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为了获得DP780高强双相钢激光拼焊接头的模拟参数,根据混合法则对激光拼焊接头进行区域细化,采用ABAQUS有限元仿真软件对母材、焊缝和纵向接头的拉伸实验以及极限拱顶高度实验进行了有限元建模,依据拉伸实验的工程应力-工程应变、拉伸试样断裂位置及拼焊板断裂失效模式结果并结合有限元反推法,确定了接头各区域的GTN损伤模型参数,从而对横向接头的拉伸实验和极限拱顶高度实验进行了模拟。结果表明:不同热输入下接头的拉伸实验曲线与模拟曲线、模拟断裂位置与实际断裂位置较吻合;拼焊板失效时的极限拱顶高度值与实验值相接近;拼焊板失效模式与实验结果相一致。 相似文献
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选取传统高强度双相钢HC420/780DPD+Z和与其化学成分相同、组织存在一定量残余奥氏体差异的HC440/780DHD+Z为研究对象,研究了残余奥氏体对高强度双相钢断裂失效性能的影响。设计了5种表征不同断裂失效状态的试样,测试获得各试样的临界断裂应变和力-位移曲线;采用有限元法搭建了试样模型,并对比了试验和仿真关键参数误差,验证了模型的准确性。通过模型获取了各试样断裂单元的应力三轴度和临界断裂应变;基于MMC断裂失效模型拟合获得断裂失效曲线;采用90°V型弯曲试验和仿真对比分析验证了断裂失效曲线的准确性。结果表明,残余奥氏体组织加入后,高强度双相钢的抗拉强度基本保持不变,断后伸长率、强塑积和应变硬化指数明显提升;断裂失效性能明显提升,相同应力三轴度的极限断裂失效应变明显提高;90°V型弯曲模型获取的临界塑性应变与断裂失效曲线提取的数值一致,表明所获得的断裂失效曲线是可靠的;在基体组织中引入一定量的残余奥氏体组织有助于提升高强度双相钢碰撞过程中的承载吸能特性。 相似文献
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本文通过不同温度亚温淬火及回火,在15号钢中得到具有不同体积百分比及不同强度比的铁素体马氏体双相组织,并研究了这些组织对铜的力学性能及断裂过程的影响。结果表明:力学性能与双相钢中的马氏体数量及马氏体强度有关。 相似文献
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以高强双相钢CR450/780DP板材为研究对象,设计4种拉伸试样进行单向拉伸试验,获得了载荷-位移曲线与表面全场应变结果;采用有限元仿真分析手段,对4种试样的试验结果进行了对标分析,得到了材料硬化本构模型及应力三轴度、Lode角参数、等效塑性应变等历程数据;采用曲面拟合优化方法标定MMC韧性断裂准则的断裂参数。基于Keeler公式及简化的MMC韧性断裂准则分别绘制了高强双相钢CR450/780DP板材的理论和预测成形极限图,并通过半球形刚模胀形试验对预测结果进行验证。由对比结果可知,基于MMC韧性断裂准则预测的成形极限曲线与试验数据的吻合程度较高,验证了韧性断裂准则对高强双相钢CR450/780DP板材损伤与断裂预测的准确性与适用性。 相似文献
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对超高强双相钢HC820/1180DPD+Z的断裂失效模型开展研究,并分析了其微观组织和力学性能。基于MMC断裂失效准则,设计了5种失效试样,采用万能试验机和DIC获得了5种试验的断裂临界塑性应变和力-位移曲线,采用Swift和Hockett-Sherby混合硬化模型拟合并获取了材料的外延硬化曲线,并得到混合模型的最佳加权系数和5种试样的仿真模型,基于仿真模型获得5种应力状态下的应力三轴度和临界塑性应变。最后,基于MMC断裂失效模型拟合获得材料的失效曲线,并采用防撞梁落锤冲击试验与仿真对比分析,验证了断裂失效模型的准确性和精度。结果表明:混合硬化模型对材料硬化曲线的拟合精度较高,加权系数α为0.3时各断裂失效试样的最大力值误差小于3%;未应用断裂失效模型的加速度-时间曲线与试验曲线明显不符,误差较大,而应用MMC断裂失效模型的断裂形貌与试验结果相符,断裂时刻和加速度最大值时的误差分别为2.5%和1.7%,说明模型的精度较高,可以应用于整车碰撞仿真分析。 相似文献
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为了提高SS304微管液压成形性能,设计了一种轴向补料液压成形工艺。通过试验并结合GTN损伤模型和韧性断裂准则研究了不同补料量对微管胀破压力和胀形直径的影响规律。试验结果表明,微管胀破压力和胀形直径表现出一定的分散性,并且在0. 6~1. 5 mm范围内进行轴向进给量补料时,轴向补料方法能够显著提高微管胀破压力和胀形高度。数值模拟结果表明:GTN损伤模型和Ayada准则能较好地模拟轴向补料与胀破压力之间的关系;在0. 6~1. 5 mm范围进行轴向补料,Brozzo韧性断裂准则预测管件胀形最大直径的效果要优于其他准则。 相似文献
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为评估含剪切修正项GTN模型在非比例加载条件下的适用性,以一组缺口圆棒试样的拉剪变路径加载试验结果为依据,运用有限元软件ABAQUS/Explicit模块及用户子程序VUMAT进行平行仿真分析。研究结果表明:在大预变形下的拉剪变路径加载条件下,增长的预应变会加快后续拉伸过程中孔洞的增长率,导致材料提前断裂。同时,结合断口宏观与微观形貌分析,研究了非比例加载过程材料的损伤演化机理。AA2024铝合金在拉剪变路径加载条件下的断裂机制为拉-剪混合断裂,随着预扭作用的增强,剪切断裂逐渐取代拉伸断裂成为主导的断裂模式。 相似文献
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为预测合金钢的延性破裂和变形极限,本文针对静水应力对金属材料内部微孔表面能的影响,静水应力和应力偏量对内部微孔扩展的影响,提出了合金钢冷锻时的理论破裂准则,并通过压缩实验得到验证。 相似文献
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《Scripta materialia》2003,48(5):501-506
It was observed that ferrite carbide aggregate formation suppressed to cooling rates below 1 °C/s and a significant amount of austenite transformed to martensite even at the cooling rate of 0.1 °C/s (furnace cooling). The critical cooling rates for carbide formation is so low, compared with previous studies. 相似文献
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针对热冲压硼钢的相组成特点,通过不同的热处理工艺获取了6种相组成的B1500HS板料,设计了3种拉伸试样,利用数字图像相关技术(Digital Image Correlation,DIC)测量了试样的断裂应变与断裂带的应变比并计算得到了应力三轴度和洛德角参数。基于L-H断裂模型,计算得到了适用于每种相组成的断裂准则并将马氏体相体积分数引入其中。通过ABAQUS/Explicit仿真平台,对考虑相组成与不考虑相组成的材料进行了剪切仿真。结果表明,相比于不考虑相组成的仿真,考虑相组成的仿真模型得到的断面形貌与试验结果吻合较好,验证了断裂模型的准确性以及在热冲压剪切中考虑相组成的必要性。 相似文献
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《Science & Technology of Welding & Joining》2013,18(3):248-253
AbstractHigh strength steels with good formability properties have been developed in recent years, especially for the automotive industry. Joining these metals is however increasingly difficult as the fusion joining processes destroy the carefully constructed microstructure of the steels, resulting in less favourable mechanical properties in and around the joint. A possible solution to this problem is the use of joining processes that require less heat input; laser brazing is one such process. In this work, the brazability of a dual phase steel sheet has been investigated by means of bead on plate brazes produced with two consumables, CuSi3 and CuAl8. Two brazability diagrams are reported and high speed video images are used to explain the differences in operating conditions for these two consumables. Temperature measurements in the steel provide an indication about the temperatures reached during the joining process, which in turn explain the changes observed in the hardness of the steel. 相似文献
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H. L. Jaber S. P. H. Marashi M. Alizadeh-Sh R. K. Salim F. A. Hashim 《Science & Technology of Welding & Joining》2014,19(7):565-571
Phase transformations in dissimilar resistance spot welds of dual phase steel and ferritic stainless steel are analysed. In contrast to a full martensitic microstructure predicted by the Schaeffler and Balmforth diagrams, a ferrite–martensite microstructure was observed in the fusion zone. The formation of ferrite phase in the fusion zone can be attributed to the rapid cooling rate of resistance spot welding, which suppresses the post-solidification ferrite–austenite transformation. The grain growth and martensite formation were main metallurgical features of the heat affected zone of ferritic stainless steel side. Microstructure gradient of heat affected zone in dual phase steel side was dictated by martensitic transformation. The effect of weld thermal cycle on the mechanical performance of the joint is discussed. 相似文献
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《Metallography》1984,17(2):123-130
The influence of tempering on the fracture of a dual phase steel was studied. The martensite in the as-quenched dual phase steel began to deform only after the steel had attained the maximum uniform strain, while the martensite in the tempered steel started contributing to deformation from the very beginning. The fracture process in the as-quenched dual phase structure began at a much lower strain compared to that in quenched and tempered steels by nucleation of microvoids at ferrite/martensite interfaces, followed by their growth and coalescence. This was due to the difference in hardness of the tempered and untempered martensite. 相似文献