Yan Gu

To address the issues of graphite flaking and interfacial microcrack propagation during conventional polishing of multiphase heterogeneous materials such as ductile cast iron, this study designed and validated a two-dimensional non-resonant flexible vibration-assisted polishing device (RVAPD) based on a series–parallel structure combined with a Scott Russell mechanism. The device decouples spatial motion from mechanical transmission through an irregular flexible hinge network. A theoretical model is established using the flexible matrix method and Lagrange equations, and static and dynamic simulations are conducted using ABAQUS finite element software. The simulation results show that the input and output stiffness values are 19,524 N/mm and 8197 N/mm, respectively. Experimental measurements revealed a natural frequency of 1120 Hz, a maximum output displacement of 12.58 μm, an output stiffness of 7200 N/mm, a static response delay of only 114 ms, and a positioning error below 2.76 μm, confirming the device’s high stiffness, wide bandwidth, and precise motion control capabilities. Polishing experiments indicate that 200 Hz provided the best surface-quality performance among the tested excitation frequencies, at which the surface roughness Sa decreased from 0.049 μm without vibration to 0.036 μm, while the maximum height Sz decreased from 1.927 μm to 0.983 μm. The polishing performance slightly deteriorated at 300 Hz, with Sa increasing to 0.043 μm. These results indicate that the tested excitation conditions can influence the surface-quality characteristics of the polished ductile cast iron. This research provides a basis for non-resonant vibration-assisted polishing of multiphase heterogeneous alloys.

Owing to their lightweight nature, low coefficient of thermal expansion, and strong wear resistance, aluminum-based silicon carbide composites serve as pivotal components in aerospace applications. Nonetheless, traditional cutting procedures face severe limitations. The abrasive resistance imparted by ultra-hard SiC particles induces severe load spikes and causes significant micro-damage during machining. To overcome these machining barriers, this study introduces a hybrid energy-field approach, namely, pulsed laser–ultrasonic vibration-assisted composite turning (LUAT). To deconstruct the thermo-mechanical coupling mechanism, a two-dimensional finite element simulation framework was constructed to investigate dynamic force responses and transient temperature fields. Leveraging a custom-built hybrid machining system, experimental investigations systematically evaluated dynamic cutting forces, areal roughness (Sa), and micro-scale damage mechanisms across conventional turning (CT), pulsed laser-assisted turning (PLAT), and LUAT processes. The findings confirmed that laser thermal softening lowered matrix deformation resistance, while the high-frequency intermittent contact mode of LUAT effectively minimized average cutting forces compared with all benchmark processes. Operating at 40 W laser power, 600 r/min rotational speed, 4 μm cutting depth, and 2 mm/min feed rate, LUAT achieved its lowest surface roughness of Sa = 0.075 μm, demonstrating a 56% improvement over laser-assisted turning alone. This work provides valuable theoretical and practical insights for advancing the high-efficiency precision manufacturing of hard-to-machine composites with high volume fractions.