Connecting Rod Design using a Stress Analysis of 3D CAD

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1 The 4th International Conference on Design Engineering and Science, ICDES 2017 Aachen, Germany, September 17-19, Connecting Rod Design using a Stress Analysis of 3D CAD (Automatic computation of Compliance Matrix) Toshiaki KANDA *1, Masatoshi NIIZEKI *2, Nariaki UOI *3 and Toshihiro OZASA *4 Osaka Electro-Communication University 18-8 Hatsu-cho, Neyagawa-shi, Osaka , JAPAN *1 Department of Graduate School of Engineering, Division of Mechanical and Control Engineering mm16a001@oecu.jp *2 Faculty of Engineering, Department of Electro-mechanical Engineering niizeki@osakac.ac.jp *3 Department of Graduate School of Engineering, Division of Mechanical and Control Engineering mm14a001@oecu.jp *4 Faculty of Engineering, Department of Electro-mechanical Engineering ozasa@isc.osakac.ac.jp Abstract Conventionally, lubrication analysis is conducted to clarify lubrication phenomena of an engine [1][2]. However, if exercise process analysis if necessary, we must take elastic deformation into consideration [3]. This is called Elastohydrodynamic-lubrication analysis. Currently, experiments to create a prototype software to conduct Elastohydrodynamic analysis is being conducted. Experiments using a simulation software is being conducted to find the best model for analysis. This has shown that the computing cost of creating the actual model is enormous. Furthermore, analysis of the simulation software requires deep understanding of PC and analysis software [4]. The goal of this study is to shorten the analysis time and simplify the process of analysis so that analysis can be performed regardless of the presence or absence of Computer aided design skills. Keywords: computer aided design(cad), computer aided engineering(cae), finite element method(fem), elastohydrodynamic-lubrication (EHL), connecting rod, engine 1 INTRODUCTION In the current engine design, it is necessary to consider the distortion of the structure during operation [1][2][7]. Conventionally, in order to perform EHL analysis of a structure using the finite element method (FEM), a great deal of time is necessary for the creation of the shape data [3][8][9][11][12]. Also, it is not easy to apply the process to design with a parametric size change of the structure, and the relationship of the oil film pressure and bearing deformation must be determined by an FEM analysis. The matrix necessary for the analysis must be extracted from the structural analysis software, and this requires inside knowledge of structural analysis software. This is the reason that although the necessity to consider the EHL analysis has increased, it has been considered not very practical. EHL analysis would be extremely useful if it can be used in engine design. The use of the oil film stress as a result of the EHL analysis as boundary conditions of the structural analysis will produce much more realistic results in the stress analysis. [3][11][12][13][14][15] Conventionally, the time for the analysis in this research takes about one whole day [3]. The workload can been drastically reduced as a result of reviewing the analysis process and this will reduce the burden on workers to about as little as nine hours. We eliminate burden by automating the enormous amount of work such as input of load value every angle. Furthermore, by creating shape data suitable for analysis, we realized a significant reduction in time. 2 METHOD 2.1 FEM The Finite Element Method (FEM) decomposes objects with complex shapes and properties to simple element levels [10]. FEM calculates values for the whole as an approximate value by conducting simple calculations for each element and adding up the results [9]. By using this method, even complex shapes can be analyzed using a simple computational method. Accurate analysis results of complicated model shapes cannot be obtained without dividing the shape into a very fine mesh. For this reason, in this research we will create a fine mesh and obtain the computation time of each FEM analysis. Since the analysis time varies depending on the number of elements, a fine mesh requires an enormous amount of analysis time. Therefore, it is ideal to carry out calculations with as simple a model as possible. However, even with a simple model, the analysis time greatly varies depending on the processing speed of PC. When analyzing, it is necessary to pay attention to the processing speed of the PC. Also, using a fine mesh does not necessarily lead to the best results. An appropriate mesh must be used considering the stress concentration. Copyright 2017, The Organizing Committee of the ICDES 2017

2 2.2 Compliance Matrix A compliance matrix is computed during the structural analysis of the connecting rod. This matrix is obtained by adding the load to the inverse matrix of the stiffness matrix. Normally, the stiffness matrix for the structural analysis is computed according to the automatically divided mesh. However, with the automatically generated mesh, it is not possible to generate uniform node coordinates. Therefore, it becomes necessary to adjust the values to a regular calculation grid which can be used for the later lubrication analysis. In this research, we change part of the model creation procedure to simplify the computation of the compliance matrix. The modification is as follows: Before creating the mesh, model the shape of the connecting rod so that the vertices of the rod itself is included in the model. This means approximating round shapes with straight lines in the model. Modeling in this manner results in predetermined positions of mesh nodes. This modeling technique allows shortening of the creation time of the compliance matrix for this study. 2.3 Elastohydrodynamic-Lubrication (EHL) From the Reynolds equation, the following equation is obtained [1] This relationship links the variables (Clearance [m]), (Pressure [Pa]), (Bearing Radius [m]), t (time [s]), U (Speed of Journal Surface [m/s]), (Bearing Angle [rad]) and (Viscosity [Pa s]). Figure 1 shows the journal and the bearing during the lubrication analysis. cos sin cos sin tan 2 In the case of a connecting rod, because the moment of the bearing force on the piston head side must be zero, the equilibrium equation of the force must be as shown in the above formula. This formula links the variables (Bearing width [m]), (Distance between bearings from piston head to crankshaft [m]), (Bearing load in X direction []), (Bearing load in Y direction []) and (Shear force []). Therefore, the clearance between the shaft and the bearing, that is, the oil film thickness is given by the following equation obtained from the simultaneous equations of Equations 1 and 2 [3]. sin cos cos sin cos sin 3 This equation is solved for the area of 0 from the above equation. For the areas other than the in analysis target, we set 0. The variable (Radial clearance serving as reference of bearing [m]), (Eccentricity of journal center in X direction [m]), (Eccentricity of journal center in Y direction [m]) and (Deviation from the bearing circle as the reference of the bearing shape [m]) is used. When of the whole bearing surface is represented as a vector, the following expression is obtained. 4 They link the variables (Circle clearance) and (Compliance Matrix). In this study, 0. From the above equation, a stiffness matrix is calculated by the three-dimensional CAD analysis and a compliance matrix is obtained from the result. This makes it possible to calculate the deformation of the bearing. 2.4 Export and Import In this research, the 3D CAD software CATIA was used. In this software, loads are applied to the model by the importing function, and a stiffness matrix calculated by is extracted using the export function. Figure 2 shows an example in which the coordinate values of the created mesh nodes are divided from nodes of all models by one point and only one point is displayed. Fig 1. Conceptual diagram of lubrication analysis

Fig 2. Text data before import However, this study succeeded in shortening the time and simplifying the work by creating macros (auto mode) for the process.

These generated points are used to obtain the exported coordinate values. The exported points are positioned in the area on the inner surface of the bearing on the crankshaft side. 2.

Compared to past research, we aimed to shorten the time and workload of lubrication analysis. Previous papers added a small load was manually to each angle component to calculate the stiffness matrix.

Model creation Creating a load point Make the loading point of the bearing surface extractable. Export coordinate values of all load points the bearing surface Fig 3.

3 Fig 2. Text data before import However, this study succeeded in shortening the time and simplifying the work by creating macros (auto mode) for the process. The process is simplified by not creating of the point for each applied load, and using automatic meshing to generate the points where the load is applied. These generated points are used to obtain the exported coordinate values. The exported points are positioned in the area on the inner surface of the bearing on the crankshaft side. 2.5 Comparison with Conventional Analysis Method As mentioned earlier, conventional analysis requires much time and also CAD skills. Compared to past research, we aimed to shorten the time and workload of lubrication analysis. Previous papers added a small load was manually to each angle component to calculate the stiffness matrix. outward from the axis center to this divided data point to calculate the stiffness matrix. The result of this analysis produces the above-mentioned compliance matrix. Model creation Creating a load point Make the loading point of the bearing surface extractable. Export coordinate values of all load points the bearing surface Fig 3. Export (Mesh display of the model from the left, display only the mesh node, display of points only on the bearing surface) When CATIA is in the state shown on the right side of Fig. 3, a text file in which coordinate values are written is extracted by performing the export function. This is shown in Fig [5][6]. Fig. 4 Text data created by export Fig. 4 shows all the coordinate axis data of the mesh node. Fig. 2 shows this divided into one coordinate. Analysis is conducted by applying a force of 1 [N] in the direction Compliance Matrix EHL Fig 5. Flowchart of conventional analysis method Fig. 5 shows a conventional analysis procedure. By focusing on "exporting load point on the bearing surface" and "export" in the Figure, we succeeded in greatly shortening the time and reducing the amount of work by using mesh shapes optimum for automation and analysis by the program. 3 RESULTS The analysis results obtained in this study are shown below. Calculate the result when the crankshaft rotates two turns at 1,000 rpm in the clockwise direction in increments of 10 degrees. However, we will focus on the thermal expansion of the engine stroke where the load is most applied to the connecting rod, and the contents will be shown hereafter. A graph created by dividing the bearing surface at that time every 5 corner is shown in Fig. 6 below. Calculate by dividing the bearing surface at that angle every 5 corner and calculate the load exerted in the outward direction from the axis center. The graph drawn with the maximum pressure at that time is shown on the vertical axis pressure, the horizontal axis is the bearing angle, and the depth direction (Z axis) is divided into 11.

visually grasp the deformation amount of the entire connecting rod model during operation. This is shown in Fig. 7.

6 into the connecting rod bearing surface on CATIA and calculating the stress of CATIA, it is possible to Fig 6. EHL analysis at crank angle of 390 Oil film pressure Fig 7.

4 visually grasp the deformation amount of the entire connecting rod model during operation. This is shown in Fig Bearing angle[deg] Pressure[MPa] By inputting the pressure value of the graph result of Fig. 6 into the connecting rod bearing surface on CATIA and calculating the stress of CATIA, it is possible to Fig 6. EHL analysis at crank angle of 390 Oil film pressure Fig 7. Stress results at crank angle of 390 Work content Table 1. Content of analysis and time spent Before After Create Creating a load applying point - Export 8h Import 8h Total 18h 3h = No working time This result is the analysis result at the time of expansion which has the largest load during the engine stroke. From the graph, it can also be observed that stress concentration is directed from the piston side to the crankshaft side, and this is corresponds to the results obtained from the CATIA analysis. Table 1 describes the required time and the analysis process for this research. Previously, the manually conducted analysis required a huge amount of time, but the new process in this research succeeded in lowering the worker's burden rate by partially automating and other optimizations. As a result, a single model analysis can be analyzed in less than three hours, and the workers' CAD skills are no longer necessary. Now, the work by automation has become burdensome to the PC and the total time relies more on computational power.

5 4 DISCUSSION The results in this study are limited to static analysis. To obtain more reliable results, analysis of motion in the engine stroke must also be considered. In addition, deformation due to heat should also be considered. Also, in order to approach a practical connecting rod model, we must challenge the EHL analysis including small parts such as bolts and nuts included in the connecting rod. 5 CONCLUSIONS In this paper, the stress analysis of the connecting rod during the engine stroke was discussed. The analysis can be conducted in much less time and has become easier to conduct than before. REFERENCES [1] Niizeki, M., Hirose, Y., Kinoshita, A., Ozasa, T.: Elastohydrodynamic-lubrication analysis of journal bearing using CAD (1st report - Calculation method), Japan Society for Design Engineering, 50 (2015) 44. [2] Niizeki, M., Hirose, Y., Kinoshita, A., Ozasa, T.: Elastohydrodynamic-lubrication analysis of journal bearing using CAD (2nd report -Application and stress analysis of Connecting rod for engine), Japan Society for Design Engineering 50(2015), 52. [3] Ozasa, T., Kinoshita, A., Hirose, Y.: Elastohydrodynamic Lubrication Analysis of Journal Bearings Using CAD, The 3rd International Conference on Design Engineering and Science, , Sep [4] Niizeki, M., Kanda, T., Morihama, H., Hirakawa, K., Uoi, N., Ozasa, T.: Research on connecting rod design method using three dimensional CAD, Japan Society for Design Engineering Kansai branch, (2015) 49-54, Printed in Japanese. [5] Zamani, N. G., Weaver, J. M.: CATIA V5 Tutorials, Mechanism Design & Animation (Releases 14 & 15), SDC Publications, [6] Zamani, N. G.: CATIA V5 FEA Tutorials Release 15, SDC Publicaions, 2006, [7] Huang, P., Numerical calculation of lubrication Methods and programs, WILEY, [8] Huang, P., Numerical calculation of lubrication Methods and programs, WILEY, [9] Kishi, M.: Introduction to illustration, Basic and framework of latest finite element method, SHUWA SYSTEM, Printed in Japanese. [10]Shao, C.: Finite Element Method understood from basic, Morikita Publishing, 2008(2009), Printed in Japanese. [11]Ozasa, T., Yamamoto, M., Suzuki, S., Nozawa, Y., Konomi, T.: Elasto-hydrodynamic Lubrication Model of Connecting Rod Big End Bearings; Comparison with Experiments by Diesel Engine, SAE1995 Transactions Journal of Fuels & Lubricants 4-104(1996), No , [12]Suzuki, S., Ozasa, T., Yamamoto, M., Nozawa, Y. and Konomi, T.: Elasto-hydrodynamic Lubrication Characteristics of Connecting Rod Big End Bearings, SAE 1995 Transactions Journal of Fuels & Lubricants Section (1996), No , [13]Fantion, B., Godet, M., Faene, J.: Dynamic Behavior of an Elastic Connecting-Rod Bearing -- Theoretical Study, SAE Paper (1983) [14]Goenka, P. K., Oh, K. P.: An Optimum Short Bearing Theory for the Elastohydrodynamic Solution of Journal Bearings, Transactions of the ASME, Journal of Tribology, 108 (1986), 294. [15]Mclvor, J. D. C., Fenner, D. N.: Finite Element Analysis of Dynamically Loaded Flexible Journal Bearings: First Newton-Raphson Method, Transactions of the ASME, Journal of Tribology, 111(1989). Received on December 30, 2016 Accepted on March 21, 2017

Computer Life (CPL) ISSN: Finite Element Analysis of Bearing Box on SolidWorks

Computer Life (CPL) ISSN: Finite Element Analysis of Bearing Box on SolidWorks Computer Life (CPL) ISSN: 1819-4818 Delivering Quality Science to the World Finite Element Analysis of Bearing Box on SolidWorks Chenling Zheng 1, a, Hang Li 1, b and Jianyong Li 1, c 1 Shandong University