Effects of number of events and relay point density on accuracy of three-dimensional AE-tomography

This paper introduces results of numerical investigations on accuracy of elastic wave velocity distribution in Three-dimensional AE-Tomography. A series of numerical analyses is conducted by changing number of events and density of relay points for the investigation. AE-Tomography is an identification problem and its number of observation equations is in proportion to the number of events, and further, the density of the relay points is immediately correlated with the resolution of the source location that is significant for calculation of travel time from the source location to receivers. The investigation is carried out on a model of tetrahedron that is meshed by using tetrahedral cells, and 8 receivers are settled at apexes and middle of the edges of surfaces of the model. The results of the investigation demonstrate that the accuracy of the source location and wave velocity distribution is strongly conelated with the number of events. It was also demonstrated that the density of the relay points affects to the estimated elastic wave velocity distribution, and better estimation of the elastic wave velocity distribution is confirmed in case of dense installation of relay points. However, these tendencies are confirmed qualitatively and suggest that more investigation is required to figure out the effects of them to the estimated wave velocity distribution.Structural EngineeringCivil Engineering and Geoscience

Non-destructive inspection technologies for repair assessment in materials and structures

Aging infrastructure globally faces degradation, posing risks and requiring substantial repair investment. Strategic maintenance practices are crucial for evaluating structural conditions and ensuring sustainability. The growing demands on modern materials and structures necessitate enhanced health monitoring approaches. Shifting from reactive to proactive maintenance methodologies is paramount, due to lower investment while keeping the structural performance at acceptable standards. However, quantitative assurance of repair/reinforcement/retrofit programs or self-healing effect in structures is similarly crucial for the operation of the infrastructure. Non-destructive testing (NDT) techniques, such as ultrasound, acoustic emission, and optical methods, play a vital role in assessing structural health. Through real-world case studies, the effectiveness of repair in addition to damage assessment are evaluated, encouraging a more systematic approach to monitoring structural repair efficacy. The paper intends to address the research gap in monitoring the repair effectiveness in civil structures and materials and provides valuable insights to enhance repair strategies in civil engineering.Concrete Structure