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RELIM: Reliable Methods to Inspect Carbon Fibre Reinforced Plastic Composites

on 02-09-2019

... Aging aircrafts, transmission pipelines, bridges, railways, power plants and other large sections of our civilian and defense infrastructure are known to have far exceed their design lifetime. This has driven to an increasing demand of novel non-destructive evaluation (NDE) systems. NDE is an important research area that comprises the development of technologies and methodologies for assessing the structural integrity of critical materials, components and structures without affecting its future usefulness.

Gathering researchers from the Instrumentation and Measurements group, the Applied Electromagnetics group and the Optical Networking group, under the coordination of Helena Ramos, this internal IT project intended to increase accuracy and reliability to the inspection procedure by integrating complementary information obtained with two NDE techniques. The aim was to propose novel methods that push the state of art in NDE with a goal to monitor, detect and characterize hidden damage in carbon fiber polymer reinforced (CFRP) composites.

CFRP materials are increasingly being used in structures due to their lighter weight and improved strength, when compared to metals, in addition to their capability to be readily formed into custom shapes to meet unique requirements. However, NDE techniques have been problematic to employ in these new materials.

The RELIM research team joined two complementary NDE techniques: eddy current testing (ECT) and guided wave ultrasonic testing (GWUT). These two techniques were chosen, not only because they are complementary, but also because GWUT possesses propagation capabilities that enable inspection to be carried out with reduced scanning, allowing detection of damages in hidden parts of the structure or with difficult access. In addition, the use of tiny piezoelectric as sensors and actuators with GWUT is foreseen as a step forward in the direction of the development of a Structural Health Monitoring (SHM) evaluation. It is expected that in the near future, SHM shall bring huge costs and safety savings to different industries.

Photo: Locating real time impacts with PZT transducers in CFRP plates. After dropping the impactor through a tube, the guided wave signals obtained by the four PZTs are acquired by the digital oscilloscope.