7. What is spring index (C)? The ratio of mean or pitch diameter to the diameter of wire for the spring is called the spring index. 8. What is pitch? The axial distance between adjacent coils in uncompressed state. 9. What is solid length? The length of a spring under the maximum compression is called its solid length. It is the product of total number of coils and the diameter of wire. Ls = nt x d Where, nt = total number of coils. 10. What are the requirements of spring while designing? a. Spring must carry the service load without the stress exceeding the safe value. b. The spring rate must be satisfactory for the given application. 11 What are the end conditions of spring? (a) Plain end. (b) Plain and ground end (c). Squared end (d) Squared and ground end. 12. What is buckling of springs? The helical compression spring behaves like a column and buckles at a comparative small load when the length of the spring is more than 4 times the mean coil diameter. 13. What is surge in springs? The material is subjected to higher stresses, which may cause early fatigue failure. This effect is called as spring surge. 14. What is a laminated leaf spring? In order to increase, the load carrying capacity, number of flat plates are placed and below the other.
S.K.P. Engineering College, Tiruvannamalai V SEM 90 Mechanical Engineering DepartmentDesign of machine elements15. What semi –elliptical leaf springs? The spring consists of number of leaves, which are held together by U-clips. The long leaf fastened to the supported is called master leaf. Remaining leaves are called as graduated leaves. 16. What is nipping of laminated leaf spring? Prestressing of leaf springs is obtained by a difference of radii of curvature known as nipping. 17. What are the various applications of springs? The springs are used in various applications, they are a. Used to absorb energy or shocks (e.g. shock absorbers, buffers, e.t.c.) b. To apply forces as in brakes clutches, spring-loaded valves, e.t.c. c. To measure forces as in spring balances and engine indicators d. To store energy as in watches 18. Define free length. Free length of the spring is the length of the spring when it is free or unloaded condition. It is equal to the solid length plus the maximum deflection or compression plus clash allowance. Lf = solid length + Ymax + 0.15 Ymax 19. Define spring index. (ODD- 2011) Spring index (C) is defined as the ratio of the mean diameter of the coil to the diameter of the wire. C =D/d 20. Define spring rate (stiffness). (ODD- 2011)(EVEN-2016) The spring stiffness or spring constant is defined as the load required per unit deflection of the spring. K= W/y Where W-load Y-deflection
S.K.P. Engineering College, Tiruvannamalai V SEM 91 Mechanical Engineering DepartmentDesign of machine elements21. Define pitch. Pitch of the spring is defined as the axial distance between the adjacent coils in uncompressed state. Mathematically 22. What are the points to be taken into consideration while selecting the pitch of the spring?