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The self-piercing riveting (SPR) process was used to join 2.0-mm-thick aluminum alloy 6061-T6 and 1.2-mm-thick mild steel SPFC340 sheets. SPR joints produced with a conventional flat-bottom die and conical-section dies were investigated both experimentally and numerically. Lap shear tests were conducted under quasi-static conditions to evaluate the load-carrying capability of these SPR joints. The effect of variation in die geometry (such as variation in the die groove shape, cone height, and die radius) on the main mechanical response of the joints, namely the peak load and energy absorption, was discussed. The results showed that SPR joints produced with the conical-section dies exhibited a failure mode similar to those produced with a conventional die. All the joints failed by tearing of the top steel sheet. Cracks that occurred in the bottom aluminum alloy 6061-T6 sheet around the rivet leg were a result of tangential tensile stress. The cone height of a conical-section die is the most important parameter affecting the surface quality of Al/steel SPR joints. Conical-section dies with a moderate convex can ensure a good surface quality during the SPR process. In addition, SPR joints with single conical-section die allow higher tensile strength and energy absorption compared to those with double conical-section die.

First principles plane wave pseudopotential method was executed to calculate the mechanical properties with respect to the uranium-0.95 mass fraction of titanium (U-0.95 mass fraction of Ti) alloy for quenching and aging, including the elastic modulus, the value of shear modulus to bulk modulus (G/B) and the ideal tensile strength. The further research has also been done about the crack mechanism through Griffith rupture energy. These results show that the elastic moduli are 195.1 GPa for quenching orthorhombic α´ phase and 201.8 GPa for aging formed Guinier-Preston (G.P) zones, while G/B values are 0.67 and 0.56, respectively. With the phase change of uranium-titanium (U-Ti) alloy via the quenching treatment, the ideal tensile strength is diverse and distinct with different crystal orientations of the anisotropic α´ phase. Comparison of quenching and short time aging treatment, both of the strength and toughness trend to improve slightly. Further analysis about electronic density of states (DOS) in the electronic scale indicates that the strength increases continuously while toughness decreases with the aging proceeding. The equilibrium structure appears in overaging process, as a result of decomposition of metastable quenching α´ phase. Thereby the strength and toughness trend to decrease slightly. Finally, the ideal fracture energies of G.P zones and overaging structure are obtained within the framework of Griffith fracture theory, which are 4.67 J/m2 and 3.83 J/m2, respectively. These results theoretically demonstrate strengthening effect of quenching and aging heat treatment on U-Ti alloy.

Cloud manufacturing is a new kind of networked manufacturing model. In this model, manufacturing resources are organized and used on demand as market-oriented services. These services are highly uncertain and focus on users. The information between service demanders and service providers is usually incomplete. These challenges make the resource scheduling more difficult. In this study, an iterative double auction mechanism is proposed based on game theory to balance the individual benefits. Resource demanders and providers act as buyers and sellers in the auction. Resource demanders offer a price according to the budget, the delivery time, preference, and the process of auction. Meanwhile, resource providers ask for a price according to the cost, maximum expected profit, optimal reservation price, and the process of auction. A honest quotation strategy is dominant for a participant in the auction. The mechanism is capable of guaranteeing the economic benefits among different participants in the market with incomplete information. Furthermore, the mechanism is helpful for preventing harmful market behaviors such as speculation, cheating, etc. Based on the iterative double auction mechanism, manufacturing resources are optimally allocated to users with consideration of multiple objectives. The auction mechanism is also incentive compatibility.

Machining of micro holes with micro electrochemical machining (micro ECM) process has been carried out with an indigenously developed set up. This paper describes relevant problems and solutions for the circular micro holes machining process on 304 stainless steel sheets with 60 μm thickness using high speed steel cylindrical tool of diameter 500 μm and using dilute H2SO4 as electrolyte. The taper angle variation of the machined hole is analyzed and reported for different experimental setting parameters. The minimum value of the taper angle of machined holes is achieved at the parameter setting of 0.4 mol/L H2SO4, 700 kHz, 600 ns and 21 V, for stainless steel sheets and HSS tool.

Wire electrochemical machining (WECM) is a potential method for manufacturing macrostructures from difficult-to-cut materials, such as turbine slots, with good surface integrity and low costs. In this study, a novel tube electrode with array holes in the front and insulation in the back was applied using WECM to improve the machining precision and efficiency. Additionally, assisted by an immersion electrolyte and axial flushing, the electrolyte-deficient gap was supplemented to achieve the cutting of a very thick workpiece. The simulation results indicated that this method could effectively reduce the machining gap and improve the uniformity of the electric- and flow-field distributions. Experiments verified that when the uninsulated range (machining angle) was reduced from 360° to 90°, the side machining gap was reduced from 462.5 µm to 175 µm. Finally, using optimized machining parameters, array slits with gaps as small as (175±10) μm were machined on a powder superalloy René 88DT sample with a thickness of 10 mm at a feed rate of 16 µm/s. The feasibility of fabricating complex profiles using this method was verified using a self-designed servo device.

Specific energy consumption is an important indicator for a better understanding of the machinability of materials. The present study aims to estimate the specific energy consumption for abrasive metal cutting with ultra-thin discs at comparatively low and medium feed rates. Using an experimental technique, the cutting power was measured at four predefined feed rates for S235JR, intermetallic Fe-Al(40%), and C45K with different thermal treatments. The variation in the specific energy consumption with the material removal rate was analyzed through an empirical model, which enabled us to distinguish three phenomena of energy dissipation during material removal. The thermal treatment and mechanical properties of materials have a significant impact on the energy consumption pattern, its corresponding components, and cutting power. Ductile materials consume more specific cutting energy than brittle materials. The specific cutting energy is the minimum energy required to remove the material, and plowing energy is found to be the most significant phenomenon of energy dissipation.

Owing to their shape memory effect and pseudoelasticity, NiTi shape memory alloys (SMAs) are widely used as functional materials. Mechanical processes particularly influence the final formation of the product owing to thermal softening and work-hardening effects. Surface integrity is an intermediate bridge between the machining parameter and performance of the product. In this study, experiments were carried out on turning NiTi SMAs at different cutting speeds, where surface integrity characteristics were analyzed. The results show that a higher cutting speed of 125 m/min is required to turn NiTi SMAs based on the evaluation of surface integrity. The degree of work hardening is higher at 15 m/min. Consequently, as a primary effect, work hardening appears on the plastic deformation of the machined samples, leading to dislocations and defects. As the cutting speed increases, the thermal softening effect exceeds work hardening and creates a smoother surface. A stress-induced martensitic transformation is considered during the turning process, but this transformation is reversed to an austenite from the X-ray diffraction (XRD) results. According to the differential scanning calorimetry (DSC) curves, the phase state and phase transformation are less influenced by machining. Subsequently, the functional properties of NiTi-SMAs are less affected by machining.

Animals rotate their eyes to gaze at the target prey, enhancing the ability of measuring the distance to the target precisely for catching it. These animals, visual tracking includes the triangular eye-vergence control and their body’s motion control by visual servoing. The research aims to realize a bionic robot tracking performance, in which the body links moves together with eyes’ view orientation. This paper proposed a hand & eye-vergence dual control system which included two feedback loops: an outer loop for conventional visual servoing to direct a manipulator toward a target object and an inner loop for active motion control of binocular cameras to change the viewpoint along with the moving object to give an accurate and broad observation. This research also foused on how to compensate a fictional motion of the target seen by camera images in an eye-in-hand system, where the camera was fixed on the end-effector and moved together with the hand motion. A robust motion-feedforward (MFF) recognition method is proposed to compensate the fictional motion of the target based on the manipulator’s joint velocity, then the real motion of the target seen by camera images is extracted, which can improve the feedback image sensing unit to make the whole servoing system dynamically stable. The effectiveness of the proposed hand & eye-vergence visual servoing method is shown by tracking experiments using a 6-DoF robot manipulator and a 3-DoF binocular vision system.

This study aims to optimize the uniformity of the temperature field during sintering to improve part performance. A temperature-field monitoring system is established based on an infrared thermal imager and the temperature field data obtained during the sintering of a part can be measured in real time. The relationship among the sintering temperature field, sintering process parameters, and part performance is established experimentally. Subsequently, a temperature field monitoring and analysis system is constructed, and various sintering temperature-field control strategies are established for various part sizes. Finally, a dynamic control strategy for controlling the temperature field during sintering is proposed, experimentally validated, and fully integrated into a developed powder bed fusion (PBF) equipment. For eight-shaped standard parts, the range of sintering temperature field is optimized from 44.1 °C to 19.7 °C, whereas the tensile strength of the parts increased by 15.4%. For large-size H parts, localized over burning is eliminated and the final quality of the part is optimized. This strategy is critical for the optimization of the PBF process for large-sized parts, in particular in the large-sized die manufacturing industry, which offers promise in the optimization of part performance.