Crankshaft Stress Analysis—Combination of Finite Element and Classical Analysis Techniques

Abstract

The conflicting legislative and customer pressures on engine design, for example, combining low friction and a high level of refinement, require sophisticated tools if competitive designs are to be realized. This is particularly true of crankshafts, probably the most analyzed of all engine components. This paper describes the hierarchy of methods used for crankshaft stress analysis with case studies. A computer-based analysis system is described that combines FE and classical methods to allow optimized designs to be produced efficiently. At the lowest level simplified classical techniques are integrated into the CAD-based design process. These methods give the rapid feedback necessary to perform concept design iterations. Various levels of FE analysis are available to carry out more detailed analyses of the crankshaft. The FE studies may feed information to or take information from the classical methods. At the highest level a method for including the load sharing effects of the flexible crankshaft within a flexible block interconnected by nonlinear oil films is described. This method includes the FE modeling of the complete crankshaft and the consideration of its stress field throughout an engine cycle. Fatigue assessment is performed to calculate the distribution of fatigue safety factor on the surface of the crankshaft. This level of analysis can be used for failure investigation, or detailed design optimization and verification. The method is compatible with those used for vibration and oil film analysis.

Dual metal crankshaft for heavy‐duty engines by cast‐joining of DCI and forged steel

“…6. As suggested by Heath, 6 one major advantage working with a full crankshaft is no need to pay attention to setting up the critical load case, which is especially important and also difficult to define in case of only one or half throw analysis. For instance, Piraner 3 proposed that one throw model had to be simulated with at least 60 load cases for an eight‐cylinder Vee engine to find the critical load case.…”

Analysis of rigid-flexible coupled torsional vibration and vibration suppression of crankshaft system under multiple working conditions

“…The conventional research methods for addressing crankshaft system torsional vibration problems mainly include the concentrated parameter method 3,4 and finite element method. [5][6][7] The former method involves dividing the crankshaft system into finite shaft segments and establishing differential equations for 1 Southwest Petroleum University, No.8 Xindu Avenue, Chengdu, Sichuan, P.R. China 2 Southwest Oil and Gas Field Gas Branch of PetroChina Co., Ltd., Chengdu, Sichuan, P.R.…”

“…The conventional research methods for addressing crankshaft system torsional vibration problems mainly include the concentrated parameter method 3,4 and finite element method. 5–7 The former method involves dividing the crankshaft system into finite shaft segments and establishing differential equations for the vibration of the shaft system to determine the natural frequencies and vibration patterns. However, this approach increases computational complexity with the division of shaft segments and provides relatively limited solution results.…”

Multidisciplinary Design Optimization of Crankshaft Structure Based on Cooptimization and Multi-Island Genetic Algorithm

“…Consequently, it is a key factor to choose a suitable algorithm to solve this issue. Studies on crankshaft of reciprocating compressors mainly focus on vibration and stress analyses [7][8][9][10]. Although stress analyses of crankshafts are available in literature, there are few studies on the optimization of crankshaft.…”