Tear Load Research Articles

ポリ塩化ビニル被覆鋼板の機械特性に及ぼす可塑剤の影響

Strain developing polyvinyl chloride (PVC) films containing Al flake powder during formation was analyzed by a finite element method. It was found that stress in the film was concentrated at the edge of the Al flake powder, and led to breakdown of the film. Strain in rigid films was less than in flexible films. In an effort to improve the formability of PVC films containing Al flake powder used to coat sheet steel, the composition of the plasticizer in PVC plastisol was examined. It was found that by using a secondary plasticizer and a reactive plasticizer in the PVC plastisol containing Al flake powder it was possible to obtain a rigid PVC film, and the tearing load and tensile breaking load of the film were improved, resulting in good formability in a variety of roll forming processes.

接着接手における接着剤層の応力分布

In order to get the directions for the design of adhesive joints, the stress distribution in the adhesive layer of a modeled adhesive joint under shear, tear or tensile load has been analysed by using the finite element method. It has been shown that there is the stress concentration at the corner composed of the free surface and the adhesive-adherent interface of adhesive layer for the respective loads, and that the stress distribution at the mid-plane of the adhesive layer is uniform. The stress concentration tends to increase, except for the tensile load, when the Young's modulus of the adhesive increases, and is largest under the tear load. Therefore it is recommendable to use an adhesive of low stiffness and soft for a joint to be used under tear load. Furthermore, the validity of Volkersen's and Goland & Reissner's equations, which are popularly used to determine the maximum shear stress of lapped joints, has been discussed comparing the results analysed for shear load with these of both equations.

Tearing characteristics of vulcanized natural rubber

The anomalous behavior of uncompounded vulcanizate based on crystalline natural rubber leads to a pronounced dependence of the characteristic tearing energy H on the test conditions. Partial crystallization of the rubber occurs during tearing at v = const (constant average rate of tearing) and jerky tearing is observed at low averaged values of H. At Q = const (constant tearing load) low values of H are obtained for smooth tearing in the absence of crystallization and high values at the maximal degree of crystallization.

An Analysis of Tearing Failure

The tearing failure of materials depends very strongly on the conditions of use or testing which produce the non-uniform tensile stress which causes such failure. In the trapezoid tear test. the stress pattern is determined largely by variables at the disposition of the operator. The effect of these variables on the tearing strength and the relationship of the latter to the shape of the force-elongation curve have been determined. The tear load is given by an equation of the form where g is the modulus. h is the thickness. L o is the gauge length, α is the trapezoid angle. and E is the elongation of the material at break. The form of the term f( E) is deter mined by the shape of the force-elongation curve and has been calculated for the linear case and for cases yielding convex and concave curves. The validity of this equation has been evaluated with experiments on cotton and rayon fabries in which gauge length, trapezoid angle, thickness and elongation were varied The data are reasonably well tit by the equation using the form of f( E) calculated for a linear force-elongation curve.