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The time difference of arrival (TDOA) method has traditionally proven effective for locating acoustic emission (AE) sources and detecting structural defects. Nevertheless, its applicability is constrained when applied to anisotropic materials, particularly in the context of fiber-reinforced composite structures. In response, this paper introduces a novel COmposite LOcalization using Response Surface (COLORS) algorithm based on a two-step approach for precise AE source localization suitable for laminated composite structures. Leveraging a response surface developed from critical parameters, including AE velocity profiles, attenuation rates, distances, and orientations, the proposed method offers precise AE source predictions. The incorporation of updated velocity data into the algorithm yields superior localization accuracy compared to the conventional TDOA approach relying on the theoretical AE propagation velocity. The mean absolute error (MAE) for COLORS and TDOA were found to be 6.97 mm and 8.69 mm, respectively. Similarly, the root mean square error (RMSE) for COLORS and TODA methods were found to be 9.24 mm and 12.06 mm, respectively, indicating better performance of the COLORS algorithm in the context of source location accuracy. The finding underscores the significance of AE signal attenuation in minimizing AE wave velocity discrepancies and enhancing AE localization precision. The outcome of this investigation represents a substantial advancement in AE localization within laminated composite structures, holding potential implications for improved damage detection and structural health monitoring of composite structures. [ABSTRACT FROM AUTHOR]

Composite manufacturing demands mould tooling to produce dimensionally accurate parts, adding substantial capital costs to their production. Recent developments in advanced manufacturing of fibre-reinforced polymer composite elements have seen the implementation of mould-free technologies that can produce complex shaped parts off a flat tool. This paper presents eccentric fibre prestress as a novel mould-free method for producing curvatures within carbon fibre and glass fibre laminates. Tailoring the flexural rigidity along the primary orientation of the laminate is shown to result in predictable compound curvature profiles with a low average root mean square error of 1.39 across the four geometries tested. An analytical model based on Euler–Bernoulli beam theory is proposed and proven to correlate closely with the experiential laminates. Finally, an inverse design approach based on a genetic algorithm is demonstrated to design an accurate laminate configuration, achieving the top surface of a NACA 4412 aerofoil section with a low root mean square error of 1.98 using the proposed eccentric fibre prestress. [ABSTRACT FROM AUTHOR]

A strain profile measurement technique using a chirped fibre Bragg grating (CFBG) sensor by implementing an integration of differences (IOD) method is reported in this paper. Using the IOD method the spatial distribution of strain along the length of the CFBG is extracted from its power reflectance spectra. As a proof of concept demonstration, the developed technique is applied to measure the polymerisation shrinkage strain profile of a photo-cured polymer dental composite which exhibits a non-uniform strain distribution attributed to the curing lamp characteristics. The result from the CFBG technique is compared with that of an FBG array embedded in the dental composite and is correlated with the degree of conversion of the material which also depends on the curing lamp intensity distribution. This technology will have significant impact and applications in a range of medical, materials and engineering areas where strain or temperature gradient profile measurement is required in smaller scales. [ABSTRACT FROM AUTHOR]