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Abrasive water jet (AWJ) cutting systems are extensively used in industry, thus optimisation of the process parameters that determine efficiency, economy and quality of the process is becoming more and more important. However, being a complicated cutting system, the performance of AWJ is characterised by a large number of process parameters, which include water pressure, orifice diameter, traverse rate, standoff distance, impact angle, focusing tube diameter, abrasive flow rate (AFR), etc. Therefore, optimising the process parameters involves a number of challenging efforts. This paper concentrates on investigating the optimum AFR at the highest cutting speed under different water pressures, orifice diameters and focusing tube diameters. Based on a theoretical derivation combined with an experimental study, an empirical model for calculating the optimum AFR is created.

In order to alleviate the problems of complex structure and low reliability of traditional Shape Memory Alloy (SMA) rotary actuator, a planar vortex actuator (PVA) based on SMA material was proposed to directly output torque and angular displacement. Based on the calculation method of PVA and the constitutive model of the phase transition equation of SMA, the mechanical model is established, and the pre-tightening torque, temperature, output torque, and rotation angle are obtained. The relationship expression between the tests has verified the mechanical model. The results show that the relationship between the excitation temperature and the output torque, the coefficient of determination between the calculated value and the tested value, is 0.938, the minimum error is 0.46%, and the maximum error is 49.8%. In the relationship between angular displacement and torque, the coefficient of determination between the calculated value and the test value is 0.939, the maximum error is 58.5%, and the minimum error is 28.0%. The test results show that the calculated values of mechanical model and experimental data have similar representation form.