Study On Compressibility And Viscoelasticity Of Multilayer Spacer Fabric

Spacer fabric is a kind of three-dimensional fabric,which is composed of an upper surface layer,a lower surface layer,and a spacer wire intermediate layer connecting the upper and lower surface layers.The warp-knitted spacer fabric has excellent pressure-releasing performance.When it is subjected to external force,the spacer wire can produce a large bending effect,and the external pressure can be rapidly diffused,which can avoid the occurrence of stress concentration,so it is suitable for use as a pad.When used as a cushion material,the compression performance is its main performance.However,the current research on the compressive properties of spacer fabrics mainly focuses on the compressive properties of single-layer spacer fabrics,and lacks research on the compressive properties of multi-layer spacer fabrics and the comfort of multi-layer spacer fabrics.Therefore,the main research idea of this topic is to perform flat compression and spherical compression tests on multilayer spacer fabrics,extract relevant indicators from the flat compression and spherical compression results,organize and analyze them,and then establish a spacer fabric compression viscoelasticity model.The compressive performance was theoretically analyzed to reveal the internal interaction relationship.Finally,based on the optimization model,the influencing factors of the compressive elastic modulus of the spacer fabric were explored,and the relationship between the fabric modulus and the subjective comfort evaluation was established.The main research contents and conclusions of this paper are as follows:(1)The compressive properties of multi-layer spacer fabrics were studied by the lamination stacking method.Through research,it is found that the vertical stacking method has better anti-compression performance,compression resilience performance and durability.With the superposition of the spacer fabric layers,the overall compression work of the fabric keeps increasing,indicating that the more layers there are,the stronger the overall compression performance of the spacer fabric is;there is a good correlation between the compression work,recovery work,hysteresis work and other indicators between plate compression and spherical compression.There is a good correlation between indicators such as work and hysteresis work,and there is a good correlation between the compression work,recovery work,linearity and other indicators of spherical compression of different sizes,and there is a certain linear relationship between them.The parameter value of one characteristic index can be used to predict the parameter value of other characteristic index.(2)Based on the viscoelastic properties of the spacer fabric itself,a variety of viscoelastic models are established to analyze its compressive behavior.The linear spring model,Maxwell model,Kelvin model,improved Maxwell model and improved Kelvin model were established,the constitutive equations of each viscoelastic model were deduced,and the test results of plate compression were fitted and analyzed,and the most suitable model was determined.The optimal model used to describe the internal action relationship in the elastic compression stage of spacer fabrics—the improved Kelvin model;whether it is the test curve of a single-layer spacer fabric or the test curve of a multi-layer spacer fabric,the improved Kelvin model fits it The R~2 values are all above 0.99,and it can be considered that the fitted curve is completely consistent with the experimental curve.The model has a small deviation rate between the predicted value of the spacer fabric modulus and the standard value of the modulus,and the reliability is high;the improved Kelvin model can be used to analyze the elastic modulus value of spacer fabrics and the viscosity coefficient in the elastic compression stage;the improved Kelvin model constitutive relationship shows that the elastic compression stage of the spacer fabric is essentially a nonlinear stage;with the stacking of spacer fabric layers,the strength of friction between spacer fabric layers and the strength of interaction between fabric interfaces increases continuously;with the superposition of the spacer fabric layers,the proportion of energy dissipated,that is,"useless work",continues to increase,causing the spacer fabric to occur.The work of deformation,that is,the proportion of"useful work"is gradually decreasing,so the compression ratio of the spacer fabric decreases gradually with the increase of fabric layers.(3)Use the optimization model to explore the influencing factors of the compressive elastic modulus of the spacer fabric.When the spacer fabrics are stacked vertically,the elastic modulus is larger.The stacking sequence of the multi-layer spacer fabrics hardly affects the elastic modulus of the fabric.The greater the external force strength,the greater the overall elastic modulus of the fabric;the more layers of spacer fabric,the greater the elastic modulus of fabric,the higher the subjective comfort of human body;the elastic modulus of fabric increases with the increase of fabric layers,but at this time,the human body's overall comfort evaluation score for the fabric is the same before and after,indicating that when the number of fabric layers is improved to a certain extent,the difference in comfort perceived by the human body is not particularly obvious;from the perspective of consumers,in the process of actually purchasing a spacer fabric mattress,you can purchase it on demand and choose the appropriate thickness.It is not necessary to choose a mattress with a large number of layers and a large thickness.You can choose a mattress with a slightly smaller number of layers,and you can also obtain a consistent comfort experience.The elastic modulus of the fabric has an important impact on the subjective evaluation results of the human body.