A study of spherical compression properties of knitted spacer fabrics part II: comparison with experiments

The objective of this part is to compare the results calculated from the model developed in part I with experimental measurements. Five warp-knitted spacer fabrics made with polyester filaments but with different thicknesses and outer layer structures, as well as different spacer yarn fineness, are selected for testing their compression properties under both the plane plate and spherical ball compressions. The plane compression stress-strain curve of each fabric sample is divided into three regions and the curve segment in each region is approximately represented by a linear equation. The equation constants, that is, modulus E and intercept sigma(0) for each curve segment, are obtained by the linear fitting method. Based on the values of E and sigma(0) obtained, the compression curve under spherical ball compression of each fabric sample is calculated and compared with the experimental one. Three compression parameters, including the maximal compression force and compression work at the compression strain of 0.70, as well as the linear degree, are also used for comparison. Good agreements are obtained between the calculations and measurements. Thus, based on the plane compression testing results, the validated model can be used to predict the spherical compression behaviors of knitted spacer fabrics compressed with different radii of the spherical balls.