Springs

Introduction about springs

1. Unit-4 Springs

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 Closed coil helical or Tension spring Open coil helical or Compression spring

7. Closed coil helical or Tension spring

8. Open coil helical or Compression spring

9. Spiral Spring

10. Leaf Spring

11. Disc or Belleville Spring

12. Conical Spring

13. Design of Helical Compression Spring

14. 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

15. Stresses in Helical Spring

16. Subjected to Axial Load

17. formulas Torque, T = F X R But , Torque =

18. Shear & Transverse Stresses

19. Transverse shear stress Resultant shear stress

20. 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

21. Deflection of the spring C= D/d

22. Stiffness of the spring C= D/d

23. Strain Energy Stored in Spring (U) Also

24. Spring Under Impact Load Energy Absorbed in Spring

25. 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

26. Design Procedure of Helical Spring

27. The designers should find the following basic things Pitch Diameter of the coil , D Wire Diameter, d Number of turns , n Free Length , L f Solid Length, L s Spring Stiffness, q Type of Ends

28. Condition of Natural Frequency

29. Stiffness – Springs in Series

30. Stiffness – Springs in Parallel

31. Helical Spring Subjected to Variable Loading Formulas P 7.100 PSGDB

32. Helical Spring Subjected to Variable Loading Spring subjected to fluctuating stresses are designed on the basis of modified Soderberg equation

33. Design of Belleville Spring

34. 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

35. Formulas Axial Deflection

36. Constant

37. Maximum Stresses occurring at the edges

38. C1 & C2 - Constants

39. Constants finding graph In general the ratio of do / di should be 1.5 - 5

40. Belleville Spring Material Chrome Vanadium Alloy Steel Allowable stress 1500 N/mm 2 Young’s Modulus 2 x 10 5 N/mm 2 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

41. t / do 0.03 – 0.06 Cone Angle 4 – 7 degree Best value 6.5 Degree

42. INTRODUCTION

43. Formulas 7.131-PSGDB 7.131-PSGDB

44. LEAF SPRING

45. LEAF SPRING or FLAT SPRING The laminated or leaf spring (also known as flat spring or carriage spring) consists of a number of flat plates (known as leaves) of varying lengths held together by means of clamps and bolts

46. Arrangement of leaf Spring The design may be of cantilever type or simply supported type.

47. 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

48. Material

49. Design Procedure

50. Check for Pin

51. Check for Pin

52. Length of Leaf Spring Leaves Radius of Leaf Spring Leaves

53. FLY WHEEL

54. 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)

55. 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.

56. Two distinct Applications of Fly wheel

57. Types of fly wheels

58. Fly wheel effect and co-efficient of fluctuation of speed

59. 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.

60. Value of Co-efficient of Fluctuation of speed (Ks) 7.121-PSGDB

61. Mass of the fly wheel (m)

62. Co-efficient of fluctuation of energy ( K e ) The difference between maximum and minimum energy during the cycle is called fluctuation of energy

63. Values of Co-Efficient of Fluctuation of Energy ( Ke )

64. Stresses in Fly Wheel rim

65. Stresses in Fly Wheel Tensile Stress Due to Centrifugal Force

66. Cont.. Bending Stress Due to Straining Effect of Arms

67. Cont.. Resultant Stress In rim with the junctions of arms

68. Stresses in Rims Tensile Stress Due to Centrifugal Force

69. Cont.. Bending Stress Due to Torque

70. Cont.. Belt Stress Stress Due to Belt Tension

71. Design of flywheel shaft, Hub and Key Shaft Hub di = d

72. Design of flywheel shaft, Hub and Key Key

73. CONNECTING ROD

74. Formulas 7.122 - PSGDB 7.122 - PSGDB 7.122 - PSGDB

75. Formulas 7.122 - PSGDB

76. Formulas 7.122 - PSGDB

77. Formulas 7.122 - PSGDB 7.122 - PSGDB 7.122 - PSGDB

78. Whipping Stress

79. CRANK SHAFT

80. Introduction It’s a shaft used to convert a reciprocation motion of piston into rotary motion

81. Types of crank shaft

82. Material of crank shaft The crank shaft subjected to shock and fatigue loads. so its should have more tough and fatigue strength

83. Stresses in Crank Shaft