TY - CONF A1 - Mayer, K. A1 - Langenberg, K.-J. A1 - Krause, Martin A1 - Maierhofer, Christiane A1 - Milmann, Boris A1 - Kohl, Christoph T1 - Characterization of ultrasonic and radar reflector types in concrete by phase evaluation of the signal and the reconstructed image T2 - 9th European Conference on NDT CY - Berlin, Germany DA - 2006-09-25 KW - NDT-CE KW - Ultrasonic echo KW - Radar KW - Phase evaluation KW - Modeling of wave propagation KW - Reconstruction calculation PY - 2006 SN - 3-931381-86-2 SP - 1 EP - 8(?) PB - European Federation for Non-Destructive Testing CY - Berlin AN - OPUS4-14225 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 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 - CONF A1 - Ballier, G. A1 - Mayer, K. A1 - Langenberg, K.-J. A1 - Schulze, Sebastian A1 - Krause, Martin T1 - Improvement on tendon duct examination by modelling and imaging with synthetic aperture and one-way inverse methods N2 - The knowledge of the internal structure of tendon ducts is one of the important preconditions to make predictions about the stableness and the lifetime of concrete buildings – specifically concrete bridges. Ultrasonic NDT methods can be used to have a look inside those components. To understand the complex effects resulting from elastic wave propagation, it is important to build test specimens and to analyze the measurements with the aid of modelling. At BAM (German Federal Institute for Materials Research and Testing) a new specimen is under construction to realize some of the most common geometrical structures which can be expected in the field of tendon duct testing in concrete bridges. We present various measurement concepts and a comparison between measurement and modelling with EFIT (Elastic Finite Integration Technique), as well as results of imaging methods based on conventional SAFT (Synthetic Aperture Focusing Technique) or FT-SAFT (SAFT with Fourier Techniques) together with phase evaluation. In addition we will present the results of time reversal using AFIT (Acoustic Finite Integration Technique) and a one-way wave propagation method to improve the imaging. T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 16.04.2012 KW - SAFT KW - Ultrasonic NDT KW - Concrete KW - One way KW - AFIT KW - Time reversal PY - 2012 SN - 978-0-620-52872-6 SP - 1 EP - 8 AN - OPUS4-35102 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mayer, K. A1 - Chinta, P.K. A1 - Langenberg, K.-J. A1 - Krause, Martin T1 - Ultrasonic imaging of defects in known anisotropic and inmomogeneous structures with fast synthetic aperture methodes N2 - Imaging methods like Synthetic Aperture Focusing Technique (SAFT) are based on the principle of propagation of the measured ultrasonic wave field back to field sources. In the case of a pulse-echo measurement, this back propagation under some approximating conditions leads to an image of the scattering object with well known properties and imperfections. The back propagation through the object which is under concern needs the knowledge of material properties in respect of the wave propagation. If these properties are known, we can use imaging algorithms like SAFT with all their advantages (computational speed and robustness) not only for isotropic but also for anisotropic material; moreover, the inverse ropagation concept allows crossing boundaries between materials, even if the materials are anisotropic. Examples of this concept are given with modelled and measured data for tendon duct imaging in concrete structures, for 3D imaging of air cavities in wood specimens and for imaging of defects in anisotropic welds. T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 16.04.2012 KW - SAFT KW - Pulse echo technique KW - Back propagation KW - Inverse scattering KW - Imaging PY - 2012 SN - 978-0-620-52872-6 SP - 1 EP - 20 AN - OPUS4-35101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -