Effect of Spiral Angle of Flexure Bearings Used in Opposed Piston Linear Compressor.

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1 Effect of Spiral Angle of Flexure Bearings Used in Opposed Piston Linear Compressor. Fayaz Kharadi 1, A. Karthikeyan 2, Virendra Bhojwani 3, Asif Inamdar 4 1 Research Scholar, Department of Mechanical Engineering, Sathyabama University, Chennai , fayazkharadi@gmail.com 2 Department of Automobile Engineering, Sathyabama University, Chennai , naveenkarthik2004@gmail.com 3 Department of Mechanical Engineering, Savitribai Phule Pune University, Pune , India, bhojwanivk@gmail.com 4 Department of Mechanical Engineering, Savitribai Phule Pune University, Pune , India, ai23008@gmail.com ABSTRACT The present work reported in this paper is specific to select optimum parameters from selected parameter like spiral angle and effect of diameter for flexure bearing used in opposed piston linear compressor. This paper utilizes FEM as tool to find the equivalent stress and stiffness [1]. In the process of design, selection of optimized parameters is one of the most important step. The optimized parameters are one which will serve the desired objective like performance and service life at minimum cost. The main objective of this paper is to investigate effect of spiral angle of flexure bearing to enhance its performance and improve upon the service life of the flexure. The optimum spiral angle is one which gives lower operating stress and higher stiffness. Performance of the flexure, service life of the bearing can be enhanced by achieving lower operating stresses and higher stiffness Keywords: Flexure bearing, Opposed piston linear compressor, FEA, Flexure spring INTRODUCTION The function of bearing is to allow relative motion between two machine components. If relative motion between two parts is by flexing or bending, such a bearing is nothing but flexure bearing [2]. The flexure bearing used in linear compressor application is a flat circular disc having spiral slot [3]. Fig. 1 Flexure bearing The figure 1 shows CAD model of flexure bearing used in linear compressor application. The flexure is allowed to deform on application of load. The load is applied on the central hole provided at the centre of the bearing. On the application of load, the flexure deforms. The surface goes back to its original position on removal of applied load. The induced stress corresponding to maximum deformation is within the limit of elasticity. 1675

2 Since flexure bearing in linear compressor oscillates it is subjected to fatigue load, hence it is essential to investigate and ensure infinite fatigue life of the flexure bearing along with the static stresses induced. This eliminates the wear, vibration and frictional losses. Flexure bearing finds application in precision and micro machining applications and some medical applications having very low relative motion [4]. 2. METHODOLOGY Different parameters of bearing have been investigated in Ansys 14.0 workbench. The different parameters of flexure has been finalized on the basis of, 1. Stress Stresses developed for maximum deformation should be minimum. 2. Stiffness Stiffness of flexure should be maximum. (To minimize total number of flexure disc and meet desired spring stiffness with minimum space requirement) Stresses have been found out for maximum deformation of flexure with design displacement of 5 mm from mean position. Deformation has been found out to find stiffness in flexure bearing for 1N force. The mechanical stiffness is ratio of Force and corresponding deflection. 3. CATIA MODEL OF FLEXURE BEARING The model was created in Catia V5R10 version. The dimensions of model are as follows [5]. 1. The thickness of flexure 0.3mm 2. The diameter of flexure - 69mm 3. Holes for clamping along the periphery 6 mm on PCD 59mm Fig. 2 Catia model of flexure Figure 2 shows the model of flexure created in Catia V5R10 workbench. 4. ANALYSIS OF FLEXURE BEARING IN ANSYS Ansys v 14 is used to calculate equivalent stress and deformation (stiffness). Boundary conditions are as follows 1. The thickness of plate considered is 0.3mm. 2. Maximum deflection of 5mm at central hole. 3. Material taken as Beryllium Copper UNS C (TH02) [6]. 4. Clamping 12 holes as fix support. 5. Deformation has been found out by applying 1N force. Effect of following parameters for selection of best flexure has been studied. 1. Spiral angle. 5. ANSYS RESULTS 1. Spiral angle- Analysis has done by varying spiral angle

3 1. Spiral angle Fig. 3 Equivalent stress for Fig. 3 shows value of Equivalent stress MPa for 540 spiral angle. 2. Spiral angle Fig. 4 Equivalent stress for Fig. 4 shows value of Equivalent stress MPa for 560 spiral angle 3. Spiral angle Fig. 5 Equivalent stress for

4 1. Spiral angle Fig.6 Deformation for 1N force for Fig.6 shows value of deformation 0.52 mm for 540 spiral angle. 2. Spiral angle Fig.7 Deformation for 1N force Fig.7 shows value of deformation 0.6mm for 560 spiral angle. 3. Spiral angle Fig.8 Deformation for 1N force for

5 Table 1 Stress and Stiffness for different spiral angle. Table 1 shows different values of equivalent stress and stiffness for selected spiral angle. Graph 1 Spiral angle Vs Equivalent Stress and Stiffness Graph 1 states that as spiral angle goes on increasing stiffness goes on decreasing and stress goes on decreasing and again increasing by small amount. For 560 spiral angle, minimum stress has been developed that is 322.9MPa. and corresponding stiffness is N/m 6. CONCLUSION From above table and graph, it has been concluded that in all selected spiral angle, spiral angle gives minimum stresses that is 322.9MPa and corresponding value of stiffness is N/m. So is the optimum value of spiral angle in all selected angle. REFERENCES [1] T.R.Chandrupatla, A.D.Belagundu, "Finite Elements in Engineering, Pearsons Education [2] Vennapusa V Sivareddy, Modeling and Analysis of Deformation on A Flexure Bearing In Linear Compressor, International Journal of Mechanical Engineering and Robotics Research, India, Vol. 3, No. 1, January 2014, pp [3] Peckham Engineering and Tool, Manhattan Beach, CA with Phillips Laboratory, Kirtland Air Force Base. New Mexico, Precision Linear Flexure Bearing Cartridge Phase I page number 4. [4] Prof. M.V.Kavade, C.B.Patil, Optimization of Flexure Bearing Using FEA for Linear Compressor International Journal of Engineering and Science, Vol. 1, Issue 12, December 2012, PP [5] Saurabh Malpani, Yogesh Yenarkar, Dr. Suhas Deshmukh, S P Tak, D.V. Bhope Design OF Flexure Bearing For Linear Compressor by Optimization Procedure Using FEA, International Journal of Engineering Science and Technology (IJEST) Vol. 4 No.05 May 2012 pp [6] Fayaz Kharadi, Mayur Jadhav, Dr. Virendra Bhojwani, Prof. Suneeta Phadkule, Dr. M.G.Jadhav Design of high performing material in flexure bearings for linear compressor application using FEA, International Journal of Engineering Research & Technology (IJERT) Vol. 3, Issue-12, Dec 2014 pp