International standards propose several methods for measuring thermal conductivity; however, they often require expensive experimental layouts and marginally consider the uncertainty in the estimation procedure. In this article, we propose a temperature transient method and a Bayesian procedure to estimate the thermal conductivity of a homogeneous mass, and to reproduce the entire temperature profile evolution over time by means of latent temperature data. To validate the approach, experiments are conducted giving heating and cooling cycles to a polymethyl methacrylate (PMMA) specimen. Results show the applicability of the proposed approach and good estimations.

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Abstract: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 OPEN ACCESSMetals 2012, 2 212 damping ratio only when small thickness steel frames are filled with either Hybrid APM or Alulight foam.