Diesel Engine Body Coupling Analysis And Experimental Research

Under the global background of less energy sources and rigorous law of environment conservancy, the technology and the intensification coefficient of diesel engine improve quickly. So engine block is subjected heavier and heavier thermal loads and mechanical loads. Block is the basis and skeleton of the diesel engine, its deformation and stress under the fired engine operation mode determines the performance of engine assembly. This paper presents a research on coupled thermal-mechanical analysis of2D25horizontal twin diesel engine block by FEM and experimental test. So using FEM to calculate and analyze the temperature field and thermal-mechanical coupling stress distribution of engine block.1. Establish FEMEstablish the3D model of engine block, cylinder head, gasket, liner, and main bearing cap, crank case cover and bolt group using the software UG. Then mesh them and build up its FEM assembly by software SIMLAB.2. Natural Modal AnalysisUse both of the calculating modal analysis and experimental modal analysis to obtain the natural frequency and vibration mode of engine block. The first natural frequency of engine block is372.36Hz, it will not resonance in the working time. The vibration mode of experimental modal analysis and calculating modal analysis is same, and the error of natural frequency is less than7%. So the results prove that the fern modal is accurate and reliable.3. Temperature Field AnalysisThe temperature field of cylinder liner is measured. According to the measurement results, correct the heat transfer boundary again and again, in order to obtain the engine block assembly’s temperature field whose error is less than3%between calculating result and experimental result. Respectively, the temperature of block, cylinder head and liner is177.6℃,201.5℃and346.3℃The results offer the heat boundary conditions for the coupled thermal-mechanical analysis.4. Coupled Thermal-mechanical AnalysisBased on the temperature field, set up the contact, displacement, load boundary conditions reasonably. Then calculate and analyze the mechanical stress field and the thermal-mechanical coupling stress field of engine block assembly, which all under the maximum torque working condition. Both the results of above two conditions show that stress concentration locate in the areas of bolt holes. The heat load contributes to the whole block structure is less, but it influences some local regions more. It’s safe enough to meet the working condition.5. Strain gauge testFinally do the strain gauge test of the engine block and analysis the test result, meanwhile, Comparative analysis of the FEA results and test results, there are some error between them, but the results show the stress and displacement of the engine block accurately. In conclusion, it makes sure that the coupled thermal-mechanical FEA modal which established in this paper is reliable.