Fatigue crack propagation in cellular metals

摘要: Abstract Two types of cellular metals were investigated: a closed-cell aluminium foam with cell size about 3.5 mm and densities ranging from 0.25 to 0.40 g/cm 3 hollow sphere structures made stainless steel (316L) sizes 2 4 mm density 0.3 g/cm . Fatigue fatigue crack propagation tests performed on these materials using an electro-dynamic resonance testing machine. The extension was monitored by potential drop technique. Additionally, investigations carried out inside the scanning electron microscope (SEM) in situ loading device. All accompanied local deformation measurements fracture surface analyses. From it is evident that show relatively high Paris-Exponent m range 6 25 compared common ductile solid metals. Additional estimate influence closure, bridging micro cracking d /d N versus Δ K curve for materials. analyses revealed difference mechanisms between structure: contiguous can be found, where case structure concentrated vicinities sintering necks.