共查询到17条相似文献,搜索用时 187 毫秒
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以贯穿件构件为研究对象,运用ANSYS有限元分析软件,建立了其环焊缝多道焊温度场的有限元模型,采用双椭球热源模型,应用生死单元技术,利用ANSYS软件的APDL语言编写程序,实现了热源在环焊缝上的移动加载,模拟得到了贯穿件环焊缝多道焊焊接过程的瞬态温度场及各点的焊接热循环曲线.结果表明:模拟得到的温度场结果符合实际情况.多道焊温度场模拟方法能准确计算出其温度场,为以后研究贯穿件焊接过程的残余应力场数值模拟提供了依据. 相似文献
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目的为了提高发动机泵体综合机械性能和降低制造成本,采用精密热模锻技术来实现泵体的精确成形。方法通过确定锻件分模面位置,建立了泵体精密热模锻几何实体模型;在此基础上,建立了泵体热模锻过程三维有限元模型和模拟参数,实现了精密热模锻过程有限元模拟模型。结果通过数值模拟,获得了成形过程中坯料的速度场、等效应变场和温度场及载荷-行程曲线,揭示了泵体热模锻过程中金属充填模具型腔的情况及其变形机理,获得了温度场应变分布以及载荷、打击能量随行程的变化规律,优化了预成形时拍方坯料长度等参数,为确定成形工艺参数提供了科学依据。结论经试验验证,新工艺成形的锻件非加工外形面尺寸精度达到了零件要求,数值模拟结果与实验结果一致。 相似文献
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TA15钛合金作为一种高比强度结构材料具有良好的室温和高温强度、热稳定性能,广泛应用于飞机、导弹和发动机等飞行器,实现关键受力构件的减重要求.本文针对钛合金筒-锥复合曲母线构件的特点,重点开展了TA15钛合金薄壁曲母线构件热旋压成形技术的研究,采用剪切旋压预成形,强力旋压/普通旋压多道次复合旋压终成形的工艺方案,获得了成形质量较好的TA15钛合金筒-锥复合曲母线旋压件.建立了多道次曲母线构件的有限元模型,结合旋压实验解释了强旋/普旋复合成形过程中出现的典型缺陷产生机制.对热旋压过程坯料的显微组织观察分析发现,剪切旋压对显微组织具有一定程度的晶粒破碎作用,多道次强旋/普旋复合旋压成形后显微组织沿构件轴向和切向都发生伸长.经历剪切旋压和多道次强旋普旋复合旋压成形后,坯料的微观组织更加细化,且均匀性得到改善.TA15钛合金旋压成形工件的单向拉伸实验结果表明,相对于原始坯料旋压件强度明显提高,塑性略有下降. 相似文献
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激光增材制造技术加工过程中温度变化迅速而剧烈,导致成形件内部产生复杂的热应力和残余应力,这是成形件发生应力变形、翘曲、开裂等加工缺陷的根本原因。并且,剧烈的温度变化使得难以直接使用实验观察其温度场和应力场演变规律。因此,通过建立有限元模型进行数值模拟的方法来分析热-力耦合场的分布以及其对成形件质量的影响尤为必要。总结了金属激光增材制造技术温度场和应力场的数值模拟研究进展及现阶段存在的一些问题,进一步探讨了金属激光增材制造技术在数值模拟方面的未来发展方向。 相似文献
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Numerical simulation based on computational fluid dynamics (CFD) is a useful approach for quantitatively investigating the underlying thermal-mechanical conditions during FSW, such as temperature field and material deformation field. One of the critical issues in CFD simulation of FSW is the use of the frictional boundary condition, which represents the friction between the welding tool and the workpiece in the numerical models. In this study, three-dimensional numerical simulation is conducted to analyze the heat transfer and plastic deformation behaviors during the FSW of AA2024. For comparison purposes, both the boundary velocity (BV) models and the boundary shear stress (BSS) models are employed in order to assess their performances in predicting the temperature and material deformation in FSW. It is interesting to note that different boundary conditions yield similar predictions on temperature, but quite different predictions on material deformation. The numerical predictions are compared with the experimental results. The predicted deformation zone geometry by the BSS model is consistent with the experimental results while there is large difference between the predictions by the BV models and the experimental measurements. The fact that the BSS model yields more reasonable predictions on the deformation zone geometry is attributed to its capacity to automatically adjust the contact state at the tool/workpiece interface. Based on the favorable predictions on both the temperature field and the material deformation field, the BSS model is suggested to have a better performance in numerical simulation of FSW than the BV model. 相似文献
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采用不同的加热条件对镍钛合金丝进行定型,研究镍钛合金丝的力学性能及内部组织结构,确定了镍钛合金丝的最优热定型工艺参数。使用拉伸所用强力仪对镍钛丝进行拉伸性能测试,使用光学金相显微镜对镍钛丝进行金相组织观察。结果表明,热定型温度越高,加热时间越长,镍钛丝热定型效果越好,镍钛丝尺寸越接近定型模具尺寸;镍钛丝上下平台应力随加热时间的增加变小,其中,加工条件为550℃、20 min的上下平台应力最小,残余应变在加热时间多于10 min时显著增加;随着温度和加热时间的增加,镍钛丝内部奥氏体组织分布越来越均匀,奥氏体晶界越来越明显,其组织晶粒平均尺寸也越来越大。 相似文献
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采用三维弹塑性热力耦合有限元法实现了薄壁U形AZ31镁合金型材的温热张力绕弯成形的数值模拟,分析了4种温度加载模式下型材温热张力绕弯成形过程的温度场和应力场的变化。从模具预热、绕弯前温度场均匀化处理、随动热源的添加等方面实现了型材绕弯过程中温度场稳定性的提高。结果表明,绕弯前型材均匀化10s为最佳时间,随动热源的添加及模具的预热均减小了绕弯过程中型材与外界的热交换。分析了不同温度加载模式下型材内外侧等效应力及温度场的变化。模拟结果可以对AZ31镁合金型材张力绕弯成形工艺的优化提供参考。 相似文献
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The plastic deformation behavior of hot splitting spinning of TA15 titanium alloy is a complex metal forming problem with multi-factor coupling interactive effects. In this paper, on condition of considering various thermal effects, a three-dimensional (3D) elastic–plastic coupled thermo-mechanical finite element (FE) model of hot splitting spinning of TA15 titanium alloy is established using the dynamic, temp-disp, explicit module of FE software ABAQUS. Based on the analysis of flow behaviors of TA15 titanium alloy, the mechanism and influence of materials plastic deformation behavior during the forming process are studied. The results show that, the flow stress of TA15 titanium alloy generally decreases with the increase of deformation temperature; at the same strain rate, the higher temperature is, the lower flow stress is. The temperature distributions along the circumferential direction of disk blank are even and the temperature of plastic deformation area is about 984 °C. The heat from plastic deformation and friction at local plastic deformation area is less than the dissipated heat, so the temperature just falls into approximately 945 °C. Radial spinning force as the driving force of plastic deformation increases gradually and reaches about 35 kN at the end. The maximum value of equivalent stress is presented in fillet part between disk blank and two mandrels. The distributions of equivalent plastic strain appear the large strain gradients and the obvious characteristics of inhomogeneous deformation. When friction factor on interfaces between disk blank and dies ranges from 0.4 to 0.6, the forming quality and precision are highest. 相似文献
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A mathematical model for flow simulation of full penetration laser beam welding of titanium alloy is presented. In this model, the heat source comprises a plane heat source on the top surface and a cylindrical heat source along the z-direction, which takes into account the plasma effect and the keyhole absorption. By solving the conservation equations of energy, momentum and mass, the temperature and flow fields are obtained. The momentum interpolation scheme with under-relaxation parameter is used to simplify the calculation algorithm and save the storage space of computer. The mushy region is introduced to provide a simple method to dispose of the pressure and velocity boundary conditions. Results calculated from the models are found to agree with the experimental results for the geometry profile of weld. The calculated results indicate the metal flow is the main reason for forming the typical “hourglass” cross-section profile. 相似文献
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基于平面应变压缩模型的TA15钛合金热强旋组织性能预测研究 总被引:1,自引:0,他引:1
针对热强旋过程的变形特点,本文研究了基于平面应变压缩的物理模拟模型对钛合金热强旋过程的组织性能演变预测的可行性.为此本文对TA15钛合金平面应变压缩变形的组织和热强旋过程进行了对比分析,并以平面应变压缩的组织性能演变模型为基础,采用BP神经网络对TA15钛合金热强旋旋过程的组织性能进行了预测.研究结果表明,TA15钛合金平面压缩变形和热强旋过程的组织性能演变规律基本一致,采用平面应变压缩的组织性能模型可有效预测钛合金热强旋过程的组织演变.但是,由于强力旋压的多道次累积变形较平面压缩的单道次变形更为均匀充分,使得大减薄率时的预测误差略有增大趋势. 相似文献