DOI: 10.7910/dvn/0hhjff
title: Low-frequency ultrasound data (pulse-echo technique) of shear horizontal and longitudinal waves acquired on the concrete step specimen “Pk401” with embedded polystyrene foam cuboids

description: This dataset contains raw ultrasound measurement data acquired on a reference specimen made of concrete at the Bundesanstalt für Materialforschung und -prüfung (Federal Institute for Materials Research and Testing), BAM, Berlin (Germany). The internal specimen identifier is “Pk401”. The measurements were conducted using the pulse-echo method. The upper surface of the specimen was defined as measuring area. The aim of the measurements is to determine both the geometrical dimensions (thicknesses) and the positions of the embedded polystyrene foam cuboids. 
The concrete specimen is made of the heterogeneous material concrete with a maximum aggregate size of D = 16 mm. The geometrical dimensions are l=2000 mm (length l along the X-axis), b=800 mm (width b along the Y-axis), and four different thicknesses d, as the specimen includes three steps: d_1=573.8 mm, d_2=453.4 mm, d_3=333.1 mm, and d_4=210.4 mm. Each step has a length of l=500 mm and contains a polystyrene foam cuboid with a thickness of 60 mm as well as a length and width of 120 mm. The depths t of the polystyrene cuboids centres (along the Z-axis) are: t_1=270 mm, t_2=210 mm, t_3=150 mm and t_4=90 mm.
The ultrasonic measurements were performed using a combination of commercially available and self-developed equipment. The ultrasonic probes M2502 (Dual Aperture Shear Wave DPC Transducer Array) and M2503 (Dual Aperture Longitudinal Wave DPC Transducer Array) were manufactured by Acoustic Control Systems – ACS Group. The pulse generator used is a BAM in-house development. For data acquisition, a National Instruments Corp. USB-6361 system in 16-bit format has been used. The measurements were fully mechanized using an automated scanner system developed at BAM, which is operated with a self-developed control and data acquisition software based on LabVIEW.
The measuring grid consists of X = 187 points along the X-axis and Y = 71 points along the Y-axis, with a uniform spacing of 10 mm in both directions. The measurement field starts at 7 cm in the X-direction and 5 cm in the Y-direction. At each point, 4000 samples were recorded with a sampling rate of 2 MS/s. The stored data are 16-bit (signed) integers, within a range of A = ±2000 mV for the shear wave data and A = ±1000 mV for the longitudinal wave data. 
For the complete description of the real dimensions of the measuring surface with a length of l=2000 mm and a width of b=800 mm the missing data points were filled with zero vectors. This means that in total there are 201 data points along the X-axis and 81 data points along the Y-axis. Two datasets are provided for each wave type, corresponding to different probe orientations (Rot00 and Rot90). Additionally, three vector datasets are included, containing the X- and Y-coordinates of the individual measuring points (in mm) and the Z-values of the samples (in µs).
The data is provided in both .csv and .npy (NumPy) formats.
description: Python, 3.11.7
description: numpy, 1.26.4
description: In all datasets, the centre of the rectangularly designed probe serves as the reference point for defining the X- and Y-coordinates, ensuring that a rotation of the probe by 90° (Rot90) does not lead to inconsistencies. This rotation is required to change the direction of polarization and simultaneously vary the directional characteristic of the respective acoustic field, which depends on the aperture. 
The original data has been converted to *.csv and *.npy using the Python csv and numpy libraries.
The filenames of the raw datasets (provided in *.csv-format) include information about the position within the measurement area, the number of measurement points, and the orientation of the probe.
Example: Pk401(*)_Shear(**)_X000-X200(***)_Y011(****)_Rot90(*****): 
(*)-Name of the specimen; 
(**)-Type of wave (Longitudinal (Long) or shear wave (Shear)); 
(***)-X000-X200: position number X = 0 to position number X = 200 on the X-axis; 
(****)-Y011: position number Y = 11 on the Y-axis; 
(*****)-Rot90: probe orientation Rot90 or Rot00: for the orientation Rot90 of the probe the Y ̅ - axis of the probe is aligned along the measurement direction (Y-direction) and for the orientation Rot00 the X ̅ – axis of the probe is aligned along the measurement direction. 
The dataset named e.g. Pk401_Shear_X000-X200_Y011_Rot90.csv consists of all data acquired in X-direction (201 measuring points) at position Y = 11 mm in Y-direction. The Y ̅ - axis of the probe is aligned along the measurement direction (Y-direction) (Rot90).