Industrial composites |
Many materials today can be purpose-engineered to suit the task they will perform. For example, concrete can be reinforced with metal rods for tensile strength, or resin combined with carbon nanotubes to improve strength-to-weight ratios. Materials created in this way, from two or more parts, are known as composites and are widely used throughout industry.
One particular type of composite studied by our research group comprises microspheres embedded in a rubber-like host medium. These materials are frequently known as syntactic foams. The microspheres are hollow and can be made from either glass or a thermoplastic. They are of the order of 10-100 microns in diameter, with a shell wall-thickness typically around 100-300nm. The use of microspheres in materials brings forth numerous benefits which include a lower density, improved stability, increased impact strength, a smoother surface finish, greater thermal insulation, tailored acoustic properties and often a reduced cost.
The application of most interest to our group is that of acoustics, using microsphere composites as a means of reducing or modifying sound reflection. More specifically, we investigate how this sound reflection can be affected by pressure applied to the composite. Microsphere composites have been found to be useful under high pressure because the presence of shells reinforces the cavities, delaying cavity collapse and the consequent degradation in the acoustic performance of the composite. In order to understand exactly how the acoustic characteristics of the material are affected by pressure, we develop models that describe how the composite deforms mechanically under loading.
One particular type of composite studied by our research group comprises microspheres embedded in a rubber-like host medium. These materials are frequently known as syntactic foams. The microspheres are hollow and can be made from either glass or a thermoplastic. They are of the order of 10-100 microns in diameter, with a shell wall-thickness typically around 100-300nm. The use of microspheres in materials brings forth numerous benefits which include a lower density, improved stability, increased impact strength, a smoother surface finish, greater thermal insulation, tailored acoustic properties and often a reduced cost.
The application of most interest to our group is that of acoustics, using microsphere composites as a means of reducing or modifying sound reflection. More specifically, we investigate how this sound reflection can be affected by pressure applied to the composite. Microsphere composites have been found to be useful under high pressure because the presence of shells reinforces the cavities, delaying cavity collapse and the consequent degradation in the acoustic performance of the composite. In order to understand exactly how the acoustic characteristics of the material are affected by pressure, we develop models that describe how the composite deforms mechanically under loading.
- R De Pascalis, I David Abrahams, WJ Parnell. Predicting the pressure–volume curve of an elastic microsphere composite. Journal of the Mechanics and Physics of Solids 61 (4), 1106–1123.