NUMERICAL INVESTIGATIONS FOR CUTTING OF WIRES AND THREADS

Abstract

Strengthening threads or strings are incorporated in technical textiles for example to protect against vandalism. Among other things, the resistance to mechanical destruction (e.g. cut) depends on the material, the cross-section of the strengthening threads and the support points in the base fabric. An essential criterion for durability is the maximum size of the cutting force, which increases with the decrease in the span. In preceding investigations with spring steel wire, it was shown that an optimum apparently exists for this span. The purpose of the investigations was the development of methods for ascertaining the maximum cutter strengths on the basis of standardised experiments (tensile test) and the proof of the existence of a span optimum. The investigations will be focused on monofilament wireb. For the monofilament, we have succeeded in proving the existence of a span optimum on the basis of according experiments. Thereby, the FEM model is adjusted with the results of the tensile test and of a cutting experiment. The extrapolation to experimentally unrealisable small spans is made with a validated FEM model. The position determined of the optimum matches well with comparable experimental results. The corresponding size of the maximum cutting force is discussed against the background of simplifications in the FEM model. With the aid of an analytical model on the basis of the tensile test data, critical cutting force can be approximately determined.