通过关键词查论文: Thermal Shock

文章题目页数

作者: M.A. Ali, S.T. Hasan, D.P. Myriounis
摘要: An empirical solution for the thermal shock stresses in cylindrical shell presented when cylinder is subjected to heating or re-heating case and down-shock cooling by forced air case. Linear equations are developed to describe the severity of thermal shock loading. When thermal gradient and time period are in consideration, it is shown the equations displays good approximation for major characteristics of the thermal shock stress profiles.
893
作者: B.P. Fillery, Xiao Zhi Hu, Gordon Fisher
摘要: A practical method to evaluate the thermal shock stress intensity factors (TS-SIF`s) associated with a flexibly restrained edge-cracked plate (FRECP) is outlined. It is assumed that the edge crack can be represented with a spring couple, and the deformations of the edge-cracked plate are consistent with Euler-Bernoulli deformation theory. It is then demonstrated how a compliance analysis of this simplified representation can be used with a finite element analysis of equivalent crack free plates to evaluate to TS-SIF`s associated with a FRECP. The accuracy of this method is shown to be excellent by comparing it against a direct fracture mechanic finite element analysis. This method is therefore advantageous to a fracture mechanic finite element analysis as it does not require an explicit analysis of a FRECP.
157
作者: Jin Kyung Lee, Young Chul Park, Sang Ll Lee
摘要: A smart material is used as spectacle frames and brassiere frames, and partly in medical supplies because of its shape memory effect. The smart composite can be used on the wing of an airplane instead of the existing aluminium to control crack propagation. In this study, the smart composite was fabricated by a hot press method. TiNi alloy as reinforcement and Al6061 as matrix were used, respectively. The mechanical properties of the smart composite under thermal shock cycles were evaluated. In addition, Acoustic Emission techniques were also used to clarify the damage behavior of the smart composite under thermal shock cycles nondestructively.
1113
作者: Peng Fang, Lai Fei Cheng, Li Tong Zhang, Hui Mei, Jun Zhang
摘要: Three-dimensional (3D) carbon fiber reinforced silicon carbide matrix composites (C/SiC) were prepared by a low-pressure chemical vapor infiltration method. The thermal shock behaviors of the composites in different environments were researched using an advanced acoustic emission (AE) system. Damage initiation and propagation were easily detected and evaluated by AE. The thermal shock damage to C/SiC composites mainly occurred at the process of cooling and was limited at argon but unlimited at wet oxygen atmosphere. Also correlations have been established between the different damage mechanisms and the characteristics of acoustic emission signals obtained during thermal shock tests. In this way, the paper contributes to the development of the acoustic emission technique for monitoring of damage development in ceramic-matrix composites.
1585
作者: You Tang Gao, Shuo Liu, Yuan Xu
摘要: The development of infrared optical materials is always closely related to the research and exploration of material science. The infrared optical domes bears shock and produces stress when the infrared optical domes mounted on the missile moving at a high speed is shocked by high temperature. According to aerodynamics theory and thermo shock theory, the surge current will be transferred to optical parts through holding up layer and warms the surface of optical parts when infrared optical parts are shocked by high temperature. A compress stress is formed on the hot external surface of optical parts forms and a tension stress is formed on the internal surface or optical parts under the circumstance of the edge of optical parts being fixed. The windows of optical parts become curvature radius of lens with the function of pressure difference which can cause aberration change. The brittle fracture of material will be caused if peak stress is beyond the strength which is permitted for infrared materials. Therefore, limits to design of windows thickness is proposed in this paper.
332
作者: Jong Woong Kim, Hyun Suk Chun, Sang Su Ha, Jong Hyuck Chae, Jin Ho Joo, Young Eui Shin, Seung Boo Jung
摘要: Board-level reliability of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu solder joints was evaluated using thermal shock testing. In the microstructural investigation of the solder joints, the formation of Cu6Sn5 intermetallic compound (IMC) layer was observed between both solders and Cu lead frame, but any crack or newly introduced defect cannot be found even after 2000 cycles of thermal shocks. Shear test of the multi layer ceramic capacitor (MLCC) joints were also conducted to investigate the effect of microstructural variations on the bonding strength of the solder joints. Shear forces of the both solder joints decreased with increasing thermal shock cycles. The reason to the decrease in shear force was discussed with fracture surfaces of the shear tested solder joints.
633
作者: Teodoro Valente, Cecilia Bartuli, Giovanni Pulci
摘要: Next generation of reusable launch vehicles and new hypersonic space vehicle concepts are currently under development, moving from traditional aerodynamic configuration towards slender profiles. Main expected benefits are reduction of drag, enhancement in lift-to-drag ratio and reduction of interferences with radio frequency transmissions during the re-entry. Flexibility in designing sharp profiles is strictly conditioned to the availability of suitable materials and processing technologies, required to fabricate components and surfaces able to withstand higher heat fluxes induced by the new profiles. Advances in the field of CMC's for high temperature structures and TPS are the basis for innovative approaches to the design of future RLV's. Beside baseline solutions, already available and well characterized, as for C/SiC CMC's, ultra high temperature ceramics seem to offer the right chance to fabricate hot structures having the required heat-resistant and load carrying capabilities. This paper deals with technologies based on the use of diboride based CMC's which can be considered promising candidate materials for the fabrication of hot structures of slender bodies, such as nose cap and wing leading edges. Recent experimental results will be presented and discussed.
1505
作者: Sun Hui Yao, Yan Liang Su, Hung Yu Shu, Chia I Lee, Zong Ling You
摘要: This paper reports a comparative study on characterization and thermal shock behavior of air plasma sprayed Al2O3-13wt.%TiO2 coatings using two kinds of raw materials, i.e. nanostructural and micro-structural (traditional) feedstock powders. The characterization, before and after thermal shock test, was carried out using micro-Vickers hardness tester, XRD and SEM. The thermal shock test was carried out using a water quenching method by employing cyclic heat treatment between ambient temperature and 650°C in air. The results showed that in spite of having denser structure, the nanostructural coating showed hardness a little lower than the traditional one at both conditions of before and after thermal shock tests. However, the nanostructural coating showed very good thermal shock behaviour.
103
作者: Chang Rong Chen, Yan Wang, Heng An Ou
摘要: Die casting is a cost-efficient method of forming geometrically complex near net-shaped products with close tolerances and excellent surface finishes.Due to the thermal shock characteristics, a number of test methods have been proposed to understand thermal fatigue behaviours of the die material as real die casting dies experience.This study reveals the differences of these methods by numerical modelling the thermal behaviour of the test specimen. Simplified die casting process is firstlyproposed to facilitate numerical computation. Test specimens are then optimized to be more representative of a real die. From the comparison results, we can conclude that least divergence can be obtained between immersion tests and induction heating based tests while furnace heating based tests would result in low thermal shock effects on the test sample.
516
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