本文選題：帶筋管 + 充液壓形　； 參考：《哈爾濱工業(yè)大學》2017年碩士論文

【摘要】：隨著科學技術的進步和制造行業(yè)的高速發(fā)展,航空航天、武器裝備等領域迫切需要通過減輕結構質量來實現(xiàn)輕量化,而輕量化對于節(jié)約能源、環(huán)境保護、提高機動性能等方面發(fā)揮著不可替代的作用。其中帶環(huán)向加強筋的薄壁筒形件是一種比較常用的輕量化結構構件。但是由于其封閉截面形式、壁厚薄、截面復雜、尺寸大等要求帶來一系列難題。目前的成形工藝都不能很好的解決這些問題,特別是對于整體成形。本文提出了一種新的成形工藝,將充液壓形技術應用到成形帶筋管中,實現(xiàn)了帶筋管的整體成形。主要通過數(shù)值模擬結合實驗對帶筋管的成形規(guī)律進行研究,并對在成形過程中產(chǎn)生的缺陷和不足等進行力學分析。本文證實了帶筋管應用充液壓形技術整體成形的可行性。帶筋管變形的實質是曲率的變化,這里設計了三種截面形狀包括橢圓截面、半橢圓截面和矩形截面,通過數(shù)值模擬結合實驗的方法,證明了帶筋管應用充液壓形技術成形的可行性。而且對三種截面形狀的任意組合,也進一步證明了充液壓形技術可以成形出復雜截面形狀的制件。分析了帶筋管在充液壓形過程中的內(nèi)壓加載范圍和內(nèi)壓加載方式。恒壓加載路徑下,充液壓形件的材料填充性好、壁厚分布不均勻,應力波動大;線性加載路徑下,充液壓形件的材料填充性不好、壁厚分布均勻,應力波動小。根據(jù)大型薄壁帶筋構件的需求選擇線性加載方式。對帶筋管在成形過程中產(chǎn)生的缺陷進行探討分析。失穩(wěn)主要分為三種類型:筋板傾倒、筋板失穩(wěn)起皺以及薄壁管(無筋處)塌陷。傾倒主要發(fā)生在曲率增大處,失穩(wěn)主要發(fā)生在曲率減小處,而塌陷主要發(fā)生在曲率為零的直壁段。對三種缺陷分別進行受力分析,失穩(wěn)起皺和薄壁管塌陷的產(chǎn)生主要是因為當變形達到一定的變形量時,筋板或者薄壁管所受的環(huán)向應力大于其臨界失穩(wěn)應力,就會發(fā)生失穩(wěn)缺陷。傾倒缺陷產(chǎn)生的原因主要是圓角處上下筋板所受的環(huán)向應力不均勻,進而產(chǎn)生了彎矩,當彎矩增加到一定程度會發(fā)生失穩(wěn)傾倒的現(xiàn)象。對帶筋管充液壓形工藝中產(chǎn)生變形不協(xié)調現(xiàn)象進行理論分析。得出結論:成形件的筋板最外側壁厚在直壁段增厚,圓角處減薄;筋板最內(nèi)側壁厚在直壁段減薄,圓角處增厚。薄壁管壁厚不發(fā)生變化。導致圓角處筋板內(nèi)側周長小于薄壁管處周長,產(chǎn)生“收腰”現(xiàn)象。模擬和理論分析得到的結論基本一致。分析了高厚比、摩擦系數(shù)、內(nèi)壓和回彈等對帶筋管成形極限的影響。當高厚比的范圍為0"fh/t㩳6時,可以成形。由于摩擦力的作用,上圓角大于下圓角填充速度。摩擦系數(shù)越大,壁厚差越大,成形極限下降。有內(nèi)壓的加載明顯提高帶筋管的成形極限�；貜棇Ы罟艹尚螛O限影響很小,可以近似忽略。
[Abstract]:With the progress of science and technology and the rapid development of manufacturing industry, aerospace, weaponry and other fields urgently need to reduce the quality of structure to achieve lightweight, and lightweight for energy conservation, environmental protection, Improving maneuverability plays an irreplaceable role. The thin-walled cylindrical part with circumferential stiffener is a kind of light-weight structural member in common use. However, due to its closed section form, thin wall, complex section and large size, it brings a series of difficulties. The current forming process can not solve these problems well, especially for the whole forming. In this paper, a new forming technology is proposed, which is applied to the forming of stiffened tube, and the integral forming of the stiffened tube is realized. In this paper, the forming law of the stiffened tube is studied by numerical simulation and experiment, and the defects and defects in the forming process are analyzed. In this paper, the feasibility of integral forming of stiffened pipe by hydraulic filling technique is confirmed. The essence of the deformation of stiffened tube is the change of curvature. In this paper, three kinds of cross-section including elliptical section, semi-elliptical section and rectangular section are designed, and the numerical simulation is combined with the experimental method. It is proved that it is feasible to apply hydraulic forming technology to the stiffened pipe. For any combination of three cross section shapes, it is further proved that hydraulic filling technology can form parts with complex cross section shapes. The internal pressure loading range and internal pressure loading mode of the stiffened pipe in the process of hydraulic filling are analyzed. Under the constant pressure loading path, the filling property of the hydraulic filling parts is good, the wall thickness distribution is uneven, and the stress fluctuation is large; under the linear loading path, the filling property of the hydraulic filling parts is poor, the wall thickness distribution is uniform, and the stress fluctuation is small. According to the needs of large thin-walled stiffened members, the linear loading mode is chosen. The defects in the forming process of the stiffened tube are discussed and analyzed. Instability can be divided into three types: toppling, wrinkling and collapse of thin-walled tubes. The toppling occurs mainly at the increase of curvature, the instability occurs at the point where the curvature decreases, and the collapse occurs in the straight wall with zero curvature. The stress analysis of three kinds of defects shows that the buckling and collapse of thin-walled tubes are mainly due to the fact that the circumferential stress of the stiffened plate or thin-walled tube is greater than the critical instability stress when the deformation reaches a certain deformation. There will be instability defects. The main reason for the toppling defect is that the toroidal stress of the upper and lower stiffened plates at the corner is not uniform and then the bending moment is produced. When the bending moment is increased to a certain extent the instability and toppling will occur. In this paper, the phenomenon of deformation disharmony in the hydraulic filling process of stiffened pipe is analyzed theoretically. It is concluded that the outermost wall thickness of the stiffened plate is thickened at the straight wall and the thickness of the innermost wall is thinned in the straight section and the corner is thickened at the corner. The wall thickness of thin wall pipe does not change. The inner circumference of the stiffened plate is smaller than the circumference of the thin-walled tube at the round corner, which leads to the phenomenon of "waistline". The results obtained by simulation and theoretical analysis are basically consistent. The effects of thickness ratio, friction coefficient, internal pressure and springback on the forming limit of stiffened tube are analyzed. When the ratio of height to thickness is in the range of 0 "FH / t? 6, it can be formed." Due to the effect of friction, the filling speed of the upper corner is greater than that of the lower corner. The greater the friction coefficient, the greater the wall thickness difference and the lower the forming limit. The forming limit of stiffened tube is obviously increased by loading with internal pressure. The springback has little effect on the forming limit of the stiffened tube and can be neglected approximately.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG394

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