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.
Methods for Filling Hollow Structures with Aluminium Foam
Aluminium foams produced according to the powder metallurgical/foaming agent process are currently being used in several industrial sectors, such as automotive, rail transport or machine tools. Nevertheless there still is a high further application potential to be exploited. Especially in hybrid structures, e.g. in automotive structures that are locally filled with aluminium foam, great improvements regarding the energy absorption capacity and the sound absorption behaviour can be obtained. In the present paper several methods that allow for filling or local filling of hollow structures are investigated and presented. The effect of the foam filling on the energy absorption behaviour of the hybrid structure is discussed. Similar effects were also observed in compression tests on foam filled hollow profiles. The results of these investigations are presented.
EL TRATAMIENTO NEOPRAGMATISTA DE LA VERDAD EN RICHARD RORTY NEOPRAGMATIST TREATMENT OF TRUTH IN RICHARD RORTY
Richard Rorty, one of the most influential authors of our time, presents a critique of the philosophical concept of truth as correspondence. The conclusion of Rorty's neopragmatism is that the idea of truth as correspondence between language and facts is ineffective because it no longer works. The neopragmatist conception of truth indicates the only possible uses for the term «truthful,» revolving around the idea of jus - tification. In this article, the neopragmatist notion of truth is presented in order to