Research On Mechanical Properties Of Irregular Section Inclined Coil Spring

In inclined coil springs,renowned for its excellent nonlinear stiffness,are widely employed in aerospace elastic components with high performance seal structures.It is found that the compression potential of spring can be improved effectively by changing the shape of spring base surface.In view of this finding,a derived design method based on skew coil springs is proposed in this paper,and the mechanical properties of skew coil springs with irregular sections are analyzed from different angles.The main research contents are as follows:(1)The parametric structure model of the skew coil spring with irregular section is established.First of all,according to the derivation process of the parameterized guide line of the circular skew coil spring,a new idea is obtained to establish the skew coil spring with special section by changing the shape of the base surface.Secondly,the parametric equation of the guide line of the skew coil spring with irregular section is described by the segmented polar coordinate equation,and then the parametric geometric model is obtained by the sweep modeling,which provides the basis for the subsequent analysis of the mechanical properties of the skew coil spring with irregular section.(2)The nonlinear stiffness theory of skew coil spring with irregular section is studied,and Frenet movable frame is established according to the parametric equation of spring guide line to describe the stress of spring.Based on the force analysis and functional relationship of the local cylindrical section of the spring,the nonlinear stiffness calculation method is derived,and verified by finite element simulation and stiffness test.Then the structural parametric analysis of the spring is carried out,and the influence of the change of the structural parameters of the spring on its mechanical properties is obtained.It is proved that the deformed section inclined coil spring has a larger compression stroke when the structural parameters are the same.(3)The fatigue life of inclined coil spring with irregular section is predicted.Firstly,by comparing the applicable conditions of different fatigue analysis theories and cumulative damage theories,the nominal stress method and linear damage theory are used to predict the fatigue life of the spring.Secondly,various factors affecting the fatigue life of the spring and the influence trend of different structural parameters of the spring on its fatigue life are analyzed,and the methods to improve the life of the spring are obtained.