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This work focuses on an experimental and numerical investigation into monitoring damage in a cube-shaped concrete specimen under compression. Experimental monitoring uses acoustic emission (AE) signals acquired by two independent measurement apparatuses, and the same damage process is numerically simulated with the lattice discrete element method (LDEM). The results from the experiment and simulation are then compared in terms of their failure load, final configurations, and the evolution of global parameters based on AE signals, such as the b-value coefficient and the natural time approach. It is concluded that the results from the AE analysis present a significant sensitivity to the characteristics of the acquisition systems. However, natural time methods are more robust for determining such differences, indicating the same general tendency for all three data sets.

This work focuses on analyzing acoustic emission (AE) signals as a means to predict failure in structures. There are two main approaches that are considered: (i) long-range correlation analysis using both the Hurst (H) and the detrended fluctuation analysis (DFA) exponents, and (ii) natural time domain (NT) analysis. These methodologies are applied to the data that were collected from two application examples: a glass fiber-reinforced polymeric plate and a spaghetti bridge model, where both structures were subjected to increasing loads until collapse. A traditional (AE) signal analysis was also performed to reference the study of the other methods. The results indicate that the proposed methods yield reliable indication of failure in the studied structures.

This paper applies the Acoustic Emission (AE) Technique to analyze the damage process in a one-meter span bridge model that was built from spaghetti sticks during a loading test. The AE signals are analyzed in terms of four coefficients that are evaluated as predictors of structure failure, with frequency variation appearing to be the strongest indicator of instability. The AE data are also compared to theoretical predictions that are given by the Bundle Model, confirming that underlying general patterns in damage processes are highly influenced by the geometric distribution of the structure and the loading pattern that is applied to it.

This work presents a novel continuous approximation of the LuGre model, with the aim of improving its applicability in the control of a class of systems that include fluid-driven servo positioners. The main attractive of the proposed approximation is the preservation of the properties of boundedness and passivity that are inherent to the original LuGre model, a feature that is not guaranteed in the approximate models that are usually encountered in the specialized literature. The most relevant properties of the proposed approximation are demonstrated analytically, and its applicability is illustrated both analytically and experimentally in the case of a pneumatic servo positioner.