Advances in Manufacturing

Ultrasonic vibration-assisted machining: principle, design and application

Wei-Xing Xu, Liang-Chi Zhang

2015, 3(3): 173-192. doi:10.1007/s40436-015-0115-4

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Ultrasonic vibration-assisted (UVA) machining is a process which makes use of a micro-scale high frequency vibration applied to a cutting tool to improve the material removal effectiveness. Its principle is to make the tool-workpiece interaction a microscopically non-monotonic process to facilitate chip separation and to reduce machining forces. It can also reduce the deformation zone in a workpiece under machining, thereby improving the surface integrity of a component machined. There are several types of UVA machining processes, differentiated by the directions of the vibrations introduced relative to the cutting direction. Applications of UVA machining to a wide range of workpiece materials have shown that the process can considerably improve machining performance. This paper aims to provide a comprehensive discussion and review about some key aspects of UVA machining such as cutting kinematics and dynamics, effect of workpiece materials and wear of cutting tools, involving a wide range of workpiece materials including metal alloys, ceramics, amorphous and composite materials. Some aspects for further investigation are also outlined at the end.

Effect of seed particles content on texture formation of Si₃N₄ ceramics by gel-casting in a strong magnetic field

Zhi-Gang Yang, Jian-Bo Yu, Chuan-Jun Li, Kang Deng, Zhong-Ming Ren, Qiu-Liang Wang, Yin-Ming Dai, Hui Wang

2015, 3(3): 193-201. doi:10.1007/s40436-015-0106-5

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In this paper, the textured Si₃N₄ ceramics were prepared by adding seed particles during gel-casting in the magnetic field of 6 T, followed by pressureless sintering. The effect of pH on the stability and dispersibility of Si₃N₄ slurry and the effect of seed particles content on texture formation of Si₃N₄ ceramics were both studied. Those results showed that the slurry with good stability and dispersibility was obtained when pH was about 11.6. The a or b-axis of Si₃N₄ particles or crystals was aligned parallel to the direction of the magnetic field in the magnetic field of 6 T. The degree of texture of Si₃N₄ ceramics further increased during sintering. With the increasing of additional β-Si₃N₄ particles in the magnetic field of 6 T, the degree of texture increased from 0.19 without seed particles to 0.76 with 9% (mass fraction) seed particles. The increase of seed particles content promoted the texture formation of Si₃N₄ ceramics.

Modeling and state of charge estimation of lithium-ion battery

Xi-Kun Chen, Dong Sun

2015, 3(3): 202-211. doi:10.1007/s40436-015-0116-3

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Modeling and state of charge (SOC) estimation of lithium-ion (Li-ion) battery are the key techniques of battery pack management system (BMS) and critical to its reliability and safety operation. An auto-regressive with exogenous input (ARX) model is derived from RC equivalent circuit model (ECM) due to the discrete-time characteristics of BMS. For the time-varying environmental factors and the actual battery operating conditions, a variable forgetting factor recursive least square (VFFRLS) algorithm is adopted as an adaptive parameter identification method. Based on the designed model, a SOC estimator using cubature Kalman filter (CKF) algorithm is then employed to improve estimation performance and guarantee numerical stability in the computational procedure. In the battery tests, experimental results show that CKF SOC estimator has a more accuracy estimation than extended Kalman filter (EKF) algorithm, which is widely used for Li-ion battery SOC estimation, and the maximum estimation error is about 2.3%.

Study on the liquid metal flow field in FC-mold of slab continuous casting

Zhen-Qiang Zhang, Jian-Bo Yu, Zhong-Ming Ren, Kang Deng

2015, 3(3): 212-220. doi:10.1007/s40436-015-0117-2

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The flow pattern and the velocity distribution of a liquid metal in the flow control mold (FC-mold) were investigated with a mercury model by analogy to the molten steel during continuous casting. The velocity measurement was conducted by the ultrasonic Doppler velocimeter (UDV) under various magnetic distributions and flux densities. The impingement intensity and the scouring intensity of the liquid metal to the narrow wall of the mold were calculated based on the measured data, and the influence of the magnetic flux density on the liquid metal flow in the mold was analyzed. The results showed that the surface of the liquid metal became more active when only the lower magnet was assembled, and the surface fluctuation was suppressed when further applying the upper magnetic field. It was indicated that when the upper and lower magnetic flux densities were 0.18 T and 0.5 T, respectively, the optimum conditions could be obtained, under which the free surface fluctuation could be suppressed, and a flow recirculation could rapidly form.

Binding and conformation of dendrimer-based drug delivery systems: a molecular dynamics study

Fa-Da Zhang, Yi Liu, Jing-Cheng Xu, Sheng-Juan Li, Xiu-Nan Wang, Yue Sun, Xin-Luo Zhao

2015, 3(3): 221-231. doi:10.1007/s40436-015-0120-7

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All atomistic molecular dynamics simulations were performed on poly (amidoamine) (PAMAM) dendrimers that compound non-covalently with anticancer drug molecules including DOX, MTX, CE6, and SN38. The binding energies as well as their associated interaction energies and deformation energies were combined to evaluate the relative binding strength among drug, PAMAM, and PEG chains. We find that the deformation of dendrimers due to drug loading plays a crucial role in the drug binding. It is energetically favorable for the drug molecules to bind with PAMAM while the drugs bind with PEG metastable chains via kinetic confinement. Surface PEGylation helps dendrimers to accommodate more drug molecules with greater strength without inducing too much expansion. This work indicates that tuning the functionalized terminal groups of dendrimers is critical to design efficient dendrimer-based drug delivery systems.

Dynamic compressive behaviour of Ti-6Al-4V alloy processed by electron beam melting under high strain rate loading

A. Mohammadhosseini, S. H. Masood, D. Fraser, M. Jahedi

2015, 3(3): 232-243. doi:10.1007/s40436-015-0119-0

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This paper documents an investigation into the compressive deformation behaviour of electron beam melting (EBM) processing titanium alloy (Ti-6Al-4V) parts under high strain loading conditions. The dynamic compression tests were carried out at a high strain rate of over 1×10³/s using the split Hopkinson pressure bar (SHPB) test system and for comparison the quasi-static tests were performed at a low strain rate of 1×10^-3/s using a numerically controlled hydraulic materials test system (MTS) testing machine at an ambient temperature. Furthermore, microstructure analysis was carried out to study the failure mechanisms on the deformed samples. The Vickers micro-hardness values of the samples were measured before and after the compression tests. The microstructures of the compressed samples were also characterized using optical microscopy. The particle size distribution and chemical composition of powder material, which might affect the mechanical properties of the specimens, were investigated. In addition, the numerical simulation using commercial explicit finite element software was employed to verify the experimental results from SHPB test system.

Mechanical properties of U-0.95 mass fraction of Ti alloy quenching and aging treatment: a first principles study

Jian-Bo Qi, Guang-Xin Wu, Jie-Yu Zhang

2015, 3(3): 244-251. doi:10.1007/s40436-014-0090-1

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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.

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