Active hydrostatic journal bearings represent a mechatronic answer to the fast-growing industrial needs to high-performance rotary machineries. The aim of this research is to study and improve the dynamic characteristics of hydrostatic bearing, with four pockets or recess. In order to improve dynamic characteristics for hydrostatic journal bearing, this research presents an active hydrostatic journal bearing with servo control. The results of active hydrostatic journal bearing with servo control were compared with those of traditional hydrostatic journal bearing with capillary throttling. The dynamic characteristics of the newly proposed bearing and traditional bearing are studied and compared under different dynamic conditions such as variable speed, viscosity, load, pressure, and bearing clearance. The numerical result shows that the proposed active hydrostatic journal due to active lubrication has good performance including stability and controllability, high stiffness, faster response, and strong resistance. Furthermore, two strategies such as proportional–integral–derivative and integrator backstepping control are also presented to improve the performance and efficiency of active hydrostatic journal bearing with servo control. The result shows that integrator backstepping control is more effective than proportional–integral–derivative control in terms of faster response and greater amplitude reduction, quickly regaining equilibrium position, and good stiffness against load. Hence, it is observed that active lubrication in hydrostatic journal bearing provides us better dynamic characteristics which will have potential applications in heavy and high-speed machinery.

Titanium alloy materials are used in a variety of engineering applications in the aerospace, aircraft, electronics, and shipbuilding industries, and due to the continuous improvement of the contemporary age, surface integrity needs to be improved for engineering applications. Belt grinding parameters and levels directly affect the surface integrity of titanium alloys (TC4), which further affects the fatigue life of the titanium alloys during service. In order to investigate the surface integrity of titanium alloys at different roughness levels, the surfaces were repeatedly ground with the same type and different models of abrasive belts. The results showed that at roughness Ra levels of 0.4 μm to 0.2 μm, the compressive residual stresses decreased with increasing linear velocity and there were problems with large surface morphological defects. At the roughness Ra of 0.2 μm or less, grinding improves the surface morphology, the compressive residual stress increases with increasing feed rate, and the surface hardness decreases with increasing linear velocity. In addition, the research facilitates the engineering of grinding parameters and levels that affect surface integrity under different roughness conditions, providing a theoretical basis and practical reference.

Projection stereolithography creates 3D structures by projecting patterns onto the surface of a photosensitive material layer by layer. Benefiting from high efficiency and resolution, projection stereolithography 3D printing has been widely used to fabricate microstructures. To improve the geometric accuracy of projection stereolithography 3D printing for microstructures, a compensation method based on structure optimization is proposed according to mathematical analysis and simulation tests. The performance of the proposed compensation method is verified both by the simulation and the 3D printing experiments. The results indicate that the proposed compensation method is able to significantly improve the shape accuracy and reduce the error of the feature size. The proposed compensation method is also proved to improve the dimension accuracy by 21.7%, 16.5% and 19.6% for the circular, square and triangular bosses respectively. While the improvements on the dimension accuracy by 16%, 17.6% and 13.8% for the circular, square and triangular holes are achieved with the proposed compensation method. This work is expected to provide a method to improve the geometric accuracy for 3D printing microstructures by projection stereolithography.

The current research work presents a low cost, efficient and innovative active aerostatic thrust bearing which is controlled through a combination of the Arduino board, feedback transducers and high-speed valves. The purpose is to make low cost, compact active aerostatic thrust bearing with overall small dimensions and compact size. A prototype design is done in solid works with small dimensions and components are produced with the help of the high precision machining process. There are two high-speed electropneumatic valves which are controlled through pulse width modulation techniques. These high-speed electro-pneumatic valves modify the supply pressure of aerostatic bearing to achieve desired air height gap. There are two novel pressure sensors which provide a feedback signal for control. The test bench to perform experiments has been explained. The performance of the proposed aerostatic bearing is checked both in open loop and closed loop configuration with respect to static and dynamic conditions.