Dynamic Mechanical Behavior of Reinforced Cork Agglomerate

Abstract

Agglomerated cork is today mainly used for its thermal insulation and acoustic properties. As cork is a cellular material, its absorbing properties at a dynamic regime are being considered for impact-absorbing applications as core material in sandwich structures. Therefore an optimization of this material would allow to strengthen its present applications and open new ones. Ranging from the container for the transport of sensible pieces to sports items and including lightweight aeronautic components, a wide range of applications is foreseen. Cork agglomerates with and without reinforcements at a quasi similar density were studied to compare their mechanical performances. This paper investigates the effect of these foreign reinforcements on the properties of agglomerated cork under a dynamic loading. The material behavior has been determined as a function of two parameters, charge presence and strain rate. The microstructure was first observed through optical and scanning electronic microscopy, spotting charges between each cork bead. The characterization of cork at different strain rates was then carried out. Agglomerated cork was tested on two specific machines. An electromechanical testing machine has been used to apply an uni-axial compression for quasi- static strain rates. These results were completed by those obtained with a specific set- up for the high strain rates assays allowing almost constant loading speed. Results depending on the presence of charges at different strain rate regimes were obtained. Elastic modulus were compared afterward. Young’s modulus increased between 22 and 36% for reinforced samples depending on the strain rate.