Mechanical properties of sintered and non sintered stainless steel wools: experimental investigation and modeling
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1188-LL02-05
Mechanical properties of sintered and non sintered stainless steel wools: experimental investigation and modeling J.P.Masse1,2, O.Bouaziz2, Y.Brechet1, L.Salvo1 1 SIMaP, Grenoble INP, SIMAP groupe GPM2 101 rue de la physique, 38402 Saint Martin D’heres. 2 ArcelorMittal Research, Voie Romaine-BP30320, 57283 Maizières-lès-Metz Cedex, France ABSTRACT Entangled fibrous materials have a common point with cellular solids: the architecture is at the millimetric scale. However, they present one extra degree of freedom which is the connectivity on the constituents: while compressing a fibrous structure, the number of contacts between fibers is variable, by contrast to cellular solids where the building lock is the cell. In this respect, fibrous entangled solids can span a whole range of mechanical behavior depending on the possibility offered to fibers to create new contacts: from the felt where they are totally free, to the fully sintered wool where their relative motion is constrained by irreversible contacts. The purpose of this paper is to investigate the mechanical properties of this class of materials, based on micro tomography observations for the number of contacts, and on a physically based model for fiber bending and collective reorganization. The material studied is a stainless steel wool. The properties investigated are the loading curves for sintered and non sintered wools. Qualitative differences introduced by sintering motivate a modification of the classical Toll model, which will be presented together with the experimental results. INTRODUCTION Entangled materials, consisting of fibers, exist from natural material (mutton wool, cotton) as well as artificial one (steel wool, glass wool, felts …). They find applications in thermal insulation, mechanical reinforcement and filtration. However, their mechanical properties are very low compared with traditional cellular materials made from the same constitutive material, and with a similar density. One way to gain a better mechanical behavior is to create permanent bonds between fibers by means of sintering. Conventional sintering consists in the heating the material in a furnace; final density and mechanical properties depend on the sintering time and temperature [1]. The properties of these materials depend on the relative density, their constitutive material, the quality of the contact created, but also on the architectural parameters (fibers orientation, number of contacts). Mechanical properties of these materials (sintered mats of fibers [2] or 3D random bonded fibers [3]) were characterized in compressive test, as it can be done with usual cellular materials [4]. Analytical models [5,6] obtained by dimensional analysis allow to get scaling laws where the compression stress and density are related by a power law relationship. These scaling laws were recently confirmed by discrete 3D simulations [7] and they are well adapted to entangled materials. The aim of this work is to relate mechanical properties in compression of non sintered and sintere
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