Dynamic Behavior of Hybrid APM (Advanced Pore Morphology Foam) and Aluminum Foam Filled Structures
The aim of this work is to evaluate the effect of different densities of hybrid aluminum polymer foam on the frequency behavior of a foam filled steel structure with different ratios between steel and foam masses. The foam filled structure is composed of three steel tubes with a welded flange at both ends bolted together to form a portal grounded by its free ends. Structure, internal and ground constraints have been designed and manufactured in order to minimize nonlinear effects and to guarantee optimal constraint conditions. Mode shapes and frequencies were verified with finite elements models (FEM) to be in the range of experimental modal analysis, considering the frequency measurement range limits for instrumented hammer and accelerometer. Selected modes have been identified with suitable modal parameters extraction techniques. Each structure has been tested before and after filling, in order to compute the percentage variation of modal parameters. Two different densities of hybrid aluminum polymer foam have been tested and compared with structures filled with aluminum foams produced using the powder compact melting technique. All the foam fillings were able to suppress high frequency membrane modes which results in a reduction of environmental noise and an increase in performance of the components. Low frequency modes show an increase in damping ratio only when small thickness steel frames are filled with either Hybrid APM or Alulight foam.
Endurance of Damping Properties of Foam-Filled Tubes
The favorable energy-absorption properties of metal foams have been frequently proposed for damping or anti-crash applications. The aim of this paper is to investigate the endurance of these properties for composite structures, made by a metal or a hybrid metal-polymeric foam used as the core filling of a tubular metal case. The results of experimental tests are shown, run with two types of structures: 1) square steel tubes filled with aluminum or with hybrid aluminum-polymer foams; 2) round titanium tubes filled with aluminum foams. The paper shows that the damping properties of a foam-filled tube change (improve) with the number of cycles, while all other dynamic properties are nearly constant. This result is very important for several potential applications where damping is crucial, e.g., for machine tools.
Optimisation of energy absorption of an A-pillar by metal foam insert
Abstract The potential of increasing the energy absorption of a CD car A-pillar by an aluminium foam insert was investigated numerically. Physical aluminium foam inserts were produced by the powder metallurgical route on the basis of the numerically optimised geometry, density and location of the foam filler. The manufactured foam inserts were then bonded to the interior of original Ford CD car A-pillars. A central aspect in the investigation was to keep the prototype manufacture compatible with the production line, and the test specimens were therefore assembled at a real production line. The produced foam-based A-pillars were then tested for quasi-static loading conditions. The tests confirmed the numerical simulations by a gain in energy absorption of 30% at the cost of a mere 3% mass increase. The study shows a successful approach to bridge virtual development, foam-insert manufacture and production-line compatibility with the desired structural performance.