Crank Mechanism

Name Monish Kumar (S11065194) The University of the South Pacific MM313 dynamical Systems experiment 2- Crank Mechanism Aim To investigate the relationship between piston work shift and ball slant for different ratios between the connecting rod and the water ice. Also to look at the relationship between the turn of events moment on the crank sleep with and crank angle for a given force on the piston. Equipment and Instrument Introduction A crank is an arm link up at right angles to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to convert circular motion into reciprocating motion, or vice-versa.The arm may be a bent portion of the shaft, or a separate arm attached to it. Attached to the kibosh of the crank by a pivot is a rod, ordinarily called a connecting rod. The end of the rod attached to the crank moves in a circular motion, while the other end is usually constrained to move in a linear sliding motion. Theory Figur e 1. 0 skidder crank mechanism The slider crank mechanism as shown in figure 1. 0 is a kinematic mechanism. The piston displacement from the top dead centre, x, can be determined from the geometry of the mechanism, in terms of the lengths of the connecting rod, L, and crank, R, and the crank angle, ? can be expressed as x=L+R-(Lcos? -Rcos? ) Also from the geometry, it can be seen that R lousiness? =Lsin? And sin? =sin? n Hence cos? =1+sin? n21/2 Where n is a ratio n=LR Procedure Part A 1) No weights and hangers required, the unit initial starting position 0 in the protractor is setup and 90? and 270? protractor positions to be in line with the level lines in each side. 2) The unit is to be setup in its highest point, Top dead centre point was used to work out the displacement value 3) The mounted disc was turned 30? nd the displacement was noted on the results table, this meter was again repeated for different angles and different crank positions. Part B Results PART A accede 1 R esults of Piston Displacement Crank angle Displacement P1 (mm) experiment P1 (mm) possible action P2 (mm) experiment P2 (mm) theory P3 (mm) experiment P3 (mm) theory 0 0 0 0 0 0 0 30 3 3. clxxx748214 5 4. 252344481 7 5. 324742758 45 7 6. 86291501 10 9. 20565874 13 11. 55001055 60 12 11. 51142198 17 15. 51081741 20 19. 51263112 90 22 22. 02041029 31 30. 01960212 39 38. 2202662 120 31 31. 51142198 45 43. 51081741 53 55. 51263112 cxxxv 35 35. 14718626 50 48. 80363849 63 62. 4616988 150 38 37. 82176437 53 52. 74976709 68 67. 67857183 one hundred eighty 39 40 56 56 71 72 confuse 2 calculation of the angle ? Crank angle ? 0 0 30 5. 73917 45 8. 130102 60 9. 974222 90 11. 53696 120 9. 974222 cxxxv 8. 130102 150 5. 73917 180 1. 40E-15 interpret of Displacement (mm) vs. Crank angle position (? ) Sample Calculation For Displacement P1 at 30? crank angle. To find, ? , n = 5 sin? =sin? n ?=sin-1sin? n=sin-1sin305=5. 73917?To calculate the notional displacement, x x=r1-cos? +nr(1-cos? ) x= 201-cos30+nr1-cos5. 73917=3. 180748214 mm Discussion 1. After plotting the chart of Displacement versus the crank angle position, the graph show that the experimental values and the theoretical displacement can be compared, the experimental plot and the theoretical plot are almost same. 2. From the results graph the graph show that the measured displacement follows the theoretical rick very well. The maximum difference between the experimental and theoretical displacement is 2 mm. 3. For full revolution i. e. 60? the motion of the piston is close to simple harmonic, after 180? the displacement will piecemeal decrease to 0, it will form a cosine graph. PART B Piston Balance and Forces Table 3 Piston balance and forces Angle (? ) No added Piston Weight P3 (N) 4N Added Piston Weight P3 (N) LHS RHS LHS RHS 0 4. 9 4. 9 4. 9 4. 9 30 5. 3 4. 9 5. 8 4. 9 45 5. 5 4. 9 6. 1 4. 9 60 5. 7 4. 9 6. 3 4. 9 90 5. 8 4. 9 6. 2 4. 9 120 5. 5 4. 9 5. 8 4. 9 135 5. 3 4. 9 5. 6 4. 9 150 5. 1 4. 9 5. 5 4. 9 180 4. 9 4. 9 4. 9 5. 3 225 4. 9 5. 3 4. 6. 5 270 4. 9 5. 4 4. 9 6 315 4. 9 5. 5 4. 9 5. 7 Graph of Weights vs. Angle (No added Piston Weight P3 (N)) Graph of Weights vs. Angle (4N added Piston Weight P3 (N)) Discussion 1) Experimental results was not satisfactory, there was some errors made which was ascribable to friction between the mounted disc and the protractor. 2) After looking at the results graph the greatest measuring stick of force approximately at 60? to 90? for no added piston weight. The weight is 5. 8 N at LHS whereas for 4N added piston weight the greatest amount of force is 6. 5 N at 225? RHS. cobblers lastThe kinematic motion of the crank mechanism can be expressed in terms of the lengths of the crank and the conrod, and the displacement of the crankshaft. The experimental measurements of piston displacement agree with the prediction of a theoretical model of the piston motion. ascribable to friction errors were made in the second part of the experiment but still manage to pay back the results to find out the greatest amount of force being exerted on crank mechanism. Reference Experiment 2 Crank Mechanism. (2013). Suva, Fiji Islands. Kearney, M. (2005, August 15). Kinematics of a Slider- crank mechanism.