23-04-2012, 01:11 PM
To design a chassis and body of a truck.
chasis and body.docx (Size: 146.39 KB / Downloads: 70)
ABSTRACT
The paper investigates into the vibrational characteristics of the truck chassis including the natural frequencies and mode shapes. Truck chassis forms the structural backbone of a commercial vehicle. When the truck travels along the road, the truck chassis is excited by dynamic forces caused by the road roughness, engine, transmission and more. Modal analysis using Finite Element Method (FEM) can be used to determine natural frequencies and mode shapes. In this study, the modal analysis has been accomplished by the commercial finite element packaged ANSYS. The model has been simulated with appropriate accuracy and with considering the effect of bolted and riveted joints. After constructing finite element model of chassis and appropriate meshing with shell elements, model has been analyzed and first 6 frequencies that play important role in dynamic behavior of chassis, have been expanded. In addition, the relationship between natural frequencies and engine operating speed has been explained. The results show that the road excitation is the main disturbance to the truck chassis as the chassis natural frequencies lie within the road excitation frequency range. Finally advantages of the modified chassis which leads to the increase of the natural frequencies and placing them in the appropriate range, has been discussed.
DETAIL DESCRIPTION
The vehicle models that have been developed almost the same appearance since the models developed in 20 or 30 years ago. This indicates that the evolutions of these structures are still behind from other countries and research and development technology is not fully utilized in our country. This is a major challenge to truck manufactures to improve and optimize their vehicle designs in order to meet the market demand and at the same time improve the vehicles durability and performance. Since the truck chassis is a major component in the vehicle system, therefore, it is often identified for refinement and improvement for better handling and comfortably. The frame of the truck chassis is a backbone of the vehicle and integrates the main truck component systems such as the axles, suspension, power train, cab and trailer. The typical chassis is a ladder structure consisting of two C channel rails connected by cross-members as illustrated in Figure. Almost all the chassis development is varying in design, weight, complexity and cost. However, the effects of changes to the frame and cross-members are not well understood in term of vehicle response during riding especially on bumpy and off road conditions. For example, if the torsion stiffness of a suspension cross-member is lowered, what is the effect on the vehicle’s roll stability, handling, ride and durability? Therefore, the main criteria in the analysis are the behavior of truck chassis, how to improve the current design for better riding quality and suitably to customer needs.
On overall, this research study is really requiring attention to improve the existing condition for betterment of riding quality and comfortably. There are major areas need to be established in the study to come out with proper investigation on truck chassis especially research methodology on experimental and computational analysis. The ultimate result would be improvement of vehicle quality, reliability, flexibility, efficiency and low production cost.
Design goals
Vehicle Design
The predominant goal for the design of a commercial vehicle is economy during its use from acquisition until disposal ( minimal life cycle cost), and it is important to know that more than ¾ of the cost do not include the purchase. However, requirements of safety, handling and ride comfort, legal and environmental compatibility and aesthetics are also to be satisfied. Economy in a highly specialized industry means optimal performance, diversification of the design causing a multitude of types and as a consequence for the manufacture to limit production cost a modular composition of the vehicles.