Handouts
LINK: Springs
Topics:
Helical Springs
Types of Coil Ends
Useful Equations in Spring Design
Spring in Series/Parallel Leaf Springs
Leaf Springs
Exercises
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1. A helical spring is made by wrapping steel wire 20 mm diameter around a forming cylinder 160 mm in diameter. Calculate the elongation of the spring without exceeding a shearing stress of 150 MPa if it is composed of 20 turns. Let G=80,000 MPa. a. 127.4 mm b. 135.8 mm c. 152.9 mm d. 164.1 mm 2. Compute the deflection of a 20 coils helical spring having a load of 120 kg. The modulus of elasticity in shear of spring is 95 GPa, OD of 9.5 cm and wire diameter of 9.5 mm. The spring is squared and ground ends. a. 167.4 mm b. 175.3 mm c. 185.1 mm d. 194.2 mm 3. Find the Waahl factor of spring that has an OD of 120 mm and inside diameter of 110 mm. a. 1.0 b. 2.0 c. 3.0 d. 4.0 4. A spring has a load of 60 lbs with a spring index of 8. If stress induced is 95,000 psi. Calculate the wire diameter. a. 0.1234 in b. 0.2345 in c. 0.3456 in d. 0.4567 in 5. Three extension coil spring are hooked in series and support a load of 80 kg. One spring has a spring rate of 0.30 kg/mm and the other two have spring rates of 0.65 kg/mm. Find the deflection. a. 512.8 mm b. 520.3 mm c. 546.9 mm d. 587.9 mm 6. A square and ground spring ends has a free length of 300 mm. There are 12 active coils with wire diameter of 13 mm. If the spring rate is 130 kN/m and mean diameter is 120 mm, determine the solid stress. a. 2032.1 MPa b. 2470.0 MPa c. 2872.1 MPa d. 2563.0 MPa 7. What is the length needed to make a helical spring having a mean coil diameter of 1.2-in if there are 10 active coils. a. 37.7 mm b. 42.1 mm c. 32.6 mm d. 48.7 mm 8. A concentric helical spring is used to support load of 100 kN. The inner spring has a spring rate of 490 kN/m and outer spring is 125 kN/m. If initially the inner spring is 20 mm shorter than the other spring, find the percent load carried by the inner spring. a. 77.7% b. 65.2% c. 82.1% d. 60.7% 9. A spring has a diameter of 30 mm and 15 active coils. If a load of 12 kN is applied and it deflects 80 mm. Find the wire diameter of the spring. G=85 GN/m2. a. 135.3 mm b. 165.0 mm c. 156.3 mm d. 112.7 mm 10. Four compression spring coils in parallel is used to support a load of 380 kg. Each spring has a gradient of 0.725 kg/mm. Determine the total deflection. a. 122.0 mm b. 110.1 mm c. 145.9 mm d. 131.0 mm 11. Three extension coil spring are hooked in series and supports a weight of 80 kg. One spring has a spring rate of 0.20 kg/mm and the other two have spring rates of 0.650 kg/mm. Find the total deflection. a. 531.9 mm b. 646.2 mm c. 752.1 mm d. 427.5 mm 12. If it is determine experimentally that a load of 30 kg applied to an extension coil spring will provide a deflection of 180 mm. What load will deflect the spring by 50 mm. a. 6.3 kg b. 7.4 kg c. 8.3 kg d. 9.2 kg 13. A weight of 120 lbs strikes a coil spring from a height of 20 inches and deflects the spring 5 inches. Calculate the average force acting on the spring. a. 1000 lbs b. 1100 lbs c. 1200 lbs d. 1300 lbs 14. A spring sustains 300 ft-lb of energy with deflection of 5-in. Assume that the main coil diameter is 8 times the wire diameter and the allowable stress of 100000 psi, compute the wire diameter. a. 0.211 in b. 0.342 in c. 0.542 in d. 0.417 in 15. It is found that a load of 60 lbs makes a spring deflect by 10-in. What load will make the spring deflect by 3-in? a. 17 lbs b. 18 lbs c. 19 lbs d. 20 lbs 16. A spring has a load of 60 lb with a spring index of 9. If stress induced is 95000 psi, find the wire diameter. a. 0.2207 in b. 0.1297 in c. 0.3125 in d. 0.4092 in 17. An extension coil spring is to be elongated by 6 in under a load of 60 lbs. What is the spring rate? a. 8 lbs/in b. 10 lbs/in c. 9 lbs/in d. 11 lbs/in 18. A spring has a spring rate of 40 kN/m. If the wire diameter is 12 mm with a mean diameter of 80 mm, find the number of active coils. Let G=85 GN/m2. a. 10.76 b. 11.31 c. 18.31 d. 20.00 19. A spring with plain ends has 16 active coils with wire diameter of 7 mm and pitch of 12 mm. If the spring rate is 90 kN/m, find the solid force. a. 6.3 kN b. 7.2 kN c. 8.5 kN d. 5.2 kN 20. A squared and ground ends spring has a pitch of 18 mm, wire diameter of 12.4 mm. If there are 14 actual number of coils, the deflection of the spring when compressed to its solid length is ____.
a. 74.2 mm b. 67.3 mm c. 78.4 mm d. 80.1 mm 21. A leaf spring is made of 4-in wide with effective length of 15-in and thickness of 0.20-in. The spring has three full-length and six graduated leaves. If the central load carried is 1200 lb, find the deflection. a. 1.20 in b. 2.10 in c. 3.91 in d. 4.80 in 22. A leaf spring is made of 3.5-in wide with effective length of 18-in and thickness of 0.3-in. The spring has two full-length and five graduated leaves. If the central load carried is 600 lbs, find the maximum stress for the leaves. a. 19285.7 psi b. 20312.1 psi c. 17311.5 psi d. 22800.0 psi |
Helical Springs
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The smaller of two concentric helical springs is made of 22 mm diameter steel spring wire with an outside diameter of 100 mm and 10 active coils. The outer spring is made of 32 mm steel spring wire with an outer coil diameter of 250 mm and 8 active coils. Before the load is applied, the outer spring is 25 mm longer than the inner spring. If the total load of 90 kN is applied to the nest of the spring, determine the spring rate of each spring and what part of the total load is carried by each wire. SOLUTION: |
Alternating Loads in Springs
A helical compression spring made of 5.72 mm steel spring wire carries a fluctuating load, the spring index is 6, and the factor of safety is 1.50. If the average load on the spring is 535, find the permissible values for the maximum and minimum loads, Sy = 648 MPa and Se = 343 MPa.
SOLUTION:
