An Analysis of Tearing Failure

Abstract

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.