نوع مقاله: مقاله پژوهشی

نویسندگان

1 کارشناس ارشد، مهندسی مکانیک، دانشگاه صنعتی امیرکبیر، تهران، ایران

2 استادیار، پژوهشکده فناوری‌های نو، دانشگاه صنعتی امیرکبیر، تهران، ایران

3 دانشیار، مهندسی مکانیک، دانشگاه صنعتی امیرکبیر، تهران، ایران

چکیده

در این مقاله تماس لغزشی دوبعدی یک پانچ صلب استوانه‌ای روی یک سطح نیمه بی‌نهایت ساخته شده از مواد هدفمند در حضور و عدم حضور یک ترک سطحی بررسی شده است. مدول الاستیسیته در لایه هدفمند طبق مدل تی-تی-او محاسبه شده است. این مدل با تعریف پارامتر q، تاثیر برهم‌کنش‌های ریزساختارها را نیز در نظر می‌گیرد. برای حل معادلات حاکم از کد نویسی روش تفاضلات محدود در نرم‌افزار متلب استفاده شده است. اثر ناهمگنی، q، شعاع پانچ، ضخامت لایه هدفمند و ضریب اصطکاک بر نمودار نیرو – جابه‌جایی، تنش‌های ایجاد شده و ضرایب شدت تنش مود اول و دوم بررسی شده است. نتایج به‌دست آمده نشان می‌دهد که افزایش ضخامت لایه هدفمند، شعاع پانچ و ضریب ناهمگنی(r) برای جابه‌جایی‌های یکسان پانچ افزایش نیروی تماس را در پی دارد. همچنین تغییرات این پارامترها بر توزیع تنش فشاری زیر پانچ موثر است. اما تغییرات q تاثیری بر نیروی تماس و نیز توزیع تنش فشاری ندارد. در تماس بدون اصطکاک ضریب شدت تنش مود اول همواره نامثبت است و ترک تمایلی به رشد تحت این مود ندارد. افزایش ضریب اصطکاک، ضریب شدت تنش مود اول را افزایش می‌دهد؛ اما موجب کاهش ضریب شدت تنش مود دوم می‌شود.

کلیدواژه‌ها

عنوان مقاله [English]

Sliding contact between a rigid cylindrical punch and a functionally graded semi-infinite medium in the presence of a surface crack

نویسندگان [English]

  • Ali Talezadehlari 1
  • Ali Nikbakht 2
  • Mojtaba Sadighi 3

1 Department of Mechanical Engineering, Amirkabir University, Tehran, Iran

2 New Technologies Research Center, Amirkabir University, Tehran, Iran

3 Department of Mechanical Engineering, Amirkabir University, Tehran, Iran

چکیده [English]

In this article two dimensional sliding contact of a rigid cylindrical punch on a functionally graded (FG) semi-infinite medium is studied. The modulus of elasticity in the graded layer is calculated based on TTO model approximation. This model defines a parameter q which considers the microstructural interactions between the constituting phases. The governing equations are solved by finite difference (FD) method by means of MATLAB software. The effects of different parameters such as non-homogeneity­, q, the dimensions of the punch, the thickness of the graded layer and the coefficient of friction are investigated on the force-displacement diagram of the punch, stress distribution and modes I and II stress intensify factors (KI and KII). The results show that the contact force and the stress distribution under the punch are affected by the thickness of the graded layer, radius of the punch and the non-homogeneity­ coefficient. But the variation of q has no effects on the contact force and the stress distribution under the punch. In the absence of the friction, KI is always non-positive and the crack has no tendency to grow under this mode. Increasing the friction coefficient, increases KI but decreases KII.

کلیدواژه‌ها [English]

  • Contact
  • Rigid cylindrical punch
  • Stress intensity factor Functionally graded material (FGM)
  • Finite difference (FD)

 

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