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.

This article presents a concise review of modern non-destructive testing (NDT) methods that allow the detection, tracking, and measurement of cracks in reinforced concrete structures. Over the past decades, the range of solutions available on the market has increased. This provides excellent opportunities when choosing and designing systems for diagnosing and continuously monitoring structures. Cracking affects the mechanical properties, durability, and serviceability of a structure or its elements. Therefore, there is a need to develop methods that would allow the determination of the moment of a destructive process’s formation, i.e., a crack’s appearance. At the same time, it is crucial to be able to track the development of cracks for the entire structure, not just selected locations. This work also presents the concept of combining selected NDT methods and creating a system for the continuous monitoring of structural integrity and predicting changes in the durability of existing and future buildings.

This paper presents the outcomes of quality tests conducted on specimens, both smooth and V-notched, subjected to uniaxial tension, which were extracted from a gas transport pipeline. The introduction of the V-notch introduced variations in the stress and strain component fields near the plane of maximum constriction, consequently leading to their failure through different mechanisms. The process included the implementation of quality management practices such as numerical modeling and simulation of the loading of the specimens using ABAQUS. The material model employed in these calculations was defined and verified to ensure quality control. Subsequent to the numerical calculations, maps of the stress and strain component fields were generated, contributing to the quality assessment of the specimens. It was determined that the quality management process for the smooth specimen identifies the initiation of failure primarily due to the normal stress component in the central region of the plane with the largest constriction. In contrast, in the V-notched specimen, quality management efforts revealed that failure initiation occurs due to the tangential stress component, and failure proceeds through the shear mechanism. These results are valuable in developing a quality-driven methodology for monitoring the operational safety of gas network pipelines, primarily based on the analysis of acoustic emission signals.

This article presents a comprehensive improvement in the experimental analysis of cracking processes in smooth and sharp V-notched samples taken from gas transport pipelines, utilizing the acoustic emission (AE) method. The research aimed to establish a robust correlation between the failure mechanisms of uni-axially tensile samples and the distinct characteristics of AE signals for enhanced quality management in pipeline integrity. The study encompassed materials from two different straight pipe sections, encompassing both long-term used materials and new, unused materials. Through the application of the k-means grouping method to AE signal analysis, we achieved the identification of AE signal parameters characteristic of various stages of the material destruction process. This advancement introduces a significant improvement in monitoring and managing the operational safety of pipeline networks, offering a methodology that leverages advanced acoustic emission signal analysis. The outcomes present significant implications for the pipeline industry by proposing methods to enhance safety systems and more effectively manage the integrity and quality of gas infrastructure.

In accordance with applicable international regulations, construction products and elements should have appropriate physical and strength features to meet the required limit states of load-bearing capacity and serviceability in the construction objects designed by them throughout their entire lifetime. The non-destructive methods should be used to assess physical and strength features at various stages of implementation and operation. The complexity of security problems, reliability and durability in the conditions of use of modern building structures therefore requires the development and improvement of specialized research methods. Diagnostics and assessment of building objects requires the use of optimal "in situ" research methods that allow for the assessment of the boundary states of buildings with sufficient accuracy over the entire lifetime. The article presents application the acoustic emission signal (AE) in the diagnosis of technical facilities. The equipment used for signal acquisition is described. An example area of application of the AE method in technology is presented - monitoring of the technical condition of steel structures. Recording and analyzing the AE signal proved to be an effective tool in the diagnosis of this type of construction.