TY - JOUR A1 - Algernon, Daniel A1 - Wiggenhauser, Herbert T1 - Impact echo data analysis based on Hilbert-Huang transform JF - Transportation research record N2 - Impact echo is an acoustic method based on the use of transient stress waves generated by an elastic impact; it is used for nondestructive testing of concrete structures. In practical applications, the signals obtained often are superimposed by further mechanical vibrations and the so-called geometry effects, which are caused mainly by surface waves. Because of attenuation in the concrete as well as the divergence of the acoustical waves, impact echo signals are transient. As a result, the frequency content changes over time. Normally the analysis is carried out on the Fourier power spectrum of the signal. However, the Fourier spectrum is still affected by the mentioned effects and has well-known deficiencies for short transient signals within longer time sweeps. Application of the Hilbert-Huang transform is presented as a refined method for the time-frequency analysis of nonstationary impact echo data. The basic properties of the method and its practical application for time-frequency analysis of impact echo data, signal filtering, and pattern identification are presented. KW - Impact echo KW - Hilbert-Huang transformation PY - 2007 DO - https://doi.org/10.3141/2028-16 SN - 0361-1981 VL - 2028 SP - 146 EP - 153 PB - National Research Council CY - Washington, DC AN - OPUS4-20790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Alver, Ninel A1 - Wiggenhauser, Herbert T1 - Modified SIBIE procedure for ungrouted tendon ducts applied to scanning impact-echo JF - Construction and building materials N2 - The impact-echo method has been successfully applied to identify defects inside concrete. In addition, to detect ungrouted tendon ducts in a large concrete slab, a scanning impact-echo technique is developed. However, since resonant frequencies in the spectrum responsible for the travel paths via defects are only taken into account, the method could lead to erroneous results due to complicated spectra obtained in the tests. Consequently, Stack Imaging of spectral amplitudes Based on Impact-Echo (SIBIE) procedure has been developed to improve the data interpretation. Conventionally, SIBIE is applied to a single measurement data and a point information of defects is obtained at the area, where the impact test is performed. In this study, SIBIE is applied to scanning impact-echo data. Locations of ungrouted tendon ducts embedded in a large concrete specimen are investigated. In order to visualize the whole cross-section tested, the SIBIE analysis is modified, introducing an elliptical integration mode. It is demonstrated that ungrouted tendon ducts are successfully located by the modified SIBIE analysis, whereas results of the conventional B-scan analysis are not so good as the modified SIBIE analysis. KW - Impact echo KW - Scanning procedure KW - SIBIE PY - 2010 DO - https://doi.org/10.1016/j.conbuildmat.2010.05.012 SN - 0950-0618 VL - 24 IS - 12 SP - 2388 EP - 2392 PB - Elsevier Science CY - Amsterdam AN - OPUS4-23961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Colla, Camilla A1 - Krause, Martin A1 - Maierhofer, Christiane A1 - Höhberger, H.-J. A1 - Sommer, H. T1 - Combination of NDT techniques for site investigation of non-ballasted railway tracks JF - NDT & E international N2 - Today's civil engineering NDT needs are for quantitative, fast to apply and easy to interpret methods. They are required on site both for evaluation of existing structures/infrastructure and for quality control in new construction. With this purpose, BAM has carried out in-situ feasibility studies, using radar, impact-echo and ultrasonic-echo methods. Two examples are given of their combined application on different railway slab–track constructions, using high frequency radar, scanning impact-echo and ultrasonic array methods. The aim was to evaluate limitations and advantages, comparability and complementarity of these methods. The on-site measurements demonstrated the possibility to investigate, with good accuracy via NDT, the bonding conditions between sleepers and slab, to locate voids and measure layer thickness. The acoustic and electromagnetic methods used, were found to be complementary. KW - Concrete KW - NDT KW - Impact echo KW - Ultrasonics KW - Radar KW - Railway PY - 2002 DO - https://doi.org/10.1016/S0963-8695(01)00033-0 SN - 0963-8695 VL - 35 SP - 95 EP - 105 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-1858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Helmerich, Rosemarie A1 - Niederleithinger, Ernst A1 - Wiggenhauser, Herbert T1 - Toolbox with Nondestructive Testing Methods for Condition Assessment of Railway Bridges JF - Transportation research record KW - Non-destructive testing KW - Automated scanning KW - Condition assessment KW - Bridge assessment KW - Ultrasonicecho KW - Impulse radar KW - Impact echo PY - 2006 SN - 0361-1981 IS - 1943 SP - 65 EP - 73 PB - National Research Council CY - Washington, DC AN - OPUS4-14293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scherr, J. F. A1 - Kollofrath, J. A1 - Popovics, J. S. A1 - Bühling, Benjamin A1 - Grosse, C. U. T1 - Detection of Delaminations in Concrete Plates Using a Laser Ablation Impact Echo Technique JF - Journal of Nondestructive Evaluation N2 - This study investigates the non-destructive detection of delaminations in concrete plates using non-contact laser ablation, instead of the conventional hammer excitation, as part of the impact echo method. We performed tests on five concrete specimens of different sizes, two of which contained artificial delaminations. A range of steel ball hammers was used as reference impulse sources, the responses of which were compared with wave excitation generated by a 7 ns pulsed 1064 nm Nd:YAG laser with 150 mJ pulse energy. Signals were recorded by surface-mounted accelerometers and two contactless methods: microphones and a laser Doppler vibrometer. The laser generates frequencies across a broad range of frequencies (0 to 150 kHz) but with much less energy than the hammers' narrower frequency spectra; the laser pulse energy transferred into the specimen is 0.07 mJ, corresponding to about 0.5 ‰ of the impulse source energy. Because of this, the thick intact plates' characteristic thickness stretch resonance frequency can be reliably detected by the hammer excitations but not when using laser excitation. However, the laser can excite low-frequency flexural vibration modes over a shallow delamination at 3 cm depth. The low-frequency flexural vibration results are verified by numerical natural frequency analysis. KW - Concrete testing KW - Defect detection KW - Lamb waves KW - Impact echo KW - Non-destructive testing KW - Vibration PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567932 DO - https://doi.org/10.1007/s10921-022-00921-x SN - 0195-9298 VL - 42 IS - 1 SP - 1 EP - 14 PB - Springer AN - OPUS4-56793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shokouhi, Parisa A1 - Wöstmann, Jens A1 - Schneider, Gerhard A1 - Milmann, Boris A1 - Taffe, Alexander A1 - Wiggenhauser, Herbert T1 - Nondestructive detection of delamination in concrete slabs - multiple-method investigation JF - Transportation research record N2 - The delamination of concrete slabs is the separation along a plane roughly parallel to, and generally near, the surface. Corrosion-induced delamination is a common problem in old concrete bridge decks. If undetected, delaminations could expand, reach the surface, and result in spalling. Early detection of delamination is necessary for planning timely repairs that prevent costly deck replacement projects. Most bridge owners rely on routine visual and traditional surveys of bridge deck conditions. These surveys are highly subjective and can locate only large shallow delaminated zones. Several nondestructive testing (NDT) techniques have recently been employed for bridge deck evaluation to obtain more objective and comprehensive assessment. The reliability of applicable methods needs to be established before a greater role for NDT in routine inspections can be encouraged. This paper presents a validation study aimed at evaluating the effectiveness of three NDT techniques, namely impact echo, ultrasound (US) echo, and US linear array, in detection of delamination. This study is unique because the subject test specimens were deteriorated bridge deck segments preserved from the demolition of a prestressed box girder bridge. The results of the tests conducted on one of the specimens are presented and discussed here: impact echo provided satisfactory overall assessment, but the individual results were often difficult to interpret; US echo detected deep delaminations but not shallow ones; and US linear array located the extent of deep delaminations and provided indications of shallow ones. KW - Delamination KW - Concrete KW - Ultrasonic testing KW - Impact echo KW - Scanning PY - 2011 DO - https://doi.org/10.3141/2251-11 SN - 0361-1981 VL - 2251 SP - 103 EP - 113 PB - National Research Council CY - Washington, DC AN - OPUS4-25552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -