| With the development of the automotive industry and the changes in consumer demand,seating comfort has received increasing attention,and how to evaluate seat comfort has become increasingly important.In the traditional seat development process,the evaluation of seat comfort can only be conducted after the production of the seat prototype is completed,which results in high costs and waste of time.Therefore,it is of great significance to study how to evaluate and improve seating comfort through simulation methods in the early design stage.In order to obtain more accurate simulation results of body pressure distribution,in this paper,research was conducted on fine modeling of a finite element model of Chinese male individual with 95th size in stature,as well as on constitutive modeling of the seat materials and extraction of the comfort law through subjective and objective evaluation tests,aiming to achieve accurate prediction of subjective comfort during the seat design stage through simulation results and evaluation models.Firstly,a biomechanical human body model consisting of bone,skin,soft tissue,and the cavity of chest and abdomen was established based on the latest human body anthropometry data of Chinese 95th percentile male stature.In order to improve the stability and accuracy of the calculation,as many proportion as possible of hexahedral elements were adopted to mesh the soft tissues of the human body.The material properties were assigned to various tissues of the human body according to their biomechanical characteristics,and the model assembly was completed in ABAQUS.The rationality of the mass distribution of each body segment of the human body model was verified,and the simulation of the pressure distribution at the human-seat interface was conducted.The accuracy of the human body model was verified by comparing the simulation results with the experimental results.For a human-seat simulation system,the accuracy of seat modeling is also crucial.Therefore,the material constitutive modeling of the main components of the seat,sponge foam and cover,was studied.For the mechanical properties of foam materials such as nonlinearity,high resilience,and stress hysteresis,the Hyperfoam constitutive model and Mullins effect were selected to describe them.An orthotropic linear elastic constitutive model was selected for the different mechanical properties of PVC cover composites in the longitudinal and latitudinal directions.According to relevant test standards,a series of material property tests were conducted on specimens of foam and cover to obtain relevant parameters of the constitutive model.At the same time,based on the characteristics of sponge foam material curves,a method for establishing sponge materials with different hardness through curve scaling was proposed based on the existing material curve library.Finally,subjective and objective evaluation tests were conducted to establish a comfort evaluation model.In the subjective evaluation test,an evaluation scale was designed,and the participants’support and comfort rating evaluation for the body parts were collected.Weight coefficients were assigned to each body part using the entropy method.The evaluation standards were then corrected,and the corrected subjective scores were used as the dependent variable for the evaluation model.In the objective test,the participants’body pressure distribution was measured,and the regional body pressure distribution data was calculated.Subsequently,correlation analysis was conducted for each indicator,and variables were selected as independent variables of the evaluation model.The adjusted R~2 of the final regression model is 0.589,and the predicted results of the model were compared with the actual results in the test set,showing a high level of prediction accuracy.In practical applications,combined with the simulated body pressure distribution data,the prediction of comfort can be achieved during the early stages of seat design. |
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