A Non-Destructive Method for Evaluation of the Out of Plane Elastic Modulus of Porous and Composite Materials
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A Non-Destructive Method for Evaluation of the Out of Plane Elastic Modulus of Porous and Composite Materials F. Bucciarelli 1 & G. P. Malfense Fierro 1 & M. Zarrelli 2 & M. Meo 1 Received: 14 November 2018 / Accepted: 12 December 2018 / Published online: 26 January 2019 # The Author(s) 2019
Abstract This paper presents an effective and reliable non-destructive method to measure the Young Modulus of porous and out of plane Young Modulus of composite materials using sound waves. First, a Finite Element Model based on Representative Volume Element (RVE) is developed to demonstrate how the elastic properties of composite material can be estimated by acoustic measurements using an impedance tube test rig. Second, the results of the experimental measurement campaign was carried out to validate the proposed method. In particular, two soft elastic foams with different density, an epoxy-carbon fibre composite and vynilesterglass fibre composite were tested. In the proposed method, a two-microphone impedance tube setup was used where the measured acoustic pressures at two upstream locations allowed the estimation of the reflection coefficient and the acoustic impedance of the tested materials. Since the acoustic impedance can be expressed as a function of the longitudinal speed of sound (assuming a plane standing wave excitation), the elastic modulus can be estimated which is associated with the speed of sound. The elastic modulus measured using the proposed method were in good agreement with the values obtained by the standard methods such as tensile tests and ultrasound time of flight measurements. The proposed method would allow in an accurate and fast manner the non-destructive evaluation of Young Modulus of porous materials and for the first time the proposed approach is applied successfully to the measurement of out of plane Young modulus of composite materials. Keywords Elastic Modulus . Sound waves . Impedance . RVE
1 Introduction The rapid assessment of the elastic properties of materials has never been more prevalent than today, due to the acceleration in material development. Advancement of material technology
* M. Meo [email protected]
1
Department of Mechanical Engineering, University of Bath, Bath, UK
2
Institute of Polymers, Composites and Biomaterials, Naples, Italy
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Applied Composite Materials (2019) 26:871–896
has expanded the number of materials and applications for which these materials can be used. In particular, carbon fibre reinforced polymers (CFRP) have given way to a wide variety of complex materials with material characteristics that vary according to use. For example, CFRP applications range from a very specific highly technology environments (aerospace, Formula 1 and nuclear) to mass market applications (sport equipment, automotive and energy applications). At the same time the advent of commercial 3D printing has added a wide variety of materials that can be customised for a specific use, with highly varying material properties. A further area of interest is the characterisation of b
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