Dataset on full ultrasonic guided wavefield measurements of a CFRP plate with fully bonded and partially debonded omega stringer ============================== Contact informations -------------------- Pawel Kudela, pk@imp.gda.pl, Institute of Fluid Flow Machinery, Polish Academy of Sciences Maciej Radzienski, Institute of Fluid Flow Machinery, Polish Academy of Sciences Maria Moix-Bonet, Institute of Composite Structures and Adaptative Systems, German Aerospace Center Christian Willberg, Institute of Composite Structures and Adaptative Systems, German Aerospace Center Yevgeniya Lugovtsova, Federal Institute for Materials Research and Testing (BAM) Jannis Bulling, Federal Institute for Materials Research and Testing (BAM) Kilian Tschoke, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Systems for Condition Monitoring Jochen Moll, J.W. Goethe-University, Department of Physics Abstract -------------------- The fourth dataset dedicated to the Open Guided Waves platform (http://openguidedwaves.de/) [1] presented in this work aims at a carbon fiber composite plate with an additional omega stringer at constant temperature conditions. The dataset provides full ultrasonic guided wavefields. A chirp signal in the frequency range 20-500 kHz and Hann windowed tone-burst signal with 5 cycles and carrier frequencies of 16.5 kHz, 50 kHz, 100 kHz, 200 kHz and 300kHz are used to excite the wave. The piezoceramic actuator used for this purpose is attached to the center of the stringer side surface of the core plate. Three scenarios are provided with this setup: (1) wavefield measurements without damage, (2) wavefield measurements with a local stringer debond and (3) wavefield measurements with a large stringer debond. The defects were caused by impacts performed from the backside of the plate. As result, the stringer feet debonds locally which was verified with conventional ultrasound measurements. The dataset can be used for benchmarking purposes of various signal processing methods for damage imaging. Description of composite panel -------------------- The CFRP plate corresponds to the wave field plate in [2]. It was manufactured with a dimension of 0.5 m×0.5 m and a nominal thickness of 2 mm. The corresponding ply thicknessis 0.125 mm. The prepreg M21/34%/UD134/T700/300 from Hexply was used to manufacture the plates with a quasi-isotropic layup of [45/0/−45/90/−45/0/45/90]S. The material properties of a single unidirectional layer were measured based on standard test procedures [1]. The prepreg M21/34%/UD194/T700/IMA-12K from Hexply was used to separately manufacture the omega stringer. The stringer was built also in a quasi-isotropic layup [−45/0/90/45/90/−45]S with the dimensions depicted in Figure 1. The nominal thickness is 1.5 mm with a ply thickness of 0.125 mm. The material properties of plate and stringer are listed in Table 1. The omega stringer was bonded to the plate by using Loctite Hysol 9466. The adhesive was cured in vacuum at room temperature. Table 1 -------------------- |Parameter | Plate | Stringer | |:------------|:---------|:----------| |C1111 [GPa] | 130 | 174 | |C1122 [GPa] | 6.1 | 4.1 | |C1133 [GPa] | 6.1 | 4.1 | |C2222 [GPa] | 11.2 | 9.6 | |C2233 [GPa] | 5.2 | 2.9 | |C3333 [GPa] | 11.2 | 9.6 | |C1212 [GPa] | 3 | 3.3 | |C2323 [GPa] | 4.2 | 5.9 | |C1313 [GPa] | 4.2 | 5.9 | |rho [kg/m^3] | 1571 | 1580 | Data acquisition using scanning laser Doppler vibrometry -------------------- Guided waves were excited by a piezoelectric disk of diameter 10 mm attached to the back surface of the specimen (the side with omega stringer). The following excitation signals were applied in consecutive measurements: - Hann windowed tone-burst signal with 5 cycles and carrier frequencies 16.5 kHz, 50 kHz, 100 kHz, 200 kHz, 300 kHz, - chirp signal in the frequency range 20-500 kHz lasting 200 microseconds. The measurements using scanning laser Doppler vibrometer (SLDV) were conducted on the opposite side of the specimen in respect to the piezoelectric transducer and omega stringer (on the flat surface). The specimen central area excluding border of width about 9 mm was measured in 483×483 points. The specimen with highlighted measurement area is presented in Figure 1a. At every measurement point, 1024 time samples were registered with a sampling frequency of 1.28 MHz for Hann windowed signals and 2048 time samples for chirp signals.The measurements were taken 10 times in every grid point and averaged to improve the signal to noise ratio. The exception was the case of Hann windowed tone-burst signal of carrier frequency 16.5 kHz where only 3 averages were applied. The origin of the coordinate system is located in the lower-left corner of the specimen. File structure and data description -------------------- . ├── Readme.txt ├── Read_AcousticWavefield.m ├── readData.py ├── makeVideo.py ├── figure1a.png ├── figure1b.png ├── OGW_CFRP_Stringer_Wavefield_Intact │   ├── BURST_16_5kHz_5HC_10Vpp_x3 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_50kHz_5HC_10Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_100kHz_5HC_9Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_200kHz_5HC_4_5Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_300kHz_5HC_3Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── CHIRP_20-500kHz_125us_6Vpp_x3 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 ├── OGW_CFRP_Stringer_Wavefield_FirstImpact │   ├── BURST_16_5kHz_5HC_10Vpp_x3 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_50kHz_5HC_11Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_100kHz_5HC_9Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_200kHz_5HC_4Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_300kHz_5HC_3Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── CHIRP_20-500kHz_125us_6Vpp_x6 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 ├── OGW_CFRP_Stringer_Wavefield_SecondImpact │   ├── BURST_16_5kHz_5HC_10Vpp_x3 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_50kHz_5HC_11Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_100kHz_5HC_9Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_200kHz_5HC_4Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── BURST_300kHz_5HC_3Vpp_x10 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 │   ├── CHIRP_20-500kHz_125us_6Vpp_x6 │  │ ├── coordinates.h5 │  │ ├── data_z.h5 │  │ ├── time.h5 The measured datasets are organized as follows: - OGW_CFRP_Stringer_Wavefield_Intact: Baseline wavefield measurements of the intact CFRP plate with the omega stringer, - OGW_CFRP_Stringer_Wavefield_FirstImpact: Wavefield measurements of the CFRP plate with the omega stringer impacted with 15.3 J at location [0.38 m, 0.33 m], - OGW_CFRP_Stringer_Wavefield_SecondImpact: Wavefield measurements of the CFRP plate with the omega stringer impacted for the second time with 19 J at location [0.38 m, 0.34 m]. Each folder contains a number of h5-files for two excitation types: Hann-windowed burstand and chirp. The folder name for the burst excitation describes the excitation frequency and number of cycles, peak-to-peak voltage used to drive the PZT and number of averages per pointused to record the wavefield, e.g.BURST_16_5_kHz_5HC_10Vpp_x3 reads as 16.5 kHz centre excitation frequency, 5 cycles Hann-windowed burst, 10 V peak-to-peak and 3 averages per point. The folder name for the chirp excitation describes the excitation frequency range and chirp duration, peak-to-peak voltage used to drive the PZT and number of averages per point used to record the wavefield, e.g. CHIRP_20-500kHz_125us_6Vpp_x3 reads as 20-500 kHzexcitation frequency range, 125 microseconds chirp duration, 6 V peak-to-peak and 3 averages per point. It should be noted that these descriptions correspond to signals coming from a signal generator which were nextamplified 20 times by a high voltage amplifier To open a h5-file and to see how the h5-files are organized the following options are available: - HDFView https://support.hdfgroup.org/products/java/hdfview/ - HDF Compass https://github.com/HDFGroup/hdf-compass - a MATLAB command h5disp. In addition, MATLAB and Python scripts are included which can be used to read out the dataset and to visualise the wavefield. The dataset is accompanied by Matlab script Read_AcousticWavefield.m as well as Python scripts readData.py and makeVideo.py which can be used for reading and visualising data. The scripts should be copied to the desired sub-folder with *.h5 files so that data will be processed in the current path or alternatively scripts can be modified by including full paths. License -------------------- Creative Commons Attribution 4.0 International References -------------------- [1] J. Moll, J. Kathol, C.-P. Fritzen, M. Moix-Bonet, M. Rennoch, M. Koerdt, A. S. Herrmann, M. G. R. Sause, M. Bach, Open Guided Waves - Online Platform for Ultrasonic Guided Wave Measurements, Structural Health Monitoring 18 (2019) 1903–1914. [2] J. Moll, C. Kexel, J. Kathol, C.-P. Fritzen, M. Moix-Bonet, C. Willberg, M. Rennoch, M. Koerdt, A. Herrmann, Guided waves for damage detection in complex composite structures: The influence of omega stringer and different reference damage size, Applied Sciences 10 (2020).