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Technical Paper

A Method of Predicting Dent Resistance of Automobile Body Panels

Optimizing the design of automobile outer panels for weight reductions requires a consideration of stiffness and dent resistance. This paper presents a finite element analysis method for predicting the dent resistance of automobile body panels. The method is based on elastoplasticity analysis and nonlinear contact analysis. The analysis shows that dent resistance is greatly influenced not only by the stress-strain curve of the formed panel but also by the residual stress in the panel. An increase in yield stress improves dent resistance. The computed results obtained with this method compare favorably with experimental data, thereby validating this approach.
Technical Paper

Analysis of Stiffness of Truck Door Panel Effective Arrangement of Stiffeners for Improving Stiffness

Since it is more difficult for truck door panels to realize curvature than passenger car door panels, internal stiffeners are mounted between the outer panel and inner panel through the use of an adhesive for ensuring stiffness. For this reason, a problem occurs as to the proper placement of the stiffeners so as to effectively improve stiffness. By FEM prediction and experimentation, the following have been clarified: (1) Arrangement of stiffeners for effectively improving stiffness (2) Stiffness share of stiffeners and outer panel against stiffness
Technical Paper

Ceramic Tappets Cast in Aluminum Alloy for Diesel Engines

The authors developed, for use in diesel engines, ceramic tappets cast in aluminum alloy that drastically improved wear resistance and valve train dynamics. The ceramic tappets consist of two parts: a ceramic head, which contacts the cam and push rod, and a tappet body made of aluminum alloy. Concerning the ceramic, silicon nitride was the best material of the three ceramics evaluated in the tests and the sliding surface, in contact with the cam and push rod, was left unground. As for the aluminum alloy, hyper-eutectic aluminum-silicon alloy with a controlled pro-eutectic silicon size was selected. A reliability analysis using the finite-element method (FEM) was also made on the structure of the ceramic tappet for enhanced durability and reliability. The combination of this tappet and a cam made of hardened ductile cast iron, hardened steel, or chilled cast iron, respectively exhibits excellent wear resistance.
Technical Paper

Development of the Stainless Cast-Steel Exhaust Manifold

At Mitsubishi Motors, a thin-walled exhaust manifold, made of stainless cast-steel, has been developed with the aim of achieving higher heat-resisting reliability as well as weight reduction. The new exhaust manifold is made of ferritic stainless cast-steel, employing an advanced vacuum casting (CLAS). Its geometry was designed using finite element analysis and its durability was confirmed by testing both on various test devices and on a vehicle. The exhaust manifolds has been adopted on a production engine model and has proven the following advantages over a conventional cast-iron ones; excellent heat resistance. weight reduction of over 20%. possible exhaust emission reduction as a result of lower heat-capacity of the exhaust manifold.
Technical Paper

Analysis of Torsional Stiffness Share Rate of Truck Frame

In order to design a well-balanced truck frame, optimization of not only the stiffness of the entire body and stress of each member, but also the internal force of each member is necessary, including the effect of a rear body mounted on the frame. This paper proposes a new parameter, “torsional stiffness share rate,” that directly correlates the contribution of member torsional stiffness to frame torsional stiffness with the internal force of the members as to torsion of the truck frame. The merits of the torsional stiffness share rate are shown in comparison with the strain energy share rate and the stiffness contribution rate. The results of experimental and FEM analyses of the torsional stiffness share rate are also presented.
Technical Paper

A Study on a Simulation of a Head Form Impact Against Plastic Plates

A Finite Element Method (FEM) simulation was conducted to predict energy-absorbing characteristics in an impact of a head form against plastic plates. Static and dynamic material tests were conducted in order to determine material properties of the plastics. The properties were applied in an explicit FEM code. The FEM results were validated through the impact tests by the head form against the same plastic plates. It was proved that the FEM could simulate the test result well, when the precise material properties were introduced in the simulation. The method can be expected to be available to predict energy-absorbing characteristics during the impact by the head form against automobile plastic components such as shell portions of instrument panels.
Technical Paper

Development of Silicon Nitride Turbine Rotors

This paper describes fabrication of silicon nitride radial turbine wheels 90 mm in diameter. The wheels were hot spin tested without failure at turbine tip speeds up to 600 m/s. The reliability of shrink fit of metal shaft and ceramic wheel was demonstrated in a turbocharger test. Results of the hot spin test are discussed in relation to the nature of defects and compared with the analytic prediction using Weibull statistics and finite element analysis.