Keywords: truck frame, parametric modeling, cross-section.

Transcription

1 Key Engineering Materials Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland A Research and Application of Parametric Modeling Technology for Truck Frame Base on ANSYS Chai Shan 1,a,Wang Yougang 1,b, Wang Pengcheng 2,c, Li Lijun 1,d, Gang Xianyue 1,e 1 Shandong University of Technology, Zibo, Shandong, P.R.CHINA Harbin Institute of Technology at Weihai, Weihai, Shandong, P.R.CHINA a chaishan@sdut.edu.cn, b wyg6178@126.com, c wangpengcheng3930@126.com, d lilijun@sdut.edu.cn, e gangxianyue@sdut.edu.cn Keywords: truck frame, parametric modeling, cross-section. Abstract. The parameters and controlled dimensions of design objects have an explicit correspondence relation when the parameters are given different values, the different models are created. This paper discusses the parametric modeling technology of truck frame. Building the spare parts by controlling the position of the cross-section, geometry and the numbers of the Key Point.It provides a feasible scheme of the parametric modeling of the truck frame. 1 Introduction Automotive frame is the base of the whole vehicle, on which most majority of parts and assemblies are fixed, and variety of exterior loads is applied. In the process of finite element analysis of truck frame, shell element is usually used to simulate the steel plate. Since there may be various kinds of errors when the area geometry model established in three-dimensional CAD software is imported into ANSYS, it is required to build the geometric modeling of frame in the ANSYS. The traditional method of modeling is inefficient and fallibility. How to make a CAE systems express the designer s intention and complete products design with less operation becomes a problem to be solved with CAE software. urgently. Using parametric modeling technology to build truck model in ANSYS is an effective way to solve this problem [1]. 2 The parametric of longitudinal beam and transverse beam of truck frame 2.1 Parametric Design Method Study Fringe-beam frame is widely used in truck frame structure. Therefore we take it as example to illustrate the parametric design method. Fringe-beam frame consists of two longitudinal beams and several transverse beams; and there are several types of the frame, such as the width of the front beam equal the back beam, the back is wider than the front, the back is higher than the front. Generally speaking,the section of the longitudinal are uniform, but sometimes variable cross-section are necessary according to the arrangements. There are two ways to change the cross-sections: one is reducing wing of the U-section, the other is reducing web of the U-section. In order to avoid stress concentration, no matter which method is used, the transition must be uniform [2]. Usually, there are available shapes of the longitudinal beams such as L shaped, Z shaped, box-shaped, and so on. The process of parametric modeling is summarized as following: (1) create the key points of the cross section of the longitudinal beam on work plane;(2)connect the key points into lines, then connect the lines to create the cross-section;(3)move work plane, to create the next section; (4) Create areas with the key points of two adjacent cross-section (5) completed the model of longitudinal beams and transverse beams. Take the U-section of the longitudinal beam for example as the figure below: All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-13/05/16,09:10:48)

2 Key Engineering Materials Vols Figure 1 U-section longitudinal beam To establish this beam; first of all, create four key points of the first section (in the Figure 1, use the circular point to indicate), and then connect the key points into lines. The first cross-section of the beam has been completed. The coordinates of the four key points are described with the frame parameter. At the mid-point of the beam determine the origin of working plane, and then given the size of the frame sections W1, W2, W3, you can obtain the coordinates of points. Next, using the ANSYS command to move the plane, move it along the Z axis by W4, and then do the same operation to create the key points. At last, we can create the areas that between the two cross-sections by these key points. Through the introduction of the above, we can obtain the parameters that to establish the beam needed: width and height dimensions of two cross-sections, the origin of working plane, the direction of axis, and the distance of the plane movement, in other words the distance between the two cross-sections. Other beams can be created by the same way. 2.2 The creation of key points Frame modeling is beginning from the creation of the key points, and then creates the line and area through key points. Using the APDL commands to create key points need to provide the points coordinates on the working plane. Point position can be determined by the user input data. In general, the key points of different cross-sectional shapes are different. The following figure indicated the key points and store sequence of different cross-sectional shapes. Figure 2 Cross-section and store sequence of the key points 2.3 The establishment of the frame topology So-called topological relations are connectting relationships between two key points. Actually, the frame is created by areas between two adjacent cross-sections. APDL has the commands of create points. Key points should be properly chosen to create the required areas. Therefore, correct topology

3 536 Components, Packaging and Manufacturing Technology of the key points between two key points should be determined. Make full use of the function of storage array applying the key point number by determine the topological relationship. Points are stored in the array by number and the specific key points of the different sections are set in the array for the same column. If there are a number of U-section, regardless of the size parameters of cross-section, the first key point number of the cross-section is only stored in the first column of the array. Store the key points by numbers are easy to determine which key points should be used when create an area. 3 Reinforcing plate Parametric Reinforcing plate has variety of types. Six types of reinforcing plates are shown in Fig.3 Figure 3 Reinforcing Plate There are six kinds of reinforcing plate in the above figure: triangle, square, pentagonal, hexagonal, heptagonal, and octagonal. K1 ~ K8 represents the numbers of the key points. When you create the reinforcing plate, select its type,and the system will identify how many key points are needed to compose the reinforcing plate. A reinforcing plate can be created after input the coordinates of key points. 4 Rivet holes parametric In most cases, the longitudinal beams are connected with transverse beam by rivet. In order to simulate the real connections, we must punch rivet holes. The method is to create cylinder at the same location of rivet holes and the cylinder diameter is equal with the size of the rivet holes. The cylinder is among the longitudinal beam, transverse beam and rivet holes. Useing the APDL command area by volume under the APDL command divide, and then select the longitudinal beam, transverse beam and the cylinder. Punch rivet holes by this and ensure that all rivet holes are coaxial. 5 The System Design of Parametric Modeling The system of parametric modeling for frame is divided into five parts, which are parameter input data file modify, model regenerate, mapping, and frame punching. The system will pop-up the corresponding message box for input every click. The fig.4 shows the flow chart for this system. 5.1 Parameter Input The longitudinal beam and transverse beam contain infinite plane of the sections. The model of longitudinal beam and transverse beam could be created by creating and connecting all planes of the sections. The structure of reinforcing plate is relatively simple. To build its model, the key points must be obtained firstly according to the actual position. Based on this the area could be created. Thus the building of the model of reinforcing plate is completed. The interface to input the parameters is shown in Figure 5. (1) The relative coordinate and absolute coordinate. The relative coordinate can be obtained according to the relative position of section to be

4 Key Engineering Materials Vols built and the previous one. The absolute coordinate can be obtained according to the position of the section to be built in the absolute coordinate system. (2) The translation and revolution of the working plane. The working plane can be established based on the inputted translational displacement and revolution angle. (3) ID. A number to define the information of a section. (4) Sub-type. There are eight kinds of the sections available to be chosen. They are the circular-shaped, box-shaped, U-shaped, hat-shaped, L-shaped, T-shaped, I-shaped and Z-shaped. Besides, the reinforcing plate can be built with the key points. Eight key points can be chosen at most. (5) W1,W2,W3 and W4 are used to ascertain the geometry shape of the section. Parametric Modeling System of Truck Frame Parameter Input Modify datafile Re-generate model Reflect Perforation Input datafile name Select datafile Input datafile name Slect component Slect component No Exit No Datafile existed? Yes Overwrite it? Yes Input line number Modify data Generate model Finish reflect Finish perforation Input parameters interface Generate datafile Execute datafile Generate model Figure 4 Flow charts of parametric modeling Figure 5 The Message Box for Parameter Input Figure6 The message box to modify the data files

5 538 Components, Packaging and Manufacturing Technology 5.2 The modify of data file The modification of data file can be classified as follows (as is shown in Figure6): (1) modify the certain line of the file; (2) add new data to a certain line; (3) delete a certain line. After modification of the file, the button of OK on the interface must be clicked to make sure that the new data is input to the original file. 5.3 Re-generate the model After modify, click the message box for "re-generate the model, and then input the requested file. If the file read in is the one that you modified, just click OK. Then, ANSYS run the external modeling program automatically (macro file); the revised geometric model generated, and also used the file name that user input to establish components. Meanwhile, the previous model will be deleted. 5.4 Mapping Build half of the model first if it is symmetry. Then use the ANSYS command mapping to generate the other half of the model (of course, you could build the whole model in one time).above all, move the work plane as the symmetry plane. With click mapping menu of the ANSYS modeling system, the message box popped up will list all components that have been created. Select components to map and click OK, ANSYS will call the external program automatically and map the other half of the component. A new component formed by the new part and named in such a way that its name is add -c on the back of the previous one. For example, maps a component named zong ; the new part formed another component named zong-c. The two parts take working plane as the symmetric plane. This mapping program can map 20 components at the same time. 5.5 Frame Punching This part achieves the function of creating rivet holes on the frame longitudinal beam, transverse beam and reinforcing plate. The process of punching is to create cylinders at the right position of same diameter with the hole and use the cylinders to surface type of components. Then use the Boolean operation - divide in the ANSYS to punch on the right position for frame. After complete the last hole, delete all cylinders. 6 The example of system design for parametric modeling Taking a truck frame for example, establish the frame geometry model, which is shown in Figure 7: Includes two longitudinal beam, which are generate by define four cross-section; six beams, the cross-section of which are U-type; reinforcing plate between longitudinal beam and transverse beam, the shape of which are hexagon. Punching rivet holes among the longitudinal beam, transverse beam, and reinforcing plate. 7 Conclusions In this paper, we studied the method of parametric modeling for truck frame, resolved the problems of long period and low efficiency that exist in the traditional modeling process. In recent years, achieving parametric modeling is the issues that many structural analysts concerned. To achieve parametric modeling for frame, make it possible to reduce the repetitive workload and the time for finite element analysis.

6 Key Engineering Materials Vols References Figure 7 Frame geometry model [1] Zhao Dong. Parametric Technology in Ship Structural Design [J]. Ship Science and Technology2006,28(6):131~133 [2] Li Feng, Liu Yan. Brief Discussion on heavy truck frame design[j] Heavy Truck 2001(6):18~19 [3] Zhou Ning. APDL advanced engineering application analysis and secondary development. Beijing: China Waterpower Press, 2007 [4] Zhao Yujun. Chinese version of Visual Basic training curricula Beijing: Posts & Telecom Press, 2002 [5] Hu Xiaoyu. Basic Finite Element Method. Beijing: Tsinghua University Press, [6] Hu Chunyu. The Investigation of Complicated Inlet s Parametric Modeling Based on ANSYS: [a master's degree thesis]. Guangxi: Guangxi University, Mechanical College, 2007 [7] Chen Zongtie. Grinder Parametric Analysis System Based on ANSYS: [a master's degree thesis]. Guangxi: Guangxi University, Mechanical College, 2007

7 Components, Packaging and Manufacturing Technology / A Research and Application of Parametric Modeling Technology for Truck Frame Base on ANSYS /