Research On The Comfort Of Foam Cushion For Vehicle Seat

As one of the main components of the vehicle seat,foam cushion plays a role in supporting the body and vibration isolation.The basic research on the cushion foam is a hot spot in the research of automobile vibration comfort.In view of the comfort of the foam cushion of the automobile seat,this paper studies the influence of the cushion foam material on the ride comfort from the hardness and thickness of the foam.The subjective comfort evaluation experiment and the objective interface pressure measurement are conducted.The dynamic model of human-cushion is established,the influence of the foam with different thickness and hardness on the transmission characteristics of the vertical vibration of the system is analyzed and compared,which provide a reference for the production of vehicle seat foam.Firstly,foam cushion with five thickness and three hardness are made.12 male volunteers are chosen to carry the interface pressure measurement and subjective comfort evaluation about each foam cushion.The statistic method is used to process the data and find the vary trend of average pressure,max pressure,the hip max pressre gradient and contact area with the thickness and hardness of the foam.And find the influence of the thickness and hardness on the subjective comfort evaluation.The results show that the first three indexes of body pressure decrease with the increase of foam thickness,and increase with the increase of foam hardness.The subjective comfort increases with the increase of foam thickness,and decreases with the increase of hardness.The comfort feeling is poor under two conditions of smaller thickness and larger hardness.Secondly,the SVM-R method is used to establish the prediction model between the interface pressure indexes,human parameters(BMI)and the subjective comfort evaluation.Set the interface pressure indexes and BMI as attributes,and the subjective comfort evaluation as labels.The data is pre-processed by election,normalization and division,then choosing the RBF as kernel function to find the parameters by grid search.Finally the prediction model is established with a prediction accuracy of 0.911.Results show that the SVM-R method is more suitable for the small sample prediction in this paper by comparing the prediction performance of different methods.Finally,the stiffness and damping of the cushion foam with different hardness and thickness are measured.The results show that the stiffness decreases with the increase of the thickness,and increases with the hardness,and the stiffness increases with the increase of the pre-compression when the cushion if soft.The transfer function of the system under the conditions of different stiffness and damping is calculated in the human-cushion system.By analyzing the transfer function of the system,the vibration isolation performance of the foam cushion with different hardness and thickness is compared,to obtain the optimum combination of foam thickness and hardness.