Ying YeHwa Kian Chai0000-0002-4920-2821Foo Wei Lee2025-09-122025-09-122025-03-2610.3390/app15073635https://dspace-cris.utar.edu.my/handle/123456789/11341Featured Application This study highlights the potential of elastic wave-based testing, particularly Rayleigh wave (R-wave) methods, for the non-destructive evaluation of concrete structures. The developed computational approach can be applied to detect, localise, and characterise internal defects, such as voids, in concrete elements with only one-sided access. These findings can inform advanced methodologies in structural health monitoring, quality assurance during construction, and maintenance strategies for ageing infrastructure.Abstract Concrete structures require routine inspections. Within elastic wave-based non-destructive testing methods, the Rayleigh wave (R-wave)-based method shows great potential in defect characterisation with only one-side access required. This paper aims to investigate the effect of different locations and densities of voids on R-waves using a 2D finite element model. The numerical model was validated and calibrated with experimental results to increase the reliability and representativeness of the model developed. The difference between the R-wave velocity obtained from the numerical model and theory was within 5%, while the correlation between the R-wave waveform collected from the numerical and experimental data was 0.975. The developed numerical model was used to carry out a series of parametric studies investigating the relationship between different R-wave properties and void characteristics. The results revealed that the 5 kHz velocity index was the most sensitive for distributed void identification, with solid correlations up to 0.9879 reported. The correlations obtained from the data analysis suggest good feasibility of the demonstrated computational approach in evaluating the effect of defects in concrete on R-wave behaviour. This approach also offers useful insights into developing an alternative assessment methodology for internal damage localisation and characterisation utilising elastic wave measurements.envoidnon-destructive test (NDT)elastic waveRayleigh wavefinite element modellingFINITE-ELEMENTELASTIC-WAVESPROPAGATIONCRACKSjournal-article