Research On The Forward Design Of The Human Body-Seat Interface For The Ideal Pressure Distribution

The study of the human body-seat interface pressure distribution of body belongs to static comfort realm.The body pressure level and its distribution are important indices in measuring the seat comfort,and should be considered in seat comfort design.At present,in the seat comfort design subjective experience is mainly adopted to conduct the seat profile design during the early stage,and then validation is conducted in the later process by body pressure test and subjective evaluation to optimized the design.In this traditional development mode iteration is inevitable with the result of prolonging the development process and bringing the waste of cost.Therefore,to solve the above problem a forward design method is studied in this thesis to acquire the seat profile quickly with the ideal interface pressure distribution.The main design process of this paper is: Firstly,according to GB/T 10000-88 Chinese adult human body size parameters,the driving posture model was established.The ideal pressure distribution matrix is constructed based on SAE ideal pressure distribution.Then applied it to the corresponding area of the established body model surface to simulate the deformation.The body surface deforms under the action of ideal pressure,and the deformation profile is the body surface profile after the human body is seated.Based on the experimental parameters of polyurethane foam,the deformation law of sponge was calculated,and the mathematical model of the relationship between deformation amount,thickness and pressure in different regions on the body surface was established to determine the deformation amount of polyurethane foam under different pressures and thicknesses.Take that contour of the human body surface after seat as an initial position,and the position is also a seat depression profile,compensating the deformation amount of polyurethane foam under different pressures and thickness on the surface of the seat depression profile to obtain the ideal key contact area shape of the seat surface before seating,and inversely designing the ideal seat sponge shape before seating according to the obtained point cloud of the ideal key contact area.The comfort of the designed ideal seat sponge profile was verified.The 50 th human body model was assembled with the seat to simulate the real sitting posture of the human body.The effectiveness of the designed seat profile was verified according to the simulation results of seat body pressure distribution.In order to complete the modeling of the human body model,the human tissue material model was studied in the early stage.The characteristics of skin,bone and muscle materials were described in terms of anatomical structure and mechanical properties of materials.Material curves were evaluated through a large number of human body test data at home and abroad.The differences between different constitutive models were compared,and the human tissue material constitutive model was selected.In order to complete the establishment of seat sponge foam material model,the constitutive model is selected for the mechanical properties of seat sponge foam,such as high resilience,non-linear elasticity,viscoelasticity,stress relaxation and dependence on strain rate.The compression and shear test characteristics of sponge foam are designed to determine the parameters,and the accuracy of the results is verified by simulation.This paper focuses on the forward design method of automobile seat comfort.The reliability of the results is verified by comparing the pressure distribution of the reverse seat with the ideal pressure distribution.According to the simulation verification results,the deformation law of sponge foaming is explored.The influencing factors such as profile design,angle,different pressure gradient level,sponge hardness,stress and so on are analyzed from different sections.The simulation results show that compared with planar seats,curved seats have larger contact area and adhesion,significantly reduce peak pressure,and thus have higher comfort.Based on the analysis of automobile seat comfort,the forward design method is further applied to wheelchair seat cushion and electric bicycle seat.The results show that the seat has a good pressure distribution level,which verifies the universal forward design method of seat comfort oriented to ideal pressure distribution.