A mesoscale simulation on electromechanical admittance-based internal microcrack damage identification of concrete structure using polynomials spectral element method

Numerical simulation plays a key role in understanding the identification mechanism of concrete internal microcrack damage due to its inaccessibility and invisibility when using the electromechanical admittance (EMA) of surface-bonded piezoceramic (PZT) transducers. However, refined three-dimensional (3D) concrete mesoscale model for microcrack detection requires small element sizes for accurate electro-mechanical resolution and consequently results in considerable element nodes and computational consumption. To overcome the low efficiency of such a model, this paper proposed an integrated meso-element equivalent method (MEEM) and polynomials spectral element method (PSEM) to simulate the internal microcrack identification of concrete structure using the 3D concrete mesoscale model bonded with a PZT patch. The mesoscale model with side length of 100 mm was first established to obtain the EMA signatures of the concrete structure containing 30 % randomly distributed aggregates, which was compared with that using traditional finite element method (FEM) and validated by experimental measurements. Under the same boundary conditions and parameter settings, modelling validation demonstrated much higher accuracy with tested signatures both for the spectrum shapes and resonance amplitudes/frequencies meanwhile saving 62.5 % of element nodes and accelerating computational time by 14.7 times as compared with FEM. Model application to microcrack identification using the integrated PSEM-MEEM demonstrated that internal crack of concrete with minimum width of 0.1 mm, length of 2.5 mm and maximum 40 mm distant from concrete surface could be effectively identified in different orientations. Numerical results of this study provide a promising way of internal microcrack identification at mesoscale level of concrete modelling with high resolution, accuracy and efficiency.