發(fā)布時間：2018-04-14 11:01

  本文選題：高強(qiáng)鋁合金 + 復(fù)雜筋板構(gòu)件��； 參考：《中北大學(xué)》2015年博士論文

【摘要】：隨著新型裝備向輕量化、高性能的方向發(fā)展，高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件的應(yīng)用越來越廣泛，且大多是裝備中的關(guān)重構(gòu)件，往往需承受較大的載荷作用。此類構(gòu)件幾何形狀比較復(fù)雜，內(nèi)部多處有較高的加強(qiáng)筋結(jié)構(gòu)，且構(gòu)件截面尺寸變化較大，局部腹板較薄且壁厚差較大。目前采用由鋼板分體沖壓成形后焊接的加工方法使構(gòu)件的質(zhì)量較大，無法實(shí)現(xiàn)裝備輕量化的需求。而高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件的整體塑性成形比較困難，常規(guī)成形過程容易產(chǎn)生折疊、充不滿等缺陷。而高強(qiáng)鋁合金則有塑性較低、成形溫度范圍較窄、成形過程容易產(chǎn)生缺陷等問題，上述問題均增大了此類構(gòu)件加工制造的難度。研究高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件整體塑性成形新技術(shù)，突破其制造瓶頸，是現(xiàn)代裝備輕量化研究領(lǐng)域的迫切需求。 本文利用塑性成形理論與有限元數(shù)值模擬及試驗(yàn)相結(jié)合的方法，對高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件成形過程中材料流動特性進(jìn)行了研究；研究了變形過程中應(yīng)力、應(yīng)變、載荷、速度矢量等物理場量的分布及變化規(guī)律；研究了預(yù)成形毛坯結(jié)構(gòu)參數(shù)對的金屬流動規(guī)律的影響；建立了整體成形過程金屬材料流動模型，對模型各個區(qū)域進(jìn)行力學(xué)分析，研究不同成形階段金屬材料流動模式；利用主應(yīng)力法建立軸向分流成形分流面半徑計算公式；推導(dǎo)出了軸向分流單位成形力計算公式；提取并構(gòu)建V型及L型筋結(jié)構(gòu)模型，研究了成形過程金屬材料流動特性，對各變形區(qū)區(qū)域進(jìn)行了力學(xué)分析，研究工藝參數(shù)及結(jié)構(gòu)參數(shù)對成形載荷及金屬材料流動規(guī)律的影響；研究V型筋板構(gòu)件折疊缺陷形成機(jī)制，建立了V型筋板構(gòu)件折疊極限圖，研究了V型筋結(jié)構(gòu)參數(shù)對折疊極限的影響；總結(jié)歸納出鋁合金L型構(gòu)件結(jié)構(gòu)參數(shù)的基本設(shè)計準(zhǔn)則。 研究了高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件預(yù)成形毛坯結(jié)構(gòu)參數(shù)優(yōu)化設(shè)計方法，，基于試驗(yàn)設(shè)計及響應(yīng)曲面法，建立以預(yù)成形毛坯結(jié)構(gòu)參數(shù)為設(shè)計變量，以變形均勻性系數(shù)Ψm、材料利用率Vk及終成形載荷Fz為目標(biāo)函數(shù)的響應(yīng)面模型，利用線性加權(quán)法對回歸模型進(jìn)行多目標(biāo)優(yōu)化分析求解，獲得最優(yōu)化的預(yù)成形結(jié)構(gòu)參數(shù)，各目標(biāo)函數(shù)均得到了最優(yōu)解：變形均勻性系數(shù)指標(biāo)降低7%、材料利用率提高6%、終成形載荷Fz降低了7%。 研究高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件整體成形新技術(shù)，提出針對此類構(gòu)件的軸向分流成形工藝：通過優(yōu)化預(yù)成形毛坯、控制材料的軸向分流，提高材料徑向流動性，降低了坯料充填模腔的阻力，使終成形載荷降低60%以上。通過優(yōu)化軸向分流關(guān)鍵工藝參數(shù)，避免了終成形折疊及充不滿等缺陷。成功試制出高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件，綜合力學(xué)性能較常規(guī)整體成形提高10%以上，完全滿足裝備服役指標(biāo)要求。 以上研究結(jié)論及成果為高強(qiáng)鋁合金復(fù)雜筋板構(gòu)件的整體成形技術(shù)提供了理論基礎(chǔ)，對實(shí)現(xiàn)此類構(gòu)件的輕量化制造具有重要指導(dǎo)及參考意義。
[Abstract]:With the development of new equipment in the direction of light weight and high performance, the application of high strength aluminum alloy complex stiffened plate members is more and more extensive, and most of them are close and reconfigurable parts in equipment, which often need to bear large loads.The geometric shape of this kind of member is complex, and there are high stiffener structures in many places, and the section size of the member changes greatly, the local web is thin and the wall thickness difference is big.At present, the welding method which is made by split stamping of steel sheet makes the quality of components larger and can not meet the requirement of lightweight equipment.However, the integral plastic forming of high strength aluminum alloy with complex stiffeners is difficult, and the conventional forming process is easy to produce defects such as folding and filling with dissatisfaction.On the other hand, the high strength aluminum alloy has some problems, such as low plasticity, narrow forming temperature range and easy to produce defects in the forming process. All these problems increase the difficulty of processing and manufacturing of this kind of components.It is an urgent need in the field of modern equipment lightweight research to study new technology of integral plastic forming of high strength aluminum alloy complex stiffened plate member and break through its manufacturing bottleneck.By combining plastic forming theory with finite element numerical simulation and experiment, this paper studies the material flow characteristics during the forming process of high strength aluminum alloy complex stiffened plate members, and studies the stress, strain, load during deformation.The distribution and variation law of physical field such as velocity vector, the influence of structural parameters of preformed blank on metal flow law, the flow model of metal material in the whole forming process are established, and the mechanical analysis of each region of the model is carried out.The flow modes of metal materials in different forming stages are studied, the formulas for calculating the radius of axial shunt surface are established by principal stress method, the formulas for calculating the unit forming force of axial shunt are derived, and the V-shaped and L-shaped structural models are extracted and constructed.The flow characteristics of metal materials in forming process are studied, and the mechanical analysis of each deformation zone is carried out. The effects of process parameters and structure parameters on forming load and metal material flow law are studied, and the forming mechanism of folding defects of V-shaped stiffened plate members is studied.The folding limit diagram of V-shaped stiffened plate members is established, the influence of structural parameters of V-shaped stiffeners on folding limit is studied, and the basic design criteria of structural parameters of L-shaped aluminum alloy members are summarized.The optimization design method for structural parameters of preformed blank of high strength aluminum alloy complex stiffened slab was studied. Based on experimental design and response surface method, the structural parameters of preformed blank were established as design variables.Based on the response surface model with deformation uniformity coefficient 蠄 m, material utilization ratio V k and final forming load F z as the objective function, the linear weighting method is used to solve the multiobjective optimization analysis of the regression model, and the optimized preforming structure parameters are obtained.The optimal solution is obtained for each objective function: the deformation uniformity coefficient is reduced by 7 percent, the material utilization ratio is increased by 6 percent, and the final forming load Fz is reduced by 7 percent.This paper studies the new forming technology of high strength aluminum alloy complex stiffened plate, and puts forward the axial flow forming technology for this kind of component: by optimizing the preformed blank, controlling the axial flow of the material, improving the radial fluidity of the material.The resistance of blank filling cavity is reduced and the final forming load is reduced by more than 60%.By optimizing the key process parameters of axial flow, the defects such as final forming folding and filling dissatisfaction are avoided.The high strength aluminum alloy complex stiffened plate member was successfully manufactured. The comprehensive mechanical properties were improved by more than 10% compared with the conventional integral forming, which fully met the service requirements of the equipment.The above conclusions and results provide a theoretical basis for the integral forming technology of high strength aluminum alloy complex stiffened plate, and have important guidance and reference significance for the realization of lightweight manufacturing of this kind of members.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TG306

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