Novel Speed of Sound Sensor
ACMC in partnership with Valeport, Totnes
Valeport was established in 1969 with a small product range based around the 'Braystoke' impeller flow meters. Since then, the company has grown considerably with products covering many aspects of environmental, river, estuarine, coastal, hydrographic and oceanographic instrumentation, and a customer base that includes many leading academic, research and commercial organisations throughout the world. The company’s product range includes tide gauges, wave recorders, current meters and sound velocity sensors and profilers.
Sound velocity sensors use ‘time of flight’ technology. For accurate and stable operation in a variety of environments, materials are required with minimum thermal expansion. Invar superalloys are commonly used, having a coefficient of thermal expansion of around 1/10 of carbon steel. However, like all metal alloys, it suffers from corrosion, expecially in a marine environment.
High strength carbon fibres have close to zero (or even negative) thermal expansion. When combined with epoxy resin in pultruded form, a corrosion-resistant, stable material becomes an appropriate substitute for metal.
ACMC advised Valeport on materials selection, and conducted FEA to support laboratory measurements of thermal expansion coefficient in stock pultruded rod. We developed a complete assembly and bonding procedure for the new product.
FEA of thermal expansion using Strand7 software