本文關鍵詞： 板料成形 各向異性 厚向應力 成形極限 本構方程 屈服準則　出處：《北方工業(yè)大學》2017年碩士論文　論文類型：學位論文

【摘要】：板料成形具有非常悠久的歷史,在制造行業(yè)中占據(jù)著十分重要的地位,是很多加工工藝所無法替代的。板料的變形過程是一個十分復雜的過程,傳統(tǒng)加工中的經(jīng)驗模式已經(jīng)不能夠適應發(fā)展越來越快的成形工藝,為了描述板料的復雜變形過程,需要建立起堅實的理論來指導加工中的板料成形過程,避免造成不要的損失。板料成形工藝所采用的材料,是經(jīng)過多次軋制生產(chǎn)加工而成的,有些板料具有明顯的各向異性,在研究這些板料的成形性能時,需要考慮板料的各向異性對屈服準則選擇的影響。在研究板料成形過程時選用屈服準則要有針對性,針對不同的材料選用不同的屈服準則。對于適用的屈服準則在使用的時候也需要根據(jù)具體的材料對屈服準則進行修正。此外板料在成形過程中是處于復雜應力狀態(tài)下的,不是簡單的平面應力狀態(tài),還受到厚度方向的應力作用,因而在研究板料的變形時將厚度方向應力納入屈服準則與成形極限的研究是迫切需要的。本文主要以鈦合金為研究對象,通過單向拉伸實驗、成形極限實驗,對描述平面內各向異性的屈服準則進行修改。本文通過有實驗獲取4種不同厚度的鈦合金的基本力學性能參數(shù),進行有限元模型的仿真模擬,確認了厚度方向應力在板料成形過程中發(fā)揮著重要作用;通過進行數(shù)據(jù)的擬合處理,建立了更為合理的本構模型,并且通過有限元模擬驗證了本構模型的適用性;從實驗數(shù)據(jù)發(fā)現(xiàn)鈦合金材料具有明顯的平面內的各向異性,通過對Yld2000-2d屈服準則修改,更好的描述板料的平面內的各向異性;將厚向應力引入到屈服準則中,基于改進后的屈服準則和M-K失穩(wěn)準則,對成形極限進行了理論推導,并且通過實驗驗證,考慮厚向應力時推導出的理論成形極限圖與實驗更相符。
[Abstract]:Sheet metal forming has a very long history, occupies a very important position in the manufacturing industry, which can not be replaced by many processing processes. The sheet metal deformation process is a very complex process. The traditional experience mode can not adapt to the rapid development of forming process. In order to describe the complex deformation process of sheet metal, it is necessary to establish a solid theory to guide the sheet metal forming process. The material used in sheet metal forming process is produced by rolling many times, some sheet metal have obvious anisotropy, when studying the forming property of these sheet metal. The influence of anisotropy of sheet metal on the selection of yield criterion should be considered. For different materials, different yield criteria should be selected. The applicable yield criteria should also be modified according to the specific materials. In addition, the sheet metal is in the complex stress state during the forming process. In a state. It is not a simple plane stress state, but also subjected to the stress in the thickness direction. Therefore, it is urgent to study the thickness direction stress into the yield criterion and forming limit when studying the deformation of sheet metal. In this paper, we mainly take titanium alloy as the research object, through uniaxial tensile test, forming limit experiment. The yield criterion describing anisotropy in plane is modified. In this paper, the basic mechanical properties of four titanium alloys with different thickness are obtained by experiments, and the simulation of finite element model is carried out. The thickness direction stress plays an important role in sheet metal forming. A more reasonable constitutive model is established by fitting the data, and the applicability of the constitutive model is verified by finite element simulation. From the experimental data, it is found that titanium alloy material has obvious anisotropy in the plane. By modifying the Yld2000-2d yield criterion, the anisotropy in the plane of the sheet metal can be better described. The thick stress is introduced into the yield criterion. Based on the improved yield criterion and M-K instability criterion, the forming limit is derived theoretically and verified by experiments. The theoretical forming limit diagram derived when considering the thick stress is in good agreement with the experiment.
【學位授予單位】：北方工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG301

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本文編號：1444025