Volume 2, Issue 5 (May 2005)
Progress in the Characterization of the Cutting Resistance of Protective Materials
A sliding sharp edge that penetrates a material is one of the most dangerous cases of cutting because it requires the smallest applied normal load. This study aims to analyze the cutting mechanics and mechanism of protective rubber materials in the presence of friction and the effect of the material's mechanical behavior and the blade's sliding velocity on the material's cut resistance. The International Standard ISO 13997 cut test method, which consists of measuring the distance that a straight blade slides horizontally to cut through a material under a constant applied normal force, was used to investigate the cutting phenomena. In practice, the cut resistance of a material is given by the contribution of the material's intrinsic strength and the frictional distribution between the material and the blade that slides and penetrates it. This study demonstrates that two types of friction are involved in material cutting: a macroscopic friction induced by the gripping of the material and by the applied normal load on the two sides of the blade; and a sliding friction associated with cut-through of the material that occurs along the face of the blade tip. For rubber materials, commonly used in protective gloves, the adhesion force due to the gripping of the material on the blade edge could be several times greater than the friction due to the applied normal force. Thus, the cutting energy required to break the molecular chains in rubber materials is much smaller than the energy dissipated by friction. For these materials, the elastic modulus, the structure of the material, as well as the sliding velocity, have a significant effect on the friction. Therefore, all of these properties can affect the cutting resistance results. A better understanding of the cutting mechanism in protective materials is a fundamental step in developing better performing protective materials.