本文利用彎管實驗機對尖銳凹槽深度分別0.2、0.4、0.6、0.8及1.0 mm的SUS304無縫不銹鋼圓管，進行單調純彎曲鬆弛行為的實驗研究。而純彎曲鬆弛係指彎曲圓管至某個曲度量後，維持該曲度量一段長時間。至於本研究純彎曲鬆弛的控制曲度分別考慮:0.05、0.1及0.15 。
實驗結果顯示，尖銳凹槽SUS304不鏽鋼圓管承受純彎曲鬆弛負載時，彎曲力矩會急速下降，而後趨於穩態，而橢圓化也會迅速增加，而後趨於穩態。最後，本文提出兩個方程式分別來描述彎矩-時間及橢圓化-控制曲度的關係。在與實驗結果比較後發現，理論分析可合理的描述實驗結果。

In this study, the tube bending machine is used to conduct the pure bending relaxation for SUS 304 stainless steel tubes with the sharp notch depths of 0.2, 0.4, 0.6, 0.8 and 1.0 mm. The pure bending relaxation is to bend the tube to a desired curvature and keep that curvature for a period of time. As for this research, the controlled curvature of the pure bending relaxation are considered to be 0.05, 0.1 and 0.15 .
It is shown from experimental data that the bending moment drops rapidly and becomes steady, and the ovalization increases rapidly and becomes steady for sharp-notched SUS 304 stainless steel tubes subjected to pure bending relaxation. Finally, two formulations are proposed for simulating the moment-time and ovalization-controlled curvature relationships. When compares with the experimental finding, the theoretical analysis can reasonably simulate the experimental data.

1.Shaw, P. K. and Kyriakides, S., 1985, “Inelastic Analysis of Thin-Walled Tubes under Cyclic Bending,” International Journal of Solids and Structures, Vol. 21, pp. 1073-1100.
2.Shaw, P. K. and Kyriakides, S. , 1987, “Inelastic Buckling of Tubes Under Cyclic Bending,” ASME, Journal of Pressure Vessel Technology, Vol. 109, pp. 169-178.
3.Ju, G. T. and Kyriakides, S., 1992, “Bifurcation Buckling Versus Limit Load Instabilities of Elastic-Plastic Tubes under Bending and External Pressure,” Journal of Offshore Mechanics and Arctic Engineering, Vol. 113, pp. 43-52.
4.Hiromasa, I. and Katsuhiko, S., 1994, “Creep, Stress Relaxation and Biaxial Ratchetting of Type 304 Stainless Steel After Cyclic Preloading,”ASME, Journal of Engineering Materials and Technology, Vol. 116, pp. 133-141.
5.Batra, R. C. and Yang, J. S. , 1995, “Saint- Venant's Principle for Linear Elastic Porous Materials,” Journal of Elasticity, Vol. 39, pp. 265-271
6.Pan, W. F., Wang, T. R. and Hsu, C. M., 1998, “A Curvature- Ovalization Measurement Apparatus for Circular Tubes under Cyclic Bending,” Experimental Mechanics, Vol. 38, No.2, pp. 99-102.
7.Pan, W. F. and Her, Y. S., 1998, “Viscoplastic Collapse of Thin-Walled Tubes under Cyclic Bending,” Journal of Engineering Materials and Technology, Vol. 120, pp. 001-004.
8.Pan, W. F. and Fan, C. H., 1998, “An Experimental Study on the Effect of Curvature-Rate at Preloading Stage on Subsequent Creep or Relaxation of Thin-Walled Tubes under Pure Bending,” JSME International Journal, Series A, Vol. 41, No.4, pp. 525-531.
9.Haque, M.N., Langrish, T. A. G., Keep, L-B. and Keey, R. B., 2000, “Model fitting for visco-elastic creep of Pinus radiata during kiln drying,” Wood science and Technology, Vol. 34, pp. 447-457.
10.Lee, K. L., Pan, W. F. and Kuo, J. N., 2001, “The Influence of the Diameter-to-Thickness Ratio on the Stability of Circular Tubes under Cyclic Bending,” International Journal of Solids and Structures, Vol.38, pp. 2401-2413.
11.Lee, K. L. and Pan, W. F., 2002, “Pure Bending Creep of SUS 304 Stainless Steel Tuber,” Steel and Composite Structures - an International Journal, Vol. 2, No.6, pp. 461-474.
12.Lee, K. L., Shie, R. F. and Chang, K. H., 2005, “Experimental and
Theoretical Investigation of the Response and Collapse of 316L Stainless Steel Tubes Subjected to Cyclic Bending,” JSME International Journal, Series A, Vol. 48, No.3, pp. 155-162 .
13.Chang, K.H., Pan, W.F. and Lee, K.L., 2008, “Mean Moment Effect
on Circular Thin-walled Tubes under Cyclic Bending,” Structural
Engineering and Mechanics - an International Journal, Vol. 28, No.5,pp. 495-514.
14.黃鈺茜，2009，「橢圓形凹槽圓管在循環彎曲負載下橢圓化和循環至皺曲圈數關係之研究」，國立成功大學工程科學研究所碩士論文。
15.翁弘杰，2011，「尖銳凹槽圓管在循環彎曲負載下平均曲度對皺曲行為影響之實驗研究」，國立成功大學工程科學研究所碩士論文。