Review of Analysis Method of Piston

Transcription

1 Volume-6, Issue-2, March-April 2016 International Journal of Engineering and Management Research Page Number: Review of Analysis Method of Piston Chetan R. Patil 1, Prasad P.Kulkarni 2 1 Assistant Professor, Sandip Foundations's S.I.E.M, Nashik, INDIA 2 Assistnat Workshop Supritendant, Sandip Foundations's S.I.E.M, Nashik, INDIA ABSTRACT This paper discuss the method of analysis of piston using FEA software.here we investigate stress distribution over piston.by using the FEA software we optimizes the piston design.this process is reviewed in paper. It describes the mesh optimization by using FEM technique to predict the higher stress and critical region on the component. The piston under study belongs to the two stroke single cylinder engine of motorcycle. Aluminum is selected as piston material. It is important to locate the critical area of concentrated stress for appropriate modification.[1] Keywords--- FEA software, stress distribution, optimization. I. INTRODUCTION Vehicles parts are in extraordinary interest nowadays in light of expanded utilization of autos.the expanded interest is because of enhanced execution and lessened expense of these parts. Research and development and testing architects ought to create basic parts in most limited conceivable time to minimize dispatch time for new items. This requires comprehension of new advances what's more, snappy ingestion in the advancement of new items [1]. A cylinder is a moving segment that is contained by a barrel and is made gas-tight by cylinder rings. In a motor its motivation is to exchange from growing gas in the barrel to the wrench shaft through cylinder pole as well as interfacing bar. As a vital part in a motor cylinder bears the cyclic gas weight and inactivity powers at work and this working condition may bring about the exhaustion harm of the cylinder. The examinations demonstrate that most noteworthy anxiety shows up on the upper end of the cylinder and anxiety fixation is one of the principally purpose behind weakness failure[2]. II. PISTON DESIGN PROCEDURE The piston is designed according to the procedure and specification which are given in machine design and data hand books. The dimensions are in SI SUnits. The pressure applied on piston head, temperatures of various areas of the piston, heat flow, stresses, strains,length, diameter of piston and hole, thicknesses, etc., parameters are taken into consideration.[3] Design Considerations for a Piston In designing a piston for an engine, the following points should be taken into consideration: It ought to have huge quality to withstand the high weight. It ought to have least weight to withstand the dormancy powers. It ought to frame powerful oil fixing in the barrel. It ought to give adequate bearing zone to avoid undue wear. It ought to have rapid response without commotion. It ought to be of adequate unbending development to withstand warm and mechanical contortions. It ought to have adequate backing for the piston pin.[4] Procedure for Piston Design The procedure for piston designs consists of the following steps: Thickness of piston head (th) Heat flows through the piston head (H) Radial thickness of the ring (t1) Axial thickness of the ring (t2) Width of the top land (b1) Width of other ring lands (b2) The above steps are explained as below: Thickness of Piston Head (th) The piston thickness of piston head calculated using the following Grashoff s formula, th = (3pD2)/ (16σt) in mm P= maximum pressure in N/mm² D= cylinder bore/outside diameter of the piston in mm. σt=permissible tensile stress for the material of the piston. Before calculating thickness of piston head, the diameter of the piston has to be specified. 225 Copyright Vandana Publications. All Rights Reserved.

2 The piston size that has been considered here has a L*D Heat Flow through the Piston Head (H): The heat flow through the piston head is calculated using the formula H = 12.56*tH * K * (Tc-Te) Kj/sec K=thermal conductivity of material which is W/mk Tc = temperature at center of piston head in C. Te = temperature at edges of piston head in C. Radial Thickness of Ring (t1): t1 = D 3pw/σt D = cylinder bore in mm Pw= pressure of fuel on cylinder wall in N/mm². Axial Thickness of Ring (t2): The thickness of the rings may be taken as t2 = 0.7t1 to t1 Let assume t2 =5mm Minimum axial thickness (t2) = D/( 10*nr ) nr = number of rings Width of the top land (b1) The width of the top land varies from b1 = th to 1.2 th Width of other lands (b2) Width of other ring lands varies from b2 = 0.75t2 to t2 Maximum Thickness of Barrel (t3) t3 = 0.03*D + b mm b = Radial depth of piston ring groove[1] III. MODELING OF PISTON 3-D model geometry is developed in PRO-E Wildfire 4.0. Dimensions of the piston are taken from the engine model present in the college. The following is the list of steps that are used to create the required model: o The base feature is created on three orthogonal datum planes. o Creating a sketch of piston wall & head section on front plane (with the help of sketcher Option), & then revolving it with respect to vertical axis as a center for rotation i.e. piston wall and head portion is generated. o Similarly create another sketch of piston pin bore outer dia. on right plane & extrude it symmetrically with the datum plane with up to next option i.e. piston pin bore is partially generated. Similarly create another sketch of piston pin bore inner dia. on right plane & extrude it symmetrically with the datum plane with up to next & remove material option i.e. Piston pin bore is fully generated. o Create another sketch of rectangular cut section on piston skirt on right plane & extrude it symmetrically with the datum plane with up to next & remove material option i.e. rectangular cut section is generated on piston skirt. o These all features are created on datum planes. o Apply fillets to all sharp corners using Round tool. [5] Fig.1. 3-D MODEL OF PISTON 226 Copyright Vandana Publications. All Rights Reserved.

3 IV. STEPS IN CAD AND FEA The design of the piston starts with the definition of the piston geometry using 3D CAD software. This 3D CAD geometric model is then imported to FEA software and analysed under the predicted service conditions before anything is made. That speeds up the design and testing process, reduces the lead time to create new pistons designs, and produces a better product. The idea behind finite analysis is to divide a model piston into a fixed finite number of elements. Computer software generates and predicts the overall stiffness of the entire piston. Analyzing thedata it is possible predict how the piston will behave in a real engine and allows the engineer to see where the stresses and temperatures will be the greatest and how the piston will behave [4].Analysis of the piston is done to optimize the stresses and minimize the weight using ANSYS.The mathematical model of optimization is established firstly, and the FEA is carried out by using the ANSYS software. Based on the analysis of optimal result, the stress concentrates on the piston has become evaluate, which provides a better reference for redesign of piston[3]. V. MESHING During the mesh generation for the piston model, based on experiences and with several trials, the eight-node hexahedron cell SOLID70 is selected in this paper. Figure 2 shows the final finite element model after mesh generation for the piston.[2] Applying Temperatures, Convections and Loads The cylinder is separated into the zones characterized by a progression of scores for fixing rings. E. The limit conditions for mechanical recreation were characterized as the weight following up on the whole cylinder head surface (most extreme weight in the motor chamber). It is important to stack certain information on material that allude to both its mechanical and warm properties to do the coupled thermo-mechanical figurings [7]. Fig.2. Meshing of Piston VI. METHODOLOGY o Theoretical anxiety computation o Create a 3D model of cylinder for two stroke motor utilizing CAD programming like PROE or Catia. o Develop a Finite Element Model for cross section enhancement of a cylinder utilizing ANSYS 14.0 o Analyze cylinder utilizing static anxiety examination and element investigation technique o Optimize the model for mass decrease.[4] VII. OPTIMIZATION Subsequent to producing an exact limited component display a methodology for the improvement work process was characterized. Focus of the streamlining was to achieve a mass lessening of the piston[8]. Target Function: Minimize mass Subject to imperatives: (i) Maximum Vonmises stress<allowable or outline stress (ii) Factor of safety>1.2 (iii) Manufacturing imperatives (iv) After doing static auxiliary investigation the hassles in every stacking conditions weremulled over and after that territory where abundance material can be evacuated were chosen so that most extreme vonmises anxiety does not surpass suitable and element of wellbeing is kept 227 Copyright Vandana Publications. All Rights Reserved.

4 above (v) Following reasons where scope for material evacuation a. Outspread Thickness of the ring b. Pivotal Thickness of the ring[5] c. Maximum Thickness of the Barrel d. Width of the Top Land e. Width of other ring lands VIII. RESULTS The following images are shown for resulted von-mises stresses before and after optimization Fig.3.Vonmisses Stress before Optimization Fig.4.Vonmisses Stress after Optimization IX. CONCLUSION The deflection due to pressure applied after optimization is more than before optimization and this value is taken into consideration for design purpose. The stress distribution on the piston mainly depends on the deformation of piston. Therefore, in order to reduce the stress concentration, the piston crown should have enough stiffness to reduce the deformation. All the phases in this project given can be extended to the piston design with reduction of material at bottom. The material is removed to reduce the weight of the piston so as to improve the efficiency. It is essential to obtain the optimized results for new piston with reduced material.[7] 228 Copyright Vandana Publications. All Rights Reserved.

5 REFERENCES [1] A.Atish Gawale, A. Shaikh and Vinay Patil, Nonlinear Static Finite Element Analysis and Optimization of connecting rod World Journal of Science and Technology, Vol. 2(4), pp.01-04, [2] E. Ramjee and K. Vijaya Kumar Reddy, Performance analysis of a 4-stroke SI engine using CNG as an alternative fuel, Indian Journal of Science and Technology, Vol. 4, No. 7, July [3]M. Spaniel, J. Macek, M. Divis, R. Tichanek, Diesel engine head steady state analysis,international Journal of Middle European Construction and Design of Cars, Vol. 2, No.3, 2003, pp [4] Wilfried Wunderlich and Morihito Hayashi, Thermal cyclic fatigue analysis of three aluminium piston alloys, International Journal of Material and Mechanical Engineering, June [5] Dallwoo Kim, Akemi Ito et.al., Friction characteristics of steel pistons for diesel engines, Journal of Materials Research and Technology, June [6] Piotr Szurgott and Tadeusz Niezgoda, Thermo mechanical FE analysis of the engine piston made of composite material with low hysteresis Journal of KONES Powertrain and Transport, Vol. 18, No. 1, [7] Technical Data, Advanced Materials Technology, Bickenbach, Germany, DB-AMT@web.de. [7] F. S. Silva, Fatigue on engine pistons A Compendium of case studies, Department of Mechanical Engineering, University of Minho, Portugal, Engineering Failure Analysis 13 (2006) Copyright Vandana Publications. All Rights Reserved.