Abstract

Functionally graded materials are an advanced type of composite materials whose properties’ spatial evolution can be designed through the definition of the spatial distribution of the constituent phases’ mixture. This feature is particularly important if specific non-homogeneous properties’ requirements are required without introducing abrupt phases’ transitions, as happens in laminated materials. Porosities’ distributions within these materials, may constitute a design requisite for some applications, such as medical implants, but can also be highly undesirable in other cases such as for aeronautical applications. Regardless the specific situation, its characterization is of high importance to the prediction of the resulting materials’ behavior.

This work is focused on the static and free vibrations’ analysis of a sandwich plate with a porous aluminum foam core and outer aluminum skins. The porosities’ distribution is modeled by different fitting functions, based on data obtained from a preliminary image processing stage of X-ray CT image of the sandwich plate’ cross-section. A layerwise approach is considered for subsequent numerical simulations’ purpose, where the sandwich skins’ kinematics are modeled using the first order shear deformation theory, while the core is modeled by a higher order shear deformation theory. Fitting functions’ influence on the plate’ behavior is also assessed.

摘要

功能梯度材料是一种先进的复合材料，其性质的空间演变可以通过定义组成相混合物的空间分布来设计。如果需要特定的非均质特性要求而不引入突然的相转变，这一特征就特别重要，就像在层压材料中发生的那样。这些材料中的孔隙率分布可能构成某些应用（例如医疗植入物）的设计要求，但在其他情况下（例如航空应用）也可能是非常不希望的。无论具体情况如何，其表征对于预测所得材料的行为都非常重要。

这项工作的重点是对具有多孔铝泡沫芯和外铝皮的夹层板进行静态和自由振动分析。基于从夹层板横截面的 X 射线 CT 图像的初步图像处理阶段获得的数据，通过不同的拟合函数对孔隙率分布进行建模。后续数值模拟的目的考虑采用分层方法，其中夹层蒙皮的运动学使用一阶剪切变形理论建模，而核心则使用更高阶剪切变形理论建模。还评估了拟合函数对板行为的影响。