تحلیل تجربی رفتار رچتینگ لوله پلی‌استال تحت بارگذاری متناوب تک محوره و فشار داخلی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استاد، دانشکده مهندسی، دانشگاه فردوسی مشهد

2 کارشناسی ارشد، دانشکده مهندسی مکانیک، دانشگاه صنعتی شاهرود

چکیده

 
 
چکیده
 در این مقاله آزمایش­هایی تجربی به منظور تحلیل رفتار رچتینگ ماده پلی­استال تحت بارگذاری متناوب تک محوره و فشار داخلی طراحی و انجام شد. آزمایش­های تجربی در این تحقیق به­وسیله یک دستگاه پیشرفته سروهیدرولیکی انجام شده و اثر دامنه تنش، تنش میانگین و فشار داخلی بر کرنش رچتینگ و رفتار نرم­شوندگی یک لوله از جنس پلی­استال بررسی شد. یک عامل سخت­شوندگی مناسب معرفی شد و نسبت عمر خستگی ماده پلی­استال با آن مورد بررسی قرار گرفت. در یک سیکل بارگذاری معین برای نمونه­ای که عامل سخت­شوندگی آن بزرگتر باشد، عمر خستگی کمتری مشاهده شد. نرم­شوندگی ماده با افزایش تعداد سیکل بارگذاری بیشتر می­شود. نتایج نشان می­دهند نمونه­ای که مقدار کرنش رچتینگ بیشتری دارد، عمر خستگی کمتری دارد

کلیدواژه‌ها


عنوان مقاله [English]

An Experimental Study on Ratcheting Behavior of Polyacetal Tube Under Uniaxial Ioading and Internal Pressure

نویسندگان [English]

  • Mahmoud Shariati 1
  • Javad Yazdannejad 2
چکیده [English]

In this study, the experimental tests are designed and carried out to analyze the behavior of polyacetal ratcheting under both uniaxial loading and internal pressure. Experimental tests are performed by an accurate servo-hydraulic machine, Instron 8802. Three group tests were presented in which two of the stress amplitude, mean stress or internal pressure was constant to observe the effect of another factor. The effect of stress amplitude, mean stress and internal pressure on ratcheting strain and softening behavior of the polyacetal tube are investigated. Graphs of ratcheting strain, ratcheting strain range, hysteresis loops of group tests were drawn. By using these graphs, some results such as softening behavior obtained. A suitable hardening factor was presented and its relation with the polyacetal fatigue life was examined. In a specific loading cycle for the specimen, whose hardening factor is more than the others, a lower fatigue life predicted. Softening behavior of the material, increases with increasing the loading cycles. The results show that the specimen with the high ratcheting strain value has lower fatigue life.

کلیدواژه‌ها [English]

  • Ratcheting Strain
  • Polyacetal
  • Internal pressure
  • Experimental test
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