Analytical and experimental investigation of puncture-cut resistance of soft membranes

Abstract

Modeling and evaluating critical puncture-cutting force and total applied energy are among the most important steps in characterizing the resistance of protective materials to sharp-tipped object insertion. This paper explores the relationship between these two mechanical properties, force and energy, corresponding to the insertion of a pointed blade into soft membranes. The paper’s main contribution includes the addition of friction energy to the existing analytical cutting model in order to develop a more comprehensive model. This energy is provided by the normal stress (contact pressure) caused by the created fracture surface. The contact pressure is applied on both lateral sides of the pointed blade. In this work, a model describing the combined puncture and cutting of protective materials is developed using force distribution analysis and basic concepts of fracture mechanics. Results show that the critical puncture-cutting force (FP/C) required for complete insertion of a pointed blade decreases with the increase of the puncture-cut ratio, ζ, given by the shape of the pointed blade. In other words, the puncture cutting of soft membranes is easier when the pointed blade has a high cutting edge angle than when it has a small cutting edge angle. Fracture mechanics theory is then used to determine the relationship between FP/C and the total puncture-cutting energy, GTotal, that includes fracture toughness of material and friction energy. The presented model is verified by comparing the predicted values of FP/C with experimental data obtained from puncture-cutting tests of soft elastomeric materials and soft-coated fabrics by three pointed blades. According to the proposed model, the methods corresponding to force measurement (FP/C) or energy calculation (GTotal) are both able to evaluate accurately the puncture-cut resistance of protective materials by any sharp-tipped objects.