Strain-rate effects in Ni/Al composite metal foams from quasi-static to low-velocity impact behaviour

• Published in: Composites. Part A, Applied science and manufacturing Applied science and manufacturing, 2016-06, Vol.85, p.1-11
• Main Authors: Jung, A., Pullen, A.D., Proud, W.G.
• Format: Article
• Language: English
• Subjects: A. Foams; A. Multifunctional composites; Aluminum; B. Impact behaviour; Coating; D. Mechanical testing; Foamed metals; Foams; Metal foams; Microstructure; Nickel; Plastic foam
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2016.02.031

Metal foams are used as absorbers for kinetic energy but predominantly, they have only been investigated under quasi-static load-conditions. Coating of open-cell metal foams improves the mechanical properties by forming of Ni/Al hybrid foam composites. The properties are governed by the microstructure, the strut material and geometry. In this study, the strain-rate effects in open-cell aluminium foams and new Ni/Al composite foams are investigated by quasi-static compression tests and low-velocity impact. For the first time, drop weight tests are reported on open-cell metal foams, especially Ni/Al composite foams. Furthermore, size-effects were evaluated. The microstructural deformation mechanism was analysed using a high-speed camera and digital image correlation. Whereas pure aluminium foams are only strain-rate sensitive in the plastic collapse stress, Ni/Al foams show a general strain-rate sensitivity based on microinertia effects and the rate-sensitive nano-nickel coating. Ni/Al foams are superior to aluminium foams and to artificial aluminium foams with equal density.