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Time-Temperature Superposition Behavior for Accelerated Fatigue Lifetime Testing of Polycarbonate(PC)

폴리카보네이트(PC)의 가속 피로수명 시험을 위한 시간-온도 호환성

  • 김규호 (공군사관학교 교수부 기계공학과)
  • Published : 2006.08.01

Abstract

Time-temperature superposition has been studied to determine the long-term fatigue life over millions of cycles for glassy polymers. π le superposition is supposed to make an accelerated lifetime testing (ALT) technique possible. Dog-bone shaped specimens made of carbon filled Polycarbonate (PC) were tested under fatigue, based on the stress-lifetime approach (S-N curve). Fatigue-induced localized yield-like deformation is considered as the defect leading to fatigue and its evolution behavior is characterized by a modified energy activation model in which temperature is considered as fatigue acceleration factor. This model allows the reduced time concept to account for effects of different temperature in short-term fatigue data to determine long-term fatigue life through the use of time-temperature superposition that is applicable under a low frequency and isothermal conditions. The experimental results validated that the proposed technique could be a possible method for accelerated lifetime testing (ALT) of time-dependent polymeric materials.

Keywords

Accelerated Lifetime Testing;Time-Temperature Superposition;Shift Factor;Polymer;S-N Curve

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