  In our analysis, we show that what Cottenden et al. accomplish is the
derivation of the ordinary capstan equation, and a solution to a dynamic
membrane with both a zero-Poisson's ratio and a zero-mass density on a rigid
right-circular cone. The authors states that the capstan equation holds true
for an elastic obstacle, and thus, it can be used to calculate the coefficient
of friction between human skin and fabrics. However, using data that we
gathered from human trials, we show that this claim cannot be substantiated as
it is unwise to use the capstan equation (i.e. belt-friction models in general)
to calculate the friction between in-vivo skin and fabrics. This is due to the
fact that such models assume a rigid foundation, while human soft-tissue is
deformable, and thus, a portion of the applied force to the fabric is expended
on deforming the soft-tissue, which in turn leads to the illusion of a higher
coefficient of friction when using belt-friction models.
