Linking Mesoscopic and Macroscopic Aspects of Inclined Self-Weight Sandwich Beams with Functionally Graded Porous Cores Under Moving Loads

Abstract

The surging interest in porous lightweight structures has been witnessed in recent years to pursue material innovations in broad engineering disciplines for sustainable developments and multifunctional proposes. Functionally graded (FG) porous composites represent a novel way to adjust mechanical characteristics by controlling the porosity distributions. However, the further advance in this field is challenged by the scale gap between mesoscopic and macroscopic aspects of porous structural analysis, i.e. how the local cellular morphologies impact the overall behaviors. The purpose of this paper is to bridge this gap by conducting a theoretical investigation on the performance of inclined self-weight sandwich beams with FG porous cores, where Young’s modulus is obtained with representative volume elements (RVEs) in a multiscale modeling study and depends on the cellular morphologies: average cell size and cell wall thickness. The material properties of closed-cell steel foams are adopted in a two-step assessment on target beams, including a static calculation to examine their bending deformations under gravitational loading which are then imported into a forced vibration analysis considering constant and harmonic moving forces. Timoshenko beam theory is used to establish the displacement field, while Ritz and Newmark methods are employed to solve the governing equations in terms of bending, free vibration, and forced vibration. The inclined beams are assumed to rest on a Pasternak foundation, and the corresponding structural responses can be determined based on the specific cell size and cell wall thickness, of which the effects are quantitatively revealed: the stiffness degradation induced from cellular morphologies increases the dynamic deflections, while the corresponding self-weight static deformations are reduced and the fundamental natural frequencies are raised. The influence from geometrical, boundary, and foundation conditions is also discussed to provide a comprehensive overview. This will be valuable for engineers to develop devisable foam-based load-carrying components with enhanced properties.