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DESIGN OF MACHINE ELEMENTS
- 2. Introduction Spring is an elastic member which deflects under the action of load and it regains its original shape after the load is removed.
- 3. Application • Automobiles • Railway wagons • Valves • Watches
- 4. Functions of springs • To provide cushioning effect • Reduce the effect of shock or impact load • To measure forces in spring balance • To store energy such as in clocks, toys • To apply forces and to control the motions as in brakes and clutches. • To control motions by maintaining contact between two elements as in cam and followers
- 5. Types of Spring • 1. Helical springs. The helical springs are made up of a wire coiled in the form of a helix and is primarily intended for compressive or tensile loads. The cross-section of the wire from which the spring is made may be circular, square or rectangular. The two forms of helical springs are compression helical spring and tension helical spring.
- 6. Types of Helical spring Helix angle more than 10 degree Helix angle less than 10 degree 1)Closed coil helical or Tension spring 2)Open coil helical or Compression spring
- 7. Advantages of helical spring The helical springs have the following advantages: (a) These are easy to manufacture. (b) These are available in wide range. (c) These are reliable. (d) These have constant spring rate. (e) Their performance can be predicted more accurately. (f) Their characteristics can be varied by changing dimensions.
- 9. Leaf Spring
- 10. Disc or Belleville Spring
- 11. Conical Spring
- 12. Design of Helical Compression Spring
- 13. 1)Free length 2)Pitch 3)Endurance limit 4)Slenderness ratio 5)Pitch 6)Active coils 7)Solid length 8)Pitch angle TERMINOLOGIES IN A COMPRESSION HELICAL SPRING 9)Hysterisis 10)Initial tension 11)Permanent set 12)Set 13)Spring rate 14)Spring index
- 18. Stresses in Helical Spring
- 19. Subjected to Axial Load
- 20. formulas Torque, T = F X R But , Torque =
- 21. Shear & Transverse Stresses
- 23. Wahl’s Stress Concentration Factor • C should not be less than 3 • The value of C should be 5-12 • For industrial spring C= 6 -10
- 24. Deflection of the spring C= D/d
- 25. Stiffness of the spring C= D/d
- 26. Strain Energy Stored in Spring (U) Also
- 27. Spring Under Impact Load Energy Absorbed in Spring
- 28. End Conditions of Spring = Active coil + inactive coils Poor Seating Space Better Seating Space than Plain Better than other types in Seating Space Its for high stress model spring application
- 29. Design Procedure of Helical Spring
- 30. The designers should find the following basic things • Pitch • Diameter of the coil , D • Wire Diameter, d • Number of turns , n • Free Length , Lf • Solid Length, Ls • Spring Stiffness, q • Type of Ends
- 36. Condition of Natural Frequency
- 37. Stiffness – Springs in Series
- 38. Stiffness – Springs in Parallel
- 39. Helical Spring Subjected to Variable Loading Formulas P 7.100 PSGDB
- 40. Helical Spring Subjected to Variable Loading • Spring subjected to fluctuating stresses are designed on the basis of modified Soderberg equation
- 41. Design of Belleville Spring
- 42. S. NO Springs in parallel Springs in Series 1 They have high load capacity, this depends on number of discs The deflection is proportional to the number of discs
- 44. Constant
- 45. Maximum Stresses occurring at the edges
- 46. C1 & C2 - Constants
- 47. Constants finding graph In general the ratio of do / di should be 1.5 - 5
- 48. Belleville Spring Material Chrome Vanadium Alloy Steel Allowable stress 1500 N/mm2 Young’s Modulus 2 x 105 N/mm2 Poisson’s Ratio 0.3 Thickness of spring 1 – 2 mm Dia of disc at base 28 – 300 mm h / t 0.4 – 0.75 for stiffness
- 49. t / do 0.03 – 0.06 Cone Angle 4 – 7 degree Best value 6.5 Degree
- 50. INTRODUCTION
- 52. LEAF SPRING
- 53. LEAF SPRING or FLAT SPRING • The spring used not only for absorbing load , its also used to carry • Lateral Loads • Braque Torque •Driving Torque
- 54. Arrangement of leaf Spring • The design may be of cantilever type or simply supported type.
- 55. Limitations in Leaf spring They are stressed more at one specific location and the other parts are stressed lightly So some design considerations needed in this type. So they increase the width of the plate and keep the thickness as same
- 56. Material
- 57. Design Procedure
- 60. Check for Pin
- 61. Check for Pin
- 62. FLY WHEEL
- 63. INTRODUCTION Fly wheel is a heavy rotating member placed between power source and driving unit. It act as a reservoir – for storing energy (its an energy accumulator)
- 64. Functions of fly wheel • It will absorb energy when the demand is less than supply of energy. • It will release it when the demand is more than the supply of energy.
- 65. Two distinct Applications of Fly wheel
- 66. Types of fly wheels
- 67. Fly wheel effect and co-efficient of fluctuation of speed
- 68. Cont…
- 69. Maximum Fluctuation of speed Co-Efficient of fluctuation of speed The difference between maximum speed and minimum speed during the cycle is called maximum fluctuation of speed.
- 70. Value of Co-efficient of Fluctuation of speed (Ks) 7.121-PSGDB
- 71. Mass of the fly wheel (m)
- 72. Co-efficient of fluctuation of energy (Ke) The difference between maximum and minimum energy during the cycle is called fluctuation of energy
- 73. Formulas
- 74. Values of Co-Efficient of Fluctuation of Energy (Ke)
- 75. Stresses in Fly Wheel rim
- 76. Cont.. Tensile Stress Due to Centrifugal Force
- 77. Cont.. Bending Stress Due to Straining Effect of Arms
- 78. Cont.. Resultant Stress In rim with the junctions of arms
- 79. Stresses in Rims Tensile Stress Due to Centrifugal Force
- 80. Cont.. Bending Stress Due to Torque
- 81. Cont.. Belt Stress Stress Due to Belt Tension
- 82. Design of flywheel shaft, Hub and Key Shaft Hub di = d
- 83. Design of flywheel shaft, Hub and Key Key
- 84. CONNECTING ROD
- 86. Stresses in Connecting Rod
- 87. Formulas 7.122 - PSGDB 7.122 - PSGDB 7.122 - PSGDB
- 90. Formulas 7.122 - PSGDB 7.122 - PSGDB 7.122 - PSGDB
- 91. Whipping Stress
- 92. CRANK SHAFT
- 93. Introduction • It’s a shaft used to convert a reciprocation motion of piston into rotary motion
- 94. Types of crank shaft
- 95. Material of crank shaft The crank shaft subjected to shock and fatigue loads. so its should have more tough and fatigue strength
- 96. Stresses in Crank Shaft
- 97. Failure Cause The crank shaft failures are caused by a progressive fracture due to bending or reversed torsional stresses . Thus the crank shaft is under fatigue loading, so the design is based on the endurance limit of the material of the crank shaft