Collapse of Flexible Tubes - The Tube Law

These experiments provide a detailed record of the way in which flexible tubes collapse as the transmural pressure, or the pressure difference between the inside and outside of the tube, is varied, called the "tube law". The tubes have a known unstrained radius, length, and wall thickness, and they are held at a known length during the experiment. For a particular tube geometry the transmural pressure starts at 0, and is increased (positive pressure indicates a higher pressure outside the tube) in a series of discrete steps. At each of these N pressures, 7 images are taken of the tube from m positions arranged symmetrically in a circle about the longitudinal axis, separated by 45 degrees. These images allow the cross-section at the longitudinal centre of the tube, which has the smallest cross-sectional area of any point along the tube, to be reconstructed in 3 dimensions. 15 material points are marked on the tube, and the positions of these material points are reconstructed in 3 dimensions using the m images, and this allows the cross-sectional shape to be found. Hence, from our data is is possible to find the cross-sectional area as a function of the transmural pressure for tubes with various geometries. The file “Collapse of Flexible Tubes - The Tube Law.txt” contains a detailed summary of the data and code in this repository and how it can be used.