Rolls-Royce Nuclear, PO BOX 2000, Derby DE21 7XX, UK; UK Research Centre for NDE, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
Rolls-Royce Nuclear, PO BOX 2000, Derby DE21 7XX, UK.
Ultrasonics. 2014 Sep;54(7):1868-79. doi: 10.1016/j.ultras.2013.11.013. Epub 2013 Dec 12.
Commercially available Finite Element packages are being used increasingly for modelling elastic wave propagation problems. Demand for improved capability has resulted in a drive to maximise the efficiency of the solver whilst maintaining a reliable solution. Modelling waves in unbound elastic media to high levels of accuracy presents a challenge for commercial packages, requiring the removal of unwanted reflections from model boundaries. For time domain explicit solvers, Absorbing Layers by Increasing Damping (ALID) have proven successful because they offer flexible application to modellers and, unlike the Perfectly Matched Layers (PMLs) approach, they are readily implemented in most commercial Finite Element software without requiring access to the source code. However, despite good overall performance, this technique requires the spatial model to extend significantly outside the domain of interest. Here, a Stiffness Reduction Method (SRM) has been developed that operates within a significantly reduced spatial domain. The technique is applied by altering the damping and stiffness matrices of the system, inducing decay of any incident wave. Absorbing region variables are expressed as a function of known model constants, helping to apply the technique to generic elastodynamic problems. The SRM has been shown to perform significantly better than ALID, with results confirmed by both numerical and analytical means.
商业上可用的有限元软件包越来越多地被用于模拟弹性波传播问题。对更高性能的需求导致人们努力提高求解器的效率，同时保持可靠的解决方案。对无界弹性介质中的波进行高精度建模对商业软件包来说是一个挑战，需要从模型边界去除不需要的反射。对于时域显式求解器，通过增加阻尼的吸收层（ALID）已被证明是成功的，因为它们为建模人员提供了灵活的应用，并且与完全匹配层（PML）方法不同，它们可以很容易地在大多数商业有限元软件中实现，而无需访问源代码。然而，尽管整体性能良好，该技术需要将空间模型显著扩展到感兴趣域之外。在这里，开发了一种刚度降低法（SRM），它在显著减小的空间域内运行。该技术通过改变系统的阻尼和刚度矩阵来实现，从而诱导入射波的衰减。吸收区域变量表示为已知模型常数的函数，有助于将该技术应用于一般的弹性动力学问题。结果表明，SRM 的性能明显优于 ALID，数值和分析方法都证实了这一点。
