本文係探討局部尖銳凹槽SUS304不鏽鋼管在循環彎曲負載下的黏塑性力學行為及皺曲破壞。其中的尖銳凹槽深度為0.2、0.4、0.6、0.8及1.0 mm，而所控制的曲度率分別為0.35、0.035及0.0035 m-1s-1。由實驗結果得知，在曲度控制循環彎曲負載時，SUS304不鏽鋼管皆有循環硬化的現象，而經過幾個循環圈數後彎矩-曲度迴圈會呈穩定的狀態，且在較高曲度率時，其彎矩值也較大。此外，凹槽深度對彎矩-曲度關係幾乎沒有影響。至於橢圓化-曲度關係隨循環圈數增加而呈棘齒狀成長，在局部尖銳凹槽深度越大時，不僅橢圓化變化量越大，並呈現不對稱的趨勢將越明顯，且在越高曲度率時，其橢圓化變化量會越增加。
實驗結果顯示，雖然有五種局部尖銳凹槽的深度及三種曲度率，但在雙對數座標的控制曲度-循環至皺曲圈數關係上卻皆呈現幾乎平行的直線。最後，本文提出理論方程式來描述在不同的曲度率控制下，不同局部尖銳凹槽深度圓管承受循環彎曲負載的控制曲度-循環至皺曲圈數關係。在與實驗結果比較後發現，方程式能夠合理描述實驗結果。

In this study, the viscoplastic mechanical behavior and bulking failure of local sharp-notched SUS304 stainless steel tubes are discussed. The local sharp-notch depths include 0.2, 0.4, 0.6, 0.8 and 1.0 mm and und different curvature-rates include 0.35, 0.035 and 0.0035 m-1s-1. From experimental result, the moment-curvature curve that the SUS304 stainless steel tube exhibits cyclic hardening and becomes steady after a few cycles. Higher curvature-rate leads to higher moment. In addition, the notch depth doesn't have any influence on the moment-curvature relationship. As for the ovalization-curvature relationship, when the number of cycles increases, it appears the ratcheting manner. Higher depth leads to more higher and unsymmetrical ovalization- curvature relationship. Higher curvature-rate causes higher ovalization. Although five different local sharp-notched depths and three different curvature-rates are tested, but almost parallel straight lines can be seen for the relationship between the controlled curvature and number of cycles to produce buckling on the log-log scale.Finally, the theoretical equation is proposed for simulating the controlled curvature-number of cycles to produce buckling relationship for local sharp-notched circular tubes subjected to curvature-controlled symmetrical cyclic bending at the different curvature-rates. By comparing with the experimental data,the equation can properly simulate the experimental finding.

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