Papers by Keyword: Metallic Foams

Abstract: Shaping materials containing porous constituents is a critical issue. This work analyses the process of abrasive water-jet (AWJ) cutting applied to low density metal matrix composites (LD.MMCs) consisting of AA7075 alloy as matrix and porous, foamed particles of SiO₂/Al₂O₃/Fe₂O₃ or vermicular SiO₂/Al₂O₃/MgO, as reinforcements. Results show that although presenting lower density (from 1.09 g/cm³ to 1.59 g/cm³, depending on the particle type) and lower strength than the non-reinforced AA7075 alloy, the composites present some difficulties in AWJ cutting. Deflection of the jet was noticed, being more evident on vermiculite-reinforced samples. Anyhow machinability numbers for the composites analyzed are in the order of 20% higher than the AA7075 matrix alone. Jet deflection, surface quality and machinability number showed to be dependent on the internal structure of the porous ceramic particles: vermiculite can pull out under the jet while cinasite is more susceptible to suffer fracture. This mechanisms result in lower jet deflection, better surface and better overall machinability in the case of AA7075 / cinasite LD.MMC.

Abstract: In case of metallic foams the stress-strain curve observed during uniaxial compression is often not smooth, expecting plateau is often missing, and the curve instead of slowly increasing stress before final densification takes place often exhibit a lot of peaks with even local stress drops. It is generally accepted that the origin of this behavior is linked to the heterogeneity and/or anisotropy of foams, ductility or brittleness of used matrix alloy and the presence of surface skin. This contribution is designed as a recipe for metal foam investigator how to handle the uniaxial compression test results on metallic foams. Aim of this contribution is to introduce engineers and researchers also to the unusual events that can occur during foam compression test.

Abstract: The investigation of the basic principles for the production of foamed out sections using magnesium foam for support structures by including the foaming process into the cold forming of sections to produce indiviually locally strengthened components is the subject of this research project. To absorb tensile stress, the metal foam will be strengthened with three-dimensional branched struts of high-tensile materials. The quantification of the influence of locally introduced foaming elements on e.g. stiffness alterations and the influence of the resonance frequency of the total structure will be effected by destructive but particularly also by nondestructive tests.

Abstract: This paper presents the focus of research and the structure of the Collaborative Research Centre SFB 675 “Creation of High-Strength Structures and Joints by setting up local material properties” funded in 2006 by the German Research Foundation (DFG).