Realistic Modeling of the Failure of Composite Pipes Under Ring Deflection and Internal Pressure Loading Conditions

Realistic numerical models of the behavior of glass-fiber reinforced plastic (GFRP) pipes under two loading conditions — ring deflection and internal pressure — representative of their typical applications were developed and experimentally validated. A 2D modeling approach was implemented, using cohesive elements to accurately represent at the layer/laminate level the damage mechanisms leading to failure of these composite structures and estimate their ultimate strength under those loading conditions. The innovative and advantageous feature of these models is their ability to identify the load level at which damage is initiated, its location and the way it propagates thus giving a realistic assessment to the composite pipes’ behavior. Inter-layer delamination and transverse fiber breakage were identified as main damage mechanisms occurring up to the catastrophic failure of the pipes. The numerical-experimental procedure conducted in this study allowed also to determine the proper values of material’s physical properties such as inter- and intra-layer energy release rates governing the failure mechanisms.