Internal Stress Reduction in Filament Wound Composite Pipes by Humid Conditioning: Numerical Simulation

Abstract

The paper introduces a new approach which tends to lower the internal stress state within composite pipe walls by using special post-cure hygrothermal treatment. Residual curing stresses in polymer composites are particularly critical in dry conditions, it is proved that an easy way to limit their effect on the material integrity is to introduce hygrothermal stresses. The residual stresses define the initial state of the pipe before it's service life. Usual ambient conditions generate internal stresses which add to the residual manufacturing stresses. It is shown that particularly hygrothennal conditions introduced just after the manufacturing can induce transient stresses which finally will reduce the global stresses. The proposed approach makes it possible to check the influence of timevariable process temperature and pressure, and hygrothermal in-service conditions on polymer matrix composites behavior.