共查询到19条相似文献,搜索用时 62 毫秒
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《塑性工程学报》2019,(3):96-103
以600 MW护环为例,研究了外补液液压胀形加载路径确定方法。把连续的胀形强化过程离散为多个子加载段,将各子加载段锥模作用力和环坯腔内液体压力的关系简化为线性关系,采用分段匹配的方法确定各加载段的合理子加载路径,再叠加为完整的合理加载路径,确定了加载路径的形式和关键参数。将环坯液压胀形质量作为目标,两段加载路径斜率、加载路径拐点液体压力和胀形终了液体压力为设计变量,采用遗传优化算法对护环液压胀形加载路径进行优化,并进行了缩比实验。研究结果表明,外补液护环液压胀形加载路径可近似为两段线性线形,拐点对应的环坯腔内液体压力在使环坯外层完全屈服的液体压力值附近,且通过优化获得加载路径的最优参数组合能够保证护环液压胀形制品的质量。 相似文献
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加载路径对液压胀形件的最终质量有着至关重要的影响。在优化加载路径的过程中,设计变量的取值区间对模拟时间的减少及最优解的收敛有重要的意义。文章根据塑性理论分析,给出了管形件液压胀形过程中弹性变形阶段、塑性变形阶段及贴模阶段的轴向喂入量及内压力的工程计算表达式。选取应力比为优化变量,依据屈服准则,得出了胀形过程中合理的变量区间。利用有限元软件包、优化算法及工程计算表达式,得到了液压胀形最优的加载路径。实验结果和有限元模拟结果一致性较好,该方法为轴对称件的加载路径优化提供了新的思路。 相似文献
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在管件液压成形过程中,加载路径对成形过程的影响最为重要。文章给出了一种新的加载路径优化方法,即精英保留非劣排序遗传算法(NSGA-Ⅱ)与成形数值模拟软件集成,实现对加载路径的自动寻优。该方法通过优化算法程序修改加载路径,自动调用数值模拟软件进行分析,在更大的解空间内自动寻找最优方案。文中以某汽车仪表板梁为例,采用该方法对液压成形中的加载路径进行优化分析。结果表明,通过该方法所获取的加载路径较通过人工寻优所获取的加载路径更趋于最优。另外,该方法一次运算能够同时获取多个Pareto最优解,可为加载路径的制订和设计人员的决策,提供更多的选择。 相似文献
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翻转管吸能特性及翻管成形工艺的研究 总被引:1,自引:0,他引:1
介绍了一种塑性变形吸能的金属翻转管 ,并对其吸能特性进行了研究。这种翻转管可以通过在圆角模上轴压圆管进行翻制 ,讨论了与之相联系的各种变形模式。研究表明 ,采用优化的圆角半径可稳定地翻转 ,而不会屈曲和撕裂 ,并对翻转变形进行了简单的理论分析。 相似文献
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焊缝管液压胀形模拟建模及变形规律的研究 总被引:1,自引:1,他引:1
基于周向显微硬度的分布及经验公式法,确立了STKM11A焊缝管热影响区的流动应力;通过对热影响区进行分片的方式,建立了包含焊缝和热影响区的焊缝管液压胀形的有限元模拟模型。基于该模型,模拟分析了STKM11A焊缝管液压胀形时的变形规律,如截面轮廓形状、周向壁厚分布和成形极限等,并与胀形实验结果进行对比。结果表明,液压胀形后焊缝管的截面轮廓形状不对称、壁厚分布不均匀,最小壁厚位于热影响区;包含焊缝及热影响区的有限元模型在预测焊缝管液压胀形的变形规律、极限载荷和潜在胀裂位置等方面,较其他常规模型更加精确。 相似文献
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翻转管吸能特性及翻管成形工艺的研究 总被引:1,自引:0,他引:1
介绍了一种塑性变形吸能的金属翻转管,并对其吸能特性进行了研究。这种翻转管可以通过在圆角模上轴压圆和进行翻制,讨论与之相联系的各种变形模式。研究表明,采用优化的圆角半径可稳定地翻转,而不会屈曲和撕裂,并对翻转变形进行了简单的理论分析。 相似文献
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Deformation behavior, temperature evolution and coupled effects have a significant influence on forming process and quality of component formed, which are very complex in forming process of aluminum alloy 7075 cross valve under multi-way loading due to the complexity of loading path and the multiplicity of associated processing parameters. A model of the process was developed under DFEORM-3D environment based on the coupled thermo-mechanical finite element method. The comparison between two process models, the conventional isothermal process model and the non-isothermal process model developed in this study, was carried out, and the results indicate that the thermal events play an important role in the aluminum alloy forming process under multi-way loading. The distributions and evolutions of the temperature field and strain filed are obtained by non-isothermal process simulation. The plastic zone and its extension in forming process of cross valve were analyzed. The results may provide guidelines for the determination of multi-way loading forming scheme and loading conditions of the forming cross valve components. 相似文献
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Atsushi Shirayori Sadakatsu Fuchizawa Michiharu Narazaki 《Metals and Materials International》2007,13(2):185-189
Loading paths (hereafter referred as LPs) that consist of internal pressure and axial feeding are important manufacturing
conditions in tube hydroforming. Among the factors that affect LP design, friction between the forming die and tube causes
the most difficulty due to its complicated characteristics. Although there is no friction, a number of issues with LP design
remain. In this study, free hydraulic bulging (hereafter FHB) with internal pressure and axial feeding is investigated. In
FHB, tubes are freely expended without friction. It has been shown that axial feeding affects the circumferential thickness
distribution in the tube periphery. The tubes in this study are straight seamless tubes. Seamless tubes typically have predictable
thickness deviations resulting from their manufacturing processes. In general, the degree of thickness deviation will increase
as the tube expands. A FEM simulator is used to analyze the mechanism of the growth of thickness deviation. 相似文献
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Experiment on seamless tubes of aluminum alloy A6063 with initial thickness deviation of 0-20% was conducted through a free hydraulic bulging with tube ends free. The influence of initial thickness deviation on the cross-section profile, thickness distribution, maximum internal pressure and maximum radial expansion was investigated. FEM simulation was also performed in order to examine and help explaining the experimental results. The results indicate that the internal pressure and maximum internal pressure appear to be little influenced by the initial thickness deviation, and that the cross-section profile of the bulged tube changes diversely and can not be a perfect circle. The results also suggest that the increase in initial thickness deviation may lead to a remarkable decrease in maximum radial expansion, and a rapid increase in thickness deviation and the center eccentricity of the inner and outer profiles. 相似文献
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The forming quality of high-strength TA18 titanium alloy tube during numerical control bending in changing bending angle β, relative bending radius R/D and tube sizes such as diameter D and wall thickness t was clarified by finite element simulation. The results show that the distribution of wall thickness change ratio Δt and cross section deformation ratio ΔD are very similar under different β; the Δt and ΔD decrease with the increase of R/D, and to obtain the qualified bent tube, the R/D must be greater than 2.0; the wall thinning ratio Δto slightly increases with larger D and t, while the wall thickening ratio Δti and ΔD increase with the larger D and smaller t; the Δto and ΔD firstly decrease and then increase, while the Δti increases, for the same D/t with the increase of D and t. 相似文献
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文章将渐进成形的思想融入到传统的管件电磁胀形工艺中,提出管件电磁渐进成形的新工艺,即采用小尺寸线圈,通过移动多次成形的方式成形长管件。提出了适合于管件电磁渐进胀形工艺的顺序耦合数值模拟方法,并与一次放电、两次放电、三次放电的实验结果进行对比,模拟结果与3组实验数据均吻合。采用数值模拟的方法,进一步研究重叠率和成形顺序对管件变形均匀性的影响,研究结果表明,重叠率为50%、成形顺序为b→c→a时,可获得最佳的成形均匀性。电磁渐进成形技术应用于管件胀形工艺中具有可行性,对实际生产具有指导意义。 相似文献
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薄壁筒形件多道次滚珠旋压成形机理研究 总被引:4,自引:0,他引:4
为研究多道次成形条件下薄壁筒形件滚珠旋压的成形机理,采用实验和有限元法相结合对薄壁筒形件多道次滚珠旋压的应力应变、旋压力和成形性进行了分析。结果表明:各道次下的等效应力和等效应变都是由旋压件的内表面向外表面逐渐增大,且随着旋压道次数的增加,等效应力和等效应变也都是逐渐增大;每道次的轴向旋压力随着滚珠行程的增加而增大,且各道次的旋压力也逐渐增大;多道次滚珠旋压时,由于采用较小的壁厚减薄量和材料的加工硬化,金属易于稳定流动,能够保证管坯的轴向伸长。因此,通过多道次滚珠旋压可实现大减薄量薄壁筒形件的旋压成形。 相似文献
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