Research On Ride Comfort Analysis And Collaborative Optimization Of Heavy Commercial Vehicles Based On Nonlinear Mechanical Properties Of Key Parts

With the increasing demand for logistics and transportation from social development,the application of heavy commercial vehicles continues to expand,and higher requirements are placed on vehicle’s comprehensive performance.Meanwhile,heavy commercial vehicles in domestic still have a lot of room for improvement in ride comfort compared with international advanced brands.A heavy commercial vehicle,developed in domestic,is used as the research object to achieve the application purposes of accurately carrying out the simulation and improving the effectiveness of the ride comfort of heavy commercial vehicle.Succeeding,introducing these factors: the non-linearity of the mechanical properties of key components,installation angles,and balance suspension theoretical model,a novel model of ride comfort is established by applying comprehensively the rigid-flexible coupling dynamics,finite element,Lagrangian equation,numerical calculation,model modification,and other theories.Further,the reliability of the theoretical model of balanced suspension and the complete vehicle in vibration characteristics is verified through virtual prototype simulation and vehicle testing,respectively.Next,the influence analysis of operating conditions on the ride comfort and the response analysis of the coupling suspension variable on the ride comfort under random road and impact road are carried out based on the multi-software integrated calculation method.Finally,a multi-objective genetic algorithm is used to achieve collaborative optimization of ride comfort.The specific research is as follows:(1)Based on the actual structure and existing research,the key components that may affect the ride comfort of heavy commercial vehicles and have non-linear mechanical relationships are analyzed and discussed,and the mechanical models are constructed.Firstly,the three-dimensional models of the front axle leaf spring and the balanced suspension are established,and then followed by setting the contact and related constraints in the finite element software,and outputting the modal neutral files.Furthermore,the leaf spring stiffness simulation is performed through the virtual prototype model to obtain the mechanical relationship.After that,the bench test on damping is also carried out to establish a nonlinear damping force model.Ultimately,four theoretical models of balance suspension under various relationships are designed,and their responses are compared with the virtual prototype to determine a suitable balance suspension vibration model.(2)An improved ride comfort model design method and model modification method based on time-frequency domain response is proposed.Multi-axles correlation random road and impact road are first established.Kinetic energy,potential energy,and dissipated energy equations are established by the Lagrange method,and the vibration model was deduced.Farther,the corresponding linear elements are replaced by the nonlinear relations of the key components to establish the improved ride comfort model.The vehicle experiment is carried out to measure the time domain vibration acceleration of axle,sprung mass,and driver’s seat.Finally,with the sum of the RMS value of the difference for time-domain acceleration and the radius of frequency domain response as the correct target,and the unsprung mass,sprung mass,and cab quality as the correct variables,the correction for ride comfort is performed with iteration calculating.(3)Simulation analysis of ride comfort under multiple operating conditions and the response analysis of ride comfort under coupling variables is carried out.Based on the improved and correct ride comfort model,simulation is carried out under different speeds and road conditions,and the response of measuring points is extracted to explore the effects of road conditions and driving speed on ride comfort.A ride comfort analysis platform with a multi-software integrated method is established,and the ride comfort simulation under random road and impact road are carried out with full factor test method to study the effect of suspension(suspend)parameter coupling on ride comfort.(4)A collaborative optimization model for ride comfort under multiple operating conditions and performance indicators is proposed.An optimization model is established with the passenger comfort,cargo safety,and component reliability as the collaborative optimization objectives,suspension working space,natural frequency,and wheel relative dynamic load as the constraint conditions,and stiffness,damping,and installation angle of key components as the optimization variables.The multi-objective genetic algorithm is applied to perform the model drive,and the ride comfort was improved obviously after optimization,which was consistent with the verification results of the target vehicle.