120公厘鎳鉻鉬合金鋼管自緊應力之分析研究

鎳鉻鉬合金鋼管具有良好的降伏強度與抗拉強度，廣泛用於傳動軸、主軸、火砲等構件。因應未來國防武器自製政策，本研究乃以萊茵公司產製之120公厘鎳鉻鉬合金鋼光膛砲自緊應力分析為研究主題，探討自緊對砲管射擊應力之影響效應。研究方法採用單位應力分析法、Le Duc 方法及萊茵金屬公司（Rheinmetall）自緊應力演算法進行計算與分析。本研究先透過單位應力分析法以壁厚比建立砲管剖面研究模型，並藉由Le Duc 方法獲得膛壓速度曲線定出自緊剖面位置，再以萊茵金屬公司自緊應力演算法進行自緊應力分析，然後擷取出自緊剖面之等效預置合成應力及等效射擊應合成力。本研究最終獲得自緊對射擊應力與自緊百分比對射擊應力之影響結果；經由案例分析結果得到以下結論：(1)自緊預置應力抵消射擊應力使砲管皆處於安全範圍。(2)較合宜之自緊厚度百分比約50%至60%之間。

關鍵字

鎳鉻鉬合金鋼；自緊應力分析；單位應力分析法； Le Duc 方法；自緊應力演算法

並列摘要

Nickel-chromium-molybdenum alloy steel pipe with excellent yield point and tensile strength has been widely used in transmission shafts, spindles, guns and other components. In response to the policy of weapons made by self in the future, this study aims to use the autofrettage stress analysis on the 120 mm nickel-chromium- molybdenum alloy steel smoothbore gun manufactured by Rheinmetall and explores the effect of autofrettage influencing on the firing stress of the gun. The stress analysis method, element unit method, the Le Duc method and the Rheinmetall autofrettage stress algorithm are used for calculation and analysis. The preliminary results about autofrettage stress and thickness percentage for the specific case are as follows: (1) Obtain the effect of autofrettage on the firing stress, and the residual stress counteracts the firing stress so that the gun is in a safe range. (2) Obtain the effect of the percentage of autofrettage on the firing stress, and get a suitable autofrettage thickness percentage is about 50% to 60% after analysis.