Non-linear response. Advance MUltiscale Strain-basED non-destructive evaluation of composite structures.
Advance MUltiscale Strain-basED non-destructive evaluation of composite structures
The AMUSED project aims to combine the strengths of multiple full-field optical measurement techniques for inspection of high value composite structures. The challenge is to apply techniques, traditionally tethered to the laboratory, in-situ on structures that potentially contain defects or damage.
Coupon tests where conducted to enable a correlation between surface response and underlying damage types to be assessed. This example shows a simulated fibre break.
Stinger & plate setup Mode 2
Natural frequency loading
Natural frequency loading enables large strains to be achieved with minimal excitation energy. This has been tested initially on a fully clamped plate excited at its first 3 modes.
X-ray CT slice PPT data
TSA (thermoelastic stress analysis) and PPT (pulsed phase thermography) have been used to inspect carbon fibre bridge repairs, based on the experience gained in the laboratory. The next phase is to test larger, representative aircraft components and to add DIC (digital image correlation) and ESPI (electronic speckle pattern interferometry) to the tool box, with the aim to develop a strategy for integrating the four techniques on a common platform.
Fluid Structure Interactions Research Group
Infrared sensing for materials characterisation and damage assessment
Dr. Richard Frühmann - [email protected] - School of Engineering Sciences
Supervisor – Prof. J. M. Dulieu-Barton
High Speed Material Characterisation
The mechanical response of a material to an applied load or strain is dependent on the rate at which a load or strain is applied. The behaviour of composite materials under high speed deformation, such as during collisions or foreign body impacts, is currently not well understood. IR thermography is being used to measure the heat generated during a high speed deformation to inform a full thermo-mechanical material characterisation.
Initial Composite Tests
The short exposure times required for the high speed imaging impose special calibration challenges because the detector operates in the non-linear response range. A pixel-wise detector calibration procedure has been developed to accommodate the non-linear detector response and implemented as a software module (shown right). In initial tests it has been possible to capture both the thermoelastic temperature decrease and the heat released at failure.