Previously reported measurements of uniaxial compression of cellular acoustic materials have shown an intriguing loss of stiffness in the regions close to the boundaries. The present contribution attempts to further investigate if these effects may be modelled by assuming a local alteration of the microstructure in these regions close to the boundaries resulting from cutting a block of material into smaller samples. Assuming that fewer struts contribute locally to the mechanical behaviour, implies a reduced equivalent porosity, or relative density, in the boundary region. The approach explored here consists in randomly removing a portion of the struts constituting the microstructure of the cells because of damage incurred in the cutting process. The analysis is performed using a linear elastic deformation behaviour at the boundary of cellular acoustic materials.

For the modelling of the microstructure, the Kelvin cell geometry is chosen. Applying the assumption that struts are damaged in the process of cutting a block of material into smaller samples, as an explanation for the observed high-strain boundary regions, it is shown that the experimental observations may be qualitatively reproduced. It is also shown that the equivalent density in the boundary regions may be estimated from the ratio of the boundary compressive modulus to that of the interior region of the sample. Through the presented results, the approximation errors in compression stiffness measurements performed for a real material may be estimated. Although providing a viable explanation of the experimentally observed behaviour of the boundary regions, it should be understood that the proposed approach primarily offers a simple, accurate equivalent description of this phenomenon.

以前报道的蜂窝状声学材料单轴压缩的测量结果表明，在靠近边界的区域中，刚度引起了极大的损失。本贡献试图进一步研究是否可以通过假设这些材料的微观结构在靠近边界的区域中发生局部改变而建模，这些改变是由于将一块材料切成较小的样本而引起的。假设较少的支杆局部地影响机械性能，则意味着边界区域的等效孔隙率或相对密度降低。此处探讨的方法是，由于切割过程中的损坏，会随机地去除一部分组成细胞微结构的支柱。

对于微观结构的建模，选择开尔文单元的几何形状。假设在将一块材料切成较小的样本时会损坏支撑杆，作为对观察到的高应变边界区域的解释，这表明实验观察结果可以得到定性的再现。还显示出边界区域中的等效密度可以根据样品的边界压缩模量与内部区域的模量之比来估算。通过呈现的结果，可以估计对真实材料执行的压缩刚度测量中的近似误差。尽管提供了对边界区域的实验观察到的行为的可行解释，但应该理解，所提出的方法主要提供了一种简单，