scholarly journals Estimation of Strength Reliability for Ceramic/Metal Jointing Structure. The Basic Study of Thermal Stress and Residual Stress Behavior during Ceramic/Metal Joint Process.

2000 ◽  
Vol 49 (4) ◽  
pp. 461-467 ◽  
Author(s):  
Nagatoshi OKABE ◽  
Xia ZHU ◽  
Kouta HIROBE ◽  
Masako NAKAHASHI
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Basic Study ◽  
Stress Behavior ◽  
Metal Joint

21216 Basic study of thermal stress behavior on laser cleaving by using one-dimensional elastic wave model

2013 ◽  
Vol 2013.19 (0) ◽  
pp. 565-566
Author(s):  
Ryouta Numaguchi ◽  
Akira Chiba ◽  
Souta Matsusaka ◽  
Hirofumi Hidai ◽  
Noboru Morita
Keyword(s):  
Thermal Stress ◽  
Elastic Wave ◽  
Wave Model ◽  
Basic Study ◽  
One Dimensional ◽  
Stress Behavior

Residual Stress Distribution of Ceramic-Metal Joint

1990 ◽  
pp. 353-362 ◽  
Author(s):  
Masanori Kurita ◽  
Makoto Sato ◽  
Ikuo Ihara ◽  
Akira Saito
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stress Distribution ◽  
Metal Joint

scholarly journals Simulation of the Residual Stress of the Y2O3/Al2O3 Composite Deuterium Permeation Barrier under Thermal Shock

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Kezhi Huang ◽  
Weijing Wang ◽  
Qinghe Yu ◽  
Lei Hao ◽  
Jing Mi ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Thermal Shock ◽  
Principal Stress ◽  
Stress Singularity ◽  
Residual Thermal Stress ◽  
Al2o3 Coating ◽  
Element Analysis ◽  
Al2o3 Layer ◽  
Y2o3 Coating

A deuterium permeation barrier is an essential part in the core component of nuclear reactors. It can protect the structure made of steel from being penetrated by deuterium in a fusion reactor. However, residual stress induced in the operation would dramatically influence the mechanical endurance of the coating, threatening the safety of the facilities. In this paper, finite element analysis was conducted to investigate the residual stress in nanoscale Al2O3 and Y2O3 coatings and their composites under thermal shock, from 700°C to 25°C. The max principal stress is assumed as the cause of crack initiation in the coating, because ceramics are brittle and fragile under tensile stress. Max shear stress and max Mises stress in the systems are also analyzed, and the effect of thickness in the range 100 nm to 1000 nm was investigated. The max principal stress in Al2O3 coating reaches its maximum value, 1.33 GPa, when the thickness of coating reaches 450 nm. And the max principal stress decreases at a very low rate as the thickness increases exceeding 450 nm. The max principal stress in Y2O3 coating increases rapidly as the thickness increases when the thickness of the coating is below 250 nm, and the max principal stress is at about 0.9 GPa when the thickness exceeds 500 nm. The max principal stress in the Y2O3/Al2O3 (150 nm) composite coating occurs in the Al2O3 layer and shows no difference from the single layer of 150 nm thick Al2O3 coating. The max principal stress site of all three kinds of coating is located at the edge of the coating 25 nm away from the interface. The result shows that residual thermal stress in the coating increases as the thickness increases when the thickness of the coating is below 200 nm due to the stress singularity of the interface. And as the thickness exceeds 500 nm, the increase in thickness has little impact on the residual thermal stress in the coating. Coating an Y2O3 top layer will not introduce any more residual thermal stress under the thermal shock condition. The Y2O3 coating causes much less residual stress under thermal shock compared with Al2O3 owing to its much lower Young’s modulus. The max principal stress in the 300 nm thick Y2O3 coating is 0.85 GPa while that of the Al2O3 coating is 1.16 GPa. The max residual stress of the composite Y2O3/Al2O3 (150 nm) coating is determined by the Al2O3 layer.

A Study of Delamination Mechanism of Thermal Barrier Coating under Thermal Cycling and Aging Condition by Residual Stress History

2009 ◽  
Vol 417-418 ◽  
pp. 173-176
Author(s):  
Hiroyuki Waki ◽  
Akira Kobayashi
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Thermal Cycling ◽  
Thermal Aging ◽  
Ceramic Coating ◽  
Plane Surface ◽  
Diffraction Method ◽  
Thermal Barrier ◽  
Stress History ◽  
Bond Coating

Thermal barrier coatings (TBCs) have been employed for the insulation of substrates from high temperature in gas turbine plants. The TBC system consists of ceramic top coating, metallic bond coating and substrate. Delamination of the ceramic coating is important problem in TBC systems. In this paper, the delamination mechanism was studied by residual stress history under thermal aging and thermal cycle conditions. In-plane residual stress histories of ceramic coating and bond coating after thermal aging and cycling were measured by X-ray diffraction method. The residual stress under thermal cycling was also calculated by FEM analysis. The results obtained were as follows: (1) in-plane surface residual stresses of the coatings scarcely changed regardless of the increase of thermally grown oxidation (TGO). (2) high compressive thermal stress, residual stress at room temperature, in ceramic coating induced by thermal stress did not occur. It was found that stress of ceramic top coating was relaxed by micro cracks and driving stress of delamination was in-plane high compressive stress.

A modified Arrhenius model for as-quenched Al-Mg-Si alloy considering the effect of cooling rate

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ruichao Guo ◽  
Jianjun Wu ◽  
Yinxiang Ren
Keyword(s):  
Residual Stress ◽  
Flow Stress ◽  
Cooling Rate ◽  
Flow Behavior ◽  
Constitutive Behavior ◽  
Strain Rates ◽  
Arrhenius Model ◽  
Content Type ◽  
Stress Behavior ◽  
Flow Stress Behavior

Purpose Accurate prediction of residual stress requires precise knowledge of the constitutive behavior of as-quenched material. This study aims to model the flow stress behavior for as-quenched Al-Mg-Si alloy. Design Methodology Approach In the present work, the flow behavior of as-quenched Al-Mg-Si alloy is studied by the hot compression tests at various temperatures (573–723 K), strain rates (0.1–1 s−1) and cooling rates (1–10 K/s). Flow stress behavior is then experimentally observed, and an Arrhenius model is used to predict the flow behavior. However, due to the fact that materials parameters and activation energy do not remain constant, the Arrhenius model has an unsatisfied prediction for the flow behavior. Considering the effects of temperatures, strain rates and cooling rates on constitutive behavior, a revised Arrhenius model is developed to describe the flow stress behavior. Findings The experimental results show that the flow stress increases by the increasing cooling rate, increasing strain state and decreasing temperature. In comparison to the experimental data, the revised Arrhenius model has an excellent prediction for as-quenched Al-Mg-Si alloy. Originality Value With the revised Arrhenius model, the flow behaviors at different quenching conditions can be obtained, which is an essential step to the residual stress prediction when the model is implemented in a finite element code, e.g. ABAQUS, in the future.

scholarly journals Simulation of Thermal Stress and Fatigue Life Prediction of High Speed Steel Work Roll during Hot Rolling Considering the Initial Residual Stress

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 966 ◽  
Author(s):  
Kejun Hu ◽  
Fuxian Zhu ◽  
Jufang Chen ◽  
Nao-Aki Noda ◽  
Wenqin Han ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Fatigue Life ◽  
Hot Rolling ◽  
Work Roll ◽  
Roll Surface ◽  
Initial Residual Stress ◽  
Thermal Fatigue Life ◽  
Cooling Conditions ◽  
Roll Temperature

Considerable residual stress is produced during heat treatment. Compressive residual stress at the shell is conductive to improving the thermal fatigue life of a work roll, while tensile stress in the core could cause thermal breakage. In hot rolling, thermal stress occurs under the heating-cooling cycles over the roll surface due to the contact with the hot strip and water spray cooling. The combination of thermal stress and residual stress remarkably influences the life of a work roll. In this paper, finite element method (FEM) simulation of hot rolling is performed by treating the residual stress as the initial stress. Afterwards, the effects of the initial roll temperature and cooling conditions on thermal stress considering the initial residual stress are discussed. Lastly, the thermal fatigue life of a work roll is estimated based on the strain life model. The higher initial roll temperature causes a higher temperature but a lower compressive thermal stress at the roll surface. The surface temperature and compressive stress increase significantly in the insufficient cooling conditions, as well as the center tensile stress. The calculation of the fatigue life of a work roll based on the universal slopes model according to the 10% rule and 20% rule is reasonable compared with experimental results.

scholarly journals Analytical Modeling of Residual Stress in Laser Powder Bed Fusion Considering Part’s Boundary Condition

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 337 ◽  
Author(s):  
Elham Mirkoohi ◽  
Hong-Chuong Tran ◽  
Yu-Lung Lo ◽  
You-Cheng Chang ◽  
Hung-Yu Lin ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Kinematic Hardening ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Repeated Heating ◽  
Powder Bed ◽  
Heating And Cooling ◽  
Body Load ◽  
Point Body

Rapid and accurate prediction of residual stress in metal additive manufacturing processes is of great importance to guarantee the quality of the fabricated part to be used in a mission-critical application in the aerospace, automotive, and medical industries. Experimentations and numerical modeling of residual stress however are valuable but expensive and time-consuming. Thus, a fully coupled thermomechanical analytical model is proposed to predict residual stress of the additively manufactured parts rapidly and accurately. A moving point heat source approach is used to predict the temperature field by considering the effects of scan strategies, heat loss at part’s boundaries, and energy needed for solid-state phase transformation. Due to the high-temperature gradient in this process, the part experiences a high amount of thermal stress which may exceed the yield strength of the material. The thermal stress is obtained using Green’s function of stresses due to the point body load. The Johnson–Cook flow stress model is used to predict the yield surface of the part under repeated heating and cooling. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is precited using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. Experimental measurement of residual stress was conducted using X-ray diffraction on the fabricated IN718 built via laser powder bed fusion to validate the proposed model.

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