Jiakang Zhou

The turning process of SiCp/Al composites is challenging due to the inhomogeneity and complex interaction between different phases. Ultrasonic vibration-assisted cutting (UVAC) technology is one of the effective methods to improve the machinability of SiCp/Al composites, but it is still necessary to clarify the influence of ultrasonic impact effect on related physical quantities. In this paper, numerical methods and systematic cutting experiments are used to study the evolution of various physical quantities and their impact on machinability during UVAC for SiCp/Al composites. Firstly, the UVAC process is abstracted into an ultrasonic impact behavior, enabling the identification of impact parameters acting on the machined surface per unit time. Then, a 3D finite element model of equivalent homogeneous SiCp/Al composites is established to simulate the impact process. This model facilitates a comprehensive analysis of key parameters such as the process system energy, plastic deformation, stress distribution, and hydrostatic pressure. Finally, the evolution laws of physical quantities related to UVAC of SiCp/Al composites and their influence on surface quality are analyzed. The results show that the impact effect induced by UVAC changes the stress state of the machined surface and increases the average surface microhardness by 6.7%. Moreover, the presence of high compressive hydrostatic pressure in plastic deformation zone is conducive to densifying the subsurface and reducing the surface roughness by approximately 30%. These insights provide valuable theoretical guidance for the precision turning and surface treatment process of SiCp/Al composites.

Three-dimensional elliptical vibration assisted cutting (3D-EVC) technology has been widely used in many high-precision technical fields due to its high-efficiency processing characteristics. However, the hysteresis and nonlinearity caused by the piezoelectric drive in the 3D-EVC system will impact the system control accuracy. This paper mainly studies the hysteresis and nonlinearity of the system, the feedforward-gray predicted fuzzy PID compound controller based on the generalized Bouc-Wen hysteresis nonlinear model and it is designed to realize the hysteresis compensation of the system. In this paper, input voltage and output displacement are represented by a mathematical relationship, and this relationship of the 3D-EVC system will be described by the generalized Bouc-Wen model. The improved flower pollination algorithm (IFPASO) is adopted in the identification process of parameters. A compound control strategy is formed based on traditional feed-forward control combined with fuzzy PID feedback control to compensate for hysteresis and nonlinearity, and an improved gray prediction model is introduced into the feedback loop. The 3D-EVC system tracking experiment verifies the effectiveness of the designed compound controller. Experiments have proved that the hysteresis component of the system is significantly reduced after the use of the compound controller for hysteresis compensation, and the system has a higher degree of stability.

To predict the cutting force in machining of SiCp/Al composites by ultrasonic elliptical vibration-assisted turning (UEVT) technology, a semi-empirical geometric model considering the deformation and friction characteristics in different deformation areas is established in this paper. During UEVT, the resistance force acting on cutting edge is divided into three parts according to different deformation zones: shear force, interface friction, and plowing force. The vibration characteristic functions are also coupled to the semi-empirical geometric model of cutting force. A three factor and four level orthogonal tests is implemented to verify the validity of geometric model, and the single factor cutting experiments are also conducted to evaluate the influence law of relevant parameter on cutting force. Experimental results show that the deviation between the calculated value of cutting force and measured average value is less than 17%, and the average deviation is 8.16%, which proved that the semi-empirical geometric model can effectively predict the cutting force of SiCp/Al composites during UEVT. In addition, the influence of cutting parameters and volume fraction on cutting force is discussed, which provides a theoretical guidance for the outstanding machinability of SiCp/Al composites in UEVT.

In the traditional magnetorheological polishing of flat planar elements, there have been problems like low efficiency and uneven surface. To improve the surface quality of optical glass and explore the material removal mechanism, a novel reciprocating cluster magnetorheological polishing (MRP) device was designed with a magnetic field consisting of six curved permanent magnets and one static magnetic finite element for analysis. By analyzing the forces and motion behaviors of single abrasive particles during the polishing process, a novel removal model was developed and the effects of the main parameters on the material removal mechanism were investigated. The experiments ware conducted on the K9 glass through the polishing process by this proposed device and traditional cold working separately. The results showed that reciprocating cluster MRP for 120 min was able to achieve a surface roughness of 2.7 nm, a Peak to Valley (PV) value of 0.689 fr (216 nm) and a Root Mean Square (RMS) value of 0.077 fr (24 nm), respectively, which made a significant improvement on the conventional cold working. Therefore, the proposed device and novel polishing process could effectively reduce the surface roughness value and the PV value of K9 glass, while improving both the polishing efficiency and accuracy of optical components.

Three-dimensional elliptical vibration assisted cutting technology has been widely used in the past few years. The piezoelectric stack drive structure is an important part of the three-dimensional elliptical vibration aided cutting system. Its piezoelectric hysteresis characteristics affects the final output of the elliptical trajectory. Aiming at this problem, a piezoelectric hysteresis modeling method based on a generalized Bouc–Wen model is presented in this paper. An improved flower pollination algorithm (IFPASO) was used to identify Bouc–Wen model parameters. Standard test result shows that IFPASO has better algorithm performance. The model identification effect experiment proved that the Bouc–Wen model obtained by IFPASO identification, the highest modeling accuracy of the three axial subsystems, can reach 98.86%. Therefore, the model can describe the piezoelectric hysteresis characteristics of the three axial subsystems of the 3D-EVC system effectively and has higher modeling accuracy and fitting accuracy.

The machining process of SiCp/Al composites is considerably difficult because of the addition of ceramic particles. As an effective machining method, ultrasonic vibration-assisted turning is used to process SiCp/Al composites, which can effectively reduce the cutting force, improve the surface quality, and reduce the tool wear. This study developed a cutting force prediction model for ultrasonic vibration-assisted turning of SiCp/Al composites, which comprehensively considers the instantaneous depth of cut and the instantaneous shear angle. This model divides the cutting force into the chip formation force considering the instantaneous depth of cut, the friction force considering the influence of SiC particles at tool-chip interface, the particle fracture force, and the ultrasonic impact force in the cutting depth direction. By comparing the predicted value of the main cutting force with the experimental values, the results present the same trend, which verifies the feasibility of the cutting force prediction model. In addition, the influence of vibration amplitude, depth of cut, and cutting speed on the main cutting force is analyzed. The systematic cutting experiments show that ultrasonic vibration-assisted turning can significantly reduce the cutting force and improve the machinability of SiCp/Al composites.

To analyze the effect of particle shape on deformational behavior in the cutting simulation process for metal matrix composites (MMCs), two 2D mesoscopic-based finite element (FE) models reinforced with randomly distributed circular and irregular polygonal particles were developed. Different material properties (metal matrix phase, particle reinforced phase) and the properties of the particle–matrix interface were comprehensively considered in the proposed FE model. Systematic cutting experiments were conducted to compare the differences between two modeling approaches with respect to particle fracture, chip formation, cutting force and surface integrity. The results show that the irregular polygonal particle model is closer to the microstructure of MMCs, and is better able to reflect the deformation behavior of particles. The simulation model with irregular polygonal particles is even able to capture more details of the impact caused by particles, reflecting variations in the cutting force in the actual cutting process. The initiation and propagation of microcracks is mainly determined on the basis of particle geometry and further affects chip formation. Both models are able to correctly reflect surface defects, but the irregular polygonal particle model provides a more comprehensive prediction for the subsurface damage of MMCs.

Three-dimensional elliptical vibration cutting (3D-EVC) is one of the machining methods with the most potential in ultra-precision machining; its unique characteristics of intermittent cutting, friction reversal, and ease of chip removal can improve the machinability of materials in the cutting processes. However, there is still not much research about the chattering phenomenon in the 3D-EVC process. Therefore, based on the empirical mode decomposition (EMD) technique and feature extraction, a chatter identification method for 3D-EVC is proposed. In 3D-EVC operations, the vibration signal is collected by the displacement sensors and converted to frequency domain signal by fast Fourier transform (FFT). To identify tool cutting state using the vibration frequency signal, the vibration signals are decomposed using empirical mode decomposition (EMD), a series of intrinsic mode functions (IMFs), so the instantaneous frequency can be reflected by the vibration signals at any point. Then, selecting the primary IMFs which contain rich chatter information as the object in feature extraction identification, and two identification indexes, that is, the mean square frequency and self-correlation coefficient, are calculated for the primary IMFs by MATLAB software, to judge the chatter phenomenon. The experimental results showed that the mean square frequency and self-correlation coefficient of the three cutting states increase with the increase in the instability of the cutting state. The effectiveness of the improved chatter recognition method in 3D-EVC machining is verified.