Modal Sensitivity Analysis And Structural Optimization Of The Cab Of Heavy-duty Truck

Nowadays, the world industrially advanced country takes the automobile industry as one of the national economy pillar industries. The competition in automobile industry is the technology competition in the final analysis. The automobile industry in our country has mainly developed by joint venture and introducing into advanced technology in a long period time. As the rapid development of computer technology, CAE analysis technology has also been rapidly developed. In west developed counties, CAE technology has been widely applied in the process of the new car's development and has acquired great success. In our country, CAE technology is comparatively dropped behind, especially on the dynamic characteristics of the new product analysis, which still at an early stage, and particularly in the development of heavy-duty trucks.This paper was from a project which is the design of the cab of a Heavy-duty truck, according to the result of dynamic characteristics by modal analysis method that the first torsion frequency of the cab was a bit low; put forward an optimization design project to enhance the first torsion frequency.The main task of this paper included:1. Briefly introduced the CAE technology in the application of the modal analysis for new product in automobile industry, and introduced the application of the sensitivity analysis and structural optimization in the automobile design.2. Finite element model of coupling of shell and beam element of heavy-duty trucks was created, feasibility was validated.3. Sensitivity analysis of the finite element model of coupling of shell and beam element of the cab based on the beam mechanics characteristic that was the design variable was done. According to the result, sensitive beam parts were found, which was prepared for the structural optimization in the next part.4. According to the sensitive beam part, sensitive area in the FEA model was found, topography optimization in the sensitive area was done; According to topography optimization result, three optimization design projects was put forward, the second project was taken and relative static analysis, modal analysis was done to validate the model in the project.In the part of creating the finite element model of coupling of shell and beam element of heavy-duty trucks, the process of selecting the optimization area and particularizing the name and thickness of the component of the optimization area was introduced; then the beam cross-section line in the representational area was selected, the beam section line was edited and put to the property collector, the beam element of the doorframe was created area after adjusting the orientation of the beam cross-section; the rigid single-point connections was adopted to connect the beam element of the doorframe area and the shell element of the other area of the cab, then the finite element model of coupling of shell and beam element was created, and relative static analysis, modal analysis was done to validate the model.In the part of modal sensitivity analysis based on the finite element model of coupling of shell and beam element of heavy-duty trucks, dynamic structure modification method, the concept of sensitivity analysis and the modal sensitivity analysis theory was introduced; then the process of modal sensitivity analysis based on the finite element model of coupling of shell and beam element of heavy-duty trucks was presented, according to the result, sensitive beam parts were found, which was prepared for the structural optimization in the next part.In the part of the structural optimization of the cab, the modal sensitivity analysis result based on the finite element model of coupling of shell and beam element of heavy-duty trucks and the case of particular components of the doorframe area were taken into account at the same time, then the optimization area was selected, and the topography optimization in the optimization area was done to enhance the first torsion frequency of the whole cab, this was prepared for the optimization design projects in the following work. According to the topography optimization result, three optimization design projects with the cross-section shape showing in optimization area were put forward. In the three optimization design projects, the first torsion frequency of the whole cab was enhanced to some extent and the whole mass of the cab was kept the same. In the second project, relative static analysis was done to validate the model, the torsion and bend stiffness was reasonable, and the project is satisfied.This paper did the research based on the finished relative research work, according to the result of dynamic characteristics by modal analysis method that the first torsion frequency of the cab was a bit low; an optimization design project to enhance the first torsion frequency was put forward. In the process of putting forward the optimization design projects, the finite element model of coupling of shell and beam element was created, the doorframe area was expressed by the beam elements in order to describe the beam cross-section mechanics property by parameter, and then the parameter was used as design variable; in the following, the modal sensitivity analysis based on the finite element model of coupling of shell and beam element of heavy-duty trucks was made, according to the result, sensitive beam parts were found; the optimization area was selected subsequently, and the topography optimization in the optimization area was done to enhance the first torsion frequency of the whole cab, according to the topography optimization result, three optimization design projects were put forward. In the second project, relative static analysis was done to validate the model, the torsion and bend stiffness was reasonable, and the project is satisfied.