本文選題：滯后回彈　切入點：黏彈性　出處：《北京理工大學》2015年碩士論文

【摘要】：回彈是薄板沖壓成形和管材彎曲成形過程中最難控制的缺陷。隨著現(xiàn)代化工業(yè)技術(shù)的不斷發(fā)展，高強板大量應用于汽車車身制造，管材彎曲加工技術(shù)也提出了更高要求，使回彈問題日益突出。長期以來，研究人員對回彈問題的研究局限于卸載后工件因宏觀彈性應力釋放導致的瞬時回彈，，忽略了工件形狀隨時間變化的滯后回彈現(xiàn)象。 滯后回彈作為一個尚未被認知的現(xiàn)象，已引起國際塑性領(lǐng)域的關(guān)注。從目前研究看來，滯后回彈現(xiàn)象主要存在于汽車用高強板和航空航天用不銹鋼管1Cr18Ni9Ti的彎曲變成形回彈中。本文以金屬板材和管材彎曲成形回彈問題為背景，針對其滯后回彈行為，采用實驗研究、理論建模以及數(shù)值分析相結(jié)合的手段展開了深入研究，主要工作包括以下幾個方面： （1）根據(jù)各向同性空間的Wiechert機械模型假設(shè)和相關(guān)黏彈性理論，建立了金屬變形滯后回彈的本構(gòu)模型，基于有限元方法對本構(gòu)模型進行離散化，獲得了三維本構(gòu)模型的應力-時間增量形式和能量更新形式，采用Fortran語言編制程序，在ABAQUS有限元軟件中實現(xiàn)了本構(gòu)模型的UMAT二次開發(fā)； （2）進行拉伸實驗和不同應變水平下的松弛，獲得了汽車用鋁合金板材AC170PX、航空航天用不銹鋼管1Cr18Ni9Ti的力學性能參數(shù)和黏彈性參數(shù)，為有限元模擬提供必需的材料常數(shù)； （3）針對實際AC170PX板材三點彎曲實驗和1Cr18Ni9Ti管材回轉(zhuǎn)牽引彎曲實驗，建立了與之條件相符合的有限元模型進行有限元模擬，并在滯后回彈模擬中調(diào)用所編寫的UMAT子程序進行數(shù)值計算，對比模擬結(jié)果和實驗結(jié)果，驗證了所建本構(gòu)模型的準確性和可靠性，總結(jié)了板材、管材彎曲滯后回彈規(guī)律； （4）結(jié)合理論板材彎曲理論和有限元模擬結(jié)果，從殘余應力的角度解釋了板材彎曲滯后回彈現(xiàn)象的誘因。 通過本文研究，建立了金屬彎曲滯后回彈的本構(gòu)模型及數(shù)值計算方法，探討了金屬變形滯后回彈規(guī)律及起因，為金屬變形滯后回彈現(xiàn)象研究提供了有效手段。
[Abstract]:Springback is a sheet metal stamping and bending defect is the most difficult in the process of forming control. With the development of modern industrial technology, high-strength steel is widely applied in automobile body manufacturing, pipe bending processing technology also put forward higher requirements, the springback problem becomes increasingly prominent. For a long time, the research on Springback problem researchers confined to uninstall after the workpiece due to macroscopic elastic stress release caused by ignoring the instantaneous resilience, the workpiece shape changes with time lag rebound phenomenon.
As a rebound lag has not been a cognitive phenomenon, has attracted international attention in the field of plastic. It seems from the current study, lag rebound phenomenon mainly exists in the car with high strength into bending plate and aerospace 1Cr18Ni9Ti stainless steel pipe shape. The springback of sheet metal bending and springback problems as the background, according to the experimental study on the hysteretic rebound behavior, theoretical modeling and numerical analysis method of combining in-depth study, the main work includes the following aspects:
(1) under the assumption that the Wiechert mechanical model of isotropic space and viscoelastic theory, has established the metal deformation hysteresis springback constitutive model, finite element method based on the constitutive model of discrete, three-dimensional constitutive model of stress time and energy increment update form obtained by Fortran program in the ABAQUS finite element software, the constitutive model of UMAT to develop two times;
(2) relaxation and tensile experiments under different strain levels, obtained by AC170PX Aluminum Alloy 1Cr18Ni9Ti tube with stainless steel sheets for automotive, aerospace mechanical properties and viscoelastic parameters, provides the material constants required for finite element simulation;
(3) according to the actual AC170PX plate three point bending test and 1Cr18Ni9Ti rotary drawing tube bending experiments, the finite element model is established in accordance with the conditions of finite element simulation, numerical calculation and call a lag in the springback simulation written in the UMAT subroutine, comparing the simulation results and experimental results verified the constitutive the accuracy and reliability of the model, summed up the plate, tube bending springback lag;
(4) according to the theory of plate bending theory and finite element simulation results, the residual stress explained cause sheet bending springback lag.
Through this research, has established the metal bending hysteresis springback constitutive model and numerical calculation method of metal deformation hysteresis springback and causes, provides an effective method for springback research lags behind the metal to deform.

【學位授予單位】：北京理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG386

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