Torsional stress: S, total corrected stress transpose for D, P,or t Wahl curvature-stress correction factor: K a1 = 1 ++ +where C = Rectangular Wire Rate (see Fig 7 2 for factors K 1 and K 2): R = K 2 transpose for b, t, N, or D Torsional stress, corrected: S =? transpose for P or D ? is obtained from Fig 7 2 7 2 1 Solid Height of
The coil of a torsion spring experiences bending stress (despite the name of the spring) Including a stress-correction factor, the stress in the coil can be represented by The stress-correction factor at inner and outer fibers has been found analytically for round wire to be K i is always larger, giving the highest stress at the inner fiber
Every spring configuration has a spring rate, k,defined as slope of its force-deflection curve If slope is constant, it is a linear spring, and y F k = Where: F is applied force, and y is deflection When spring rate varies with deflection, it is called a nonlinear springnonlinear spring We often want a linear springto control loading
1 1 The stress correction factor relative to the spring index (C) can be determined by using the following formula or based on Fig 1 Symbols Used 1 2in Spring Design Formulae Symbols used in spring design formulae are shown in Table 1 Basic Formulae Used in Designing of Springs 1 2 1Compression Springs, and TensionSprings without Initial D1 L D
The spring legs were loaded using Ø9mm pins at a radius of 40mm from the jig centre When deflecting to a fixed angle, the torque, and hence stress, was lower when using a smaller mandrel, but the spring visibly sheared producing stresses that were not the same at each of the strain gauge location The average stress measured with each mandrel was
The stress equation at a given load (P) is a function of the coil diameter and wire diameter Our goal is for the stress at solid to be 40 of the minimum tensile strength (MTS) The MTS is a function of the wire size, which we don’t know The Advanced Spring Design program uses an iterative process to solve this snarled mess of equations
Stresses in Helical Springs Th C boards Spring rate and stress distribution can be controlled with The curvature correction factor can now be obtained by