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The article presents the application of the acoustic emission (AE) technique for detecting crack initiation and examining the crack growth process in steel used in engineering structures. The tests were carried out on 40CrMo steel specimens with a single edge notch in bending (SENB). In the tests crack opening displacement, force parameter, and potential drop signal were measured. The fracture mechanism under loading was classified as brittle. Accurate AE investigations of the cracking process and SEM observations of the fracture surfaces helped to determine that the cracking process is a more complex phenomenon than the commonly understood brittle fracture. The AE signals showed that the frequency range in the initial stage of crack development and in the further crack growth stages vary. Based on the analysis of parameters and frequencies of AE signals, it was found that the process of apparently brittle fracture begins and ends according to the mechanisms characteristic of ductile crack growth. The work focuses on the comparison of selected parameters of AE signals recorded in the pre-initiation phase and during the growth of brittle fracture cracking.

Abstract. In this paper, a global monitoring system based on the measurement of acoustic emission (AE) due to active deterioration processes is presented. This allows us to examine the entire volume of an element and to locate and identify the type and the dynamics of the deterioration processes under service conditions. The resulting data are used to determine and locate the damage processes that are dangerous in construction made of pre-stress concrete, steel and fiber glass and to assess the general condition of the structure.

Featured Application: The data collected can be the basis for determining the structural condition of the structure.Abstract: Durability, safety, and usability are the three foundations of structural reliability, vital in the economic and social context. As the locating and tracking of potential damage and evaluating its impact on the condition of the structure are part of service life assessment, relevant methods should be developed that would detect the onset of the deterioration process and enable the monitoring of its progress within the entire volume of the structure, not only in the areas selected in a subjective way. The acoustic emission (AE) method relying on the analysis of active destructive processes can be the best choice. This article reports the results of the application of the AE method for identifying active destructive processes and tracking their development during the routine operation of various types of structures.

In this paper, a global monitoring system based on the measurement of acoustic emission (AE) due to active deterioration processes is presented. This allows to examine the entire volume of an element and to locate (with an accuracy of the measuring zones) and identify the type and the dynamics of deterioration processes under service conditions. The resulting data are used to determine and locate the damage processes that are dangerous in construction and to assess the general condition of the structure as well as the degree of risk.

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Abstract. The study presents the analysis of the process of crack formation and crack width growth in statically determinate and hyperstatic reinforced concrete beams with the IADP acoustic emission method. The beams were subjected to the monotonic, variable with unloading, and variable cyclic loading schemes. The criteria of structural damage were established to account for the structure durability.