An ultralight graphene oxide (GO)/polyvinyl alcohol (PVA) aerogel (GPA) is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and sound transmission losses. The interaction between GO sheets and PVA molecules is exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffold. The aerogels possess an enhanced ability to dissipate sound energy, with an extremely low density of 2.10 kg m−3, one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimised the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times on acoustic properties and assessed the relationships between the acoustic and non-acoustic properties of the materials. Over the 400–2500 Hz range, the reported average sound absorption coefficients are as high as 0.79, while the average sound transmission losses can reach 15.8 dB. We envisage that our subwavelength thin and light aerogel-based materials will possess other functional properties such as fire resistance and EMI shielding, and will prove to be novel acoustic materials for advanced engineering applications.

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Self-healing composites using a thermally mendable polymer based on Diels-Alder reaction were fabricated and subjected to various multiple damage loads. Unlike the traditional destructive methods, this work presents a nonlinear ultrasound technique to evaluate the efficiency of the structural recovery of the proposed self-healing laminate structures. The results were compared to Computer Tomography (CT) and linear ultrasound methods. The laminates were subjected to multiple loading/healing cycles and the extent of damage at each of these stages was evaluated using various NDT/E techniques. The results highlight the benefit and added advantage of the use of a nonlinear based methodology to monitor the structural recovery of self-healing composites.

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An ultralight Graphene Oxide/Polyvinyl Alcohol (GO/PVA) aerogel is proposed as a new class of acoustic materials with tuneable and broadband sound absorption and transmission loss. The interaction between GO sheets and PVA molecules are exploited in our environmentally friendly manufacturing process to fabricate aerogels with hierarchical and tuneable porosity embedded in a honeycomb scaffolding. The developed aerogels show an enhanced dissipation of sound energy, with an extremely low density of 2.10 kg m-3 , one of the lowest values ever reported for acoustic materials. We have first experimentally evaluated and optimized the effects of composition and thickness on the acoustic properties, namely sound absorption and sound transmission losses. Subsequently, we have employed a semi-analytical approach to evaluate the effect of different processing times and find the relationships between the acoustic and non-acoustic properties of the materials. Over the 400 – 2500 Hz range, the reported average sound absorption coefficients are as high as 0.79 for low density aerogels, while the average sound transmission losses can reach 15.8 dB for higher density aerogels. We envision our subwavelength aerogel-based design, tailored at achieving optimal acoustic performance, as a novel lightweight material for advanced engineering applications.