Study On The Mechanical Properties And Comfort Of The Cushion Of The Flat Loofah Sofa

The application of natural green material loofah in the sofa seat cushion core will expand the source of sofa seat cushion filling materials and reduce environmental risks.The loofah segment has been flattened by hot pressing to different degrees,and the elasticity,stiffness,flexibility,support,recovery,and elasticity of the loofah segment under different densities and different hot pressing processes are characterized through a series of mechanical property tests.Comfort and other characteristics,and compared and optimized the low-density loofah with a hot-pressed thickness of 40 mm,which is similar to the mechanical characteristics of the sponge,for the production of the cushion core;4 types of loofah seats were designed and produced according to different cushion arrangements.Cushion,carried out a variety of tests including measuring the vertical deflection to test the deformation characteristics of the cushion,introducing the theoretical creep model to solve the rheological parameters to analyze the viscoelasticity of the cushion,and measuring and observing the resilience and collapse.Mechanical properties were investigated.And through the body pressure distribution test and the 7-level semantic scale,a scientific analysis of the comfort of the loofah seat cushion was done combining subjective and objective.The research results are as follows:(1)The load-displacement curve of the high-density loofah with a hot-pressed thickness of 10 mm and the low-density loofah with a hot-pressed thickness of 10 mm and 20 mm continues to plastically deform,and the materials are basically inelastic,which are not suitable for sofa seat cushion cores.High-density loofah has the highest elastic modulus and yield strength,and is very difficult to deform.The stiffness is too large compared to sponge,and there are problems caused by excessive stiffness and poor flexibility.The high-density loofah with a hot-pressed thickness of 20 mm has the highest stiffness and flexibility Poor,very unsuitable for sofa seat upholstery.The indicators of low-density loofah are similar to those of sponge,and the elastic deformation range is larger.Among them,the low-density loofah with a hot-pressed thickness of 40 mm is the most similar to S50 sponge.(2)The hot-pressed thickness has a linear negative correlation with the indentation hardness of the high-density and low-density flattened loofah.There was no significant effect on the 24 h deformation recovery rate of high-density and low-density flat loofah,and the compression deformation characteristics of low-density loofah.Indentation hardness and compression deformation characteristics are in the order of high-density loofah > low-density loofah > sponge,and the overall support performance of the loofah seat cushion is better than that of sponge.However,the recovery ability of the sponge under compression is stronger than that of the loofah,and the low-density loofah with a thickness of 50 mm under hot pressing is obviously the worst.The closest to the sponge indentation hardness and compression deformation characteristics is the low-density loofah with a hot-pressed thickness of50 mm,and the closest to the sponge deformation recovery rate is the low-density loofah with a hot-pressed thickness of 40 mm,and both are the most similar to the S50 sponge.near.(3)The average vertical deflection and the average deflection per unit distance of the three types of seat cushions all decrease from the center to the outside,and the load force is positively correlated with the average vertical deflection and negatively correlated with the average vertical deflection per unit distance.The loofah seat has uneven deformation in different directions,while the sponge seat has more uniform deformation in all directions under the action of concentrated load.The subsidence depth and deformation degree of the sponge seat cushion are significantly larger than those of the loofah seat cushion,and the subsidence and deformation of the bottom layer of the loofah seat cushion are smaller in the same direction than in the opposite direction.(4)The creep curves of the three seat cushions all show that the subsidence displacement increases with time,and shows a very obvious nonlinear change.After reaching a certain value,it tends to be stable,and the deformation is close to a certain value.The elastic deformation coefficient of the fitted creep model reflects that the deformation resistance of the loofah seat cushion is significantly lower than that of the sponge seat cushion.The viscosity coefficient reflects the minimum permanent deformation of the foam seat.Compared with the different direction arrangement,the middle and bottom layers of the loofah seat cushion are arranged in the same direction,which can improve the deformation resistance of the seat cushion and reduce the permanent deformation.Compared with the sponge seat cushion,the loofah cushion has a large amount of rebound and a rapid rebound trend,and slightly collapses.(5)In the objective evaluation of comfort,a number of pressure values reflect that the stiffness of the loofah seat cushion is slightly higher than that of the sponge seat cushion.The M-Y-D saddle is relatively stiffer and less flexible.The longitudinal pressure distribution curve reflects that the body pressure distribution of several seat cushions is reasonable in the direction of sitting depth,but the lateral pressure distribution reflects that the body pressure distribution of the middle and bottom layers of the loofah cushion core is more symmetrical than that of the opposite direction,and the comfort is better.high.In terms of subjective evaluation,the M-T-A seat cushion is the best,and the sponge seat is the worst.The loofah seat cushion can be comparable to or even better than the high-density and high-hardness sponge seat cushion,and the middle and bottom cushion cores are arranged in the same direction,which is more comfortable than the opposite direction.In terms of subjective and objective correlation,the larger the contact area,the stronger the stability;the greater the average pressure,the stronger the buttocks wrapping feeling;the greater the maximum pressure,the more uncomfortable the buttocks,and other subjective and objective indicators have little correlation.