Theory for accelerated slow crack propagation in polyethylene fuel pipes. Annual report 1984-1985

Technical Report · Mon Apr 01 00:00:00 EST 1985

OSTI ID:6164436

Moet, A; Chudnovsky, A; Sehanobish, K; Kasakevich, M L; Chaoui, K

Studies of field failure indicate that polyethylene fuel pipe fails by brittle crack propagation. To reproduce this type of failure in accelerated laboratory testing requires a similarity criterion. Quantitative fractographic analysis of field failure in MDPE pipe suggests that the number of ligaments broken per unit brittle crack excursion could probably serve as a similarity parameter. Efforts to accelerate brittle fracture in polyethylene has been successful under fatigue loading in 4'' MDPE pipe and in HDPE. The latter, used as a model material, displayed significant damage evolution that enabled the authors to apply concepts of the crack layer theory to describe entire slow crack-propagation regime. It is found that rate of crack extension is controlled by the rate of expansion and distortion (shape changes) of the damage zone preceding the crack. A method was developed to quantify this phenomena. It is also found that the observed energy release rate is significantly less than the theoretical predictions, for large cracks. Research is continued to develop quantitative account of this phenomena within the framework of the crack-layer theory.

• Research Organization: Case Western Reserve Univ., Cleveland, OH (USA). Dept. of Macromolecular Science
• OSTI ID: 6164436
• Report Number(s): PB-86-136454/XAB
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
02 PETROLEUM
NATURAL GAS
PIPELINES
PETROLEUM PRODUCTS
CRACK PROPAGATION
POLYETHYLENES
FUELS
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUEL GAS
GAS FUELS
GASES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
032000* - Natural Gas- Transport
Handling
& Storage
022000 - Petroleum- Transport
Handling
& Storage