The effects of thermal shock waves on the crack initiation around a moving heat source

1989 ◽  
Vol 34 (5-6) ◽  
pp. 1109-1118 ◽  
Author(s):  
Tzou Da Yu
Keyword(s):  
Crack Initiation ◽  
Shock Waves ◽  
Heat Source ◽  
Thermal Shock ◽  
Moving Heat Source

The Vibration of Nano-Beam Subjected to Thermal Shock and Moving Heat Source with Constant Speed

2020 ◽  
Vol 61 ◽  
pp. 136-150 ◽  
Author(s):  
Najat A. Alghamdi
Keyword(s):  
Heat Source ◽  
Thermal Shock ◽  
Numerical Solutions ◽  
Time Variable ◽  
Constant Speed ◽  
Moving Heat Source ◽  
Governing Equations ◽  
Lateral Deflection ◽  
Temperature Increment ◽  
Fourier Heat Conduction

This paper deals with a mathematical model of thermoelastic rectangular nano-beam, which is thermally loaded by thermal shock and subjected to moving heat source with constant speed. The nano-beam has been clamped-clamped and its length along the x-axis. The governing equations have been written by using the Euler–Bernoulli equation of nano-beams and the non-Fourier heat conduction with one-relaxation time. Laplace transform has been applied with respect to the time variable, and the solutions have been derived in its domain. The numerical solutions for the Silicon material have been done by using Tzou method. The results have been shown in figures for the temperature increment and the lateral deflection with various values of heat source speed to stand on its effects. Moreover, the effects of the ratio between the length and the width of the beam have been discussed. The speed of the heat source and the dimensions of the beam have significant effects on the temperature increment and the lateral deflection of the beam.

On the Thermal Shock Wave Induced by a Moving Heat Source

1989 ◽  
Vol 111 (2) ◽  
pp. 232-238 ◽  
Author(s):  
D. Y. Tzou
Keyword(s):  
Shock Wave ◽  
Temperature Field ◽  
Heat Source ◽  
Thermal Shock ◽  
Thermal Field ◽  
Heat Propagation ◽  
Moving Heat Source ◽  
Finite Speed ◽  
Wave Angle ◽  
Wave Induced

Analytical solutions for the temperature field around a moving heat source in a solid with finite speed of heat propagation are obtained via the method of Green’s functions. When the speed of the moving heat source is equal to or faster than that of the thermal wave propagated in the solid, the thermal shock wave is shown to exist in the thermal field. The shock wave angle is obtained as sin−1 (1/M) for M ≥1. Orientation of crack initiation in the vicinity of the heat source is also estimated by considering the temperature gradient T,θ along the circumference of a continuum circle centered at the heat source. Such an orientation is established as a function of the thermal Mach number in the subsonic, transonic, and supersonic regimes, respectively.

Effects of Cooling Conditions on Thermal Crack Initiation of Brittle Cutting Tools during Intermittent Cutting

2015 ◽  
Vol 656-657 ◽  
pp. 237-242
Author(s):  
Kenji Yamaguchi ◽  
Tsuyoshi Fujita ◽  
Yasuo Kondo ◽  
Satoshi Sakamoto ◽  
Mitsugu Yamaguchi ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Thermal Shock ◽  
High Speed ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Cutting Condition ◽  
Thermal Crack ◽  
Cooling Conditions ◽  
Cutting Operation ◽  
Intermittent Cutting

It is well known that a series of cracks running perpendicular to the cutting edge are sometimes formed on the rake face of brittle cutting tools during intermittent cutting. The cutting tool is exposed to elevated temperatures during the periods of cutting and is cooled quickly during noncutting times. It has been suggested that repeated thermal shocks to the tool during intermittent cutting generate thermal fatigue and result in the observed thermal cracks. Recently, a high speed machining technique has attracted attention. The tool temperature during the period of cutting corresponds to the cutting speed. In addition, the cooling and lubricating conditions affect the tool temperature during noncutting times. The thermal shock applied to the tool increases with increasing cutting speed and cooling conditions. Therefore, to achieve high-speed cutting, the evaluation of the thermal shock and thermal crack resistance of the cutting tool is important. In this study, as a basis for improving the thermal shock resistance of brittle cutting tools during high-speed intermittent cutting from the viewpoint of cutting conditions, we focused on the cooling conditions of the cutting operation. An experimental study was conducted to examine the effects of noncutting time on thermal crack initiation. Thermal crack initiation was found to be restrained by reducing the noncutting time. In the turning experiments, when the noncutting time was less than 10 ms, thermal crack initiation was remarkably decreased even for a cutting speed of 500 m/min. In the milling operation, the number of cutting cycles before thermal crack initiation decreased with increasing cutting speed under conditions where the cutting speed was less than 500 m/min. However, when the cutting speed was greater than 600 m/min, thermal crack initiation was restrained. We applied the minimal quantity lubrication (MQL) coolant supply to the intermittent cutting operation. The experimental results showed that the MQL diminished tool wear compared with that under the dry cutting condition and inhibited thermal crack initiation compared with that under the wet cutting condition.

Prediction of suitable heat treatment for H13 tool steels by application of thermal shock fatigue cycle

2021 ◽  
pp. 135065012110118
Author(s):  
Palani Karthikeyan ◽  
Sumit Pramanik
Keyword(s):  
Heat Treatment ◽  
Crack Initiation ◽  
Thermal Shock ◽  
Tool Steel ◽  
Treatment Method ◽  
Industrial Applications ◽  
Tool Steels ◽  
H13 Steel ◽  
H13 Tool Steel ◽  
Cyclic Treatment

In industry, thermally shocked components lead to early failures and unexpected breakdowns during production resulting in huge losses in profit. Thus, the present study investigates the as-received, hardened and hardened and nitrogen treated H13 tool steels subjected to a thermal shock gradient similar to the actual industrial applications. The thermal shock gradients were created by using an in-house-built thermal shock fatigue cyclic treatment machine. The effect of thermal shock fatigue cyclic treatments at 1000 and 2000 thermal shock cycles in hot and molten metal chambers was noticed. All the thermal shock fatigue cyclic-treated samples were analysed by hardness, X-ray diffraction, microscopy and magnetic tests. The interesting changes in hardness, distorted crystal structure and crack initiation were found to be different for differently treated H13 tool steel specimens. The molten aluminium was more prone to stick to the surface of as-received as well as hardened and nitrogen treated steel compared to the hardened H13 steel specimens, which would delay the crack initiation. The wear resistance properties of the hardened H13 steel specimens were found to be higher than as-received and hardened and nitrogen treated H13 steel specimens after thermal shock fatigue cyclic treatment. The loss in magnetic properties was significant for the hardened and hardened and nitrogen treated samples compared to as-received H13 tool steel specimens. Therefore, the present 1000 and 2000 thermal fatigue cycles for 30 s at 670 °C would be worthy to predict the proper heat treatment method to design the parameters as well as the life of die-casting components and to help in the economical production of casting.

scholarly journals Analysis of hyperbolic Pennes bioheat equation in perfused homogeneous biological tissue subject to the instantaneous moving heat source

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Ali Kabiri ◽  
Mohammad Reza Talaee
Keyword(s):  
Heat Source ◽  
Closed Form ◽  
Method Comparison ◽  
Closed Form Solution ◽  
Form Solution ◽  
Temperature Profiles ◽  
Moving Heat Source ◽  
Bioheat Equation ◽  
Perfusion Rate

AbstractThe one-dimensional hyperbolic Pennes bioheat equation under instantaneous moving heat source is solved analytically based on the Eigenvalue method. Comparison with results of in vivo experiments performed earlier by other authors shows the excellent prediction of the presented closed-form solution. We present three examples for calculating the Arrhenius equation to predict the tissue thermal damage analysis with our solution, i.e., characteristics of skin, liver, and kidney are modeled by using their thermophysical properties. Furthermore, the effects of moving velocity and perfusion rate on temperature profiles and thermal tissue damage are investigated. Results illustrate that the perfusion rate plays the cooling role in the heating source moving path. Also, increasing the moving velocity leads to a decrease in absorbed heat and temperature profiles. The closed-form analytical solution could be applied to verify the numerical heating model and optimize surgery planning parameters.

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