| Abstract: | The term softness is loosely used to describe the physical as well as sensory attributes of fabric and other textiles, and several psychophysical evaluation methods as well as its predicting equations exist. However, the information for physiological mechanism of fabric softness is lack. To explain the biomechanical and the potential neurophysiological phenomenon for exploring fabric softness,accompanying to the procedures in manual exploration for softness and the anatomical multilayer structures of human finger, a contact finite element (FE) model between finger and fabric is made to conduct an active contact analysis. In present FE model, the effect of surface friction index,compression modulus, Poisson's ratio of fabric on softness discrimination is investigated. The interests are in the contributions of these fabric property variables to contact area, interfacial friction shear stress and contact pressure distributions, which are significant cognitive variables or stimulus parameters in peripheral neural levels. The mechanistic data for fabric specimens indicates that the basis for the perception of softness of flexible and bulk fabric is likely on the spatial variation of pressure on the skin (or,equivalently the skin displacement and its derivatives)resulting from surface friction phenomenon and compression property of fabric. In present model, however, the effect of Poisson's ratio on the total force exerted by fingertip is not significant statistically. Therefore, compression modulus of fabric is, not the only underlying physical variable accounting for peripheral neural response, and also the surface friction phenomenon plays an important role in feeltouch softness of fabric, i.e. the compressibility and surface properties of fabric are the necessary physical variables involved for the haptic rendering of its softness. |
