Beading phenomenon

During the dimensioning phase, and more specifically when determining tube wall thicknesses, the designer uses an appropriate construction code. The latter refers to standards that indicate how to determine the mechanical characteristics of materials. In the case of homogeneous materials, i.e. metals or thermoplastic polymers, these characteristics are modulus of elasticity, stress at plasticity threshold or stress at rupture. They are determined in static tensile tests on standard specimens. They can also be deduced from tests on tubes subjected to internal pressure. In the case of these materials, tube rupture is manifested by bursting, resulting in the total loss of mechanical and sealing properties. The burst pressure is related to the stress at rupture of the material by the following equation [2] :