1 Stress Analysis and Design Validation of Crankshafts under Dynamic Loading using CAE Sanjay B Chikalthankar, V M Nandedkar, Surender Kumar Kaundal Abstract—The complicated geometry of crankshaft and the complex torque applied by cylinders make their analysis difficult. But optimized meshing and accurate simulation of boundary conditions along with ability to apply complex torque, provided by various FEA packages have helped the designer to carry vibration analysis with the investigation of critical stresses. As the crankshaft is subjected to varying load the dynamic analysis become critical with increase in excitation forces. This results in high natural frequencies of free vibration. Therefore crankshaft is analyzed for natural frequency, rigid body mode shapes, critical stresses and factor of safety by ANSYS. The main objective of this study was to investigate stresses developed in crankshaft under dynamic loading. In this study a dynamic simulation was conducted on crankshaft, Finite element analysis was performed to obtain the stresses developed in crankshaft. The pressure-volume diagram was used to calculate the load boundary condition in dynamic simulation model, and other simulation inputs were taken from the engine specification chart. This load was then applied to the FE model, and boundary conditions were applied according to the engine mounting conditions. Results obtained from the analysis are very useful in optimization of this crankshaft. Index Terms — Computer aided engineering (CAE), Finite element analysis (FEA), Experimental modal analysis (EMA), Crankshaft, forged, NX, ANSYS, Dynamic loading. ——————————  —————————— 1 INTRODUCTION Crankshaft is a large component with a complex geometry in the engine, which converts the reciprocating displacement of the piston to a rotary motion with a four link mechanism. Since the crankshaft experiences a large number of load cycles during its service life, fatigue performance and durability of this component has to be considered in the design process. Design developments have always been an important issue in the crankshaft production industry, in order to manufacture a less expensive component with the minimum weight possible and proper fatigue strength and other functional requirements. These improvements result in lighter and smaller engines with better fuel efficiency and higher power output. In recent studies crankshaft torsional vibration analysis was done by the empirical formulae and iterative procedures, but the simplifying assumption that a throw of crankshaft has one degree of freedom is only partially true for torsional modes of vibrations. More degrees of freedom are required to get information about other modes of vibration and stress distribution. Since last decade advent of powerful finite element analysis (FEA) packages have proven good tool to accurately analyze them. FEM enables to find critical locations and quantitative analysis of the stress distribution and deformed shapes under loads. However detailed modeling and specialized knowledge of FEM theory are indispensable to perform these analyses with high accuracy. They also require complicated meshing strategies. Simulations of actual boundary conditions to equivalent FE boundary conditions have to be done carefully because a wrongly modeled boundary condition leads to erroneous results. The solution of such large scale FEM problem requires both large memory and disc space as computing resources. 2 LITERATURE REVIEW An extensive work has been done on crankshaft to analyses the stresses using numerical simulation methods. But a few researches have carried for the complete analysis using FEA. The analysis becomes a CAE analysis, if FEA is to be used. The basic literature available is provided by Jouji Kimura presented the correlation between the crankshaft torsional vibrations and the dynamic stresses at the front and rear fillets of the first crankpin under operating conditions. Kripal Singh [18] explained construction of crankshaft in detail. R.Heath [12] explains simple modeling techniques and discusses simulation of boundary conditions. V. Prakash [6] discusses simulation of boundary conditions. The theory of dynamic analysis and the practical approach using these theories. Peter and Chung [4] had studied the crankshaft torsional vibrations a long back. They described a refined method for the analysis of a crankshaft torsional vibration. Hans H. Mullar had given stress concentration factors; these were used for crankshaft fillet stress analysis. The theory of vibration analysis using FEM is well explained in [20]. Shrinivasa presented procedure to design crankshaft for finite life. P.Seshu also analyzes the crankshaft torsional vibration using finite element analysis. 3 MEASUREMENT OF NATURAL FREQUENCY Now we have to find the natural frequencies for the crankshaft by using FFT machine & ANSYS software. The dynamic analysis is the analysis of the system under consideration when forces are acting on the system. It considers external excitation forces and inertia forces. FEA approach is widely used to solve dynamic analysis problems. The dynamic analysis is divided into two types either transient or frequency response. In case of transient response the forcing functions are defined as functions of ————————————————  Prof. Sanjay B Chikalthankar, Department of mechanical engineering, Govt. College of Engineering, Aurangabad, (M.S.) India. E-mail: sbchikalthankar@gmail.com  Prof. V M Nandedkar, Department of Production Engineering, SGGSIE&T, Nanded, (M.S.) India. E-mail: vilas.nandedkar@gmail.com  Surender Kumar Kaundal is currently pursuing masters degree program in mechanical engineering, Govt. College of Engineering, Aurangabad,(M.S.) India. E-mail: suren.kaundal@gmail.com