TY - CONF A1 - Straße, Anne A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Preliminary study to investigate the applicability of optical strain measurement technique for the detection of hot cracks in laser metal deposited layers N2 - Laser metal deposition (LMD) as an additive manufacturing technique became increasingly important in recent years and thus the demand for component safety. This is the reason, for the need for reliable in-situ defect detection techniques. For laser beam weld seams an optical measurement technique based on an optical flow algorithm was successfully used to define the critical straining conditions that lead to hot cracking. This algorithm was adapted for bead-on-plate weld seams on LMD deposited layers of IN718 alloy while performing external strain on the specimen in an externally loaded hot cacking test facility. The resulting transversal hot cracks along the weld seam were localized via X-Ray inspection and the type of cracking confirmed by Scanning Electron Microscopy (SEM). The strain distribution was measured in the vicinity of the solidification front and correlated to the detected hot cracks. Based on the results this technique could be adopted for LMD experiments. T2 - 12th CIRP Conference on Photonic Technologies [LANE 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Strain measurement KW - Optical flow KW - Laser Metal Deposition (LMD) KW - Critical strain PY - 2022 AN - OPUS4-55642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straße, Anne A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Schmidt, B. M. T1 - Preliminary study to investigate the applicability of optical strain measurement technique for the detection of hot cracks in laser metal deposited layers JF - Procedia CIRP N2 - Laser metal deposition (LMD) as an additive manufacturing technique became increasingly important in recent years and thus the demand for component safety. This is the reason, for the need for reliable in-situ defect detection techniques. For laser beam weld seams an optical measurement technique based on an optical flow algorithm was successfully used to define the critical straining conditions that lead to hot cracking. This algorithm was adapted for bead-on-plate weld seams on LMD deposited layers of IN718 alloy while performing external strain on the specimen in an externally loaded hot cacking test facility. The resulting transversal hot cracks along the weld seam were localized via X-Ray inspection and the type of cracking confirmed by Scanning Electron Microscopy (SEM). The strain distribution was measured in the vicinity of the solidification front and correlated to the detected hot cracks. Based on the results this technique could be adopted for LMD experiments. T2 - 12th CIRP Conference on Photonic Technologies [LANE 2022] CY - Fürth, Germany DA - 04.09.2022 KW - Laser Metal Deposition (LMD) KW - Strain measurement KW - Optical flow KW - Critical strain PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556445 DO - https://doi.org/10.1016/j.procir.2022.08.034 VL - 111 SP - 335 EP - 339 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-55644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Krebber, Katerina T1 - Applications and prospects for distributed sensing using polymer optical fibres T2 - Transforming the Future of Infrastructure Through Smarter Information, Proceedings of the International Conference on Smart Infrastructure and Construction N2 - One of the unique advantages of polymer optical fibres (POF) is that they can be used to measure very high strain values up to 100 % and beyond exceeding the strain limits of silica fibre-based sensor principles. In this paper the distributed strain measurement capabilities of POF based on backscatter change evaluation are summarized and distributed backscatter measurement technologies are intro-duced. Application examples in the structural health monitoring (SHM) field are presented: a promising approach is the integration into technical textiles for high-strain measurement in earthwork structures and crack detection in buildings. The potential of POF for future applications in SHM such as distributed relative humidity sensing is discussed. T2 - International Conference on Smart Infrastructure and Construction CY - Cambridge, UK DA - 27.06.2016 KW - Strain measurement KW - Structural health monitoring KW - OTDR KW - Polymer Optical Fibre KW - Distributed sensing PY - 2016 UR - http://www.icevirtuallibrary.com/doi/abs/10.1680/tfitsi.61279.093 SN - 978-0-7277-6127-9 DO - https://doi.org/10.1680/tfi tsi.61279.093 SP - 93 EP - 98 PB - ICE Publishing CY - London, UK AN - OPUS4-37230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Krebber, Katerina T1 - Applications and prospects for distributed sensing using polymer optical fibres N2 - One of the unique advantages of polymer optical fibres (POF) is that they can be used to measure very high strain values up to 100 % and beyond exceeding the strain limits of silica fibre-based sensor principles. In this paper the distributed strain measurement capabilities of POF based on backscatter change evaluation are summarized and distributed backscatter measurement technologies are intro-duced. Application examples in the structural health monitoring (SHM) field are presented: a promising approach is the integration into technical textiles for high-strain measurement in earthwork structures and crack detection in buildings. The potential of POF for future applications in SHM such as distributed relative humidity sensing is discussed. T2 - International Conference on Smart Infrastructure and Construction CY - Cambridge, UK DA - 27.06.2016 KW - Strain measurement KW - Structural health monitoring KW - OTDR KW - Polymer Optical Fibre KW - Distributed sensing PY - 2016 UR - http://www.icevirtuallibrary.com/doi/abs/10.1680/tfitsi.61279.093 DO - https://doi.org/10.1680/tfitsi.61279.093 AN - OPUS4-37231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -