Mechanics and Test Study of Two-Dimensional Flexible Membranes

Numerous enclosure wall systems as well as roof systems employ membranes that are not fully adhered, common examples being mechanically attached roofing membranes and housewraps in screen-type exterior wall systemsder a negative air pressure differential, these membranes can deform or balloon. Ballooning of the membrane will affect many aspects of performance. For instance, it will change the volume of the air chamber in screen-type wall systems and will, therefore, affect both the extent of screen pressure moderation and the nature of ventilation within the wall. This paper develops the structural mechanics for flexible membranes ballooning in two dimensions under an air pressure differential. The governing differential' equation is derived and solved numerically. A second-order parabola is assumed to describe the ballooning shape of the two-dimensional flexible membrane. Alternative theories for the ballooning shape are reviewed and compared. A series of physical tests were carried out to confirm the deformed shape and the magnitude of the peak deflection.