Determination of Dynamic Modulus of Syntactic and Particulate Foams by a Non‐Destructive Approach

Abstract

Abstract: Developments in aviation posed requirement of lightweight, high strength and highly damage‐tolerant materials. Sandwich‐structured composites fulfilling these requirements have become the first choice for many aerospace applications as well as structural components for ground transport and marine vessels. Sandwich composites are a special class of composite materials which are widely used because of their high specific strength and high bending stiffness. Syntactic foams, which are hollow particle‐filled core materials used in sandwich composites, have recently emerged as attractive material for applications requiring low weight, low moisture absorption and high insulation properties. Quasi‐static and dynamic properties of these syntactic foams are commonly determined though various destructive techniques such as quasi‐static compression and split Hopkinson pressure bar testing. However, there is a need for characterising these materials non‐destructively in the field. The present study focuses on the prediction of dynamic Young's modulus using ultrasonic testing in various types of hollow particle‐reinforced syntactic foam and solid particulate composites. Hollow particle‐filled syntactic foams and solid particulate composites are fabricated with three different volume fractions of 10%, 30% and 60%. Longitudinal and shear wave velocities are used for calculating the dynamic modulus. Effect of longitudinal attenuation behaviour along with longitudinal and shear wave velocities on the varying density and volume fraction of syntactic foams is also discussed.