Mechanical Interaction Behavior Between Human Body And Palm Fiber Mattress

In recent years,with the increase of the aging population and work pressure,people's sleep quality has been more or less influenced.The distribution of contact stress between the body and the mattress is an important measure to evaluate the comfort of the mattress.The irrational distribution of contact stress may cause back pain and bedsore.The establishment of suitable human models for numerical simulation has been a difficult problem in the industry.In the past,most of the research on mattress is based on the experiment.The measurement of body pressure is not only expensive and time-consuming,but also difficult to get the ideal effect.Therefore,through the combination of the three-dimensional scanning technique and the finite element method,the contact stress of the body and palm fiber mattress is predicted and analyzed effectively.People can choose the suitable mattress according to the distribution of the body pressure on the mattress of different materials,thus effectively reducing the back pain and improving the quality of sleep.First,a large amount of compression experiments are carried out to determine the mechanical properties of the palm fiber mattress,and the stress and strain data obtained by the experiment are linear fitting,and the mechanical constants are obtained.Secondly,the pressure distribution measurement system Tactilus is used to determine the body pressure distribution of the selected human body on the palm fiber mattress,and the body pressure data of the selected body are obtained.Then,the body is scanned to obtain the external contour of the human body.Because of the point cloud data,the scanning data of the human body is processed by the reverse software Geomagic Studio,and the entity model of the human body is obtained.Finally,the human body model composed of skin and muscle tissue is established.The contact pressure between the body model and the mattress is predicted,and the correlation between the experimental value and the simulated value is compared by the Pearson coefficient.Considering the geometric nonlinearity,material nonlinearity and contact nonlinearity of the human bed system,the contact stress of a variety of material models of human body and mattress is simulated in different conditions,and the changes of the maximum contact stress,the mean stress value and the correlation degree are compared and analyzed.The results show that the simulation of the human skin using the linear elastic model and muscle using the hyperelastic Mooney-Rivlin model is in good agreement with the experimental results.The hyperelastic model of the muscle tissue is more accurate than the linear elastic model to simulate the contact stress in the supine position.In the finite element simulation,the change of the mattress density and the skin thickness in a certain range has little influence on the distribution of contact pressure in the simulation.The finite element modeling and calculation method proposed in this paper provide a basis for optimizing the design of mattress and have practical significance for the private customization of mattresses.