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This paper reports on the analysis of mechanisms concerning the engine exciting force and the rotational couple of forces. Because the new V10 engine has the biggest power and displacement which is 441kw and 30 litters respectively, its exciting force of 2.5th and 5th orders are very large. On the other hand, as the V-bank angular is 80 degrees, the additional 1st order yawing vibration is also occurred by the generation of the rotational couple of forces. So, the optimum design is needed to reduce these vibrations by the frequency response analysis when these forces are added to the engine crank shaft. Finally, the vibration level could be reduced much lower than the lower-powered engine by the optimum design of engine mounting by using the FEM and the adoption of the new mechanism for the cancellation of a rotational couple of force.

Every year the trucking industry demands lighter weight and lower cost truck components. But it is very difficult to achieve both these targets. This paper describes the example of a suspension system design which was conducted by computer simulation, so called CAE. The computer simulation by FEM was used completely to decide the detailed shape of each part. This paper also introduces a casting method to strengthen the aluminum alloy cast using high pressure during casting. By using this method, products have a precise metallographic structure. As a result, both the development cost and period were reduced by over the half the time required of the current system and lighter and strong parts were created.

Basically, it is recommended that non-linear analysis shoud be used with consideration for friction and etc., when engineers calculate to design the trunnion suspension system for heavy duty trucks. But non-linear analysis was very difficult. so linear analysis per piece parts was conducted under assumed conditions. According to this method, it is difficult to obtain the calculated values matching with experimental values, thus “trial and error” must be repeated consuming much man hours. Recently, accuracy of non-linear analysis has been improved by the progress of the super computer in conjunction with the development of soft-wear such as pre-post or solver. Now, non-linear analysis of the total suspension system was conducted by taking contact and friction between each part into consideration. while at the same time divergence of the solution was prevented by optimum modeling.

In this study, the air suspension is newly applied to the engine mounting layout for getting the significant vibration isolation effect. In this case, the genetic algorithm so called GA is also applied for the optimization of many parameters, calculations of stiffness matrix and inverse stiffness matrix to prevent the coupled vibration of lateral and rolling modes and to obtain the displacement of each mounting point. As a result, inexperienced engineers can easily obtain the optimum engine mounting layout in a minute. By the confirmation test of FEM, the engine lateral vibration level at 25Hz dropped below 1/10 and its effect was significant.

When a heavy duty truck with 2 rear axles is turning a curve at slow speed, a large side bending force to the chassis frame occurres as vehicle turning radius becomes smaller. In the past, the stress produced by side bending forces was little analyzed. By our research work of FEM, side bending stress of heavy duty truck could be analyzed accurately.