本文選題：矯直 + 強(qiáng)化材料　； 參考：《北京科技大學(xué)》2015年博士論文

【摘要】：輥式矯直作為修正軋后帶鋼缺陷的一道重要工序,普遍被用于消除由于外力作用、溫度變化及內(nèi)力消長而發(fā)生的彎曲或扭轉(zhuǎn)變形。輥式矯直對(duì)帶鋼控制的實(shí)質(zhì)是對(duì)其彎曲程度與內(nèi)應(yīng)力的控制,而經(jīng)典模型假設(shè)帶鋼無初始應(yīng)力,并且矯直過程不會(huì)產(chǎn)生新的殘余應(yīng)力,這對(duì)矯直過程的精確分析具有一定的局限性。本文著重研究矯直過程中的應(yīng)力演變方式,以分析計(jì)算殘余應(yīng)力與殘余曲率為核心,建立了基于解析法與數(shù)值法的強(qiáng)化材料連續(xù)矯直過程模型,并對(duì)不同矯直策略進(jìn)行了深入研究。論文得出了以下創(chuàng)新性成果： (1)利用彈塑性力學(xué)基本原理對(duì)連續(xù)彈塑性彎曲過程的應(yīng)力演變方式與規(guī)律進(jìn)行了解析。研究表明連續(xù)彈塑性彎曲過程截面應(yīng)力的演變依賴于彎曲變形歷史,從理論上證明了考慮應(yīng)力傳遞效應(yīng)影響的彈塑性彎曲分析方法更適合于連續(xù)矯直過程。在此基礎(chǔ)上對(duì)比分析了強(qiáng)化材料與理想彈塑性材料彎曲特性的差異,發(fā)現(xiàn)了強(qiáng)化材料彈塑性彎曲過程的回彈比更大,有利于其矯后保持受彎時(shí)的形態(tài)。 (2)利用應(yīng)力線性疊加原則,建立了連續(xù)矯直過程應(yīng)力分布求解模型,在此基礎(chǔ)上對(duì)不同矯直策略進(jìn)行了分析。結(jié)果表明：大變形矯直策略與小變形矯直策略相比,隨彎曲次數(shù)的增加殘余曲率在較小的范圍內(nèi)波動(dòng)。從而證明了大變形矯直策殘余曲率控制能力優(yōu)于小變形矯直策略。 (3)選取殘余曲率控制能力較優(yōu)的大變形矯直策略,提出了殘余曲率二次收斂矯直方案,并基于改進(jìn)的復(fù)合梯形積分,建立了壓彎撓度計(jì)算方法,實(shí)現(xiàn)了對(duì)矯直過程中截面力學(xué)參數(shù)與幾何缺陷同步控制的矯直工藝設(shè)定方法。 (4)利用ANSYS/LS-DYNA仿真軟件,建立了連續(xù)矯直過程有限元模型。對(duì)比數(shù)值解與解析解結(jié)果,得到截面邊部縱向加載應(yīng)力和卸載應(yīng)力偏差分別為4.1%、9.31%；同時(shí),采集現(xiàn)場實(shí)驗(yàn)矯直力數(shù)據(jù),計(jì)算得到彎矩比變化過程曲線,與解析模型計(jì)算值偏差在13%以內(nèi)。從而在數(shù)值模擬和現(xiàn)場實(shí)驗(yàn)兩方面驗(yàn)證了連續(xù)矯直過程應(yīng)力分布求解模型的正確性。
[Abstract]:Roller straightening is an important procedure to correct the defects of strip after rolling. It is widely used to eliminate the bending or torsional deformation caused by external force, temperature change and internal force change. The essence of roller straightening control of strip is to control the degree of bending and internal stress, while the classical model assumes that the strip has no initial stress, and no new residual stress will be produced in the straightening process. This is limited to the accurate analysis of straightening process. In this paper, the stress evolution mode in straightening process is studied. Based on the analysis and calculation of residual stress and residual curvature, a continuous straightening process model for strengthening materials is established based on analytical and numerical methods. Different straightening strategies are also studied. The main contributions are as follows: (1) the stress evolution mode and law of continuous elastic-plastic bending process are analyzed by using the basic principles of elastoplastic mechanics. It is shown that the evolution of cross-section stress in continuous elastic-plastic bending process depends on the history of bending deformation. It is theoretically proved that the elastic-plastic bending analysis method considering the effect of stress transfer effect is more suitable for continuous straightening process. On this basis, the difference between the flexural properties of the strengthened material and the ideal elastoplastic material is compared and analyzed. It is found that the springback ratio of the elastoplastic bending process of the strengthened material is greater than that of the ideal elastoplastic material. (2) based on the principle of linear superposition of stress, the stress distribution model of continuous straightening process is established, and the different straightening strategies are analyzed. The results show that the residual curvature fluctuates in a small range with the increase of bending times compared with the small deformation straightening strategy. It is proved that the residual curvature control ability of the large deformation straightening strategy is superior to that of the small deformation straightening strategy. (3) selecting the large deformation straightening strategy with the better residual curvature control ability, the secondary convergence correction scheme of the residual curvature is proposed. Based on the improved composite trapezoid integral, the calculation method of bending deflection is established, and the method of setting up the straightening process is realized. (4) the simulation software ANSYS / LS-DYNA is used to realize the simultaneous control of the cross-section mechanical parameters and geometric defects in the straightening process. The finite element model of continuous straightening process is established. By comparing the numerical solution with the analytical solution, the longitudinal loading stress and unloading stress deviation of the side of the section are found to be 4. 1 and 9. 31, respectively. At the same time, the field experimental straightening force data are collected and the bending moment ratio changing process curve is calculated. The deviation from the calculated value of the analytical model is less than 13%. The model of stress distribution in continuous straightening process is verified by numerical simulation and field experiment.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG333.23

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