高强铝合金复杂筋板构件整体成形技术研究

发布时间：2018-04-14 11:01

本文选题：高强铝合金 + 复杂筋板构件　；参考：《中北大学》2015年博士论文

【摘要】：随着新型装备向轻量化、高性能的方向发展，高强铝合金复杂筋板构件的应用越来越广泛，且大多是装备中的关重构件，往往需承受较大的载荷作用。此类构件几何形状比较复杂，内部多处有较高的加强筋结构，且构件截面尺寸变化较大，局部腹板较薄且壁厚差较大。目前采用由钢板分体冲压成形后焊接的加工方法使构件的质量较大，无法实现装备轻量化的需求。而高强铝合金复杂筋板构件的整体塑性成形比较困难，常规成形过程容易产生折叠、充不满等缺陷。而高强铝合金则有塑性较低、成形温度范围较窄、成形过程容易产生缺陷等问题，上述问题均增大了此类构件加工制造的难度。研究高强铝合金复杂筋板构件整体塑性成形新技术，突破其制造瓶颈，是现代装备轻量化研究领域的迫切需求。本文利用塑性成形理论与有限元数值模拟及试验相结合的方法，对高强铝合金复杂筋板构件成形过程中材料流动特性进行了研究；研究了变形过程中应力、应变、载荷、速度矢量等物理场量的分布及变化规律；研究了预成形毛坯结构参数对的金属流动规律的影响；建立了整体成形过程金属材料流动模型，对模型各个区域进行力学分析，研究不同成形阶段金属材料流动模式；利用主应力法建立轴向分流成形分流面半径计算公式；推导出了轴向分流单位成形力计算公式；提取并构建V型及L型筋结构模型，研究了成形过程金属材料流动特性，对各变形区区域进行了力学分析，研究工艺参数及结构参数对成形载荷及金属材料流动规律的影响；研究V型筋板构件折叠缺陷形成机制，建立了V型筋板构件折叠极限图，研究了V型筋结构参数对折叠极限的影响；总结归纳出铝合金L型构件结构参数的基本设计准则。研究了高强铝合金复杂筋板构件预成形毛坯结构参数优化设计方法，，基于试验设计及响应曲面法，建立以预成形毛坯结构参数为设计变量，以变形均匀性系数Ψm、材料利用率Vk及终成形载荷Fz为目标函数的响应面模型，利用线性加权法对回归模型进行多目标优化分析求解，获得最优化的预成形结构参数，各目标函数均得到了最优解：变形均匀性系数指标降低7%、材料利用率提高6%、终成形载荷Fz降低了7%。研究高强铝合金复杂筋板构件整体成形新技术，提出针对此类构件的轴向分流成形工艺：通过优化预成形毛坯、控制材料的轴向分流，提高材料径向流动性，降低了坯料充填模腔的阻力，使终成形载荷降低60%以上。通过优化轴向分流关键工艺参数，避免了终成形折叠及充不满等缺陷。成功试制出高强铝合金复杂筋板构件，综合力学性能较常规整体成形提高10%以上，完全满足装备服役指标要求。以上研究结论及成果为高强铝合金复杂筋板构件的整体成形技术提供了理论基础，对实现此类构件的轻量化制造具有重要指导及参考意义。
[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.
【学位授予单位】：中北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG306

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