The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC) is a novel cutting technique which is a significant development potential for difficult-to-cut materials. However, few studies have been conducted on processing the Ti-6Al-4V alloy using the non-resonant 3D-EVC technique, the effect of surface quality, roughness, topography and freeform surface has not been clearly researched yet. Therefore, the machinability of Ti-6Al-4V alloy using the non-resonant 3D-EVC apparatus is studied in this paper. Firstly, the principle of non-resonant 3D-EVC technique and the model of cutter motion are introduced. Then the tool path is synthesized. The comparison experiments are carried out with traditional continuous cutting (TCC), two-dimension elliptical vibration cutting (2D-EVC), and the non-resonant 3D-EVC method. The experimental results shown that the excellent surface and lower roughness (77.3 nm) could be obtained using the non-resonant 3D-EVC method; the shape and dimension of elliptical cutting mark also relates to the cutting speed and vibration frequency, and the concave/convex spherical surface topography are achieved by non-resonant 3D-EVC in the Ti-6Al-4V alloy. This proved that the non-resonant 3D-EVC technique has the better machinability compared with the TCC and 2D-EVC methods.

Elliptical vibration cutting (EVC) technology has been paid much attention as the unique characteristics of the intermittent cutting and friction reversal, but the residual-height between adjacent trajectories can not be eliminated. In order to solve the problem, we developed a new vibration assisted rotation cutting (VARC) system in this paper. The system has the characteristics of the pseudo-intermittent cutting and friction reversal, which greatly extends the tool-life, reduces cutting forces, and improves the accuracy of the work-piece. The mechanical system based on the parallel kinematic configuration of the two-axis, where the positioning of the tool position has ensured by the rotary motion platform (RMP). The L-shaped flexure hinges are used as the guidance flexure mechanism, to rotate of the RMP. Flexures hinge structure and piezoelectrically actuated are employed positioning in the design. The kinematic analysis of the pseudo-rigid-body model, the matrix-based compliance modeling method is applied for the compliance modeling, and the dynamics characteristic is modeled by using the Lagrangian principle of VARC system. The structural parameters are optimized by the improved differential evolution algorithm, and the theoretical modeling is validated by finite element analysis. Off-machine performance examinations were conducted to evaluate the parasitic motions, resolution, hysteresis, stroke, and frequency of the developed system. The results showed that the motion stroke of the piezoelectric actuator input end could reach up to 26.34 μm with a resolution of 8 nm, moreover, the coupling ration could be effectively decreased within 0.64%. The superior performances and easily achievable structure well facilitate practical applications of the proposed system in micro/nano-machining.

Carbon fiber reinforced plastic (CFRP) is the main material of aircraft skin. Preparing superhydrophobic anti-icing/deicing surface on the CFRP is of great importance for aircraft flight safety. In this work, a variety of multi-scale micro-nano structures were imprinted on CFRP by femtosecond laser processing, and a transition from hydrophilic to superhydrophobic CFRP was realized. After being optimized by different geometries and laser conditions, the water contact angle, which is tested at 24.3 °C and 34% humidity, increased from 88 ± 2° (pristine) to 149 ± 3° (100 μm groove) and 153 ± 3° (80 μm grid). A further anti-icing test at −10 °C (measured on the cooling platform) and 28% humidity showed that the freezing time was increased from 78 ± 10 s (pristine) to 282 ± 25 s (80 μm grid). Most importantly, the tensile tests showed that the femtosecond laser processing method did not deteriorate the mechanical properties of CFRP. This work provides great significance for aircraft passive deicing technology.

In order to solve the precision and stability control problems of nonlinear uncertain systems applied in machining systems, in this paper, a robust adaptive fuzzy control technique based on Dynamic Surface Control (DSC) method is proposed for the generalized single-input single-output (SISO) uncertain nonlinear system. A first-order low-pass filter is introduced in each step of the traditional robust control method to overcome the "calculation expansion" problem, and Takagi-Sugeno (T-S) fuzzy logic system is applied to approximate an uncertain nonlinear function of unknown structure in the system. e designed robust adaptive fuzzy controller is applied to the 3D elliptical vibration cutting (3D EVC) device system model, and the effectiveness of the controller design is verified by analysis of position tracking, speed tracking, and tracking error. e results of studies show that the robust adaptive fuzzy controller can effectively suppress the jitter problem of the three-dimensional elliptical vibration cutting device so that the control object can be stabilized quickly even if it has a little jitter at the beginning. It can be smoothed to move along the ideal displacement and velocity signals. It is verified that the designed controller has strong robust adaptability. adaptive control and robust control methods cannot be used for controller design. However, for such problems, neural networks and fuzzy control can approximate uncertain continuous functions of the unknown structure in the system [11,12]. Ge et al. researched a robust adaptive neural network control method for a perturbed strictly feedback nonlinear system, which can guarantee the final boundedness in the case of unknown structural uncertainty [13]; Cao et al. proposed a new system control strategy using the global approximation property of the fuzzy system to approximate the unknown function of the designed system and ensure the stability of the whole system [14].However, in the system described above, it is satisfied that the unknown nonlinearity and the control input appear in the same state space model equation. In order to overcome the limitations of such systems, relevant research scholars have proposed adaptive post-push technology [4,6,15,16], furthermore successfully solved the constraint

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