Validation experiments on finite element models of an ostrich (Struthio camelus) cranium.
Validation experiments on finite element models of an ostrich (Struthio camelus) cranium.
复制标题
对鸵鸟（Struthio Camelus）颅骨有限元模型的验证实验。
作者：
Cuff AR;Bright JA;Rayfield EJ
第一次有限元（FE）验证一个完整的鸟类头盖骨上现存的古颚，鸵鸟（Struthio骆驼）。从颅骨和rhamphotheca收集离体菌株。然后将这些实验应变与经过收敛性测试的特定有限元（FE）模型进行比较。FE模型包含从micro-CT扫描数据中识别的分段皮质骨和松质骨、缝线和角化钩鞘。根据文献或纳米压痕，为每种材料分配各向同性材料特性，并将FE模型与离体结果进行比较。有限元模型通常复制峰值应变的位置，并反映喙部区域的正确变形模式。该模型在实验记录的高应变区域中过于刚性，而在实验记录的低应变区域中过于弹性。FE模型无法复制低应变颅神经区域的变形模式，尽管模型在某些区域复制了10°以内的应变方向，但在大多数区域，相关性并不强。颅缝，如以前在其他类群中发现的，是重要的修改应变幅度和应变模式在整个头骨，但特别是相对缝交界处之间。在实验中，我们发现，在rhamphotheca表面的应变远低于附近的骨骼。有限元模型产生更高的主应变，尽管类似的应变比在整个rhamphotheca。这项研究强调了尝试验证FE模型，模拟鸟类缝线和rhamphothecae的重要性，并表明，虽然峰值应变和变形模式的位置可以建模，但在鸟类颅骨的数字模型中复制实验数据仍然存在问题。
The first finite element (FE) validation of a complete avian cranium was performed on an extant palaeognath, the ostrich (Struthio camelus). Ex-vivo strains were collected from the cranial bone and rhamphotheca. These experimental strains were then compared to convergence tested, specimen-specific finite element (FE) models. The FE models contained segmented cortical and trabecular bone, sutures and the keratinous rhamphotheca as identified from micro-CT scan data. Each of these individual materials was assigned isotropic material properties either from the literature or from nanoindentation, and the FE models compared to the ex-vivo results. The FE models generally replicate the location of peak strains and reflect the correct mode of deformation in the rostral region. The models are too stiff in regions of experimentally recorded high strain and too elastic in regions of low experimentally recorded low strain. The mode of deformation in the low strain neurocranial region is not replicated by the FE models, and although the models replicate strain orientations to within 10° in some regions, in most regions the correlation is not strong. Cranial sutures, as has previously been found in other taxa, are important for modifying both strain magnitude and strain patterns across the entire skull, but especially between opposing the sutural junctions. Experimentally, we find that the strains on the surface of the rhamphotheca are much lower than those found on nearby bone. The FE models produce much higher principal strains despite similar strain ratios across the entirety of the rhamphotheca. This study emphasises the importance of attempting to validate FE models, modelling sutures and rhamphothecae in birds, and shows that whilst location of peak strain and patterns of deformation can be modelled, replicating experimental data in digital models of avian crania remains problematic.