Study On The Forward Design Method Of The Body Section Of Extruded Aluminum Profile

The car body stiffness is an important performance index in vehicle design, which is closely related to the safety and ride comfort of the train. To the extruded aluminum profile car body, the car body section is the foundation of the following design, the stiffness of the whole car body is directly determined by the stiffness of the section. At present, the research on the design of the extruded aluminum profile car body section cavity is not sufficient, and it has important engineering significance and theoretical value for the forward design of the car body cross section.At first, the paper introduces the background and significance of the research, the research status at home and abroad were analyzed, summarized the classes and methods of current car body section contour design and car body section profile design, then explains the research ideas and innovations. Subsequently, the development history of extruded aluminum profile car body and material advantages are described, and the development and application of forward design and reverse design are analyzed. Finally, the car body crosses section design method is introduced in detail. The design of the car body section is divided into three steps:First step, to solve the car body inside and outside contour line. According to the known vehicle gauges, calculated car body offset according to the CJJ96-2003 "Standard of Metro gauges" and reverse obtained key point coordinate-values on the outer contour line, and analysis the sensitivity of parameters in gauge calculation. In the observation of the relationship between the internal and external contour line of existing extrusion aluminum profile car body, summarizes the geometry relationship between the internal and external contour line of different parts on the car body, then calculated the internal contour line. Second step, the car body cross section stiffened plate layout design. With the thickness of car body skin, the thickness of the stiffened plate, the angle between stiffened plates and skins as variables to calculate the stiffened plate layout of different circumstances, and obtain key point coordinate-values which represent the position of the reinforced plate. Third step, the secondary development of Hypermesh. Realizing car body section parametric modeling and extracting section parameters, so as to calculate the car body section stiffness value. Calculation of the ratio of inertia moment and sectional area of a certain type of EMU and compare with the calculation results of the stiffened plate layout scheme of the car body to prove the validity of the method.Design the car body cross section contour and car body section stiffened plate layout in MATLAB, the input and output are all point coordinate-values, the parameters used in the calculation formula are expressed in the form of variables, with a certain type of EMU parameters as the default value, designers can change the parameters as needs. Carries on the secondary development to the Hypermesh to realize the car body cross section parametric modelling and the extraction of section parameters.This study uses forward design method, car body section stiffness performance oriented, section quality constraints, vehicle parameters for driving, stiffened plate thickness and angle as basis for parametric design, to avoid incorrect design, redundant design, reduce the iterations of engineering change, shorten the product development cycle effectively, reduce the cost of product development.