A Comparison of Wavelet Packet,Wavelet Leaders Multifractal,and p‑Leader Multifractal Method in Chatter Detection

An efficient stability analysis contributes to the improvement of machining stability and chatter suppression.First,this paper presents three chatter detection approaches that were developed on the application of wavelet transforms.Second,the feasibility of the methods for chatter detection is verified by combining numerical simulations and experimental research.Finally,the recognition performance of the three methods is compared.The analysis results indicate that the proposed three methods can distinguish different machining states.The p-leader multifractal method(PLMM)provides the best recognition performance but takes the longest time,the wavelet leader multifractal method(WLMM)comes second,and the wavelet packet method(WPM)is the worst but takes the shortest amount of time.Therefore,the PLMM can be used for identifying signals with high accuracy requirements,whereas the WLMM or WPM can be used otherwise.

Design and Experimentation of a Novel Separable Vibration-Assisted Stage

In this paper,a novel,separable two-degrees-of-freedom stage with high-precision motion and resolution is proposed for the application of vibration-assisted micromilling.A separable design was realized on the basis of the detachable structure of the platform.Flexible stages with different dimensions and types can be utilized in the devices.A circular-fillet hinge is selected as the flexible unit with a parallel structure to realize output decoupling and reduce the coupling error between the two vibration directions.Analytical modeling is conducted to explore the static and dynamic characteristics of the stage.Results reveal a good agreement with the finite element simulation result.A series of experiments were conducted to assess the static and dynamic performances of the flexible stage,encompassing tests such as amplitude response,motion trajectory,and coupling trajectory.The results of these tests revealed that the designed vibration-assisted system exhibits precise movement capabilities.

The Study on the Anti-corrosion Performance of NiTi Alloy in Human Body Solution with the Fabricating Processes of Laser Irradiation and PDMS Modification

This paper presents a new and safe method of fabricating super-hydrophobic surface on NiTi Shape Memory Alloy(SMA),which aims to further improve the corrosion resistance performance and biocompatibility of NiTi SMA.The super-hydrophobic surfaces with Water Contact Angle(WCA)of 155.4°±0.9°and Water Sliding Angle(WSA)of 4.4°±1.1°were obtained by the hybrid of laser irradiation and polydimethylsiloxane(PDMS)modification.The forming mechanism was systematically revealed via Scanming Electron Microscopy(SEM)and X-ray Photoelectron Spectroscopy(XPS).The ant-corrosion of samples was investigated in Simulated Body Fluid(SBF)via the potentiodynamie polarization(PDP)and Electrochemical Impedance Spectroscopy(EIS)tests.PDMS super-hydrophobic coatings showed superior anti-corrosion performance.The Ni ions release experiment was also conducted and the corresponding result demonstrated that the super-hydrophobic samplcs effectively inhibited the rclease of Ni ions both in clctrolyte and SBF Besides,biocompaibility was further analyzed,indicating that the prepared super-hydrophobic surfaces present a huge potential advantage in biocompatibility.