the material, the battery upper and lower housing have been designed using CAE and adapted for a conventional stamping operation.
The selected sandwich materials, Hybrix™ consisted of 0.2/0.3mm carbon steel as face material (total thickness 0.9/1.2mm). A specific constitutive model with failure criteria has been developed and implemented for the core material in two commercial software IMPETUS Afea and LSDYNA. The CAE tool has been used to predict accurately the feasibility of the stamping process. The durability and strength of the multi-layer material have been evaluated by performing a cluster of analyses. Figure 2 illustrates a part of the development route like design, stamping, and performance analyses of the battery housing.
Figure 2. The numerical investigations using CAE tool.
Ramin Moshfegh is CTO at Lamera AB since 2016. Skilled in Industrial Engineering, Sheet Metal Forming, CAE, Manufacturing Engineering, and technical sales support. He has a Doctor of Philosophy (Ph.D.) focused on Solid Mechanics from Linköping University, Sweden.
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