Stress-rupture lifetimes of organic fiber-epoxy strands and pressure vessels

Conference · Tue Aug 21 00:00:00 EDT 1979

OSTI ID:5660993

Hahn, H T; Chiu, I L; Gates, T L

Long-term behavior of filament-wound pressure vessels were tested, Kevlar 49 epoxy strands were studied in stress-rupture for more than a year. Because the strands are the smallest structural unit in filament winding, their behavior directly controls the performance of vessels. Five different stress levels were studied: 86, 80, 74, 68, and 50% of the mean ultimate tensile strength (UTS). At each stress level, approximately one-hundred strands were hung in a room maintained at 22 to 24/sup 0/C and below 20% relative humidity. Failure times were automatically recorded by a data acquisition system. Lifetimes were analyzed statistically using a two-parameter Weibull distribution. The maximum-likelihood method was used to estimate the parameters. The shape parameter, which is a measure of scatter and failure-rate change, increased with decreasing stress level. Less scatter and increasing failure rates were observed at lower stresses. There was no sign of an endurance limit down to 68% UTS. At 50% UTS no failure had yet occurred after 9000 h. The strand data were compared with data on lifetimes of pressure vessels wound with the same fiber and epoxy. The strands had slightly longer characteristic lifetimes, except at 86% UTS, and slightly less scatter, except at 68% UTS. The results of this study indicate that strands can provide valuable information about the long-term performance of filament-wound pressure vessels.

• Research Organization: California Univ., Livermore (USA). Lawrence Livermore Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5660993
• Report Number(s): UCRL-82862; CONF-800203-1; TRN: 80-003285
• Resource Relation: Conference: 35. annual conference of the SPI reinforced plastics/composites institute, New Orleans, LA, USA, 4 Feb 1980
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
22 GENERAL STUDIES OF NUCLEAR REACTORS
ARAMIDS
MECHANICAL PROPERTIES
EPOXIDES
PRESSURE VESSELS
FAILURES
RUPTURES
SHAPE
STRESSES
WIRES
CONFIGURATION
CONTAINERS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
360403* - Materials- Polymers & Plastics- Mechanical Properties- (-1987)
220200 - Nuclear Reactor Technology- Components & Accessories