• Title/Summary/Keyword: Thermal mechanical 1 test

Search Result 445, Processing Time 0.022 seconds

Thermal Fatigue Test of an Annular Structure

  • Hwang Jeong-Ki;Suh Chang-Min;Kim Chae-Ho
    • Journal of Mechanical Science and Technology
    • /
    • v.20 no.1
    • /
    • pp.59-65
    • /
    • 2006
  • A half-scaled large test model for the main components of the real annular structure was built and the thermal behaviors were experimented and obtained by thermal cyclic loads. The model design and the test conditions for the thermal loads were determined to take into consideration the thermal and mechanical loads acting on the real annular structure by finite element analyses. Temperature profiles and strains of the main components of the model were measured at an early stage of the test and periodically throughout the test in the given test conditions. After completion of the thermal cyclic tests, no evidence of crack initiation and propagation were identified by a dye penetration test. The measured strains at the critical parts were slightly increased proportionally with the increase in the number of the thermal cycles.

A Study on The Degradation Characteristics of MLCCs SAC305 Lead-Free Solder Joints and Growth IMCs by Thermal Shock Test (열충격 시험을 통한 MLCCs SAC305 무연 솔더 접합부의 IMCs 성장과 접합특성 저하에 관한 연구)

  • Jung, Sang-Won;Kang, Min-Soo;Jeon, Yu-Jae;Kim, Do-Seok;Shin, Young-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.29 no.3
    • /
    • pp.152-158
    • /
    • 2016
  • The bonding characteristics of MLCCs (multi layer ceramic capacitor, C1608) lead-free solder (SAC305) joints were evaluated through thermal shock test ($-40^{\circ}C{\sim}125^{\circ}C$, total 1,800 cycle). After the test, IMCs( intermetallic compounds) growth and cracks were verified, also shear strengths were measured for degradation of solder joints. In addition, The thermal stress distributions at solder joints were analyzed to compare the solder joints changes before and after according to thermal shock test by FEA (finite elements analysis). We considered the effects of IMCs growth at solder joints. As results, the bonding characteristics degradation was occurred according to initial crack, crack propagations and thermal stress concentration at solder-IMCs interface, when the IMCs grown to solder inside.

Thermal Shock Resistance of Bilayered YSZ Thermal Barrier Coating

  • Lee, Dong Heon;Kim, Tae Woo;Lee, Kee Sung;Kim, Chul
    • Journal of the Korean Ceramic Society
    • /
    • v.55 no.5
    • /
    • pp.452-460
    • /
    • 2018
  • This study investigate changes in mechanical behaviors such as indentation load-displacement and hardness of thermal barrier coatings (TBCs) using cycling of thermal shock test. Relatively dense and porous TBCs on nickel-based bondcoat/super alloy are prepared using different starting granules, 204C-NS and 204NS commercial powers, and the effect of double layers of 204C-NS on 204NS and 204NS on 204C-NS are investigated. The highest temperature applied during thermal shock test is $1100^{\circ}C$ and the maximum number of cycles is 1,200. The results indicate that bilayered TBC showed a relatively mechanically resistant property during thermal shock cycles and that the mechanical behavior is influenced by the microstructure of TBCs by exposure to high temperature during tests or different starting granules.

Electric Degradation of Failure Mode of Solar Cell by Thermal Shock Test (열충격 시험 후 태양전지 파괴 모드에 따른 전기적 특성변화)

  • Kang, Min-Soo;Jeon, Yu-Jae;Shin, Young-Eui
    • Journal of Energy Engineering
    • /
    • v.22 no.4
    • /
    • pp.327-332
    • /
    • 2013
  • 일본 연구에서는 열충격 시험을 통한 태양전지의 파괴모드에 따른 전기적 특성을 분석하였다. 시편은 Photovoltaic Module을 만들기 전 3 line Ribbon을 Tabbing한 단결정 Solar Cell을 제작하였다. 열충격 시험 Test 1의 온도조건은 저온 $-40^{\circ}C$, 고온 $85^{\circ}C$, Test 2는 저온 $-40^{\circ}C$, 고온 $120^{\circ}C$에서 Ramping Time을 포함하여 각각 15분씩, 총 30분을 1사이클로 500사이클을 각각의 조건으로 수행하였다. 열충격 시험 후 Test 1에서는 4.0%의 효율 감소율과 1.5%의 Fill Factor 감소율을 확인하였으며, Test 2에서는 24.5%의 효율 감소율과 11.8%의 Fill Factor 감소율을 확인하였다. EL(Electroluminescence)촬영 및 단면을 분석한 결과, Test 1과 Test 2 시편 모두 Cell 표면 및 내부에서의 Crack이 발견되었다. 하지만, Test 2의 시험이 Test 1보다 가혹한 온도조건의 시험으로 인해 Test 1에서 나타나지 않았던, Cell 파괴를 Test 2에서 확인하였다. 결국, Test 1에서 효율의 직접적인 감소 원인은 Cell 내부에서의 Crack이며, Test 2에서는 Cell 내부에서의 Crack 및 Cell 파괴로 인한 Cell 자체의 성능저하로 효율이 크게 감소한다는 것을 본 실험을 통하여 규명하였다.

A Study on the Mechanical Strength Change by Thermal Aging of 2.25Cr-1Mo Steel (발전설비용 2.25Cr-1Mo 강의 시효에 의한 기계적 강도 특성 변화에 대한 연구)

  • Yang, Hyeon-Tae;Kim, Sang-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.7 s.178
    • /
    • pp.1771-1778
    • /
    • 2000
  • The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature for the extended periods. Original, aged artificiall y and used material were tested to obtain the tensile strength, hardness and impact absorbed energy. Tensile strength, hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

Study on Performance and Aging Test of Porcelain Insulators for Transmission Line (송전용 자기재 애자의 성능평가 및 가속열화시험)

  • 한세원;조한구;박기호;이동일;최인혁
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.16 no.9
    • /
    • pp.842-850
    • /
    • 2003
  • The suspension insulators are subjected to harsh environments in service for a long time. The long-term reliability of tile insulators is required for both mechanical and electrical performances. This study describes some basic performance tests and accelerated aging test by cool-heat cycling methods and thermal mechanical performance test methods on alumina porcelain insulators (new and aged) used for transmission line in KOREA. There was no fail in electrical and mechanical performance tests such as a high voltage strength, a flashover voltage, and an impact strength in all samples. But in the case of accelerating aging tests which have above 9$0^{\circ}C$ temperature gradient, fracture phenomena was happened by a thermal shock in tile aged sample(sample A) with low alumina porcelain body. It was indicated that sample A was more severely aged than other samples. According to results of HRB test and microstructural analysis, it was reasoned that insulator bodies with the matrix reinforced with alumina crystalline phase have advantages over the suppression of crack advance. And cool-heat aging and mechanical thermal ageing tests shows that a temperature gradient is more effective to accelerating than a cycling number.

Thermal Shock Tests and Thermal Shock Parameters for Ceramics

  • Awaji, Hideo;Choi, Seong-Min
    • Journal of the Korean Ceramic Society
    • /
    • v.49 no.4
    • /
    • pp.385-396
    • /
    • 2012
  • Thermal shock test methods and thermal shock parameters for ceramics were reviewed from the following viewpoints: (1) The test methods should be based on the precise estimation of both temperature and thermal stress distributions in a specimen taking into account the temperature-dependent thermo-mechanical properties; (2) The thermal shock parameters must be defined as a physical property of the materials and described as a function of temperature at the fracture point of the specimen; (3) The relation between the strength and fracture toughness of brittle ceramics under a thermal shock load must be the same as the relation under a mechanical load. In addition, appropriate thermal shock parameters should be defined by the thermal shock strength and thermal shock fracture toughness based on stress and energy criteria, respectively. A constant heat flux method is introduced as a testing technique suitable for estimating these thermal shock parameters directly from the electric power charged.

Cryogenic Fracture Toughness Evaluation for Austenitic Stainless Steels by Means of Unloading Compliance Method

  • Yu, Hyo-Sun;Kwon, Il-Hyun
    • Journal of Mechanical Science and Technology
    • /
    • v.15 no.1
    • /
    • pp.26-34
    • /
    • 2001
  • Most research to date concerning the cryogenic toughness of austenitic stainless steels has concentrated on the base metal and weld metal in weldments. The most severe problem faced on the conventional austenitic stainless steel is the thermal aging degradation such as sensitization and carbide induced embrittlement. In this paper, we investigate the cryogenic toughness degradation which can be occurred for austenitic stainless in welding. The test materials are austenitic stainless JN1, JJ1 and JK2 steels, which are materials recently developed for use in nuclear fusion apparatus at cryogenic temperature. The small punch(SP) test was conducted to detect similar isothermally aging condition with material degradation occurred in service welding. The single-specimen unloading compliance method was used to determine toughness degradation caused by thermal aging for austenitic stainless steels. In addition, we have investigated size effect on fracture toughness by using 20% side-grooved 0.5TCT specimens.

  • PDF

Thermal-Mechanical and Low Cycle Fatigue Characteristics of 12Cr Heat Resisting Steel with Hold Time Effects (유지시간 효과를 고려한 12Cr 내열강의 열피로 및 저주기 피로 특성)

  • Ha, J.S.;Koh, S.K.;Ong, J.W.
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.3 no.1
    • /
    • pp.1-12
    • /
    • 1995
  • Isothermal and thermal-mechanical fatigue characteristics of 12Cr heat resisting steel used for high temperature applications were investigated including hold time effects. Isothermal low cycle fatigue test at $600^{\circ}C$ and in-phase, out-of-phase thermal-mechanical fatigue test at 350 to $600^{\circ}C$ were conducted using smooth cylindrical hollow specimen under strain-control with total strain ranges from 0.006 to 0.015. Regardless of thermal-mechanical and isothermal fatigue tests, cyclic softening behavior was observed and much more pronounced in the thermal-mechanical fatigue tests with hold times due to the stress relaxation during the hold time. The phase difference between temperature and strain in thermal-mechanical fatigue tests resulted in significantly shorter fatigue life for out-of-phase compared to in-phase. The differences in fatigue lives were dependent upon the magnitudes of plastic strain ranges and mean stresses. During the hold time in the strain-controlled fatigue tests, the increase in the plastic strain range and the stress relaxation were observed. It appeared that the increase in plastic strain range per cycle and the introduction of creep damage made important contributions to the reduction of thermal-mechanical fatigue life with hold time, and the life reduction tendency was more remarkable in the in-phase than in the out-of-phase thermal-mechanical fatigue. Isothermal fatigue tests performed under the combination of fast and slow strain rates at $600^{\circ}C$ showed that the fatigue life decreased as the strain rate and frequency decreased,especially for the low strain ranges.

  • PDF

Changes in the Mechanical Behavior of Thermal Barrier Coatings Caused by Thermal Shock (열충격에 의한 열차폐 코팅재의 기계적 거동 변화)

  • Jang, Bin;Lee, Kee Sung;Kim, Tae Woo;Kim, Chul
    • Korean Journal of Materials Research
    • /
    • v.27 no.1
    • /
    • pp.25-31
    • /
    • 2017
  • This study investigates changes in the mechanical behaviors, especially hardness and indentation load-displacement curves, of thermal barrier coatings (TBCs) brought about by thermal shock. The TBCs on the Nickel-based bondcoat/superalloy was prepared with diameters of 25.4 mm and $600{\mu}m$ thickness. The results of thermal shock cycling test from $1100^{\circ}C$ of the highest temperature indicate that the thermal shock do not influence on the mechanical behavior, but a continuous decrease in porosity and increase in hardness were observed after 1200 thermal shock cycles; these changes are believed to be due to sintering of thermal barrier coating materials. The results that no degradation in the indentation load-displacement curves indicate that the coating shows good thermal shock resistance up to 1200 cycles at $1100^{\circ}C$ in air.