IJE TRANSACTIONS A: Basics Vol. 26, No. 1 (January 2013) 83-90   

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M. Poursina, B. Amini, K. Hassanpour and M. Barati
( Received: March 06, 2012 – Accepted: November 15, 2012 )

Abstract    Thin-walled tube bending has common applications in the automobile and aerospace industries. The rotary-draw-bending method is a complex physical process with multi-factor interactive effects and is one of the advanced tube forming processes with high efficiency, high forming precision, low consumption and good flexibility for bending angle changes. However, it may cause a wrinkling phenomenon, over thinning and cross-section distortion if the process parameters are inappropriate. Wrinkles propagate in thin-walled tube, but in some cases, localize in a finite zone and lead to failure. Wrinkling prediction in thin-walled tube bending processes has been an important and challenging subject in the related industry. In this paper, the plastic deforming behavior and wrinkling mechanism for a thin-walled tube is simulated and the results are compared with the available experimental ones. Next, the effect of anisotropy on ovalization, thickness and wrinkling of tube is investigated using FEM. Numerical results are presented showing the effects of the various kinds of materials and geometric parameters on wrinkling using anisotropic yield function.


Keywords    Thin-walled tube, Normal Anisotropy, Wrinkling, FEM


چکیده    خمش لوله های جدار نازک، معمولا در صنایع هوافضا و ماشین سازی کاربرد دارد. فرآیند خمش کششی دورانی یکی از فرآیندهای پیچیده و پیشرفته شکل دهی فلزات با راندمان بالا بوده که پارامترهای متفاوتی بر آن حاکم می باشد. اگر پارامترهای حاکم بر این فرآیند نامناسب باشند، ممکن است عیوبی همچون چروکیدگی، نازک شدگی دیواره بیرونی و اعوجاج مقطع عرضی لوله بوجود آید. در حالت کلی چروکیدگی در لوله منتشر می شود، اما در حالت های خاص ممکن است که چروکیدگی در یک ناحیه انباشته شده و منجر به تغییر شکل های نامطلوب گردد. لذا پیش بینی چروکیدگی در فرآیند خمش لوله های جدار نازک در صنایع وابسته یک موضوع مهم و چالش انگیز می باشد. در این تحقیق، نحوه تغییر شکل پلاستیک و چروکیدگی لوله در فرآیند خمش شبیه سازی می شود و نتایج بدست آمده با نتایج موجود در مقالات مقایسه می گردد. پس از آن اثر ناهمسانگردی بر روی چروکیدگی، نازک شدگی دیواره بیرونی و اعوجاج مقطع عرضی لوله مورد بررسی قرار می گیرد.


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