Prediction of Wire Breakage in Wire Electrical Discharge Machining by using a Thermomechanical Damage Model

Wire breakage is the main limitation to productivity in Wire Electrical Discharge Machining (WEDM). This study investigates the thermomechanical mechanisms of wire failure and develops a physics-based cumulative damage model for predicting breakage under realistic loading conditions. Experimental results show that wire failure is governed by a thermally activated loss of load-carrying capacity that depends on temperature, stress, and time — not on instantaneous thermal thresholds alone. A damage-rate model combining power-law stress dependence and Arrhenius-type temperature activation is proposed and calibrated from experiments under varying stress levels and heating rates. Implemented in the SPARC finite-element simulation framework, the model correctly distinguishes between safe and critical operating conditions, in qualitative agreement with observed machine behavior.