An investigation on flexible pipes birdcaging triggering

Structural behavior assessment of a flexible pipe under axial compressive loads using digital image correlation

“…11 and 12, one can qualitatively compare measured and observed external polymer sheath profiles. It seems reasonable to state that the profile of the outer polymeric sheath indicates the breakdown of the helical wire armor, in agreement with Rabelo et al conjecture, [17].…”

“…Complementarily, another conjecture for the radial instabilities deflagration mechanism has been raised in a recent study; Rabelo [16]; and Rabelo et al [17]. As per conjecture, radial instabilities at mid-sections are triggered by the axisymmetric (radial) plastic instability of the outer polymeric layer.…”

“…Experimental tests and numerical models seem to corroborate that hypothesis. In fact, Rabelo et al [17] developed analytical, numerical and experimental studies to investigate the axisymmetric instability of polymeric pipes under combined loads (axial compression and internal pressurization). Results were shown to have fairly good agreement with numerical and experimental birdcaging investigations performed by Sousa et al [27].…”

“…The present work had been planned aiming at giving additional support to Rabelo's birdcaging triggering mechanism conjecture [16,17]. For that, an experimental test was designed and conducted with a 675-mm, 2.5-inch flexible pipe sample, under purely compressive loads.…”

“…Following another way of reasoning, Rabelo [16] developed a birdcaging deflagration criterion, conjecturing that the axisymmetric structural instability of the outer polymeric layer plays a fundamental role in the birdcaging triggering; see also Rabelo [17].…”