Researchers at the University of Adelaide are developing a new system of electrical devices which can reveal any defects or damage in built structures by bouncing signals through them like ripples through water.
The devices, known as transducers, can either be embedded into the structure when it is built or bonded to the surface after construction. The data they collect is transferred to a control centre where it can be monitored online, around the clock, to ensure structural integrity at all times.
The low-cost technology, researchers say, should help improve public safety and significantly reduce the cost of maintenance and repair.
“It will allow us to talk to the structure to see whether there are any defects, where they are and, ultimately, provide detail about the shape of any damage and how extensive it is – just like someone going to the doctor for a health check,” says researcher Dr Alex Ng, a lecturer at the University of Adelaide’s School of Civil, Environmental and Mining Engineering.
Although the system has been developed primarily for structures made from high-tech materials called fibre-composite laminates, at present widely employed in the aerospace, construction, energy and transport sectors, it is also applicable to other structural materials such as steel.
“These composite materials are incredibly attractive for structural purposes because they are lightweight but extremely strong, with potentially significant energy efficiencies and better fuel consumption,” says Ng.
“For example, the new Boeing 787 Dreamliner is 80 per cent composite materials by volume. However, being a laminated material, it is difficult to accurately determine whether the internal layers are damaged without undertaking destructive testing. Developing cost-effective, non-destructive techniques will be of great value to these industries and for public safety.”
Ng said visual inspection is not enough to ensure a building is safe, citing the collapse in 2007 of the Minneapolis bridge in the US, which raised questions about inspection as well as design.
“Eventually Australia will face the same problem,” he said.
Ng, a member of the executive committee of Australian Network of Structural Health Monitoring, received an Australian Research Council (ARC) Discovery Early Career Researcher Award for this three-year project, which started this year.
“To date we’ve developed a laboratory system to generate the structural waves and receive back signals with some good preliminary results,” he said. “Right now we can only detect where the damage is. By the end of three years we aim to also know the size and shape of any defects, ultimately producing a detailed picture of the inside of the structure.”