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Finite element modelling of shot peening and peen forming processes and characterisation of peened AA2024-T351 aluminium alloy.

机译:喷丸和喷丸成形过程的有限元建模以及AA2024-T351铝合金的特征化。

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摘要

The main purpose of this thesis was to develop and validate finite element (FE) simulation tools for shot peening and peen forming. The specific aim was to achieve quantitatively accurate predictions for both processes and demonstrate the potential of reliable FE modelling for scientific investigation and industrial applications.;First, an improved dynamic impact model that takes into account the stochastic nature of shot peening was proposed by carefully studying its dimensions, introducing a dispersion of shot sizes and significantly reducing its computational cost. In addition, cyclic mechanical testing was conducted to define a suitable material constitutive theory for aluminium alloy (AA) 2024-T3/T351 subjected to shot peening. By combining a realistic shot peening model with an appropriate material law, fairly good residual stress predictions were achieved for three different sets of shot peening parameters.;Second, an experimental and numerical characterization of AA2024-T351 shot peened with parameters representative of fatigue life improvement applications was conducted. Multiple techniques, such as micro-indentation, residual stress determination and electron backscatter diffraction, were combined to gain a better understanding of the influence of shot peening on the material. The potential uses of finite element simulation to complement experimental data were also studied. The material heterogeneity arising from the random impact sequence was investigated and it was found that the impact modelling methodology could provide useful information on such heterogeneities.;Third, a novel peen forming simulation methodology was introduced. The impact model provided the necessary input data as part of a multiscale approach. Numerically calculated unbalanced induced stress profiles were input into shell elements and the deformed shape after peen forming was computed as a springback analysis. In addition, a simple interpolation method was proposed to model the incremental nature of peen forming in a computationally efficient manner. The process was therefore simulated as a series of springback analyses. This approach was first validated using data from small-scale experimental trials.;The potential effect of sheet orthotropy was then investigated numerically and experimentally. This factor could have a significant influence in industrial applications since peen formed components usually originate from rolled sheets and plates. The orientation of the rolling direction was found to have a significant effect on resulting curvatures for small AA2024-T3 sheets. The experimentally determined orthotropic elastic properties and initial stress state of the samples were input into forming simulations and numerical results correlated well with small-scale experimental data for one of the two sets of peening parameters under study.;The modelling methodology was improved further so as to take into account the trajectory of the peening nozzle. This led to a more realistic representation of actual peen forming procedures used for large components, which require moving peening equipment over the surfaces. The peening trajectory and boundary conditions considered in small-scale tests led to complex distributions of radius of curvature and FE simulations correctly predicted the experimentally observed trends.;Finally, the potential applications of the novel simulation strategy were demonstrated by simulating peen forming of typical wing skin panels. The modelled components had realistic features such as variable thicknesses and integral stiffeners and were subjected to multiple representative peen forming treatments using different shot types. (Abstract shortened by UMI.).
机译:本文的主要目的是开发和验证用于喷丸处理和喷丸成形的有限元(FE)仿真工具。具体目标是对这两个过程都实现定量准确的预测,并证明可靠的有限元建模在科学研究和工业应用中的潜力。首先,通过认真研究,提出了一种改进的动态影响模型,该模型考虑了喷丸的随机性它的尺寸,分散了镜头大小,并显着降低了计算成本。另外,进行了循环机械测试以定义适用于经受喷丸处理的铝合金(AA)2024-T3 / T351的材料本构理论。通过将现实的喷丸处理模型与适当的材料定律相结合,对三组不同的喷丸处理参数获得了相当不错的残余应力预测。第二,对具有改善疲劳寿命的参数的AA2024-T351喷丸处理进行了实验和数值表征进行了申请。结合了多种技术,例如微压痕,残余应力确定和电子反向散射衍射,可以更好地了解喷丸处理对材料的影响。还研究了有限元模拟在补充实验数据方面的潜在用途。对随机冲击序列产生的材料异质性进行了研究,发现该冲击建模方法可以为此类异质性提供有用的信息。作为多尺度方法的一部分,影响模型提供了必要的输入数据。数值计算的不平衡感应应力分布被输入到壳单元中,并计算出喷头成形后的变形形状作为回弹分析。此外,提出了一种简单的插值方法,以计算有效的方式对喷头成形的增量特性进行建模。因此,将该过程模拟为一系列回弹分析。首先使用小规模实验数据验证了该方法。然后,通过数值和实验研究了板正交异性的潜在影响。这个因素在工业应用中可能会产生重大影响,因为尖锐的成型部件通常源自轧制板和板。发现对于小的AA2024-T3板,轧制方向的取向对所得的曲率具有显着影响。将实验确定的正交各向异性弹性特性和样品的初始应力状态输入到成形模拟中,并将数值结果与正在研究的两组喷丸参数之一的小规模实验数据很好地关联。;对建模方法进行了进一步改进,以便考虑到喷头的轨迹。这导致了用于大型部件的实际喷头成形程序的更真实的表示,这需要在表面上移动喷丸设备。小规模试验中考虑的喷丸轨迹和边界条件导致曲率半径的复杂分布,有限元模拟正确地预测了实验观察到的趋势。最后,通过模拟典型机翼的尖锐成形,证明了该新型模拟策略的潜在应用皮肤面板。建模的组件具有逼真的功能,例如厚度可变和整体加劲,并使用不同的压射类型进行了多次代表性的喷头成形处理。 (摘要由UMI缩短。)。

著录项

  • 作者

    Gariepy, Alexandre.;

  • 作者单位

    Ecole Polytechnique, Montreal (Canada).;

  • 授予单位 Ecole Polytechnique, Montreal (Canada).;
  • 学科 Engineering Mechanical.;Engineering Materials Science.;Applied Mechanics.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 275 p.
  • 总页数 275
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:43:11

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