The mechanical behaviour of bamboo is greatly influenced by its transverse properties, which are not easily measured by experiment. This study develops a framework and the computational tools required to evaluate the material and mechanical properties of bamboo in its full-culm form. A numerical model of bamboo as a transversely isotropic material with functionally graded material properties in the radial direction is developed. The random field method was introduced as a means of quantifying the measured uncertainty of bamboo with respect to the mechanical characterisation of its full-culm state. Four increasingly complex approaches to model circumferential compression tests of bamboo are presented: a theoretical evaluation using Castigliano’s theorem; an orthotropic model neglecting the graded nature of the culm wall; and, two models—one discrete and one continuum-based that define a transversely isotropic graded material. Output from each model is compared, calibrated and validated with experimental results. While the models developed were robust, their application has drawn into question the fundamental hypothesis that the functionally graded behaviour of bamboo can be captured using the rule of mixtures.

中文翻译：

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将全秆竹建模为一种自然变化的功能分级材料

竹子的力学行为受其横向特性的影响很大，这些特性不容易通过实验测量。本研究开发了一个框架和计算工具，以评估竹子全秆形式的材料和机械性能。开发了竹子作为横向各向同性材料的数值模型，在径向方向上具有功能梯度材料特性。引入随机场法作为量化竹子全秆状态力学特性测量不确定度的一种手段。介绍了四种日益复杂的竹子圆周压缩试验模型方法：使用卡斯蒂利亚诺定理的理论评估；一个正交各向异性模型，忽略了秆壁的分级性质；和，两个模型——一个离散模型和一个基于连续体的模型，用于定义横向各向同性渐变材料。将每个模型的输出与实验结果进行比较、校准和验证。虽然开发的模型是稳健的，但它们的应用使竹子的功能分级行为可以使用混合物规则捕获的基本假设受到质疑。