Fabric bending stiffness test

Years of development have led to a standardized system for objective evaluation of fabric hand (129). This, the Kawabata evaluation system (KES), consists of four basic testing machines a tensile and shear tester, a bending tester, a compression tester, and a surface tester for measuring friction and surface roughness. To complete the evaluation, fabric weight and thickness are determined. The measurements result in 16 different hand parameters or characteristic values, which have been correlated to appraisals of fabric hand by panels of experts (121). Translation formulas have also been developed based on required levels of each hand property for specific end uses (129). The properties include stiffness, smoothness, and fullness levels as well as the total hand value. In more recent years, abundant research has been documented concerning hand assessment (130—133). 

In most applications where bending apparently takes place, the rubber is also deformed in shear, tension or compression, for example in a shaped door seal, when the test for stiffness would be a compression test on the actual part. Generally, rubbers are not stiff enough in flexure to support appreciable loads so that there is not much need for flexural tests and, at the same time, the lack of stiffness makes such tests a little difficult to carry out with precision. There are, however, some cases where stiffness in bend is of interest, for example with thin sheet and coated fabrics as a measure of... 

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