README

***Deformations of floating membrane in wave tank*** 
Athors: H.Pot, J.Westerweel, S.Schreier
TU Delft, Faculty of Mechanical Engineering, Department of Marine and Transport Technology

Corresponding author: H.Pot

Contact information: h.m.pot@tudelft.nl

Delft University of Technology - Faculty of Mechanical Engineering
Mekelweg 2
2628 CD Delft 
The Netherlands

***General Introduction***
This dataset contains data collected during the experiments of a floating membrane in a wave tank. This data is used for the publication 'Stereoscopic Digital Image Correlation for hydroelastic waves of floating membranes' in the journal of Measurement Science and Technology. 

The data in this dataset contains two separate experiments. The data named W1-dataset-of-5-regular-hydroelastic-waves and W2-dataset-of-5-regular-hydroelastic-waves was collected in the Ship Hydromechanics Lab, in Towing tank no. 2 at Mechanical Engineering, Delft University of Technology between February 2024 and April 2024. The data named Perturbation-test-dic-dataset was collected in the Ship Hydromechanics Lab, in the Flumetank, at Mechanical Engineering, Delft University of Technology between August 2023 and September 2023. This research project was funded by the Dutch Research Council (NWO) under the grant number 19002 ("FlexFloat") in the Open Technology Program (OTP).  

***Purpose of the test campaign***
The purpose of these test is to investigate the hydroelastic wave response of membranes floating membranes. 

***Test equipment***
The deformations of the membrane are captured with stereoscopic Digital Image Correlation, and thus measured with a camera system. The detailed experimental conditions are found in the related publication. The waves of the regular wave tests in the wave flume are characterized by: 
W1: wave amplitude = 0.03 m, wave period = 1.4 s, wave length = 3.02 m; 
W2: wave amplitude = 0.05 m, wave period = 1.0 s, wave length = 1.56 m.
The model for this test is made of neoprene, with dimensions 5.0 m by 1.0 m by 0.005 m (Length, width, thickness), Elasticity Modulus 0.83 MP, and material density 145 kg/m^3. 
The depth of the wave tank is 1.23 m, the width of the tank is 2.75 m and the tank spans 85 m in length. The model was positioned in the center of the tank and the water temperature was 20 degrees Celsius. The camera acquisition rate was 30 Hz.

For the perturbation test, a steel ball with a mass of 8.3 grams was dropped in the center of the neoprene floating membrane with length 0.5 m, width 0.5 m and thickness 0.002 m, Elasticity modulus 1.4 +- 0.4 MPa, and density 124 kg/m^3. The water depth was 0.45 m. The camera acquisition rate was 2000 Hz.

***Description of the data in this dataset***
Regular wave test: 
The two zip files contain the data of five wave cycles of W1 and W2, respectively. The data is stored in .csv files, each csv file containing one time step and acquisition is done at 30 Hz. The columns contain the following information:
x [mm] - (initial) x-location of the datapoint
y [mm] - (initial) y-location of the datapoint
z [mm] - (initial) z-location of the datapoint
x-displacement [mm] - displacement in x-direction of this datapoint
y-displacement [mm] - displacement in y-direction of this datapoint
z-displacement [mm] - displacement in z-direction of this datapoint
Displacement [mm] - total displacement of this datapoint
Stereo reconstruction error [pixel] - error related to the stereocorrelation
Surface height reconstruction error [pixel] - error related to the surface height reconstruction

Perturbation test
The zip file contains the data of the perturbation test. Each file contains one time step. The recording frequency is 2000 Hz. The column headers are the headers used by open source software 'Digital Image Correlation Engine (DICe)'. 





