TY - CHAP A1 - Bohse, Jürgen A1 - Brunner, A.J. ED - S. Sridharan, T1 - Acoustic emission in delamination investigation KW - Acoustic emission KW - Delamination KW - Polymer composites PY - 2008 SN - 978-1-84569-244-5 IS - Part 2 / Chapter 9 SP - 1 EP - 58 PB - Woodhead Publishing Ltd AN - OPUS4-18220 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bohse, Jürgen T1 - Acoustic emission characteristics of micro-failure processes in polymer blends and composites N2 - Acoustic emission (AE) characteristics of micro-failure processes in HDPE/PP blends with and without compatibilizer, single-fibre composites (glass/epoxy, carbon/epoxy, glass/polycarbonate) and unidirectionally reinforced multi-fibre composites (glass/polypropylene) were studied. For blends, the number and the elastic fracture energy release of micro-failure processes are theoretically approximated and correlated with the number of AE signals and the AE energy. A qualitative correlation of the mechanical energy released from fibre/matrix debonding and fibre-fracture processes in single-fibre pull-out experiments with the measured AE energy is demonstrated. For the single-fibre fragmentation of glass fibres and carbon fibres, a quantitative approximation of the AE amplitudes at locations of the fragmentation sources is achieved. A new method for the selection of single transient acoustic emissions and the classification of failure mechanisms in composites is introduced. Selected emissions are classified into matrix cracking, fibre breakage and interface processes (fibre/matrix debonding or fibre pull-out) from their total power in defined frequency intervals of the spectral power density. A fracture-mechanics investigation of the delamination behaviour of unidirectional composites accompanied by AE examinations is discussed. The extension of the damage zone around the crack tip is quantified by the location of AE events and compared with the theoretically approximated dimensions. The size of the damage zone is used for theoretical calculations of the mechanical energy release from micro-failure processes. A correlation of the AE energy-release rates with the mechanical energy-release rates from participated failure mechanisms like matrix cacking, fibre/matrix debonding and fibre breakage is presented. KW - Polymer blends KW - Polymer-matrix composites KW - Fracture toughness KW - Delamination KW - Acoustic emission PY - 2000 DO - https://doi.org/10.1016/S0266-3538(00)00060-9 SN - 0266-3538 VL - 60 SP - 1213 EP - 1226 PB - Elsevier CY - Barking AN - OPUS4-4155 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Bohse, Jürgen ED - Czichos, Horst T1 - Acoustic emission N2 - This chapter presents the principles and applications of acoustic emission (AE) analysis to detect microscale symptoms and syndromes of faults and failures in technical structures and systems. KW - Acoustic emission KW - Technical diagnostics KW - Structural health monitoring PY - 2013 SN - 978-3-642-25849-7 SN - 978-3-642-25850-3 DO - https://doi.org/10.1007/978-3-642-25850-3_8 IS - Chapter 8 SP - 137 EP - 160 PB - Springer CY - Berlin Heidelberg AN - OPUS4-27653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bohse, Jürgen T1 - Discrimination of acoustic emission source mechanisms N2 - The Interpretation of acoustic emission (AE) test results and source severity grading according to Standards for AE examination actually is based on the intensity and activity analysis of burst-type AE signals generated by located single events or event clusters. For identification of involved source mechanisms to date correlation plots of conventional Features of AE signals or distribution of AE peak amplitudes are applied. Modern, advanced methods for analysis of AE signals might help in better discrimination of source mechanisms. By means of practical examples some important influences on the characteristics of AE signals and resulting physical and technical restrictions for discrimination of AE source mechanisms are discussed. T2 - ICEAF III - 3rd International conference of engineering against failure CY - Kos, Greece DA - 26.03.2013 KW - Acoustic emission KW - Wave modes KW - Signal analysis KW - Source mechanisms PY - 2013 SN - 978-960-88104-3-3 SN - 2241-5890 SP - 316 EP - 324 AN - OPUS4-28827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hussels, Maria-Teresa A1 - Chruscicki, Sebastian A1 - Baer, Wolfram A1 - Wossidlo, Peter A1 - Weltschev, Margit A1 - Schmidt, Dirk A1 - Baensch, Franziska A1 - Bohse, Jürgen A1 - Prager, Jens A1 - Habib, Abdel Karim T1 - AGIFAMOR – Application of distributed acoustic and fibre optic sensors for continuous monitoring of pipes N2 - Pipelines and industrial piping systems are particularly relevant regarding technical safety, availability and maintenance. Large flow rates of hazardous substances imply that even smallest leakages can lead to high environmental impacts. Therefore, and to ensure the availability of infrastructure, an early detection and localization of potentially hazardous degradations to the walls (e.g. cracks, pittings, sedimentation, etc.) of the containments is necessary. However, in many cases it is not feasible to equip pipelines with a large number of point sensors at reasonable expense. The principle of distributed fibre optic sensing relies on one single optical fibre, which simultaneously acts as a spatially continuous sensor as well as the signal transducer. Therefore, extensive structures can be provided with this type of sensor with comparatively low efforts. As a consequence, monitoring oil and gas pipelines using distributed fibre optic sensors is on the upswing. Besides the established methods to measure temperature and strain, distributed acoustic sensing (DAS) has lately received considerable attention as a means to detect and localize third party threats to pipelines (approach of vehicles, digging, mechanical manipulation). The so far not utilized potential of DAS as a means for continuous condition monitoring of pipes by detecting and localizing acoustic signals that point to certain damage scenarios, is currently under investigation in an interdisciplinary research project at BAM (AGIFAMOR, Ageing Infrastructures – Fibre Optic Monitoring of Pipes). In order to qualify distributed acoustic fibre optic sensors for this application area, we especially focus on detecting and identifying the relevant acoustic emissions of interesting degradations as well as on the optimal way of application of the optical fibres to the specimen to achieve an optimal signal transmission of acoustic signals. T2 - 12th Pipeline Technology Conference CY - Berlin, Germany DA - 02.05.2017 KW - Monitoring KW - Pipelines KW - Fibre optic sensing KW - Acoustic emission KW - Accelerometer PY - 2017 SN - 2198-428X VL - 2017 SP - Session 3.2 Leak Detection, 1 EP - 8 PB - EITEP (Euro Institute for Information and Technology Transfer in Environmental Protection) CY - Hannover AN - OPUS4-40186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fischer, G. A1 - Bohse, Jürgen T1 - Observation and analysis of fracture processes in concrete with acoustic emission (AE) and digital image correlation (DIC) N2 - Fracture processes in concrete can be characterized by the formation of a Fracture Process Zone (FPZ), which is a region of the crack extending between the elastic region ahead of the crack tip over the crack bridging zone to the region where the crack opening is sufficiently large to prevent transfer of load across the crack faces. The formation of cracks and the development of the FPZ have typically been documented by Acoustic Emission (AE) methods and important conclusions regarding the nature of the FPZ and the propagation mechanisms of concrete have been drawn to form the basis of current fracture models for concrete. The study presented in this paper focuses on Mode I cracking of concrete using compact tension specimens and is comparing the results of AE measurements to those obtained from documenting the cracking process by Digital Image Correlation (DIC). The findings from this comparison show that distinctly different AE events occur ahead of the crack tip, in the cementitious matrix at the crack tip and in the wake of the crack due to the increasing separation of the crack flanks and further opening of the crack. The DIC measurements indicate that crack initiation occurs with locally corresponding AE signals and furthermore suggest a continuous path of the crack from initiation to eventual transition to the stress-free zone. Based on these comparative measurements the study suggests that crack formation in unreinforced concrete is initiated by an individual, sharp microcrack rather than by a region of diffuse microcracking ahead of the eventual crack tip. Later on sharp crack branches originate from the main macrocrack path. Furthermore, the measurements with AE and DIC result in information on the nature of the deformation mechanisms occurring in distinct regions of the entire cracking process. AE signals detected using wideband sensors show quite different characteristics in time (waveform) and frequency (bandwidth) domain. T2 - 31st Conference of the European working group on acoustic emission (EWGAE) CY - Dresden, Germany DA - 03.09.2014 KW - Concrete KW - Acoustic emission KW - Digital image correlation KW - Signal analysis KW - Fracture process KW - Source mechanisms PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-313471 SN - 978-3-940283-63-4 IS - DGZfP-BB 149 SP - Th.3.A.4, 1 EP - 8 PB - BAM / DGZfP AN - OPUS4-31347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachsmuth, Janne A1 - Malikoutsakis, M. A1 - Savaidis, G. A1 - Savaidis, A. A1 - Bohse, Jürgen T1 - Corrosion and fatigue crack monitoring by means of acoustic emission for application in transportation means N2 - Corrosion damages and fatigue cracks are the main causes of structural failures in vessels and transport products. Acoustic emission is suggested as an alternative to the conventional inspection processes enabling continuous health monitoring of the structures. Comprehensive finite element analyses have been performed on the example of a 3-compartment road tanker taking the corresponding ADR design loads into account. The numerical results reveal various weld joints as the structure’s failure-critical hot spots. Welded plates made of fine grain steel were stressed by corrosion and fatigue. Damage development in the material was measured and analyzed by acoustic emission testing. It is shown that the different degradation mechanisms, corrosion and fatigue crack growth in welded areas, can be reliably detected by acoustic emission. In addition, principal differences of the acoustic emission signals depending on the degradation mechanism are also explored. KW - Acoustic emission KW - Health monitoring KW - Fatigue crack growth KW - Corrosion KW - Finite elements KW - Welds PY - 2012 SN - 1943-3514 VL - 5 IS - 1 SP - 9 EP - 17 PB - Global Scientech CY - Basking Ridge, NJ, USA AN - OPUS4-27610 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -