Analytical Design Research On Two-Stage Auxiliary Spring Type Parabolic Variable Section Main Auxiliary Spring

Two-stage auxiliary spring type parabolic variable section main auxiliary spring has three levels of stiffness,which can make the vehicle suspension under different loads of frequency offset basically maintain stability,so that the vehicle has good ride,the structural plate spring also has the advantages of low manufacturing cost,long service life,so it is highly valued by the suspension field experts and related enterprises.However,for the new structural plate spring,the mechanical model established in the past cannot fit the actual situation well.At the same time,restricted by the analytical calculation theory of the mechanical characteristics of the two-stage auxiliary spring type parabolic variable section main auxiliary spring,the current design of its key parameters mostly adopts the methods of approximate value,empirical value and repeated trial and error,without forming a systematic and reliable forward design process.Especially for the design of the contact position clearance,only the approximate value of the main spring endpoint deflection and curvature affects the contact load,and further leads to the plate spring does not meet the design requirements.In order to solve the above problems,starting from the analytical calculation theory,this paper conducts a systematic study on the mechanical characteristics and parameter design of the two-stage auxiliary spring type parabolic variable section main auxiliary spring.The main work and innovation achievements are as follows:(1)The mechanical model of the two-stage auxiliary spring type parabolic variable section main auxiliary spring was established,and substitute the equivalent width and coordinate offset into the analytical calculation formula of mechanical properties;Based on the bending deformation theory of cantilever beams,using the Mohr integral,combined with the calculation methods of flexibility addition and stiffness superposition,the analytical calculation formula for stiffness at all levels was established;Based on the linear elastic assumption,the analytical formula for calculating the end deflection was established;Applying the unit force in the Mohr integral to the contact position,the analytical formula for calculating the deflection of the contact position was established;Based on the principle of equivalent thickness and load distribution,the analytical formula for calculating the stress at any position of the single leaf spring was established.(2)Based on the established analytical calculation formula for the mechanical properties of the two-stage auxiliary spring type parabolic variable section main auxiliary spring,the analytical design method for the thickness and length of the flat and straight section of the plate spring was established through joint constraints of stiffness and stress;According to the requirements of residual arc height and prestress matching,the design method of plate spring arc height was established;Based on the contact position deflection,the analytical design method for the clearance of leaf springs at all levels was established;According to the stress distribution characteristics of the main and auxiliary springs,the design method for the maximum limit deflection was established with the constraint that the impact stress meets the strength check.(3)The influence of the structural parameters of the two-stage auxiliary spring type parabolic variable section main auxiliary spring on their mechanical properties was analyzed and summarized.Using the single variable method,by changing the structural parameters of each level of leaf spring,the comparative diagram of the mechanical properties of the primary and auxiliary springs with different parameters was drawn;The stress concentration locations that should be paid special attention to in forward design were analyzed to provide reference for the optimization and adjustment of forward design results.It reduces the possibility of relying on empirical values,repeated trial and error,and other methods to bring significant deviation to the design results.Through example design,finite element simulation,and prototype testing,the correctness of the analytical calculation method for mechanical properties and key parameters of the two-stage auxiliary spring type parabolic variable section main auxiliary spring established in this paper was verified,providing guidance for the forward development,design,and digital production of the two-stage auxiliary spring type parabolic variable section main auxiliary spring.