Research On Design Of Multi-point Force Value Vehicle Shock Absorber Based On Multi-objective Optimization

Shock absorber is an important part of vehicle suspension structure,and its performance directly affects vehicle stability,ride performance and driving safety.In the early stage of development of shock absorber,auto-manufacturer provide the key parameterto the shock absorber manufacturer such as desired damper dimensions,travel and attention point speed indicator characteristics.As the ride performance and comfort of the vehicle are increasing gradually,the acceptance conditions for the performance of the shock absorber are becoming more and more stringent at present,which demands the multiple speed points of the damper performance characteristics.The production and design of multi-point force value shock absorber is still mainly adopted by the model of "experience + repeated test" which is low design precision,long research and development cycle and high cost.The main reason is that the internal structure of the multi point force value shock absorber is complex,the influence factors are numerous and the influence of each parameter on its performance characteristics is indefinite.It will not be able to predict the performance of the absorber in the design stage.On the other hand,the multi-point force shock absorber contains different requirements for the performance characteristics at multiple velocity points,but the design factors corresponding to the performance characteristics of different velocity points is different.The design of multi-point force value shock absorber is a typical multi-objective optimization problem.How to select the design factors of the multi point-force value shock absorber and how to weigh the contradiction between the target values of each velocity point to achieve the established performance goal is a major challenge for the current multi-point force value shock absorber design.Based on this,the design of multi-point force shock absorber is studied in this paper.The specific research work is as follows:1.The theoretical analysis and simulation model validation of the multi-point force absorber.By analyzing the working principle of the shock absorber,combined with the structure of the rear suspension double cylinder hydraulic shock absorber of a passenger car,the corresponding simulation model is built in Amesim,and the confidence level of the model is verified by bench test.2.The analysis of influence factors and sensitivity of multi-point force absorber.The center difference scheme of traditional sensitivity analysis is carried out in the one-dimensional to analyze the influence of the influence factors on the performance characteristics at different speeds.3.The concept of "feasible area contribution" is proposed and the influence factor of the multi-point force damper performance characteristic "feasible area contribution" are calculated."feasible area contribution" circumventing the error of traditional multiobjective optimization analysis process,the traditional sensitivity analysis does not take into account the actual value interval of the influencing factors,while There are specific situations,such as the sensitivity is large but the actual value interval is small,and the sensitivity is small but the actual value interval is large,and then the effect of the parameters is great.Major miscarriage of justice is carried out.The "feasible area contribution" of the multi-point force shock absorber factors which are determined by the range of the experience value of the cooperative enterprises and abnormal sound boundary.4.The contradiction subdivision method of multi-objective optimization problems and the design variables selection and combination of multi-point force value shock absorbers.Using the result of " feasible area contribution ",the contradiction of multi-objective problem is divided into several contradictory groups according to the strong relevance of the contradiction,and then analyze each contradictory group in detail,and choose the main influencing factors and adjustment factors to achieve the tradeoff and compromise of each contradictory group.The above method is used to divide ten optimal targets in the design of multi-point force value damper into three contradictory groups,and each contradiction group is selected to coordinate the contradictions of each group.A total of ten design variables are selected for multi-objective optimization design of multi-point force shock absorbers.5.The establishment of RSM model and multi-objective optimization design of multi-point force damper.In order to improve the efficiency of multi-objective optimization,450 experiments are carried out with one dimensional Amesim model of shock absorber combined with the optimized design method of Latin hypercube test.The simulation results are calculated by iSIGHT software,and the accuracy of corresponding RSM model is verified.multiple points Force-value damper design software is developed using the graphical user interface(GUI)of MATLAB.Finally,the performance characteristics of two groups of shock absorbers under multiple speed conditions proposed by cooperative enterprises are optimized.The maximum error rate of the two groups is 3.27%,the average error rate is less than 1%,and the optimization accuracy is higher than the existing design cases.6.The design regulation of multi point-force value shock absorber is formulated by the sumary of the above analysis.The design procedure is more efficient than the "experience + repeated test" model and the conventional multi-objective design method can better meet the requirements of the multi point performance characteristics of the shock absorber.It provides guidance for solving similar engineering problems.There are several innovative points in this topic:1.The traditional multi-objective optimization process is improved to increase the efficiency and precision of the multi-objective optimization problem in the process of product design,and reduce the research and development cycle and the cost of research and development.The concept of " feasible area contribution " is proposed for the first time,which combined the sensitivity of the design variable with the feasible range.It is applied to the process of parameter selection in the multi-objective optimization process.It avoids the misunderstanding of traditional sensitivity analysis,and makes the optimization result more practical.And it is the first time to refine the contradiction of the multi-objective problem,that is to divide the multiple targets into several contradictory groups according to the strong relevance of the contradiction,and then analyze each contradictory group in detail,and select the main influencing factors and the adjustment factors to achieve the tradeoff and compromise of each contradictory group.It provides a new and effective way for multi-target analysis and processing.2.Multi-point force value shock absorber design rules is established and formed.The steps of the built of simulation model,the failure form of multi point force value shock absorber,that is the source of the feasible domain,the combination of the design variables and the multi-objective optimization design,are synthesized to guide the treatment of similar engineering problems in a standardized way,and provide reference for the solution of the same kind of engineering problems.The design procedure is more efficient than the "experience + repeated test" model and the conventional multi-objective design method can better meet the requirements of the damper's multi point performance characteristics.