William M. Jordan

Relating Resin Mechanical Properties to Composite Delamination Fracture Toughness

The relationship between resin mechanical properties and the resultant composite Mode I and Mode II delamination fracture toughnesses in graphite-epoxy systems was examined. The tensile property that best correlated with composite delamina tion toughness was the resin tensile elongation. Resins with higher tensile elongations pro duced composites with a higher delamination toughness, though the relationship between the two may not be a simple one. The method used to toughen the resin affected the resulting composite delamination toughness. A rubber toughened resin would produce a tougher composite than would a resin that had the same tensile elongation (but with a lower crosslink density rather than rubber particle additions).

Long-Term Material Characterization of a Cured In Place Plastic (CIPP) Sewer Rehabilitation Liner Material

Publisher Summary Cured-In-Place-Plastic (CIPP) pipeline rehabilitation liners are designed to prevent creep-induced collapse caused by external groundwater pressure. Current liner design models account for the time dependent response of liner materials using estimates of the creep modulus at 50 years. Room and elevated temperature creep testing of a CIPP material are reported here in an attempt to more accurately determine the value of the creep modulus at 50 years. The compressive creep modulus predicted at 50 years is found to be 275 ksi. CIPP pipe liners are commonly employed to rehabilitate deteriorated sewer and water lines. Such liners are often installed below the water table and are consequently subjected to external hydrostatic pressure that may lead to creep-induced buckling of the liner within the host pipe before the anticipated service life of 50+ years is achieved. Insufficient understanding of this buckling phenomenon is regarded as a significant limitation of the technology and a barrier to more costeffective sewer rehabilitation.