TY - CONF A1 - Vössing, Konrad T1 - Zerstörungsfreie Prüfung von Holzwerkstoffen mittels Luftultraschall und Radar N2 - The detection of delamination, rot, and cracks in wooden construction elements is a key task for nondestructive testing (NDT). Air-coupled ultrasound (ACU) is used to detect defects and damage without altering the structure permanently. Using through transmission it is possible to detect even small holes and missing adhesive. After interpretation of the inspection data, an assessment of the mechanical properties based on an appraisal of internal defects in the material is feasible. Novel ferroelectret transducers with a high signal-to-noise ratio (SNR) enable a high-precision structure recognition. The transducers made of cellular polypropylene (PP) are quite suitable for ACU testing due to their extremely low Young’s modulus and low density which result in a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. Thus, structures with great dimensions, thickness up to 300 mm and material densities under 500 kg/m³ can be inspected. Promising results were obtained under laboratory conditions with frequencies from 90 kHz to 200 kHz. The advantage of ACU transducers is that they do not require contact to the sample, are accurate, and cost effective. Ultrasonic quality assurance for wood is an important attempt to increase the acceptance of wooden structures and towards sustainability in civil engineering in general. T2 - Graduiertentagung Cusanuswerk CY - Goslar, Germany DA - 09.05.2018 KW - Air-coupled ultrasound KW - Cellular polypropylene KW - Defect detection KW - Nondestructive testing KW - Wood-based materials PY - 2018 AN - OPUS4-44885 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -