Optimization of Plastic Parts for Lighter Vehicles: A Case Study of Kanto Auto Works

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In a bid to reduce carbon dioxide emissions and contribute to the prevention of global warming, the automobile industry has been working on improving vehicle body structures and engine efficiency. A significant part of this effort is the drive to make vehicle bodies lighter, thereby improving fuel efficiency. While metals like steel and aluminum make up most of a car's weight, there has been a growing trend to replace some of these materials with lighter plastic. However, plastic, which now accounts for about 9% of a car's weight, presents its own challenges. It is significantly lighter than metal and can be molded into complex shapes, but it also deforms easily under external force or high temperatures. Kanto Auto Works, a core member of the Toyota Group, was faced with the challenge of making plastic parts lighter while ensuring they maintained sufficient rigidity and heat resistance.

Kanto Auto Works, Ltd., which later became Toyota Motor East Japan, Inc., is a core member of the Toyota Group. The company is responsible for developing and producing Toyota vehicle bodies. The organic-material engineering department of the company evaluates and develops plastic parts to be used in vehicle bodies. In the initial stage of development for large plastic parts, such as instrument panels, the department verifies rigidity and heat resistance using computer aided engineering (CAE). The company's commitment to reducing vehicle weight and improving fuel efficiency is part of a larger global effort to reduce carbon dioxide emissions and combat global warming.

To address the challenge, Kanto Auto Works began using OptiStruct, a structural optimization tool from Altair. This tool allowed the company to visualize areas that required reinforcement. OptiStruct combines a choice of optimization functions to create innovative new shapes at any stage of the design process using information that cannot be obtained through experience alone. It enables the creation of lighter parts and reduces steps in the production process by determining optimal materials, identifying where reinforcement is and is not necessary, automatically beading or embossing, optimizing finite element modeling, and determining the optimal sheet thickness and cross-sectional shape of joist structures. Topology optimization calculations were carried out using OptiStruct to visualize areas requiring reinforcement to prevent deformation caused by external force. For heat resistance, calculations were carried out based on the test results for the plastic test plates to determine the load required to cause deformation in the plates.

• The use of OptiStruct's topology optimization function has led to significant improvements in the development of plastic parts for vehicles at Kanto Auto Works. The tool has enabled the company to visualize areas requiring reinforcement, leading to the creation of lighter parts with sufficient rigidity and heat resistance. This has not only resulted in a 20 percent weight reduction but also improved the overall efficiency of the production process. The company has successfully applied this reinforcement method to instrument panels and plans to expand its use to the development of other large plastic parts, such as bumpers, to further reduce the weight of such parts. This innovative approach to vehicle body development is a significant step towards achieving the company's goal of reducing carbon dioxide emissions and contributing to the global effort to prevent global warming.

• Achieved a 20 percent weight reduction in plastic parts.
• Improved rigidity and heat resistance through reinforcement of the smallest possible areas.
• Reduced steps in the production process by determining optimal materials and identifying where reinforcement is and is not necessary.