Controlled Fracture of Nonmetallic Thin Wafers Using a Laser Thermal Shock Method

2004 ◽  
Vol 126 (1) ◽  
pp. 142-147 ◽  
Author(s):  
T. Elperin ◽  
G. Rudin
Keyword(s):  
Theoretical Model ◽  
Thermal Shock ◽  
Operating Parameters ◽  
Laser Shock ◽  
Suggested Model ◽  
Spontaneous Transition ◽  
Bending Stresses ◽  
Controlled Fracture ◽  
Two Stages ◽  
Surface Microcrack

We developed a theoretical model of a novel thermal laser shock method for separation of glass and glass-ceramic wafers into chips. The suggested model allowed us to determine the operating parameters of the device for wafer splitting. The investigated method involves two stages: 1) formation of a surface (blind) microcrack (or a grid of surface microcracks) using a double thermal shock method, and 2) splitting the cracked wafer into chips along the microcrack contour by applying small bending stresses. The emphasis was given to splitting of thin wafers with the thickness less than 1 mm. The latter process is more involved because of the undesirable spontaneous transition of a surface microcrack into a through crack.

The Internationalization of Family Firms

2013 ◽  
Vol 27 (2) ◽  
pp. 103-125 ◽  
Author(s):  
Thilo J. Pukall ◽  
Andrea Calabrò
Keyword(s):  
Theoretical Model ◽  
Family Firms ◽  
Future Research ◽  
Risk Attitudes ◽  
Journal Articles ◽  
Suggested Model ◽  
Socioemotional Wealth ◽  
Uppsala Model ◽  
Research Themes

This article systematically reviews and critically examines 72 journal articles published (from 1980 to 2012) on the internationalization of family firms. Stemming from existing literature, core aspects and main gaps are identified. We aim to overcome the inconclusiveness of findings of previous research by offering an integrative theoretical model integrating the concept of socioemotional wealth with the revised Uppsala model. Our framework helps understand behaviors of internationalizing family firms by focusing on when and how they internationalize, especially related to risk attitudes, the role of knowledge and networks. Ultimately, we provide future research themes flowing from our suggested model.

scholarly journals Evaluating the parameters of a mobile maize dryer in practice

2013 ◽  
Vol 61 (6) ◽  
pp. 1779-1784
Author(s):  
Josef Los ◽  
Jiří Fryč ◽  
Zdeněk Konrád
Keyword(s):  
Large Scale ◽  
Electric Energy ◽  
Operating Parameters ◽  
The Czech Republic ◽  
Maize Hybrids ◽  
Post Harvest ◽  
Second Stage ◽  
Energy Intensiveness ◽  
Two Stages ◽  
The Given

The method of drying maize for grain has been recently employed on a large scale in the Czech Republic not only thanks to new maize hybrids but also thanks to the existence of new models of drying plants. One of the new post-harvest lines is a plant in Lipoltice (mobile dryer installed in 2010, storage base in 2012) where basic operational measurements were made of the energy intensiveness of drying and operating parameters of the maize dryer were evaluated. The process of maize drying had two stages, i.e. pre-drying from the initial average grain humidity of 28.55% to 19.6% in the first stage, and the additional drying from 16.7% to a final storage grain humidity of 13.7%. Mean volumes of natural gas consumed per 1 t% for drying in the first and second stage amounted to 1.275 m3 and 1.56 m3, respectively. The total mean consumption of electric energy per 1 t% was calculated to be 1.372 kWh for the given configuration of the post-harvest line.

The Effects of Constraint, Size and Aspect Ratio on Thermal Shock Resistance of ZNS Wave-Transparent Ceramic in its Actual Service

2015 ◽  
Vol 31 (4) ◽  
pp. 449-455 ◽  
Author(s):  
W.-G. Li ◽  
D.-J. Li ◽  
T.-B. Cheng ◽  
D.-N. Fang
Keyword(s):  
Theoretical Model ◽  
Aspect Ratio ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Transparent Ceramic ◽  
Aerodynamic Heating ◽  
Mechanical And Thermal Properties ◽  
Pneumatic Pressure ◽  
Actual Service ◽  
Shock Resistance

AbstractThe thermal shock resistance (TSR) of ZnS wave-transparent ceramic depends on not only the mechanical and thermal properties of materials, but also the aerodynamic heating, pneumatic pressure, external constraint, size, aspect ratio and other factors in its actual service process. The theoretical model was established by introducing the analytical solution of transient heat conduction problem of ZnS plate under aerodynamic heating into its thermal stress field model and the pneumatic pressure was introduced. The present work mainly focused on the influences of constraint, size and aspect ratio on the critical rupture temperature difference of ZnS plate subjected to aerodynamic heating and pneumatic pressure. The numerical simulation was also conducted to verify the theoretical model. The results show that the large heat transfer condition corresponds to the poor TSR unless the constraint is too strong; the square plate provides the better TSR in case of different pneumatic pressures; a reasonable side length according to the range of pneumatic pressure would lead to the better TSR.

Wire Stress Calculations in Helical Strands Undergoing Bending

1992 ◽  
Vol 114 (3) ◽  
pp. 212-219 ◽  
Author(s):  
M. Raoof ◽  
Y. P. Huang
Keyword(s):  
Theoretical Model ◽  
Axial Stress ◽  
Operating Conditions ◽  
Radius Of Curvature ◽  
Axial Component ◽  
Practical Applications ◽  
Bending Stresses ◽  
Parametric Studies ◽  
Steel Cables ◽  
The Individual

Steel cables play an important role in many offshore applications. In many cases, an understanding of the magnitude and pattern of bending stresses in the individual component wires of a bent strand is essential for minimizing the risk of their failure under operating conditions. Following previously reported experimental observations, a theoretical model is proposed for obtaining the magnitude of wire bending stresses in a multi-layered and axially preloaded spiral strand fixed at one end and subsequently bent to a constant radius of curvature. The individual wire bending stresses are shown to be composed of two components. The first component is the axial stress generated in the wires due to interwire/interlayer shear interactions between the wires in a bent cable, and the second component is associated with the wires bending about their own axes. Using the theoretical model, which includes the effects of interwire friction, parametric studies on a number of realistic helical strands with widely different cable (and wire) diameters and lay angles subjected to a range of practical mean axial loads, and subsequently bent to a range of radii of curvature with one end of the cable fixed against rotation, have been carried out. It is shown that for most practical applications, the axial component of wire stresses due to friction is much greater than the second component of bending stresses associated with the individual wires bending about their own axes.

Thermal Shock Experiment and Simulation of Ceramic/Metal Gradient Thermal Barrier Coating

2007 ◽  
Vol 336-338 ◽  
pp. 1818-1822
Author(s):  
Jin Sheng Xiao ◽  
Kun Liu ◽  
Wen Hua Zhao ◽  
Wei Biao Fu
Keyword(s):  
Heat Transfer ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Stresses ◽  
Initial Temperature ◽  
Thermal Barrier ◽  
Water Spray ◽  
Barrier Coating ◽  
Shock Experiment ◽  
Two Stages

A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The experiment procedure includes two stages, heating the specimen from the initial temperature 30°C for 40s, and then cooling for 20s. The heat transfer and the associated thermal stresses produced during the thermal shock procedure are simulated by finite element method. Experimental results indicated that the specimen of gradient coating behaves better in thermal shock experiments, which agree with the results of simulation.

scholarly journals Controlling fracture cascades through twisting and quenching

2018 ◽  
Vol 115 (35) ◽  
pp. 8665-8670 ◽  
Author(s):  
Ronald H. Heisser ◽  
Vishal P. Patil ◽  
Norbert Stoop ◽  
Emmanuel Villermaux ◽  
Jörn Dunkel
Keyword(s):  
General Character ◽  
Scaling Relations ◽  
Pure Bending ◽  
Wide Range ◽  
Bending Stresses ◽  
Fracture Control ◽  
Quench Dynamics ◽  
Controlled Fracture ◽  
Fracture Processes ◽  
Asymptotic Scaling

Fracture fundamentally limits the structural stability of macroscopic and microscopic matter, from beams and bones to microtubules and nanotubes. Despite substantial recent experimental and theoretical progress, fracture control continues to present profound practical and theoretical challenges. While bending-induced fracture of elongated rod-like objects has been intensely studied, the effects of twist and quench dynamics have yet to be explored systematically. Here, we show how twist and quench protocols may be used to control such fracture processes, by revisiting Feynman’s observation that dry spaghetti typically breaks into three or more pieces when exposed to large pure bending stresses. Combining theory and experiment, we demonstrate controlled binary fracture of brittle elastic rods for two distinct protocols based on twisting and nonadiabatic quenching. Our experimental data for twist-controlled fracture agree quantitatively with a theoretically predicted phase diagram, and we establish asymptotic scaling relations for quenched fracture. Due to their general character, these results are expected to apply to torsional and kinetic fracture processes in a wide range of systems.

Research on the Theory of the Laser Shock Processing Technology

2014 ◽  
Vol 610 ◽  
pp. 1021-1028
Author(s):  
Jin Lan Lin ◽  
Jian Hong Fan
Keyword(s):  
Theoretical Model ◽  
Transmission Coefficient ◽  
Plasma Layer ◽  
Processing Technology ◽  
Laser Shock ◽  
Incident Laser ◽  
Laser Shock Processing ◽  
One Dimensional ◽  
Shock Processing ◽  
Maximum Transmission

In this paper the laser shock processing technology (LSPT) is investigated theoretically. A one-dimensional theoretical model is presented to express analytically the transmission coefficient of the incident laser beam through four different layers, i.e., the air layer, the constrained layer, the plasma layer, and the absorbing coating. Based on this model, the key parameters of LSPT can be further optimized to obtain the maximum transmission coefficient and the best surface-hardening effect. This one-dimensional theoretical model presented can be further used in guiding the parameter optimization for this technology.

Impedance Measurements of Inertance Tubes for Pulse Tube Cryocoolers

2013 ◽  
Vol 718-720 ◽  
pp. 739-744
Author(s):  
S.S. Li ◽  
Y.N. Wu
Keyword(s):  
Theoretical Model ◽  
Turbulent Flow ◽  
Experimental Results ◽  
Operating Parameters ◽  
Pulse Tube ◽  
Impedance Measurements ◽  
General Rules ◽  
Wide Range ◽  
Compressor Piston ◽  
Mass Flows

The impedance of the inertance tubes which include the mass flows, pressure amplitudes and phase shifts between them at the inlet of the inertance tubes were measured by correcting the mass flows at the surface of the compressor piston. The experimental results are compared with the theoretical values based on simplified turbulent-flow thermoacoustic model. The wide range of impedance measurements with different inertance tube geometries and operating parameters enable us to summarize the general rules of their effects on impedance respectively, also the differences between the experiments and calculations can be used to modify the theoretical model.

scholarly journals Thermal Absorptivity Model of Knitted Rib Fabric and its Experimental Verification

2018 ◽  
Vol 18 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Asif Elahi Mangat ◽  
Lubos Hes ◽  
Vladimir Bajzik ◽  
Adnan Mazari
Keyword(s):  
Theoretical Model ◽  
Surface Profile ◽  
Suggested Model ◽  
Polyester Yarn ◽  
Textile Materials ◽  
Simple Theoretical Model ◽  
Fabric Surface ◽  
Solid Form ◽  
Non Destructive ◽  
Thermal Absorptivity

Abstract Thermal absorptivity is an indicator of warm and cool feeling of textile materials. An equation based on thermal absorptivity of polyester in solid form, porosity of a fabric, and relative contact area of human skin and fabric surface has been developed to characterize thermal absorptivity of fabric. For verification of suggested model, 15 knitted rib fabrics were produced using 100% polyester yarn and having different surface profile. ALAMBETA semiautomatic non-destructive instrument has been used for measuring the effective thermal absorptivity of knitted rib fabric. It was found that the suggested simple theoretical model exhibits significant agreement with the measured thermal absorptivity values of knitted rib fabric, which endorsed the approach applied.

Characteristic Wave Impedance of Ti-Mo System Composites and FGM

2005 ◽  
Vol 475-479 ◽  
pp. 1537-1540
Author(s):  
Chuan Bin Wang ◽  
Qiang Shen ◽  
Guoqiang Luo ◽  
Lian Meng Zhang
Keyword(s):  
Theoretical Model ◽  
Longitudinal Wave ◽  
Mixture Model ◽  
Wave Impedance ◽  
Experimental Results ◽  
Suggested Model ◽  
Characteristic Wave ◽  
Wave Velocities ◽  
The Relationship

In the present paper, the relationship between characteristic wave impedance and compositions was mainly investigated in order to find a suitable theoretical model for predicting the impedance value of Ti-Mo system composites and FGM. At first, dense Ti-Mo composites with different weight fractions of Mo were prepared. Then the transverse and longitudinal wave velocities of the samples were measured and the characteristic wave impedance values were obtained. A mixture model was adopted to estimate the characteristic wave impedance value of Ti-Mo composites. Comparisons between the estimated and experimental results demonstrated that the suggested model was sufficiently accurate to predict the characteristic wave impedance value of Ti-Mo system composites and FGM.

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