An investigation of cutting resistance in stretched polymer films

An investigation is made into the fracture properties of polymer films and laminates under cutting by a sharp tool and lateral tension under pure shear conditions. The method involves use of a sharp razor blade applied to the crack tip of polymer films which are also stretched orthogonal to the direction of the blade. The reaction force is measured as the cutting tool cuts the material and the force from applying a lateral strain is measured. The analysis and tests assume quasi-static conditions. The method is applied to a polyester film and three polyester laminates.Steady-state cutting forces are observed from cutting tests and loads at crack initiation are observed from lateral stretching tests. With fracture mechanics analysis the energy contributions from cutting and tearing are used to determine apparent fracture properties from the experimental results. It is observed that the cutting and tearing tests yield similar fracture toughness properties for the three tested polyester laminates, despite the different crack tip geometry at the point of crack growth. However, significantly larger fracture toughness values are measured from tearing tests versus cutting tests for the tested polyester film.