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 - JOUR A1 - Jagenbrein, A. A1 - Tscheliesnig, P. A1 - Wachsmuth, Janne A1 - Bohse, Jürgen T1 - Detection of corrosion processes and fatigue cracks by means of acoustic emission monitoring N2 - Fatigue crack growth and active corrosion processes are the main causes for structural failures of transport products like road tankers, railway tank cars, and ships. Within the 7th EC framework programme the aim of project CORFAT is to develop a new monitoring technology based on acoustic emission testing (AT) of the structural integrity in terms of proceeding degradation. Differentiation of acoustic emission (AE) signals of real degradation processes by fatigue crack growth or active corrosion from operational or environmental background noise requires the signal classification using also pattern recognition. Therefore, a data base of AE signals related to the different source mechanisms was built up experimentally. In this article selected results of corrosion and fatigue tests in the laboratory as well as results of monitoring background noise during moving of a road tanker are described. KW - Acoustic emission monitoring KW - Corrosion processes KW - Fatigue cracks KW - Background noise KW - Signal classification KW - Transport products PY - 2012 DO - https://doi.org/10.3139/120.110391 SN - 0025-5300 VL - 54 IS - 11-12 SP - 769 EP - 778 PB - Hanser CY - München AN - OPUS4-27061 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -