Jib Crane Analysis Using FEM - IJSRD

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IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 04, 2015 ISSN (online): 2321-0613 Jib Crane Analysis using FEM S. S. Kiranalli1 N.U. Patil2 1,2 Department of Mechanical Engineering 1,2 Trinity Polytechnic, Pune Abstract— This work deals with the analysis of Free Standing Jib Crane using Finite Element Method. Modeling of the parts is done using Finite Element based software ANSYS. Initially two-dimensional analysis of simple beam and simple column is done to check the suitability of type of element in three dimensional analysis. Besides, comparison of the results of these simple Finite Element models is done using the analytical solutions to ensure that mesh density used for the analysis gives correct results. Then analysis of complete jib crane is carried out using two-dimensional model. Further, the results obtained are used for the validation of the three-dimensional model. 8 Node Brick 45 (SOLID45) elements are used for meshing of threedimensional model. For loading, various factors such as trolley weight and dynamic factor are taken into consideration. The trolley weight considered is 15% of the rated capacity of the crane. For impact loading, dynamic factor is taken into account. The value of dynamic factor is 25% of the rated capacity of crane. Thus crane is analyzed at a total factor of 1.4 of the capacity of the crane. During the post-processing maximum deformation & Von Mises Stresses are observed. Effect of various parameters like web thickness, web height and load is studied systematically. Key words: Jib crane, web thickness, web height, FEM and ANSYS I. INTRODUCTION Jib crane, a type of crane where a horizontal member (jib or boom) is supporting and moveable hoist, a key element of hoisting mechanism as an integral part of the machine. A typical jib crane consists of a top beam which is rotating around a fixed column. This configuration may be referred to as an L-shaped structure. The top beam is attached to the column at two points, directly on top and with down support. The trolley, with the hoist and payload, is moving along the top beam. It is helpful for providing a heavy lifting facility covering virtually the whole area of the industry such as shipyards, factories, nuclear installations and high-building constructions. Cranes, whether fixed or mobile are driven manually or by power. Also, their design features vary widely according to their major operational specifications such as type of motion of the crane structure, weight, type of the load, location of the crane, geometric features, operating regimes and environmental conditions. Since the crane design procedures are highly standardized with these components, most effort and time are spent on interpreting and implementing the available design standards (1, 2). Various international or national standards and rules e.g. BS 357, AISE Standard No.6, CMAA No.70, JIS B8801, DINTaschenbuch 44, FEM Rules are available to guide the crane designers which offer design methods and empirical approaches and formulae that are based on previous design experiences and widely accepted design procedures (3-7). Many reports are available on the structural and component stresses, safety under static loading and dynamic behaviour of cranes (8-15). It is believed from the study of literature that, computer automated access to above standards with pre-loaded interpretation and guidance rules increase speed and reliability of the design procedures and increase efficiency of the crane designers. In view of above, in the present work we have tried to demonstrate to modify the dimension of web thickness and web height to decrease the deformation and stress induced in the boom, for same capacity of loading. Fig. 1: Main Parts of Free Standing Jib Crane II. DESIGN CONSIDERATIONS OF JIB CRANES As discussed earlier design features of cranes vary widely according to their major operational specifications. The design factor for the stresses in the crane is based on the capacity plus 25% of the rated load for impact and 15% of the rated load for the weight of the hoist and trolley. Generally, this is used all along with the average yield stress of the material to find out the type of the design. This design provides a margin to allow for variations in material properties, operating conditions, and design assumptions. No crane should be supposed to ever, in any circumstance, be weighted beyond its rated capability. III. ANALYTICAL SOLUTION An existing jib crane from Industries is taken for the analysis. The details of the same are as below in Table No. I and Table No II. The analysis will be done for static condition. For the sake of convenience load is applied at the end of the beam. Effect of various parameters, like web thickness, web height, and load will be studied during the analysis. Also tie rod will be used for the further part of analysis & effect of cross sectional area of tie rod will be seen. Deflection & Von Mises stresses will be observed throughout the analysis. All rights reserved by www.ijsrd.com 185

Jib Crane Analysis using FEM (IJSRD/Vol. 3/Issue 04/2015/049) C) Analysis of Cantilever Beam With Self-Weight & Load at The End Total deflection at (Deflection due to load only) free end (Deflection due to self-weight only) Hence, Total deflection 2.8912 0.31877 3.20977 mm (1.4) D) Analysis of Column (Mast) Only Mast is also analyzed for some arbitrary value of load. This arbitrary value is 1000 N. Table 1: Specifications of Jib Crane Considered In Present Work Here is deflection of column. P applied force. L length of the column or mast. A cross sectional area of column E Young‟s modulus of the material of column Table 2: Properties of Strucutred Steel Analytically the deflection at the end of the cantilever beam is calculated as below. wxl 3 3ExI Where, deflection at the free end of beam w Load applied Rated capacity x Design Factor 1112.454 x 1.4 1557.43 N L Length of beam E Young‟s modulus of the material of the beam I Area moment of Inertia of beam about an axis passing through its center of gravity 1557.43x 24403 3 x 2.1x10 5 x1242.09x10 4 2.8912 mm Deflection due to load at the end 2.8912mm (1.1) B) Analysis of Cantilever Beam Considering Only SelfWeight Analytically the deflection at the end of the beam is calculated as below. Deflection due to self-weight is calculated by following formula. 1000x3000 2691.73x 2.1x105 0.0053 mm A) Analysis of Only Cantilever Beam Considering Load at Free End PxL AxE (1.4) IV. FINITE ELEMENT ANALYSIS APPLIED TO JIB CRANE Load Condition & Boundary Condition are used as in Table No. III Boundary Condition: The beam is constrained at left end for all degrees of freedom. i.e. rotary & linear are constrained. Load Condition: Load is applied at the right end. Sr Nature of Parameters Values No Parameters Length of Beam 2440 mm Area of Cross 2440.6 mm2 section of Beam Geometric 1 Parameters Area Moment of 1242.09x104mm4 Inertia of Beam Height of Beam 175 mm Loading 2 Force 1557.43 N Parameters Young‟s 2.1x 105 N/mm2 Material Modulus 3 Properties Poisson‟s Ratio 0.3 The length of element is taken as 100 mm. Figure No 2. Shows the discretized model. wxl 4 8 xExI In the above formula, w is weight per unit of beam. Considering the density of material, its value is (19.13 x 9.81) N/m 19.13x9.81x 2.444 8 x 2.1x105 x106 x1242.09x10 8 0.00031877 m 0.31877 mm Deflection due to self-weight only 0.31877 mm Fig. 2: Model With Load Condition & Boundary Condition (1.2) All rights reserved by www.ijsrd.com 186

Jib Crane Analysis using FEM (IJSRD/Vol. 3/Issue 04/2015/049) A. Deflection At Free End Fig. 5: Deformation of Column (Mast) Fig. 3: Deflection At Free End The deflection at the free end obtained by Finite Element based software ANSYS is 2.891 mm. The same is seen in the figure No 3. Ansys 2.891 mm Observing the analytical & Finite Element analysis values it can be said that the type of element & mesh density used for above analysis is correct. The maximum stress for the above case is also observed in the post processing. B. Maximum Stress Is Also Observed In The Post Processing. The Same Is Shown Figure No 4. Fig. 6: Three Dimensional Model of the Jib Crane Fig.4. Maximum Stress Is Observed In The Post Processing Is Shown. Maximum Stress (Direct Bending) 30.707MPa (1.5) C. Finite Element Analysis of Column Only Sr No Nature of Parameters Parameters Values 1 Geometric Parameters Height of Column Area of Cross section of Column Area Moment of Inertia of Column 3000 mm 2691.73 mm2 613.93 x 104 mm4 2 Loading Parameters Force 1557.43 N Fig. 7: Loads Applied At The End Of Beam of Jib Crane 2.1x 105 N/mm2 Poisson‟s Ratio 0.3 Table 4: Input Parameters For Analysis of Column (Mast) Material Properties 3 Young‟s Modulus D. Load condition & Boundary condition are used as in Table No. 4. Load condition: Load applied is a tensile force of 1000 N. Boundary condition: All motions of the bottom end are constrained Fig. 8: Deformation of Jib Crane During the post-processing Von Mises Stresses are also observed. The maximum value of Von Mises Stress is 108.849 MPa. Figure No. 9. shows Von Mises stresses at All rights reserved by www.ijsrd.com 187

Jib Crane Analysis using FEM (IJSRD/Vol. 3/Issue 04/2015/049) various locations on the jib crane. Location of this high stress region is at the left end of the beam near the top edge of the column or mast. As beam is fixed here, there will be almost no deformation & hence stresses will be higher whereas at free end of the beam, highest deformation will be there leading to lowest stress. B. During the Study, Web Height Is Varied & Its Effect On The Stresses & Deformation Is Observed. Sr. No. 1 2 3 4 5 Web height (mm) Max. Deformation (mm) Max. Stress (MPa) Von Mises 108.983 108.821 108.849 107.084 110.431 147 34.601 152 34.549 157 34.454 162 34.258 167 34.192 Table 6: Effect of Web Height Here, it is observed that, as the web height increases, the maximum deformation decreases continuously as shown in the fig No.11. And effect of varying Web Height as shown on table No. VI. C. Even Though, The Cranes Should Not Be Loaded For More Than Their Capacity, Still Effect Of Overloading On The Values Of Maximum Deformation & Maximum Von Mises Stress Is Done. Fig. 9: Von Mises Stresses In Jib Crane V. RESULTS A. During This Study, Variation of Web Thickness Is Done To Observe Its Effect on the Stresses & Deformation Sr. No. 1 2 3 4 5 Web Max. Max. Stress thickness Deformation (MPa) (mm) (mm) Von Mises 4.8 34.858 116.435 5.3 34.739 118.363 5.8 34.454 108.849 6.3 34.5 106.147 6.8 33.882 97.408 Table 5: Effect of Web Thickness Fig. 11: Effect of Web Height on Maximum Deformation Max. Sr. Load Max.Stress Deformation No. (N) (MPa)Von Mises (mm) 1 1557.43 34.454 108.849 2 1757.43 38.325 121.016 3 1957.43 42.196 133.183 4 2157.43 46.067 145.35 5 2357.43 49.939 157.517 Table 7: Effect of Load On Boom Effect of varying the Load on Boom at free end what Maximum Deflection and Stress Induced is shown in Table No. VII. Fig. 10: Effect of Web Thickness on Maximum Deformation From the above graph Fig No. 10, it is seen that as initially there is increase in the web thickness, there is small decrease in the maximum deformation of the beam after a certain value of web thickness, there is slight increase in the maximum deformation of the beam but afterwards it decreases at a higher rate. And effect of varying Web Thickness as shown on Table No. V. Fig. 12: Effect of Load on Maximum Deformation All rights reserved by www.ijsrd.com 188

Jib Crane Analysis using FEM (IJSRD/Vol. 3/Issue 04/2015/049) From the above graph Fig No.12., it is seen that there is straight line relationship between the load & maximum deformation. As load increases, maximum deformation increases. Effect on varying the Load of Boom is shown in Table No VII. VI. CONCLUSION [14] [15] Reemsyder, H. S., Demo, D. A.: “Fatigue Cracking in Welded Crane Runway Girders, Causes and Repair Procedures.” Iron and Steel Engineer, Vol.55 (1978), No. 4, p. 52. Rowswell, J. C., Packer, J. A.: “Crane Girder TieBack Connections.” Iron and Steel Engineer, Vol.66 (1989), No. 1, p. 58. 1) The maximum value of Von Mises Stress 30.707MPa is occurred at the junction of at the left end of the beam near the top edge of the column or mast. 2) At the free end of the beam, highest deformation 3.20977 mm has occurred leading to lowest stresses. 3) As the web thickness increases, deformation decreases but this decrease in not uniform. 4) As the web height increases, the deformation decreases continuously. REFERENCE [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] Erden, A.: “Computer Automated Access to the „F.E.M. Rules‟ for Crane Design.” Anadolu University Journal of Science and Technology, Vol.3 (2002), No. 1, p. 115–130. C. Alkin, C. E. Imrak, H. Kocabas, “Solid Modeling and Finite Element Analysis of an Overhead Crane Bridge”, Acta Polytechnica 45 3 (2005) 61-67. Anon (1965). BS 357, Power Driven Traveling Jib Cranes. British Standards Institution. Anon (1966). AISE Standard No.6, Specification for Electric Overhead Traveling Cranes for Steel Mill Service. Association of Iron and Steel Engineers. Anon (1971). CMAA No.70,.Specificationsfor Electric Overhead Traveling Cranes. Crane Manufacturers Association of America Ine. 55p. Anon (1974). 1IS B8801, Japanese Industrial Standard Electric Overhead Traveling Cranes. Japanese Standards Association. Anon (1987). F.E.M. Rules, Rules for the Design of Hoisting Appliances - Section I. Federation Europeenne de la Manutention, France, Booklet I. Baker, J.: “Cranes in Need of Change.” Engineering, Vol. 211 (1971), No. 3, p. 298. Buffington, K.E.: “Application and Maintenance of Radio Controlled Overhead Travelling Cranes.” Iron and Steel Engineer, Vol.62 (1985), No. 12, p. 36. Demokritov, V. N.: “Selection of Optimal System Criteria for Crane Girders.” Russian Engineering Journal, Vol. 54 (1974), No. 4, p. 7 Erofeev, M. J.: “Expert Systems Applied to Mechanical Engineering Design Experience with Bearing Selection and Application Program.” Computer Aided Design, Vol. 55 (1987), No. 6, p. 31. Lemeur, M., Ritcher, C., Hesser, L.: “Newest Methods Applied to Crane Wheel Calculations in Europe.” Iron and Steel Engineer, Vol. 51 (1977), No. 9, p. 66. McCaffery,F.P.: “Designing Overhead Cranes for Non flat Runways.” Iron and Steel Engineer, Vol.62 (1985), No. 12, p. 32. All rights reserved by www.ijsrd.com 189

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