共查询到20条相似文献,搜索用时 15 毫秒
1.
Residual stress analysis of the thermal barrier coating system by considering the plasma spraying process 总被引:2,自引:0,他引:2
Myung-Jae Lee Byung-Chai Lee Jang-Gyun Lim Moon-Ki Kim 《Journal of Mechanical Science and Technology》2014,28(6):2161-2168
The residual stress is the key factor causing the reliability problem of thermal barrier coating (TBC). The failure of plasma spray coatings due to residual stresses is a serious and recurring problem of TBC. The difference of thermal expansion coefficient between the substrate and each coating combined with temperature evolution and temperature gradients during deposition process determine the residual stress for the whole TBC system. The magnitudes and distributions of the residual stresses are affected by deposition process and deposition characteristics. Most of FEA (finite element analysis) has been performed under the assumption that the multilayer coating system is stacked at once without considering the deposition process during plasma spraying. In this research, FEA for a coupled heat transfer and elastic-plastic thermal stress was performed to obtain the more detailed and reliable result of residual stress of the TBC system using the element activation/deactivation technique. The residual stress variation from the start of plasma spraying to cooling stage with room temperature was obtained systematically considering the deposition process. It can be used as reference data to improve the performance of TBC. In addition, the relationship between residual stress and coating conditions such as cooling rate and time is also examined thoroughly. 相似文献
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分析了某多层堆叠模块的焊接残余应力,讨论了各功能层不同选材、焊接顺序对模块残余应力的影响,并给出了优化方案。利用 ANSYS 软件进行有限元分析计算,采用 ANAND 本构模型描述焊锡的黏塑性行为,采用基于接触的多点约束(Multi-point Constraint, MPC)算法实现焊锡层与功能层的跨尺度自由度耦合。计算结果表明,焊接顺序对模块残余应力影响较小,各功能层的选材需要综合考虑模块变形及应力安全裕度。刚度较大的底板层可以同时降低模块变形和高温共烧陶瓷(High Temperature Co-fired Ceramic, HTCC)层应力。热膨胀系数较小的盖板层可以降低 HTCC 层应力,但会增大模块整体变形。底板选用 Al/ SiCp(65%),盖板采用可伐合金,可以得到变形及应力安全裕度均满足要求的方案。 相似文献
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J. Ding P. Colegrove J. Mehnen S. Williams F. Wang P. Sequeira Almeida 《The International Journal of Advanced Manufacturing Technology》2014,70(1-4):227-236
Wire and arc additive manufacturing (WAAM) is an emerging technology which has the potential to significantly reduce material usage and manufacturing time through the production of near net-shape components with high deposition rates. One of the main problems of this process is the residual stresses and distortions of the deposited workpiece. To help understand and optimise the process, finite element (FE) models are commonly used; however, the conventional transient models are not efficient for simulating a large-scale WAAM process. In this paper, the stress evolution during the thermal cycles of the WAAM process was investigated with the help of a transient thermomechanical FE model. It was found that the peak temperatures experienced during the thermal cycles of the WAAM process determine the residual stress of that point. Based on this finding, an efficient “engineering” FE model was developed. Compared to the conventional transient thermomechanical approach, this model can save the computational time by 99 %. This new model produced distortion and residual stress predictions that were nearly identical to the original transient model and the experimental results. 相似文献
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Hui-Jun Yi Jong-Yun Kim Jin-Ho Yoon Sung-Soo Kang 《Journal of Mechanical Science and Technology》2011,25(12):3185-3193
In the present work, both experimental and numerical simulation methods are used to investigate the characteristics of welding
distortion and residual stress distribution. A 3D thermo-mechanical Finite Element Analysis (FEA) method is used to predict
the welding distortion and residual stress of cylinder-shaped multi-pass layer weldments. Each weld pass is performed using
a quarter-circle balanced welding procedure. To investigate the influence of deposition sequence and welding heat input on
the welding distortion and residual stress, a continuous welding procedure is also calculated. The corresponding FEA models
considered a moving heat source, the deposition sequence, and temperature-dependent thermal and mechanical properties. The
results predicted by 3D FEA model are generally in good agreement with the measurements. Finally, the numerical and experimental
results suggest that both deposition sequence and heat input affect welding distortion and residual stress distribution. Furthermore,
the 3D thermal-mechanical FEA method can predict cylinder-type welding distortion. 相似文献
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基板预热对激光金属沉积成形过程热应力的影响 总被引:5,自引:1,他引:4
为降低沉积过程的热应力,抑制成形过程中裂缝的产生,研究基板预热对激光金属沉积成形(Laser metal deposition shaping, LMDS)过程热应力的影响具有非常重要的意义。根据有限元分析中的“单元生死”思想,利用APDL (ANSYS parametric design language)编程建立多道多层激光金属沉积成形过程的数值模拟模型,深入探讨基板未预热和预热到400 ℃时对成形过程热应力的影响。计算结果表明,基板预热到400 ℃可以显著降低成形过程中试样的热应力变化波动性,试样的Von Mises热应力最大值可降低10%左右,其中x方向热应力最大值可降低8.5%左右,z方向热应力最大值可降低8.1%左右。在与模拟过程相同的条件下,利用自行研制的激光金属沉积成形设备进行了成形试验,成形试验的结果与模拟结果基本吻合。 相似文献
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Coupled finite element analysis of MIG welding assembly on auto-body high-strength steel panel and door hinge 总被引:2,自引:2,他引:0
Wen-feng Zhu Chun Xu Lu Zeng 《The International Journal of Advanced Manufacturing Technology》2010,51(5-8):551-559
Automotive doors are assembled to auto-body side-frame through hinges by metal inertial gas arc-welding process. Because of thermal effect, the after-welding geometrical deformation of hinges seriously affects assembly accuracy of door position, causing functional problems such as poor sealing, abnormal sound during closing and opening, as well as large residual stress. In order to solve the complexity involved in auto-body arc-welding assembly process due to dynamic coupling between temperature field and structural field, a multi-field coupling finite element method employing the subroutine of commercial code ANSYS-APDL is proposed, and numerical analysis model is established in quantitative detail. Focusing on the arc-welding assembly process for the auto-body plate (which uses high-strength hot-dip galvanized steel), the promising lightweight material, and door hinge (which uses conventional low-carbon steel), moving heating source and birth–death element method are both adopted in this thermal–structural coupling analysis in order to obtain the complicated transient temperature distribution and mechanical stress behavior during the sequential formulation of arc-welding seam. Experiment is carried out to confirm the validity of this newly developed method, including temperature measurement by thermocouple and residual stress test by X-ray diffraction. The agreement between the experimental and numerical results is satisfactory, indicating the reasonability and feasibility of this method in lightweight auto-body assembly research. It can be concluded that the moving heating source multi-field coupling arc-welding model can strongly support the process parameters optimization for obtaining minimum weld deformation and residual stress. 相似文献
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选取焊盘长度、焊盘宽度、钢网厚度和间隙高度为四个关键因素,采用水平正交表L25(56)设计25种不同参数水平组合的底部引线塑料封装(bottom leaded plastic,BLP)器件焊点,建立25种焊点的形态预测模型和有限元分析模型;对热循环加载条件下BLP焊点进行非线性有限元分析,计算25种不同焊点形态的BLP焊点热疲劳寿命;基于热疲劳寿命计算结果进行极差分析.结果表明,四个因素对BLP焊点热疲劳寿命影响由大到小的顺序依次是焊盘宽度、焊盘长度、间隙高度和钢网厚度;可靠性最高的BLP焊点工艺参数水平组合为焊盘长度1.1 mm、焊盘宽度0.65 mm、钢网厚度0.15 mm和间隙高度0.09 mm. 相似文献
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Q. Z. Zhang B. F. Shu M. B. Chen Q. B. Liang C. Fan Z. Q. Feng P. J. Verlinden 《Journal of Mechanical Science and Technology》2015,29(2):655-662
A series of simulations were carried out to investigate the residual stress induced in the photovoltaic laminate during the cooling process after lamination with a global model and several submodels. The simulations focus separately on the effects of the cooling rate, the cell layout and anisotropy on the residual stress and deformation of the photovoltaic laminate in a comparative manner with the finite element method. The results have shown that significant stress concentration and twist occurs in the interconnection region in the cell. In addition, different cooling rates, cell layouts and anisotropy only influence the largest stress rather than the stress distribution and deformation. Therefore, the results of a uniform stationary isotropic model with fewer cells can provide enough insight into the stress distribution in real photovoltaic laminates and the modified largest first principal stress can be used for design and verification. 相似文献
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斜角切削过程的三维热—弹塑性有限元分析 总被引:2,自引:0,他引:2
基于大变形理论和虚功原理,建立了斜角切削加工过程的三维热一弹塑性有限元模型.分析和研究了涉及切削加工有限元模拟的关键技术.采用通用有限元求解器ABAQUS/Explicit对斜角切削过程进行了有限元模拟,分析了切削过程中切屑的形成过程及其形貌、三维切削力的变化情况,以及应力、应变、切削温度和已加工表面残余应力的分布规律.通过与试验数据的比较,证明了所建立有限元模型的正确性.斜角切削过程的三维热一弹塑性有限元模拟研究为铝合金高速切削加工的工艺参数优化、刀具几何参数的合理选择提供了参考. 相似文献
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深槽密封是通过力变形和热变形在密封面形成周向的波度和径向的锥度,从而产生热流体动力楔效应。通过热平衡分析和模型简化,应用有限元软件建立斜直深槽机械密封有限元分析模型,并对密封环温度场、力热变形进行求解,获得斜直深槽密封环的温度分布规律以及热变形规律。分析结果表明:斜直深槽密封端面结构产生的变形,能够形成周向波度和径向锥度,能够产生一定的流体动压效应,但规则波形的产生同流体槽的结构参数有关,需针对具体的工况参数进行相应的优化设计,方能达到所需要的流体动压效果。 相似文献
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Ki-Hoon Shin 《Journal of Mechanical Science and Technology》2011,25(5):1119-1128
UBM (under bump metallurgy) of micro-system packages consists of several heterogeneous layers such as solder wetting, diffusion
barrier, adhesion, and IMC (inter-metallic compound) layers. In particular, the IMC layer, formed between the solder wetting
layer (e.g., Cu or Ni) and the solder, grows gradually and thus its composition changes with time (i.e., time-variant). The
primary failure mechanism of the solder joints in micro-system packages is widely known as the fatigue failure caused by thermal
fatigue and electro-migration damage. However, these phenomena have thus far been viewed from experimental investigations.
Therefore, finite element analysis (FEA) becomes an important step for the optimal design and reliability analysis of heterogeneous
objects such as in micro-system packages. However, the accuracy of the FEA wholly depends on the quality of finite element
models. There thus exists an increasing need for generating finite element models adaptive to both geometric complexity and
material distribution. In this sense, this paper presents a new method for modeling of time-variant heterogeneous objects
such as in micro-system packages whose composition changes with time. Heterogeneous Boolean operators based on the diffusion
process are proposed to construct time-variant heterogeneous objects. Once a time-variant heterogeneous solid model is constructed,
it is then discretized into an object model onto which appropriate material properties are mapped. Discretization converts
continuous material variations inside an object into stepwise variations. Next, the object model is adaptively meshed and
converted into a finite element model. FEA using commercial software is finally performed to check failure criteria. An example
(UBM in micro-system package) is shown to illustrate the entire modeling procedure. 相似文献
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基于GAP单元的滚动轴承应力分析 总被引:1,自引:0,他引:1
利用有限元分析软件MSC.Marc/Mentat对某一滚动轴承进行有限元分析,采用GAP单元代替滚动体模拟轴承内外圈间的接触,在某组载荷工况下,计算该简化模型的应力结果;在同组工况下,对比实体轴承模型与GAP单元简化模型的有限元分析结果,对比各自的最大应力值;同时用理论计算方法计算轴承在相同工况下的最大应力值,来验证有限元结果的正确性.结果表明:GAP单元可以有效的模拟滚动轴承内外圈之间的接触,从而为滚动轴承建模及与轴承连接的组合件之间的建模提供了一种简便且有效的方法. 相似文献
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厚板窄间隙多道埋弧焊温度和残余应力分布 总被引:3,自引:0,他引:3
通过有限元数值模拟的方法,分析厚板窄间隙埋弧焊的温度分布,同时给出了厚板上、下表面和厚度方向上的残余应力分布曲线.通过热电偶构成的温度测量系统测得试板特定点上的温度分布,且在焊接完成冷却一段时间后利用盲孔法测量了试板上、下表面特定点上残余应力大小.有限元计算结果和试验测量结果吻合较好,证明了该有限元模型的合理性,为评价焊接接头性能提供了参考.特别是,在厚度方向上不便测量的残余应力分布曲线可以通过有限元数值模拟的方法获得,为实际考查厚板内部残余应力分布提供依据.对于两者结果有较大偏差的地方,分析该偏差出现的原因. 相似文献
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微力电系统中多层膜的端部应力集中 总被引:1,自引:0,他引:1
微电子技术的发展对其本身及封装的结构可靠性提出了更高的要求,微机械的出现又使得微电子-机械元器件的电学行为和力学行为密不可分,从而扩展成为一个统一的微力电系统,微力电系统的强度问题主要是多层膜在制造和使用过程中,由于不同材料热学与力学参量的失配引起的残余热应力,特别是在界面和端部的应力集中,本文应用有限元方法分析了在不同的端部几何形状和组合形状下,多层膜中应力沿界的分布,对于微电子元件在成型过程中 相似文献
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Common compliant joints generally have limited range of motion, reduced fatigue life and high stress concentration. To overcome these shortcomings, periodically corrugated cantilever beam is applied to design compliant joints. Basic corrugated beam unit is modeled by using pseudo-rigid-body method. The trajectory and deformation behavior of periodically corrugated cantilever beam are estimated by the transformation of coordinate and superposition of the deformation of corrugated beam units. Finite element analysis(FEA) is carried out on corrugated cantilever beam to estimate the accuracy of the pseudo-rigid-body model. Results show that the kinetostatic behaviors obtained by this method, which has a relative error less than 6%, has good applicability and corrugated cantilever beam has the characteristics of a large range of motion and high mechanical strength. The corrugated cantilever beam is then applied to design a flexible rotational joint to obtain a larger angle output. The paper proposes a pseudo-rigid-body model for corrugated cantilever beam and designed a flexible rotational joint with large angle output. 相似文献