Stochastic modelling of surface texture generated by high-energy jets

The surfaces produced by two different jet cutting processes, namely, abrasive waterjet (AWJ) cutting and laser machining, are characterized for a comparative study. The surface profile measurements from experiments are modelled using auto regressive moving average (ARMA) models. The characteristics of the different profiles are identified by analyzing these models. To describe the surface adequately, a sufficiently large sized sample is utilized for modelling. A novel method for identifying ARMA models based on the concept of model distance, which is ideal for large size samples, is adopted here. The relative advantages of this method are quantified in terms of the accuracy ratio. The profile characteristics (both dynamic as well as static) reveal more information about the nature of these processes. Scanning electron microscope (SEM) photographs of the surfaces generated by laser and AWJ are analyzed to obtain more insight into the physics of these processes.