scholarly journals Thermal shock resistance of solids associated with hyperbolic heat conduction theory

2013 ◽  
Vol 469 (2153) ◽  
pp. 20120754 ◽  
Author(s):  
B. L. Wang ◽  
J. E. Li
Keyword(s):  
Heat Conduction ◽  
Thermal Stress ◽  
Stress Intensity ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Closed Form Solution ◽  
Hyperbolic Heat Conduction ◽  
Conduction Model ◽  
Fourier Heat Conduction ◽  
Shock Resistance

The thermal shock resistance of solids is analysed for a plate subjected to a sudden temperature change under the framework of hyperbolic, non-Fourier heat conduction. The closed form solution for the temperature field and the associated thermal stress are obtained for the plate without cracking. The transient thermal stress intensity factors are obtained through a weight function method. The maximum thermal shock temperature that the plate can sustain without catastrophic failure is obtained according to the two distinct criteria: (i) maximum local tensile stress criterion and (ii) maximum stress intensity factor criterion. The difference between the non-Fourier solutions and the classical Fourier solution is discussed. The traditional Fourier heat conduction considerably overestimates the thermal shock resistance of the solid. This confirms the fact that introduction of the non-Fourier heat conduction model is essential in the evaluation of thermal shock resistance of solids.

scholarly journals Thermal shock fracture mechanics analysis of a semi-infinite medium based on the dual-phase-lag heat conduction model

2015 ◽  
Vol 471 (2174) ◽  
pp. 20140595 ◽  
Author(s):  
B. Wang ◽  
J. E. Li ◽  
C. Yang
Keyword(s):  
Stress Intensity Factor ◽  
Heat Conduction ◽  
Thermal Stress ◽  
Stress Intensity ◽  
Thermal Shock ◽  
Infinite Medium ◽  
Phase Lag ◽  
Dual Phase ◽  
Conduction Model ◽  
Heat Conduction Model

The generalized lagging behaviour in solids is very important in understanding heat conduction in small-scale and high-rate heating. In this paper, an edge crack in a semi-infinite medium subjected to a heat shock on its surface is studied under the framework of the dual-phase-lag (DPL) heat conduction model. The transient thermal stress in the medium without crack is obtained first. This stress is used as the crack surface traction with an opposite sign to formulate the crack problem. Numerical results of thermal stress intensity factor are obtained as the functions of crack length and thermal shock time. Crack propagation predictions are conducted and results based on the DPL model and those based on the classical Fourier heat conduction model are compared. The thermal shock strength that the medium can sustain without catastrophic failure is established according to the maximum local stress criterion and the stress intensity factor criterion.

Improvement on Thermal Shock Resistance of Ceramic Components by Using Self-Healing

2010 ◽  
Author(s):  
Wataru Nakao
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Thermal Shock ◽  
Stress Fracture ◽  
Thermal Shock Resistance ◽  
Self Healing ◽  
Quenching Rate ◽  
Ceramic Components ◽  
Shock Resistance ◽  
Quenching Method

Availability of self-healing on the thermal shock resistance of ceramic components was investigated. Using gas quenching method, the crack-healed alumina-18 vol% SiC composite, which has excellent self-healing ability, was applied to thermal shock of the arbitrary quenching rate. The procedure could give rise to the thermal stress fracture at high temperature. The critical quenching rate at thermal stress fracture of the healed specimen was found to be 6.47 K/s, corresponding to the thermal stress of 452.3 MPa. Alternatively, that of the cracked specimen was found to be 5.02 K/s, corresponding to the thermal stress of 350 MPa. From the obtained results, usage of self-healing was confirmed to improve extremely thermal shock resistance. The present result suggests that usage of self-healing gives a large advantage to design the high temperature ceramic components, because the mechanically reliable design and thermal shock resistance cannot coexist due to low thermal conductivity.

Fabrication, Microstructure, and Properties of Zirconium Diboride Matrix Ceramic

2013 ◽  
pp. 354-412 ◽  
Author(s):  
Zhi Wang ◽  
Zhanjun Wu
Keyword(s):  
Thermal Stress ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Zirconium Diboride ◽  
Isothermal Oxidation ◽  
Rate Of Change ◽  
Oxide Layers ◽  
Sic Ceramic ◽  
Shock Resistance ◽  
Quenching Method

The crystal structure, synthesis, and densification of zirconium diboride (ZrB2) are summarized in detail. In this chapter, ZrB2-ZrC-SiC ceramic was synthesized by reactive hot pressing a mixture of Zr, B4C, and Si powders. The thermal shock resistance of the ZrB2-SiC-ZrC ceramic was estimated by the water-quenching method and was significantly greater than that of a ZrB2-15vol.% SiC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at constant temperatures of 1000±15, 1200±15, and 1400±15 ºC for different amounts of time at each temperature. The mechanism of strength increase for the oxidized specimen indicated that the strength increased with the reaction rate, which was related to the rate of change in volume induced by reaction, initial crack geometry, elastic modulus, and surface free energy. The formation of oxide layers resulted in (I) repair of surface flaws, (II) increase in flexural strength, (III) appearance of a compressive stress zone beneath the surface oxide layers, (IV) decrease in thermal stress, and (V) consumption of thermal stress. These five aspects were favorable to the improvement of the thermal shock resistance of the ZrB2-SiC-ZrC ceramic. The isothermal oxidation of the ZrB2-SiC-ZrC ceramic was carried out in static air at 1600±15 ºC. In the different oxidation stages, quantitative models were proposed for predicting oxidation kinetics.

Fracture of a Finite Medium with a Circular Internal Crack under Hyperbolic Heat Conduction-Prescribed Crack Face Thermal Flux

2013 ◽  
Vol 706-708 ◽  
pp. 1373-1378
Author(s):  
B. Wang
Keyword(s):  
Stress Intensity Factor ◽  
Heat Conduction ◽  
Thermal Stress ◽  
Stress Intensity ◽  
Thermal Flux ◽  
Internal Crack ◽  
Hyperbolic Heat Conduction ◽  
Crack Face ◽  
Thermal Stress Intensity Factor ◽  
Finite Medium

This paper studies the fracture mechanics of a thermoelastic medium with an internal circular crack subjecting to a prescribed thermal flux. The time varying crack tip thermal stress intensity factor is solved. Solution for the infinite medium under steady heat conduction is given in closed form. Comparisons between the non-Fourier results and the classical Fourier results are made. Numerical results show that the non-Fourier heat model predicts considerable high transient thermal stress intensity factor than the Fourier model. This paper, together with our previous paper entitled fracture of a finite medium with a circular internal crack under hyperbolic heat conduction-prescribed crack face temperature, completes the analysis of a finite medium with a circular internal crack under hyperbolic heat conduction.

The Study of Optimum Shape to Evaluation for Thermal Shock Behavior of Graphite

2006 ◽  
Vol 326-328 ◽  
pp. 915-918 ◽  
Author(s):  
Song Heo Koo ◽  
Young Shin Lee
Keyword(s):  
Mechanical Property ◽  
Thermal Stress ◽  
Thermal Shock ◽  
Laser Irradiation ◽  
Power Density ◽  
Thermal Shock Resistance ◽  
Central Area ◽  
Optimum Shape ◽  
Transient Temperature ◽  
Shock Resistance

The purpose of the present study is to evaluate thermal shock properties of the ATJ graphite using laser irradiation techniques. Cracks of thermal shock specimens are initiated by maximum tensile stress field. Thermal shock resistance of the ATJ graphite is correlated with thermal parameter and mechanical property. To simulate the thermal stress conditions of rocket nozzle throat for the evaluation of the thermal shock resistance of ATJ graphite, the laser irradiation was applied at the central area of disk specimen. Thermal shock resistance was related to the geometry, the maximum stress, and the thermal and mechanical property. Also the analyses of transient temperature and thermal stress were performed by the finite element method with nonlinear code ABAQUS. Analyses were specially performed for several kinds of shape to determine the minimum power density which could be cracked the specimen. The shape of the thermal shock specimen which was cracked under the lower power density was obtained and the result will be proved to the test.

Development of High Performance Mid-Temperature Burnt Al2O3-ZrO2-C Slide Gates

2012 ◽  
Vol 510 ◽  
pp. 689-693
Author(s):  
Wei Li ◽  
Hou Xing Zhang ◽  
Ze Ming Tong ◽  
Yan Ming Li
Keyword(s):  
Thermal Stress ◽  
Thermal Shock ◽  
Molten Steel ◽  
Thermal Shock Resistance ◽  
High Performance ◽  
Slide Gate ◽  
Refining Process ◽  
Thermal Gradients ◽  
Edge Part ◽  
Shock Resistance

Slide gates are installed at the bottom of a ladle or tundish to control the flow of molten steel. It plays an important role in ladle refining process and continuous casting. Al2O3-ZrO2-C refractories are widely used as slide gate materials due to its excellent corrosion and thermal shock resistance. At the start of casting, molten steel almost 1600°C passes through the bore of slide gate, the plate is rapidly heated up, the temperature difference between the bore and edge part, the slide gates are subject to large thermal gradients, so there is large thermal stress in the plate. This paper will show the results of our improved slide gates with good thermal shock resistance.

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