Micro Groove Forming on AlN/hBN Composites Using Powder Blasting Process

2006 ◽  
Vol 510-511 ◽  
pp. 1018-1021
Author(s):  
Won Seung Cho ◽  
Myeong Woo Cho ◽  
Dong Sam Park
Keyword(s):  
Material Properties ◽  
Experimental Results ◽  
Powder Blasting ◽  
Experimental Works

In this study, powder blasting techniques are applied for micro groove forming on the developed AlN/hBN composites. First, material properties of the composites are evaluated according to the variation of h-BN contents. And, a series of required experimental works are performed to determine optimum powder blasting conditions for micro groove forming. The experiments are performed for the prepared samples with masked patterns. As the results, it can be observed that the machiniability of the developed AlN/hBN composites increases as h-BN contents in the composites. Also, from the experimental results, it is possible to determine the optimum blasting conditions for micro groove forming on the developed AlN/hBN composites.

Application of Powder Blasting Techniques to Micro-Pattern Making Process for Si3N4-hBN Composites

2005 ◽  
Vol 287 ◽  
pp. 51-56 ◽  
Author(s):  
Myeong Woo Cho ◽  
Won Seung Cho ◽  
Dong Sam Park ◽  
Jae Hyung Lee ◽  
Eun Sang Lee ◽  
...  
Keyword(s):  
Material Properties ◽  
Experimental Results ◽  
Powder Blasting ◽  
Micro Pattern ◽  
Experimental Works

In this study, micro powder blasting techniques are applied to micro-pattern making process using developed Si3N4-hBN composites. Material properties of the developed machinable ceramics according to the variation of h-BN contents, those are used to give good machinability to the ceramics, are evaluated. And, a series of required experimental works are performed to determine optimum powder blasting conditions for micro-pattern making. The experiments are performed for the prepared samples with no mask, and samples with three different mask patterns. As the results, it can be observed that the machinability of the developed Si3N4-hBN composites increases as the h-BN contents in the composites. Also, from the experimental results, it is possible to determine the optimum blasting conditions for micro-pattern making process with Si3N4-hBN composites.

Micro Pattern Making Method on AlN-hBN Composites Using Powder Blasting Process

2008 ◽  
Vol 368-372 ◽  
pp. 943-946
Author(s):  
Si Young Beck ◽  
Jung Won Lee ◽  
Myeong Woo Cho ◽  
Dong Sam Park ◽  
Ho Su Jang ◽  
...  
Keyword(s):  
Material Properties ◽  
Brittle Materials ◽  
Experimental Results ◽  
Micro Machining ◽  
Powder Blasting ◽  
Micro Pattern ◽  
Hard And Brittle Materials ◽  
Micro Patterns

In this study, micro patterns were formed on the developed AlN-hBN composites using powder blasting techniques, which have been considered as one of the most appropriate micro machining methods for hard and brittle materials such as ceramics. To achieve the objective, first, material properties of the developed AlN-hBN composites were evaluated according to the variation of h-BN contents. And, a series of required experiments were performed, and the results were analyzed. As the results, it was investigated that the machiniability of the developed AlN-hBN composites increased with the increase of the h-BN contents in the composites. From the experimental results, it was possible to determine optimum blasting conditions for micro pattern making on the developed AlN-hBN composites.

Determination of Charge Coefficient of Piezoelectric Films Using a Combined Finite Element Model and Dynamic Loading Technique

2020 ◽  
Vol 835 ◽  
pp. 229-242
Author(s):  
Oboso P. Bernard ◽  
Nagih M. Shaalan ◽  
Mohab Hossam ◽  
Mohsen A. Hassan
Keyword(s):  
Finite Element ◽  
Dynamic Loading ◽  
Material Properties ◽  
Accurate Determination ◽  
Substrate Material ◽  
Experimental Results ◽  
Piezoelectric Composite ◽  
Piezoelectric Film ◽  
Piezoelectric Charge

Accurate determination of piezoelectric properties such as piezoelectric charge coefficients (d33) is an essential step in the design process of sensors and actuators using piezoelectric effect. In this study, a cost-effective and accurate method based on dynamic loading technique was proposed to determine the piezoelectric charge coefficient d33. Finite element analysis (FEA) model was developed in order to estimate d33 and validate the obtained values with experimental results. The experiment was conducted on a piezoelectric disc with a known d33 value. The effect of measuring boundary conditions, substrate material properties and specimen geometry on measured d33 value were conducted. The experimental results reveal that the determined d33 coefficient by this technique is accurate as it falls within the manufactures tolerance specifications of PZT-5A piezoelectric film d33. Further, obtained simulation results on fibre reinforced and particle reinforced piezoelectric composite were found to be similar to those that have been obtained using more advanced techniques. FE-results showed that the measured d33 coefficients depend on measuring boundary condition, piezoelectric film thickness, and substrate material properties. This method was proved to be suitable for determination of d33 coefficient effectively for piezoelectric samples of any arbitrary geometry without compromising on the accuracy of measured d33.

Effect of Ramp Angle on the Anti-Loosening Ability of Wedge Self-Locking Nuts Under Vibration

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Jianhua Liu ◽  
Hao Gong ◽  
Xiaoyu Ding
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Production Technology ◽  
Material Properties ◽  
Threshold Value ◽  
Commercial Production ◽  
Experimental Results ◽  
Fe Method ◽  
Transversal Vibration

Recently, the wedge self-locking nut, a special anti-loosening product, is receiving more attention because of its excellent reliability in preventing loosening failure under vibration conditions. The key characteristic of a wedge self-locking nut is the special wedge ramp at the root of the thread. In this work, the effect of ramp angle on the anti-loosening ability of wedge self-locking nuts was studied systematically based on numerical simulations and experiments. Wedge self-locking nuts with nine ramp angles (10 deg, 15 deg, 20 deg, 25 deg, 30 deg, 35 deg, 40 deg, 45 deg, and 50 deg) were modeled using a finite element (FE) method, and manufactured using commercial production technology. Their anti-loosening abilities under transversal vibration conditions were analyzed based on numerical and experimental results. It was found that there is a threshold value of the initial preload below which the wedge self-locking nuts would lose their anti-loosening ability. This threshold value of initial preload was then proposed for use as a criterion to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively and to determine the optimal ramp angle. Based on this criterion, it was demonstrated, numerically and experimentally, that a 30 deg wedge ramp resulted in the best anti-loosening ability among nine ramp angles studied. The significance of this study is that it provides an effective method to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively, and determined the optimal ramp angle in terms of anti-loosening ability. The proposed method can also be used to optimize other parameters, such as the material properties and other dimensions, to guarantee the best anti-loosening ability of wedge self-locking nuts.

High Efficiency Molding by Real-Time Control of Distance Between Nozzle and Melt Pool in Directed Energy Deposition Process

2020 ◽  
Author(s):  
Kengo Aizawa ◽  
Masahiro Ueda ◽  
Teppei Shimada ◽  
Hideki Aoyama ◽  
Kazuo Yamazaki
Keyword(s):  
Additive Manufacturing ◽  
Real Time ◽  
Material Properties ◽  
High Efficiency ◽  
Dimensional Accuracy ◽  
Deposition Process ◽  
Deposition Efficiency ◽  
Experimental Results ◽  
Real Time Control ◽  
Molding Process

Abstract Laser metal deposition (LMD) is an additive manufacturing technique, whose performance can be influenced by a considerable number of factors and parameters. Typically, a powder is carried by an inert gas and sprayed by a nozzle, with a coaxial laser beam passing through the nozzle and overlapping the powder flow, thereby generating a molten material pool on a substrate. Monitoring the evolution of this process allows for a better comprehension and control of the process, thereby enhancing the deposition quality. As the metal additive manufacturing mechanism has not yet been elucidated, it is not clear how process parameters affect material properties, molding accuracy, and molding efficiency. When cladding is performed under uncertain conditions, a molded part with poor material properties and dimensional accuracy is created. In this paper, we propose a method for high efficiency molding by controlling the distance between the head nozzle and the molten pool in real time. The distance is identified by an originally developed sensor based on a triangulation method. According to the distance, the head nozzle is automatically controlled into the optimum position. As a result, an ideal molding process can be generated, so that high efficiency molding and high-quality material properties can be obtained. Experimental results show that continuing deposition at the optimum distance assists in achieving deposition efficiency and dimensional accuracy. According to the specific experimental results of this method, the modeling efficiency was increased by 27% compared to the method without correction, and the modeling was successful with an error within 1 mm.

Plastic Collapse of Thin Internally Pressurized Torispherical Shells

1979 ◽  
Vol 101 (4) ◽  
pp. 311-320 ◽  
Author(s):  
S. K. Radhamohan ◽  
G. D. Galletly
Keyword(s):  
Strain Hardening ◽  
Yield Stress ◽  
Material Properties ◽  
Parametric Study ◽  
Companion Paper ◽  
Experimental Results ◽  
Plastic Collapse ◽  
Approximate Design ◽  
Mode Of Failure ◽  
Hardening Coefficient

The plastic collapse pressures of internally pressurized thin torispherical shells are given in the present paper. The influence of both the geometric parameters (i.e., r/D, RS/D and D/t) and the material properties (yield stress σyp and the strain-hardening coefficient) on the plastic collapse pressures were investigated. Both steel and aluminium shells were analyzed and, based on the present parametric study, approximate design equations for calculating the plastic collapse pressures are suggested. The asymmetric buckling pressures, pcr, for torispherical shells (obtained from a companion paper) are also compared with the plastic collapse pressures, pc, to determine which are the lower and, thus, control the mode of failure. In addition, the approximate design equations for pcr and pc are compared with some experimental results on small machined models; the agreement between theory and test was quite good.

Studies of Micro-Hole Burr Improvement for Aluminum Alloy Materials Using Vibrated Abrasive Grinding Machining

2015 ◽  
Vol 642 ◽  
pp. 202-206 ◽  
Author(s):  
Shie Chen Yang ◽  
Tsuo Fei Mao ◽  
Feng Che Tsai ◽  
Hsi Chuan Huang
Keyword(s):  
Image Processing ◽  
Aluminum Alloy ◽  
Material Properties ◽  
Vertical Direction ◽  
Experimental Results ◽  
Processing Technology ◽  
Vibration Energy ◽  
Abrasive Particles ◽  
Image Processing Technology ◽  
Micro Hole

This study investigated the removal improvement of micro burrs of aluminum alloy materials using vibrated abrasive grinding machining. The image processing technology is used to examine and quantify the micro-hole burr profiles. The experimental results show that the micro burr was uniformly removed as the workpiece is fixture with vertical direction. In addition, the burr removal improvements are effectively influenced by the flowing velocity and the vibration energy of abrasive particles. The flowing velocities are dependent on the size and gravity of the abrasives and the vibration energy is determined by the material properties and the hardness of the abrasives.

Machining Characteristics of AlN-hBN Composites in End-Milling and Precision Lapping Processes

2008 ◽  
Vol 368-372 ◽  
pp. 947-950
Author(s):  
Si Young Beck ◽  
Bong Cheol Shin ◽  
Myeong Woo Cho ◽  
Eun Sang Lee ◽  
Dong Sam Park ◽  
...  
Keyword(s):  
Material Properties ◽  
End Milling ◽  
Milling Process ◽  
Cutting Conditions ◽  
Cutting Process ◽  
Depth Of Cut ◽  
Micro Cracks ◽  
Experimental Works ◽  
Machining Characteristics ◽  
End Milling Process

In this study, the machining characteristics of developed AlN-hBN composites were investigated in the end-milling and precision lapping processes. To achieve the objectives, material properties of the developed AlN-hBN composites were evaluated according to the variation of hBN contents. And, required experimental works were performed to investigate the machining characteristics of the composites. First, the machiniability of the composite was evaluated in the end-milling process under various cutting conditions, such as spindle speed, feederate, and depth of cut variations. Also, generated micro cracks caused by the cutting process were investigated via SEM photographs. Next, precision lapping experiments were performed under various conditions, and the results were estimated.

MEMS Metrology Using Resonant Structures

2001 ◽  
Author(s):  
A. Miller Allen ◽  
George C. Johnson
Keyword(s):  
Analytical Model ◽  
Material Properties ◽  
Analytical Method ◽  
A Priori ◽  
Experimental Results ◽  
A Priori Knowledge ◽  
Comb Drive ◽  
Resonant Frequencies ◽  
Resonant Structures

Abstract We present an analytical method and experiment to determine the “as-built” geometry of surface micro-machined micro-electromechanical structures. The analysis is based on the use of the lateral resonant frequencies of electrostatic comb drive resonators. The method can be used in situ and does not require a priori knowledge of the mechanical material properties of the structure. The variation between designed geometry and “as-built” geometry is determined from a fit of experimental results to the analytical model.

On the Use of the Theory of Critical Distances to Estimate KIc and ∆Kth from Experimental Results Generated by Testing Standard Notches

2009 ◽  
Vol 417-418 ◽  
pp. 25-28
Author(s):  
Luca Susmel ◽  
David Taylor
Keyword(s):  
Fatigue Limit ◽  
Material Properties ◽  
Reliable Method ◽  
Threshold Value ◽  
Experimental Results ◽  
Plane Strain Fracture Toughness ◽  
Linear Elastic ◽  
Experimental Strategy ◽  
Strain Fracture ◽  
Elastic Fracture

The present paper is concerned with the use of the Theory of Critical Distances (TCD), applied in the form of the Point Method (PM), to estimate the range of the threshold value of the stress intensity factor, Kth, as well as the plane strain fracture toughness, KIc. In more detail, by reanalysing a large amount of experimental data taken from the literature, it is proved that Kth can successfully be evaluated through the plain fatigue limit and another fatigue limit generated by testing samples containing a known geometrical feature, whereas KIc is suggested here as being estimated by using experimental results generated by testing samples weakened by notches of different sharpness. The validation exercise summarised in the present paper fully confirms that the TCD is not only a reliable method suitable for performing the static and fatigue assessment of real components, but also an efficient experimental strategy capable of accurately estimating the classical Linear Elastic Fracture Mechanics (LEFM) material properties.

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