Research On Pefrormance Evaluation For Passenger Car Chassis Development

Research on performance evaluation for passenger car chassis developmentAlongside with the growths and re-structures of Chinese vehicle market, it is urgent thatthe strict requirements of vehicle quality and performance be met. Nevertheless, traditionalchassis research and design, based on structure developments, rest with the experiences ofengineers who set the performance parameters and repeatedly modify the products accordingto a huge number of experiments, which leaves the problem of longer manufacturing time,high cost and risk and fails. Spontaneously, developing vehicles to meet the customers’needs and realizing independent development which stems from the performancerequirements should be taken at the first possible time.In a bid to overcome shortcomings brought out from traditional vehicle developments,engineers are confronted with big challenges on more scientific and efficient developingmethod, taking accurate parameters from objective evaluation as CAE simulation andoptimization targets; through structure optimization and performance simulation by use ofCAE, provide with more practicable improvement scheme and shorten development period;subjective evaluation, representing customers, takes driving subjective experience in toaccount to determine the function of objective target, so as to pave the way to improve andoptimize vehicle performance and remedy the defects, from the standpoint of customers,yielded from CAE and objective evaluation. Henceforth, the coordinate and concordantrelationship between subjective and objective evaluation, alongside with CAE decides theperformance of classis and development level.This paper focuses on the performance evaluation research of passenger cars’ chassis.By separately building system which bases upon subjective evaluation of customers,objective system bases on subjectivity, evaluation research bases on the development ofperformance and classis adjustment research bases on subjective evaluation, try to accuratelygrasp the relationship between subjective and objective evaluation and realize the forwarddirection independent development of passenger cars in the meantime. The main contents areas follows:First and foremost, specify evaluation items and terms via analyzing the customersdriving manipulations and vehicle dynamical philosophy; set standard and generatesubjective evaluation frame with4level rating system. Taking account the characteristics ofrating scale with symmetry, orientation, range and scale factors, then introduce relative evaluation methodology and uncertainty options to build a10points rating scale withoutoffset and subjective evaluation rating systems relative to rating combination. In order toguarantee the repeatability and consistency of the manipulation of the evaluation program,develop an evaluation software, which consider all effects of prove ground, evaluation task,rating scale and evaluation procedure.Secondly, attempting to ensure the validity of the result of the objective evaluation, tirepressure configuration meter is defined along with the loading distribution and chassisride-height configurations according to evaluation items’ function, sets the requirement andtolerance of wheel alignment. Standardize customers driving manipulation by simulation andset objective evaluation items and evaluation index. Build up objective evaluation systemfacing subjective frame based upon subjective evaluation, combining with the test facilities,data dealing computer program, test standards and proving ground. Provide reliable andrepeatable objective evaluation index for the research of the relationship between subjectiveand objective evaluation as well as vehicle performance development through the newobjective evaluation system.Furthermore, facing the development of vehicle performance, proceed data processing,characteristics abstraction, data mining, weight analysis, etc. Taking On-Center test data asan example, uses ICA technique, alongside with PAC drop dimensional processor, to filterthe dynamic precision of processor, the road surface disturbance, the deviation of subjectiveoperation and process data via interception, filtering and validity analysis to abstract morepure and effective data without noise and then pretreat original data. Build mathematicalmodel which could analysis multi-element main ingredients and used in objectivelyanalyzing the internal relationship between every index. Build handling stability evaluationindex by drop dimension and combine factor analysis model to structure new handlingstability rating formula, realizing handling stability objective evaluation rating intocentesimal grade. Using deviation maximum multi-attribute algorithm to rate the4levelsubjective evaluation system, using benefit model decision to set up decision matrixoptimization target to get third level evaluated score. Take advantage of CWAA to combinethe result of third level evaluation on balance factors set up by different decision makers, andthen get the second level subjective decision score, as the same manner to get the first levelscore to avoid individual decision makers’ preference influence the setting of subjectiveevaluation target resulting partiality caused by developers, henceforth, reflecting thedemocratic thought in the performance of joint-decision making. Last but not least, select appropriate absorber which could precious reflect the responseof steering and ride comfort and combine with subjective and objective evaluation systemand technique to develop applying research. According to the statistics of northeast roadcondition, using sampling method of fuzzy clustering hierarchy, select12typical drivingsections of railway and import ADAMS model of suspension to analyze the motioncharacteristics of absorbers. Set up4kinds of driving operation to simulate customers’ordinary driving condition to pass the test, and then count the motion characteristics ofabsorbers under several typical driving conditions. From those could get the absorber motioncharacteristics under the condition of small displacement and0.03-0.2mm/s speed andtypical braking condition which appears as large displacement and small speed motioncharacteristics. Set up absorber liquid-solid coupling model and gain liquid characteristics,friction characteristics and gas rebound data from bench test as well as the test of absorberdisassembly to set up the original characteristics of AMEPilot model and buildAmeim-iSight model to conduct the optimization analysis of the valve and then finish theoptimization of absorber, at the same time, analyze the sensitivity of valve to guide theabsorber adjustment and the design of valve. By derivate the formulas about interior heatconduction, the analysis of the mechanism of thermal convection, build heat-liquid-soliddacboevsuopiarltbiniegorns,af brasonomdr b t3he0er%nm fotiond de2l0o t%uot saatt u itndhfyel eh dcotaiwmon tp hepero vitneetml oapct erit aty1ura5ren℃ige.n f Mluof ee0an.nc0we the viscosity properties of3h~i le0,.2rmes/est, tthoe g puearrfaonrtmeea nthceeconsistency of the adjustment result.Through setting up subjective and objective evaluation system and subjective andobjective evaluation technique and applying research, associating with a certain product,using subjective and objective evaluation system and technique in the phase of productdefinition, determine development target. Cascade the targets to the performance parametersof the chassis assembles and components. Combined with CAE analysis, define the tuningparts parameters and the performance tolerance. By DOE analyzing on the compliable tuningcomponents, provides guidance for performance tuning; Apply the developed passenger carsubjective evaluation software tool(SSED), does the evaluation and calibration development,such as tire evaluate, EPS calibrate and validate etc. provide effective tools and methods tocarry out subjective evaluation database and data mining research; Apply the shock absorbermodel to analyze damper valves sensitivity and valves setting rules, adjustable shockabsorbers provide quick guidance, and vendor specific demands and performance characteristics of the damp-abrupt point; Prove the subjective and objective systems built inthe thesis can be effectively applied to the V-word development of vehicles and realizevehicle development procedure dominated by performance.The major innovation of this thesis is as follows:1. Based on the research of the subjective evaluation and objective evaluation,define the evaluation items and terminologies, which explained the customer’smanipulation and feeling with vehicle dynamical philosophy. Program the objectiveevaluation by standard some subjective evaluation items, quantity the evaluation indexes.Build up the subjective and objective evaluation system facing the chassis performancedevelopment, which satisfies the customers’ market requirements.2. Based on multivariate statistical approach to deal the objective test data, extractand analyze objective comprehensive evaluation index with statistical loading factors.Based on multi-attribute decision analysis method for maximizing deviation of thesubjective evaluation points of the project, setting statistical weight and ordering as theinformation aggregated. Establish the evaluation methods applied to the subjective andobjective evaluation system.3. Build the liquid-solid coupling shock absorber model and find the dampervalves setting rules by the sensitivity analysis of different valves compounding, analyzethe damper motion based on the piston displacement and speed using the optimizedmodel. Build heat-liquid-solid coupling model, so as to study the temperaturecharacteristics, determine the range influenced by the temperature, and then combine thesimulation and test of absorber motion characteristics, reset the damper performancedeviation, realize the subjective and objective evaluation technique application on theperformance development of chassis.