• 제목/요약/키워드: Thermal Crack

검색결과 736건 처리시간 0.029초

Synthesis of Epoxy Functional Siloxane and its Effect on Thermal Stress

  • Hyun, Dae-Sup;Jeong, Noh-Hee
    • 한국응용과학기술학회지
    • /
    • 제26권4호
    • /
    • pp.379-384
    • /
    • 2009
  • Epoxy resin based encapsulants are widely used in semiconductor packaging applications. Epoxy resin based encapsulants are often subject to crack or delamination during the reliability test due to the thermal stress caused by high modulus nature of epoxy resins. Epoxy functional siloxanes are often added into epoxy resin to reduce the modulus so that the thermal stress can be reduced. Epoxy functional siloxanes, additives for reduced modulus, were synthesized and added into the curable epoxy resins. The modulus and the coefficient of thermal expansion (CTE) were also measured to investigate the thermal stress and to see whether the epoxy functional siloxane adversely affects the CTE or not. As a result, around 26% to 72% of thermal stress reduction was observed with no adverse effect on CTE.

원형 T분기배관 내 누설유동의 열성층화와 난류침투에 관한 전산해석적 연구 (Numerical Analysis of Thermal Stratification and Turbulence Penetration into Leaking Flow in a Circular Branch Piping)

  • 한성민;최영돈
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2003년도 춘계학술대회
    • /
    • pp.1833-1838
    • /
    • 2003
  • In the nuclear power plant, emergency core coolant system(ECCS) is furnished at reactor coolant system(RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can be occurred due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack(TFC) accident. In the present study, when the turbulence penetration occurs in the branch piping, the maximum temperature differences of fluid at the pipe cross-sections of the T-branch with thermal stratification are examine

  • PDF

고온하의 시멘트 경화체의 공극구조 (Pore Structure of Cement Matrix Exposed to High Temperatures)

  • 송훈;도정윤;소승영;소양섭
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2003년도 가을 학술발표회 논문집
    • /
    • pp.509-512
    • /
    • 2003
  • Dehydration and micro crack thermal expansion occur in cement hydrates of concrete structure heated by fire for a long time. The characteristic of concrete exposed to high temperature can be analyzed from distribution of porosity and pore size. Porosity showed a tendency to increase irrespective of specimen types. This is due to both the outbreak of collapse of gel comprising the cement and a micro crack by heating. Porosity did not affect the variety of specimen and increased with the same tendency throughout every specimen. In addition, the deteriorate of compressive strength resulted from increase in porosity

  • PDF

세라믹 Nd:YAG 레이저 매질의 균열 해석 (Analysis of Crack Behavior in a Ceramic Nd:YAG)

  • 김덕래;김병태
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
    • /
    • pp.186-186
    • /
    • 2010
  • The crack behavior in the ceramic Nd:YAG at a laser-diode end-pumped Nd:YAG ceramic laser was investigated. The fracture critical temperature difference of the ceramic Nd:YAG is about $355^{\circ}C$. The fracture of the 2 at% and the 4 at.% ceramic Nd:YAG occurred more than 14.9 W and 6.9 W pump powers, respectively, under lasing conditions.

  • PDF

강도적 불균질을 갖는 구조물의 동적하중하에서의 연성크랙 발생조건 (Criterion for ductile crack initiation with strength mismatch under dynamic loading)

  • 안규백;일본명;일본명;방한서;일본명
    • 대한용접접합학회:학술대회논문집
    • /
    • 대한용접접합학회 2003년도 추계학술발표대회 개요집
    • /
    • pp.179-181
    • /
    • 2003
  • The present study focuses on the effect of geometrical discontinuity, strength mismatch, which can elevate plastic constraint due to heterogeneous plastic straining, and loading rate on the ductile crack initiation using two-parameter criterion. Fracture initiation testing has been conducted under static and dynamic loading using circumferentially notched round-bar specimens. In order to evaluate the stress/strain state in the specimens, especially under dynamic loading, a thermal elastic-plastic dynamic finite element (FE) analysis considering the temperature rise due to plastic deformation has been carried out.

  • PDF