Development of Thermo Plastic Gears for Heavy Duty Applications Using APDL

Transcription

1 Developent of Thero Plastic Gears for Heavy Duty Applications Using APDL 1 S.Rajesh Kuar, 2 Dr.M.Kannan and 3 V.Bakkiyaraj, 1 PG Scholar, 2 Professor, 3 Assistant Professor, 1,2,3 Departent of Mechanical Engineering, 1,3 SKP Engineering College, Tiruvannaalai, 2 M.A.M. College of Engineering, Trichy, India Abstract: The ai of this project to evaluate the contact stress of plastic aterial in gear for heavy duty loading condition. Plastic gears have good qualities like self-lubrication, low density, corrosion resistance and sooth running besides its lower strength. Plastic aterials provide adequate strength with weight reduction and they are eerging as a better alternative for replacing etallic gears. In this work various plastic aterials used. The Plastic aterials considered as Poly Ether Ether Ketone (PEEK),Poly Butylenes Terephthalate (PBT), Poly Aide (PA), Poly carbonate (PC) aterials is used. These plastic aterials have sei crystalline thero plastic with excellent echanical and cheical resistance properties that are retained to high teperatures. An APDL gear odel has been developed for the design evaluation and coparison study. Gear design paraeter like odule, face width and pitch circle radius etc can be varied to optiize the design paraeter in the geared APDL odel to ake plastics as feasible gear odel. The contact stress of plastic spur gears are calculated by Finite Eleent Analysis using FEA software ANSYS 13.0.Contact Stress of various plastic gears was analysed in this project. Keywords: Plastics Spur gear, ANSYS APDL, Contact Stress, Finite Eleent Analysis. I. INTRODUCTION The spur gears when in action, are subjected to several stresses but out of all, two types of stresses viz., bending stress and contact stress are iportant fro the design point of view. The bending stresses are theoretically analysed by Lewis equation and contact stresses by Hertz equation. Since spur gears have coplicated geoetry, a need arises for iproved analysis using nuerical ethods which provide ore accurate solutions than the theoretical ethods. Finite Eleent Analysis is one such ethod which has been extensively used in analysis of coponents used in various echanical systes. Plastic gears have positioned theselves as serious alternatives to traditional etal gears in a wide variety of applications. The use of plastic gears has expanded fro low power, precision otion transission into ore deanding power transission applications. As designers push the liits of acceptable plastic gear applications, ore is learned about the behaviour of plastics in gearing and how to take advantage of their unique characteristics. Plastic gears provide a nuber of advantages over etal gears. They have less weight, lower inertia and run uch quieter than their etal counterparts. Plastic gears often require no lubrication or can be copounded with internal lubricants such as silicone. Plastic gears usually have a lower unit cost than etal gears, and can be designed to incorporate other features needed in the assebly (part consolidation).these gears are also resistant to any corrosive environents. The plastic aterials have corrosion resistance, low electrical and theral conductivity, easily fored into coplex shapes, wide choices of appearance, colours and transparencies. The introduction of plastic aterials was ade it possible to reduce the weight of the spur gear without any reduction on load carrying capacity and stiffness. The Finite eleent analysis of spur gears has been reported by soe researchers in the recent past. Bharat Gupta et al., [1] reported the contact stress analysis of spur gears and concluded that the contact stress fors the basis of resisting the gear pitting failure. They also concluded that odule is an iportant paraeter for gear design and showed that for the transission of large power and iniization of contact stress, a spur gear with higher odule ust be preferred. T. Shoba Rani et al., [2] have perfored finite eleent analysis on spur gear using different aterials viz., nylon, cast iron and polycarbonate. They observed that in order to get good efficiency, life and less noise cast iron gears can be replaced by nylon gears because of the fact that the deflection of cast iron is ore than that of nylon. Sushil Kuar Tiwari et al., [3] analysed the contact stress and bending stress of involute spur gear teethby FEA and copared the sae with Hertz equation, Lewis equation and AGMA/ANSI equations. The FEA results showed a good degree of agreeent with the theoretical results. V. Siva Prasad et al., [4] This paper describes design and analysis of spur gear and it is proposed to substitute the etallic gears of sugarcane juice achine with polyer gears to reduce the weight and noise. A virtual odel of spur gear was created in PRO-E, Model is iported in ANSYS 10.0 for analysis by applying noral load condition. The ain purpose of this paper to analysis the different polyer gears naely nylon, polycarbonate and their viability checked with counterpart etallic gear like as cast iron. Concluding the study using the FEA ethodology, it can be proved that the coposite gears, if well designed and analysed, will give the useful properties like as a low cost, noise, Weight, vibration and perfor its operation siilar to the etallic gears. Based on the static analysis Nylon gear are suitable for the application of sugarcane juice achine under liited load condition in coparison with cast iron spur gears. Vivek Karaveer et al., [5] This paper presents the stress analysis of ating teeth of the spur gear to find axiu contact stress in the gear tooth. The results obtained fro finite eleent analysis are copared with theoretical Hertz equation values. The spur gear are odelled and assebled in ANSYS DESIGN MODELER and stress analysis of Spur gear tooth is done by the ANSYS 14.5 software. It was found that the results fro both Hertz equation and Finite Eleent Analysis are coparable. Fro the deforation pattern of steel and grey cast iron, it could be concluded that difference between the axiu values of steel and grey CI gear deforation is very less. Available Online@ 304

2 Mahebub Vohra et al., [6] In this paper, Metallic aterial Cast iron and Non Metallic aterial Nylon are investigated. The stress analysis of the lathe achine headstock gear box isanalysed by finite eleent analysis. Analytical bending stress is calculated by two forula Lewis forula and AGMA forula. Analytical results are copared with the finite eleent ethod result for validation. Concluding the study, we observed that finite eleent ethod software ANSYS have values of stress distribution were in good agreeent with the theoretical results. Besides non-etallic aterial can be used instead of etallic aterial because non-etallic aterial provide extra benefits like as less cost, self-lubricating, low noise, low vibration and easy anufacturing. II. MATERIAL PROPERTIES The aterial chosen for the study is Plastics. Table 1 shows the properties of various plastic aterials as presented in ANSYS APDL 13.0 engineering data sources. Table 1: Material Properties of various plastics aterials product. In this paper odule, pressure angle, nubers of teeth of spur gear are taken as input paraeters. Ansys uses these paraeters, in cobination with its features to generate the geoetry of the Spur gear and all essential inforation to create the odel. By using the relational equation in Ansys APDL, the accurate three diensional Spur gear odel is developed. The paraetrical process can increase design accuracy, reduce lead ties and iprove overall engineering productivity. Spur Gear Modeling Three Teeth: Material Property Young s Modulus (GPa) PEEK Acetal PA PET PC PBT Poisson s ratio Density (Kg/ 3 ) Coefficient offriction The plastic aterials taken for analysis as Poly Ether Ether Ketone (PEEK), Acetal, Poly aide (PA), Poly ethylene Terephthalate (PET), Poly carbonate (PC) and Poly Butylenes Terephthalate (PBT). III. PARAMETRIC MODELING OF SPUR GEAR PAIR The spur gear is sketched and odeled in ANSYS APDL The paraeters of the gear set are given in table 2. Table 2:Diensions of the Spur Gears S. No. Description Sybol Value Units 1 Module Pressure Angle ϕ 20 3 No of teeth Z 60 4 Center distance a Face width b 25 6 Pitch Circle Diaeter dp Base Circle Radius rb Addendu Circle Radius ra Dedendu Circle Radius rd Addendu ha Dedendu hd Fillet Radius rp Shaft Radius rs Total angle Ta Botto clearance c 0.25 Figure 1: Three Diensional Model of Spur Gear IV. SPUR GEAR DESIGN Specifications of gear: Module () = 2.5 Center distance (a) = 150 Pressure angle (α) = 20 degree Power (P) = 2.25 Kw Speed (N) = 750 rp Design Calculation: Power (P) = 2*π*N*T / = (2*π*750*T) / 60 T = (2250*60)/ (2*π*750) Torque = N- Torque T Force = F * (d/2) F = T/ (d/2) = /0.075 Force F = N Calculation of tangential load: F t = P V * K O Where, P= power v= pitch line velocity K o = Service factor= 1.25 (ediu) V = V = π D 1 N 1 60 π v = /s Paraetric odeling allows the design engineer to let the characteristic paraeters of a product drive the design of that Available Online@ 305 F t =

3 F t = Calculation of initial dynaic load: F d = F t * C v Velocity factor 1 + v v F d = F d = Calculation of bea strength: F s = π b σ b y Face width b = 10 Allowable static stress σ b = N/ 2 For factor = y y = z y = F s =π ** 10* 58.86* F s = Calculation of odule: F s F d = = Take higher standard odule = 2.5 Then, Face width b = 10 = 25 Pitch circle diaeter d 1 = *z 1 = 150 Pitch line velocity v = /s Recalculation of bea strength: F s = π b σ b y F s = π *2.5* 25* 58.86* F s = N Calculation of accurate dynaic load: F d = F t * C v F t = P V = F t = N 1 + v v F d = * F d = N Check for bea strength (tooth breakage): F s > F d > The design is safe. Calculation of wear load: F w = d 1 *b*q* k w Q = Ratio factor Q = 2i i + 1 Q = Q = 1 k w =Load stress factor =1.4 N/ 2 (For non-etallic gear) Check for wear: F w = 150*25*1*1.4 F w = 5250 N F w > F d 5250> The design is Safe. Safe for surface durability. V. FINITE ELEMENT ANALYSIS USING ANSYS APDL 13.0 Finite eleent odeling is described as the representation of the geoetric odel in ters of a finite nuber of eleent and nodes. It is actually a nuerical ethod eployed for the solution of structures or a coplex region defining a continuu. Solutions obtained by this ethod are rarely exact for analysis in ANSYS The loading conditions are assued to be static. Load applied at rotational pressure inside driving gear ri and DOF applied at driven pinion inside ri. To siulate gear contact surfaces, contact conditions are a special class of discontinuous constraint, allowing forces to be transitted fro one part of the odel to another. The constraint is discontinuous because it is applied only when the two surfaces are in contact. When the two surfaces separate, no constraint is applied. The analysis has to be able to detect when two surfaces are in contact and apply the contact constraints accordingly. An accurate contact siulation can be achieved using the latest non-linear FEA techniques by defining the contact surfaces of the teeth as the contact pairs which are special eleents designed to treat cases of changing echanical contact between the parts of an assebly or between different faces of a single part in ANSYS software Available Online@ 306

4 In the present study, FEA software ANSYS 13.0 APDL has been used to deterine the axiu allowable contact stress in plastics spur gears. Fine eshing as shown in figure 2, has been done in order to get accurate results. A oent of 7599 N- is applied in clockwise direction on the inner ri of the upper gear. Figure 2: Meshing of spur gear To apply finite eleent ethod in contact stress a special technique was used rather the regular eleents, to distinguish between the contact regions which were in two parts. One was the first body naed target region and the other body was naed contact region. For target region, target eleents were used and in contact region contact eleents were used. ANSYS software presents a significant technique for this purpose which was used here. Figure 5: Non-linear convergence graph VI. RESULTS AND DISCUSSIONS Figure 3: Contact pair of spur gear A coputer progra was developed to plot one pair of teeth in contact. This Progra used to build finite eleent contact odels and contact finite eleent analysis was done under the load and aterial conditions were naed. In gear eshing, the contact of the teeth is a surface-surface contact and the profiles of the teeth are curves. Therefore, TARGE170 and CONTA174 are chosen as the contact eleents to represent the contact pairs. TARGE170 is used to represent the 3-D target surfaces for the associated contact eleents. This target surface is discretized by a set of target segent eleents. CONTA174 is used to represent contact and sliding between 3-D "target" surfaces. Contact occurs when the eleent surface penetrates one of the target segent eleents on a specified target surface. Figure 6: Stress distribution Figure 7: Deforation pattern Figure 4: Boundary conditions of spur gear Available Online@ 307

5 Contact Stress (MPa) Deflection () International Journal of Trend in Research and Developent, Volue 3(2), ISSN: Graph 2: Deflection Vs various plastic aterials Figure 8: Strain As is clearly indicated in figure 6, the axiu allowable contact stress for plastic spur gears of diensions given in table 2 and for transitted torque of N- is 1.24MPa, as deterined by FEA using ANSYS APDL Analysis Result for Various Plastic Gear Materials: S.No Table 3: Analysis results tabulation Plastic Materials Contact Stress (MPa) Deflection () 1 Peek Acetal PA PET PC PBT Fro the static analysis using ansys the deflections and vonise stress values for the Poly Ether Ether Ketone (PEEK), Acetal, Poly aide (PA), Poly ethylene Terephthalate (PET), Poly carbonate (PC) and Poly Butylenes Terephthalate (PBT) and polycarbonate aterials are obtained as following above tables. Graph 1: Contact stress Vs various plastic aterials PEEK ACETAL PA PET PC PBT Plastic Materials PEEK ACETAL PA PET PC PBT Plastic Materials CONCLUSION In this project we have to calculate the contact stress of plastic gear aterials. The finite eleent odeling and analysis of spur gear is done to deterine the contact stress by ANSYS 13.0 APDL. In the present study, we report the contact analysis of 20 degree full depth involute plastic spur gears during the transission of power of 2.25kW by FEA using ANSYS. A general atheatical odel is proposed for evaluating the contact stress in plastic spur gears of equal geoetry in esh using FEA. Maxiu contact stress and deflection for various plastic gear aterials are obtained in this study. Fro the deforation pattern of various plastic aterials, it could be concluded that Peek gear deforation is very less. According to the study, analysis, results and Graphs it was concluded that the plastic gear can be used for heavy duty applications. References [1] Gupta, Mr Bharat, Mr Abhishek Choubey, and Mr Gauta V. Varde. "Contact stress analysis of spur gear." In International Journal of Engineering Research and Technology, vol. 1, no. 4 (June-2012). ESRSA Publications, [2] Rani, T.Shoba, and T.Dada Khalandar. "SPUR GEAR." International Journal of Coputational Engineering Research 3, no. 11 (2013): [3] Tiwari, Sushil Kuar, and Upendra Kuar Joshi. "Stress analysis of ating involute spur gear teeth." In International Journal of Engineering Research and Technology, vol. 1, no. 9 (Noveber-2012). ESRSA Publications, [4] Karaveer, Vivek, Ashish Mogrekar, and T. Prean Reynold Joseph. "Modeling and Finite Eleent Analysis of Spur Gear." International Journal of Current Engineering and Technology ISSN (2013): [5] Lee, Huei-Huang. Finite eleent siulations with ANSYS workbench 14. SDC publications, [6] Raja Roy, M., S. Phani Kuar, and D.S. Sai Ravi Kiran. "Contact Pressure Analysis of Spur Gear Using FEA." International Journal of Advanced Engineering Applications 7, no. 3 (2014): Available Online@ 308

6 [7] Bhandari, V. B. Design of achine eleents. Tata McGraw-Hill Education, [8] Gopinath, K., and M. M. Mayura. "Spur Gear Design." Nptel. Accessed February 08, MADRAS/Machine_Design_II/pdf/2_8.pdf. [9] "Spur Gears." Khkgears. Accessed February 08, break/ Spur tech.pdf. [10] "Finite Eleent Method." Wikipedia. Accessed February 14, [11] Vivek KaraveerȦ*, Ashish MogrekarȦ and T. Prean Reynold JosephȦ, " Modelling and Finite Eleent Analysis of Spur Gear", Dec 2013, International Journal of Current Engineering and Technology, Vol 3. [12] Mahebub Vohra, Prof. Kevin Vyas, "Coparative Finite Eleent Analysis of Metallic and non Metallic spur gear", May-June 2014, IOSR Journal of Mechanical and Civil Engineering, Vol-11/3,pp [13] V. Siva Prasad, Syed Altaf Hussain, V. Pandurangadu, K. PalaniKuar, " Modeling and Analysis of spur gear for Sugarcane Juice Machine under Static Load Condition by Using FEA",July-Aug 2012,International Journal of Modern Engineering Research,Vol- 2/4, pp Available 309