Investigation on the Curvature Correction Factor of Extension Spring.

P S Tan,Ali Akhavan Farid,Atefeh Karimzadeh,Seyed Saeid Rahimian Koloor,Michal Petrů

doi:10.3390/ma13184199

P S Tan, Ali Akhavan Farid + Show 3 more

Open Access

https://doi.org/10.3390/ma13184199

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Abstract

The curvature correction factor is an important parameter in the stress calculation formulation of a helical extension spring, which describes the effect of spring wire curvature on the stress increase towards its inner radius. In this study, the parameters affecting the curvature correction factor were investigated through theoretical and numerical methods. Several finite element (FE) models of an extension spring were generated to obtain the distribution of the tensile stress in the spring. In this investigation, the hook orientation and the number of coils of the extension spring showed significant effects on the curvature correction factor. These parameters were not considered in the theoretical model for the calculation of the curvature correction factor, causing a deviation between the results of the FE model and the theoretical approach. A set of equations is proposed for the curvature correction factor, which relates both the spring index and the number of coils. These equations can be applied directly to the design of extension springs with a higher safety factor.

Highlights

Extension springs are extensively used in many industrial applications, such as in several parts and instruments in automotive, aerospace, robotics and machinery industries, in which spring failure could cause the failure of a whole system [1,2,3,4]
The curvature correction factor (K) was calculated at the locations shown in Figure 8 for different hook orientations, and the results are presented in Figure 9 in comparison with the results predicted by the theory
Based on the graphs plotted for hook orientation analysis analysis (HOA), the correction factor obtained from the finite element (FE) simulation appears to have a sinusoidal pattern over a period of one revolution of a coil

Summary

Introduction

Extension springs are extensively used in many industrial applications, such as in several parts and instruments in automotive, aerospace, robotics and machinery industries, in which spring failure could cause the failure of a whole system [1,2,3,4]. Extension springs are a part of the helical spring family. They are recognizable by the hooks on the ends of their body. Known as tension springs, extension springs are used for tension applications to provide pulling force when extended. The hooks on the end of an extension spring’s body facilitate the transferring of tension loads to the body of the spring. Knowing the distribution of stress in the spring coil is necessary for the design of this part

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