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The control of the gap between tool and support, and the analysis of its effect on the accuracy of CNC incremental forming Hu Zhu1,a, Zhijun Liu1,b and Nan Li1,c 1 College of Mechanical and Electrical Engineering, Shenyang Aerospace University, Shenyang, Liaoning 110136, China azhuhu100@yahoo.com.cn, bdongfangshenglong@163.com, clinanxiujiao@163.com Keywords: Incremental forming, Forming accuracy, Digital simulation, Pressing path.
There are many factors that influence the CNC incremental forming precision, among which the gap between pressing tool head and support is one of the main factors that influence the forming precision of ISMF.
In the paper, the methods for the control of the gap between pressing tool head and support and theirs affects on the forming accuracy are researched and analyzed by using the digital simulation technology.
On the contrary, if the gap between pressing tool head and support is thicker than sheet thickness, the extrusion force will decrease to some extent, which makes the sheet to incline forward, wrinkle, rebound in the forming process and seriously affects forming precision [4].
The mechanical property parameters are shown in Table.1.

Fault Diagnosis of Wet-shift clutch Based on STFT and Wavelet Chen Man1,a, Ma Biao1,b 1 School of mechanical and vehicle engineering, Beijing Institute of Technology, Beijing 100081, China chenman2010@foxmail.com mabiao@bit.edu.cn Keywords: wet shifting clutch, STFT, wavelet analysis, fault diagnosis, online processing Abstract.
Figure 1 The structure of wet shifting clutch Usually the processing, assembly, and other factors may cause relatively minor degree of initial deformation of the friction plate, which may result in the uneven contact in the sliding process, and it is easy to lead to the local overheating of the friction plate.
Affected by irregular deformation of the contact surface, the contact should be a short-lived collision slipping process, and the collision factor is dominant [3].
The failure state of transmission device in practical application is relatively complex, there may be the collision excitation caused by other factors, which may also cause similar high-frequency signal, then it is unable to effectively identify the failure only with the vibration signal STFT analysis at any time.
The method of changing the shape of the time-frequency window may be used for the wavelet transform, the overview and details of the signals may be observed with different resolutions; there are very good localization properties in both the time domain and frequency domain, so it is suitable for detailed analysis with the collision signal.

Introduction In recent years, magnesium has been attracting the attention of different industrial sectors such as aeronautical and automotion, mainly, due to its low density (1740 kg/m3) and to its good structural properties [1-4].
Factors, levels and ranges, along with response variables are set
Table 1 shows factors, levels fixed for them and their designations.
Table 4 Factors and levels.
In addition, the following conclusions are extracted about the rest of factors studied: § Statistically, the machining length and the generatrix are not influential factors.

Meanwhile, we selected elastic-plastic mechanical model and incremental theory to analyze the problem. 1.1 Establishing heat source model Because the hot spread quickly in metal, highly concentrated heat source was used to transfer much more heat to workpiece in an instant and causes time-variation and unsteady characteristics during welding. we selected realistic model of normal heat considering materials’ physical properties changes with temperature[3].
Assuming the distribution of heat is Gaussian normal distribution function, then integrates the equation is: （1） （2） （3） Where: q—effective heat power, J/s； k—heat concentration factor,1/mm2； r—the distance between a point within the circle heat source and the center.
Therefore, judging from thermal expansion and contraction properties of the metal, different parts of the weldment will get different temperatures, and will lead to different thermal expansion.
However, the materials thermal expansion close to molten pool affected by mental around gets deeper than that away from weld seam, which will result in the materials In the weld and around subject to relatively large compressive stress.
Temperature Field of Thick Welding Process, Three-dimensional Finite Element Numerical Simulation of the Stress Field[J],Chinese Mechanical Engineering,2001,12(2):183~186

High-temperature hot deformation is linked with dynamic recovery and recrystallization which affect the alloy structure and properties.
When optimizing hot processing of austenitic alloys, such factors should be taken into account as [3]: grain size, intermetallic phases and carbides precipitation processes and strain parameters.
Two of the above-mentioned factors are considered most important: austenite grain size and the course of recrystallization during hot deformation.
This is particularly important in creep-resisting steels and austenitic alloys, where grain refining has an advantageous influence on their mechanical properties and creep characteristics [2, 4].
The alloy deformed in the temperature range 1000÷1050 °C exhibited the properties characteristic of dynamically recrystallized structures.

Microwave Absorbing Properties of Flaky Fe-Si-Al Alloy Powder-Rubber Composites Kyung-Sub Lee1,a , Yeo-Chun Yun2,b , In-Bum Jeong 3,c , and Sung-Soo Kim 4,d 1-3 R&D Center, Changsung Corporation, 11-9, Namdong Industrial Area, Namdong-ku, Incheon, Korea 4 Department of Materials Engineering, Chungbuk National University, heungduk-ku, Gaesin-dong 12, Cheongju 361-763, Korea a kslee121@changsung.com, b ycyun@changsung.com, c ibjeong@changsung.com, d sskim@chungbuk.ac.kr Keywords: magnetic composite, absorber, reflection loss, permeability, permittivity, flake Abstract.
The frequency profile of complex permeability (μr) and permittivity (εr) and their relationship with microwave absorbing properties are investigated in soft magnetic metal-polymer composite materials.
Thin flake Fe-Si-Al particles were prepared by mechanical forging of spherical powders using an attrition mill.
It is evident that the permittivity of magnetic composite was strongly affected by the thickness of flaky powder and aspect ratio variation as shown in figures 3 and 4.
This is believed that the decrease of the permittivity and density of the flexible sheets manufactured in calendaring process may be factors responsible for the shift to high frequency of maximum reflection loss peak.

These mechanisms are depend on sheet thickness, laser beam dimensions, scanning speed and physical properties of irradiated material [1].
Several studies have been carried out in order to investigate the relationship among the process parameters, the mechanical and thermal properties of the material, the material-source interaction and the final geometrical properties, such as the bending angle of the sheet.
In order to reduce the number of experimental tests, a mixed Taguchi orthogonal array L-16 with three factors, has been selected, as summarized in Table 1.
Orthogonal array L16 with three factors used in the experiments.
As shown by MEP, all the experimental factors were found to have significant influence on production time as confirmed by analysis of variance (ANOVA).

The key properties of the copper electrode are presented in Table 1.
The chemical composition of this alloy can be found in Table 2, while Table 3 provides information on its physical properties.
Electrode material properties Electrode material Specific heat capacity (J/g °C) Electrical resistivity (ohm cm) Thermal conductivity (W/cm °C) Melting point (°C) Copper 0.385 1.69 3.91 1083 Table 2.
Physical composition of Hastelloy C276 PROPERTIES Heat capacity (J/ kg °C) Density (g/cm3) Modulus of Rigidity (Gpa) Hardness (HRB) VALUES 427 8.89 205 87 Selection of process parameters Many factors influence machining performance in EDM.
TR = D0 -D12t (4) Where, D0 = Average diameter of hole at entry side (mm) D1 = Average diameter of hole at exit side (mm) t = Thickness of the workpiece (mm) Results and Discussion RSM is a mathematical and statistical tool used to analyse problems where a dependent variable (response) is affected by multiple independent variables (factors).

The molar concentrations of impurities considered in this analysis are experimental findings lifted from [3] and are tabulated together with their properties [13] in Table 2.
Thermodynamic properties of the impurities considered in this study SN Thermodynamic properties Impurities considered H2S Pentane Propane 1 Critical temperature [K] 373.2 469.7 364.9 2 Critical pressure [Pa] 8.9×10-6 3.37×10-6 4.35×10-6 3 Acentric factor [ω] 98.6 304 203 4 Molar concentration [mol] 5.6×10-8 4.5×10-7 8×10-6 3.0 Results and Discussions 3.1 Pressure Variation with Different Combination of Impurities Four (4) scenarios were considered in this analysis: scenario 1, hydrogen alone, scenario 2, hydrogen mix with H2S, scenario 3, hydrogen mix with H2S and pentane, and scenario 4, hydrogen mix with H2S, pentane, and propane.
This can be attributed, among other factors, to variations in the acentric factors of gases [15].
Gases with high acentric factors possess very strong intermolecular forces of attraction and are closely packed together, which can lead to a decrease in the gas pressure, as demonstrated by pentane.
Poling, The properties of gases and liquids.

The group of AlZn-based alloys with Zn content increased to 30‒50 at% has a special combination of properties that allows them to be used for shaped castings with good damping and tribological properties [2-7].
However, their wider application in practice requires the improvement of rather poor mechanical properties, e.g. ductility, strength and abrasion resistance.
Savaskan, Mechanical and tribological properties of Al–40Zn–Cu alloys, Tribol.
Krajewski, Trends in developments of high-aluminium zinc alloys of stable structure and properties, Arch.
Haberl, New developments on optimizing properties of high-Zn aluminium cast alloys, IOP Conf.