Thermal Stress in Functionally Graded Plates with a Gradation of the Coefficient of Thermal Expansion Only

2022 ◽  
Author(s):  
T. Baytak ◽  
O. Bulut
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Coefficient Of Thermal Expansion ◽  
Functionally Graded ◽  
Functionally Graded Plates

Thermal stress analysis of in-plane two-directional functionally graded plates subjected to in-plane edge heat fluxes

2016 ◽  
Vol 232 (8) ◽  
pp. 693-716
Author(s):  
MK Apalak ◽  
MD Demirbas
Keyword(s):  
Mechanical Properties ◽  
Thermal Stress ◽  
Functionally Graded ◽  
Heat Fluxes ◽  
Material Composition ◽  
Stress Distributions ◽  
Thermal And Mechanical Properties ◽  
Functionally Graded Plates ◽  
Spatial Derivatives ◽  
Derivatives Of

This study investigates the thermal stress and deformation states of bi-directional functionally graded clamped plates subjected to constant in-plane heat fluxes along two ceramic edges. The material properties of the functionally graded plates were assumed to vary with a power law along two in-plane directions not through the plate thickness direction. The spatial derivatives of thermal and mechanical properties of the material composition were considered, and the effects of the bi-directional composition variations and spatial derivative terms on the displacement, strain and stress distributions were also investigated. The heat conduction and Navier equations describing the two-dimensional thermo-elastic problem were discretized using finite-difference method, and the set of linear equations were solved using the pseudo singular value method. The compositional gradient exponents and the spatial derivatives of thermal and mechanical properties of the material composition were observed to play an important role especially on the heat transfer durations, the displacement and strain distributions, but had a minor effect on the temperature and stress distributions.

scholarly journals Thermal analysis of metal-ceramic bonding using finite element method

2014 ◽  
Vol 3 (2) ◽  
pp. 216 ◽  
Author(s):  
S. Gopinath ◽  
R Sabarish ◽  
R. Sasidharan
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Bonding Strength ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Processing Temperature ◽  
Element Analysis ◽  
Metal Ceramic ◽  
The Difference

This paper reports a finite element study of effect of bonding strength between metal and ceramic. The bonding strength is evaluated with different processing temperature and holding time. The difference between the coefficients of linear thermal expansion (CTEs) of the metal and ceramic induces thermal stress at the interface. The mismatch thermal stress at the interface region plays an important role in improving bonding strength. Hence, it is essential to evaluate the interface bonding in metal-ceramics joints. The Al/SiC bonding was modeled and analyzed using finite element analysis in ANSYS (v.10). Keywords: Bonding Strength, Coefficient of Thermal Expansion, Thermal Stress, Interface, Al/Sic, FEA.

Dielectric Properties of LTCC System of Al2O3 and Borosilicate Glass

2007 ◽  
Vol 336-338 ◽  
pp. 783-785 ◽  
Author(s):  
Yang Liu ◽  
Yan Wang ◽  
Ju Sheng Ma
Keyword(s):  
Dielectric Constant ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Dielectric Properties ◽  
Borosilicate Glass ◽  
Coefficient Of Thermal Expansion ◽  
Al2o3 Content ◽  
Powder Size ◽  
Al2o3 Powder ◽  
Low Permittivity

In this paper, three types of Al2O3 powders with different sizes (1.6μm, 0.7μm, and 0.3μm) were used in a LTCC system of Al2O3 and borosilicate glass (BSG). Al2O3 and BSG are selected on account of their coefficient of thermal expansion (CTE) similar to silicon, which can reduce thermal stress. It was found that the dielectric constant, ε, of substrates drops with the decrease of Al2O3 powder size. ε increases with the increase of Al2O3 content for the sample with 1.6 μm Al2O3 powder, but decreases with the increase of Al2O3 content for the samples with 0.7 μm and 0.3 μm Al2O3 powders. SEM observations revealed that more pores with low permittivity appeared for the samples with smaller Al2O3 powders, resulting in the drop of dielectric constant of the sample finally.

A Technique for Deducing In-Plane Modulus and Coefficient of Thermal Expansion of a Supported Thin Film

2002 ◽  
Vol 124 (2) ◽  
pp. 274-277 ◽  
Author(s):  
Martin Y. M. Chiang ◽  
Chwan K. Chiang ◽  
Wen-li Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Properties ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Elastic Modulus ◽  
Coefficient Of Thermal Expansion ◽  
Thermal And Mechanical Properties ◽  
Reduction Scheme ◽  
Coupled Equations

A technique for determining the in-plane modulus and the coefficient of thermal expansion (CTE) of supported thin films has been developed. The modulus and CTE are calculated by solving two coupled equations that relate the curvature of film samples deposited on two different substrates to the thermal and mechanical properties of the constituents. In contrast with the conventional method used to calculate modulus and CTE, which involves differentiation of the thermal stress in the film, this new technique does not require the differentiation of the thermal stress, and can also provide the temperature-dependence of the in-plane CTE and elastic modulus of supported thin films. The data reduction scheme used for deducing CTE and elastic modulus is direct and reliable.

scholarly journals The periodic resin configuration design for ceramic-resin composite structure using topology optimization

2014 ◽  
Vol 5 ◽  
pp. A12 ◽  
Author(s):  
Ji-Hong Zhu ◽  
Qing Li ◽  
Wei-Hong Zhang
Keyword(s):  
Thermal Expansion ◽  
Topology Optimization ◽  
Thermal Stress ◽  
Composite Structure ◽  
Thermal Protection ◽  
Coefficient Of Thermal Expansion ◽  
Resin Composite ◽  
Configuration Design ◽  
Ceramic Shell ◽  
Periodic Model

The ceramic-resin composite structure has broad prospects in many fields like rapid casting and thermal protection. Due to the coefficient of thermal expansion (CTE) of resin is about 10 times higher than that of ceramic, the excessive thermal expansion of the resin pattern will lead to the undesirable crack of the ceramic shell during the heating procedure. The proposed approach is to find a reasonable resin configuration minimizing the thermal stress in the ceramic shell. Simultaneously, the mechanical stiffness of the whole structure should be maintained at a certain level to resist the pressure applied on the ceramic shell. In the actual production, the periodic resin configurations are more operable than the disordered configuration, so finding reasonable periodic resin configurations for ceramic-resin composite structure has lots of significance. The purpose of this paper is to introduce the topology optimization method into the periodic resin configuration design for ceramic-resin composite structure. A structural topology optimization procedure in combination with thermo-mechanical finite element analysis has been developed. A single-layer periodic model and a double-layer periodic model are optimized and respective CAD models are rebuilt according to the optimal results. By comparing with the existing hexagonal honeycomb configuration, two optimal designs have shown better performances both in reducing the thermal stress in the ceramic shell and maintaining the stiffness of the whole structure.

Thermal stress analysis of one- and two-dimensional functionally graded plates subjected to in-plane heat fluxes

2017 ◽  
Vol 233 (4) ◽  
pp. 546-562 ◽  
Author(s):  
M Didem Demirbas ◽  
M Kemal Apalak
Keyword(s):  
Heat Flux ◽  
Thermal Stress ◽  
Functionally Graded ◽  
Heat Fluxes ◽  
Gradient Material ◽  
Two Dimensional ◽  
Functionally Graded Plates ◽  
Functionally Gradient Material ◽  
Functionally Gradient ◽  
Composition Variation

This study addresses the thermal stress analysis of one- and two-dimensional functionally graded plates subjected to in-plane heat fluxes. The material composition variation is assumed in-plane, not through the plate thickness according to a power-law distribution in terms of the volume fraction of the constituents. The mathematical model considers the spatial derivatives of local mechanical and thermal properties. The heat transfer and Navier equations of the two-dimensional thermo-elastic model were discretized using the finite difference method, and the set of linear equations were solved using the pseudo singular value method. The performance of both one- and two-dimensional functionally gradient material plates was investigated under two types of in-plane fluxes: one-edge and two-edges. For each type of heat fluxes, one- and two-dimensional functionally gradient material plates exhibited different displacement, stress and strain distributions. The temperature levels and distributions were affected with increasing ceramic constituent in the composition variation of the plate. One-dimensional functionally gradient material plate was more suitable for an one-edge heat flux along the direction of material composition variation, whereas two-dimensional functionally gradient material plate was more effective on the relieving the thermal stresses for a two-edges heat flux.

Effect of Different Sintering Temperature on the Performance of Mullite-Corundum Refractory Materials

2013 ◽  
Vol 750-752 ◽  
pp. 521-524
Author(s):  
Ping Li ◽  
Xing Yong Gu ◽  
Ting Luo ◽  
Yun Xia Chen
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Stress Fracture ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Refractory Materials ◽  
Corundum Refractory ◽  
X Ray Diffraction

Al (OH)3, Suzhou kaolin, AlF3 and V2O5 were premixed and pelleted to form the precursor for fabricating the mullite whisker, and then the precursor was added into the calcined bauxite and Suzhou kaolin mixture according to a certain mass percent. The mullite-corundum refractory materials with well-dispersed needle-like mullite formed in-situ were prepared. Through studying the effect of different sintering temperatures on the performances of the as-fabricated mullite-corundum refractory materials, it was concluded that the appropriate sintering temperature was 1450 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), water absorption, bending strength, coefficient of thermal expansion and the first thermal stress fracture factor were used to characterize and evaluate the materials. The results show that the sintering character and thermal expansion coefficient of the refractory materials increase with the rising sintering temperature. The bending strength of the refractory materials sintered at 1500 °C presented the maximum value and the first thermal stress fracture factor appeared the highest value at 1450 °C.

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