Wrinkle Behavior Research Articles

The Wrinkle Behavior of Wool Fabrics Introduced Thiol Groups and the Effects of Hg Ion Adsorption.

In order to improve the wrinkle recovery of wool fabrics, various methods have been proposed, for example, incorporation of some bulky molecules, crosslinking with appropriate bifunctional compounds, and treatment with mercury(II) acetate and so on. In this paper, a new attempt for improving the wrinkle recovery of wool fabrics has been proposed, that is an introduction of much thiol(-SH) groups in the fabrics, considering the theory of wrinkle formation. The analysis of physical properties of the much -SH groups introduced wool fabrics, reveals that the wrinkle recovery and set property have been improved without any changes in weight, in color and handling. The sulfur content in the treated wool was found to be increased by analysing with X-ray fluorometry. This fact leads us to an conclusion that the wrinkle recovery mechanism of the present method might be based on the formation of disulfide(-SS-) groups in wool fabrics. As a comparison, we examined the wrinkle recovery mechanism by mercury(II) acetate treatment, and found that Hg ions could present as -S-Hg+ in the fabrics, which might eliminate the hydrogen bond.

Wrinkled Membranes and Cable-Stayed Bridges

In seeking an efficient arrangement for the bearing cables of a cable-stayed bridge, inspiration is drawn from the natural wrinkling behavior of in-plane stressed triangular membranes. The bridge deck is thought of as being sustained by such a membrane, rather than stays, and the wrinkle pattern is studied as vertical loads act on the deck. Since it can be shown that the resulting wrinkles are straight and develop in such a way as to offer maximum stiffness towards impinging actions, the idea is to place cables according to their layout. The examined cases consider various ratios between the height of the towers and the main span of the bridge, reproducing as well the scheme of significant existing bridges and the possible presence of notches in the membrane. In all the cases, the patterns assumed by the wrinkles show evident resemblance to the traditional harp, half-fan, and fan schemes, and reveal surprising similarities with the disposal of the stays really adopted in existing bridges.

Postbifurcation behavior of wrinkles in square metal sheets under Yoshida Test

The stretching of a square sheet along one of its diagonals, called “Yoshida Test”, has been developed to simulate the wrinkling behavior in press forming of steel sheets into autobody panels. The finite deformation, onset of wrinkling and growth of wrinkles in such a specimen are investigated. Hill’s yield criterion for sheet materials have the normal anisotropy and Hill’s quasi-static bifurcation criterion are employed. The growth of wrinkles in the finite deformation process is incrementally and numerically determined by a thin shell finite element in a convected coordinate system. The Lagrangian formulation of the thin shell finite element is based on Hill’s variational principle for elastic-plastic solids, a modification of Love-Kirchhoff postulates and a quasi-conforming element technique. The shell element fulfills the inter-element C1 continuity condition in a variational sense. Reasonable agreements between the present numerical results and available analytical and experimental results are shown.

Water Transport and Wrinkle Recovery of Wool

A "ratchet" mechanism is discussed for the formation and recovery of wrinkles in wool fabric. During the wrinkling stage, in which local temperature and humidity are raised, stress relaxation rates are increased by the lowering of the glass transition temperature by plasticization with water, by the ambient increase in temperature, and by additional heating caused by a positive heat of sorption. During recovery, the temperature and relative humidity decrease, giving a greatly reduced relaxation rate that delays wrinkle recovery. On the assumption that wrinkle behavior can be improved by reducing the rate of water transport, measurements were made of the water desorption rate from a fabric taken from 86% to 65% RH. Fabrics were treated with phenyl isocyanate, urea, acetic anhydride, esterification with methanol, potas sium dichromate, and mercuric acetate. Although a part of the altered wrinkle behavior may be due to changes in equilibrium water content, the data suggest that slowing the desorption rate is a primary factor in improving wrinkle recovery.