Prediction Of The Mechanical Behaviour Of Helical Springs Using Coupling Cross-Section Finite Element Technique

Mechanical springs are very important machinery parts which are used for cushion,shock absorption and storing energy.The design and precision of mechinical springs directly determine the whole machine's performance.The cylindrical helical springs are the most widely used mechanical springs.At present,the widely applied design and calculation method of cylindrical helical springs is based on simplified analytical method. Due to the mathematical complexity involved, the effect of helix angle has not been well considered in the available design formulae.With the improvement of design and manufacturing level and the widely application of large helix angle springs in industries such as auto industry ,the traditional design and calculation formula hasn't meet the requirement of calculation precision. In this paper,the traditional analytical method is inspected and couping cross-section finite element technique is used to analyse the statical properties of helical springs. The new results derived in this paper can provide valuable means for the design of new spring for the accurate.As helical springs are helical symmetrical structures, when they are subjected to axial symmetric loads (extension or/and torsion, but not bending) the deformation and warping on any cross-sections will be the same. This deformation characteristic can be render the analysis of helical springs to be performed on only a slice of the spring wire provided that the spring termination effects are neglected. Precise boundary conditions can be implemented. First of all, the numerical results of circular cross-sectional springs are used to deive new valuable accurate design formulae fully considering the helix angle effects through mathematical regression. Then normalized load-deformation relationship for large deformation springs are given. Finally the use of the coupling cross-section finite element technique for the analysis of composite springs are also addressed. It is believed that the new results in this thesis can provide valuable reference for the accurate analysis and design of new springs.