具有薄外壁的闭孔泡沫铝棒的弯曲行为

Bending Behavior of Closed-Cell Aluminum Foam Bar with Thin Outer Wall

摘要:

通过熔融发泡法制备了具有薄外壁的铝泡沫棒（aluminum foam bar，AFB）。通过悬臂梁弯曲实验和有限元模拟研究了跨度、直径和孔隙率对其弯曲变形行为的影响。采用高速摄像机记录了AFB的弯曲变形行为，并得到了载荷和位移之间的关系。基于三维有限元的X射线微断层扫描技术（Micro-CT）重建AFB，并进行了数值模拟。结果表明，跨度对破坏行为有重要影响，跨度的增加导致了能量吸收能力下降。此外，直径和相对密度的增加也使得峰值载荷提高。有限元模拟结果与实验结果相吻合，这说明孔壁在弯曲过程中由于不同类型的应力而失效。在失效过程中，裂纹遵循孔壁最薄弱的路径传播。

Abstract:

Aluminum foam bar (AFB) with thin outer wall was prepared by melt foaming method. The effect of span, diameter and porosity on its bending deformation behavior was investigated by cantilever beam bending experiment and finite element simulation. Bending deformation behavior was recorded by high-speed camera and the relationship between load and displacement was obtained. X-ray micro-computer tomography (Micro-CT) technique based on 3D finite elements was selected to scan and to reconstruct AFB, by which numerical simulation was carried out. The results show that span has important effect on the failure behavior and the increased span leads to decreased energy absorption capacity. In addition, increased diameter and relative density contribute to peak load improvement. Finite element simulation results match well with the experimental results, which clarifies that cell walls fail due to different types of stress during the bending process. Crack propagation follows the weakest cell walls path link during the failure process.