non-invasive continuous surface wave measurements for in situ damping ratio profiling of soils

Non-contact surface wave measurements on pavements

In this thesis, nondestructive surface wave measurements are presented for characterization of dynamic modulus and layer thickness on different pavements and cement concrete slabs. Air-coupled microphones enable rapid data acquisition without physical contact with the pavement surface. Quality control of asphalt concrete pavements is crucial to verify the specified properties and to prevent pre...

In situ non-contact measurements of surface roughness

Surface roughness measurements are often required to validate a machining process. However, when using a 3D surface roughness measuring instruments it is usually necessary to remove the part from the machine tool between two operations, potentially introducing systematic errors. Furthermore, surface roughness measuring instruments are not suited for measuring heavy and large parts such as stamp...

Analysis of coherent surface wave dispersion and damping for non destructive testing of concrete

The durability of concrete structures is a major issue in civil engineering. Cover concrete monitoring is particularly important as it is in direct contact with the outside. High frequency surface waves (50-200 kHz) are adapted to provide information about this part of concrete, since they investigate materials at a depth close to the wavelength. The high degree of heterogeneities in concrete i...

Effect of Surface Unevenness on In Situ Measurements and Theoretical Simulation in Non-Contact Surface Wave Measurements Using a Rolling Microphone Array

Non-destructive seismic testing using air-coupled microphones is today an attractive alternative to the more conventional stationary accelerometer testing, in order to perform fast and reliable material characterization on pavement structures. A multichannel microphone array enables fast mobile data collection using a rolling trolley. It is essential that the microphone array and the material s...

In-Situ Measurements of Surface Reflection Properties

In order to characterize surfaces with respect to their sound reflecting properties, the absorption and the scattering or diffusion coefficient can currently be measured under standardized laboratory conditions. However it is questionable whether the data from measurements performed under such laboratory conditions can be used to accurately model the actual sound field in rooms. Additionally, i...

Wave equations with non-dissipative damping