AN ENERGY APPROACH TO THE CHARACTERIZATION OF THE FRACTURE-RESISTANCEOF LEATHER

The fracture resistance of chrome-tanned bovine hides was quantitative ly characterized by measuring the total energy required to break the l eather. This physical quantity named fracture energy is observed to mo re truthfully represent the fracture resistance of leather than the te nsile strength or breaking elongation. Three major independent variabl es, moisture content, strain rate, and sampling angle were arranged ac cording to Box-Hunter's experimental design matrix, thereby deriving a second order polynomial equation. The statistical model so obtained c oncisely expressed the relationship between the variables and correspo nding fracture resistance. The results showed that water acting as a p lasticizer enhances the fracture resistance of leather. However, fract ure energy started to decrease once the moisture content increased to around 90%. Contrary to its effect on tensile strength, the sampling a ngle has shown little effect on the fracture energy of leather. The ef fect of strain rates on fracture energy is not straightforward. The fr acture energy at first decreases then increases with increasing strain rates. The ratio of tensile strength of Young's modulus was used to r epresent the toughness of leather. This parameter is dimensionless, in dependent of the geometric shape of the leather samples. A correlation was observed between this parameter and fracture energy.