Accession Number : ADA183776

Title :   The Transition from Brittle to Ductile Failure in Polyethylenes.

Descriptive Note : Master's thesis,

Corporate Author : PENNSYLVANIA UNIV PHILADELPHIA SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s) : D'Onofrio, John L

PDF Url : ADA183776

Report Date : Aug 1987

Pagination or Media Count : 174

Abstract : The focus of this thesis is to study the evolution of notch-tip damage to failure of two polyethylenes associated with pipe manufacture, at various stress levels characterizing the competition between brittle and ductile modes of failure. This thesis investigates the failure behavior of polyethylene as the stress is increased, approaching the yield point where failure is in the ductile mode. The mechanical behavior of polyethylene is explored as the transition from brittle failure to ductile failure occurs. This project provides for a continuation of earlier research by studying the characteristics of the failure of polyethylene exposed to stress levels from about one half and up to the yield point. In order to provide a continuity in results, experiments were conducted on Marlex 6006, the same material used in previous research. Also studied was TR 418, a branched polyethylene, typical of the material used in the actual manufacture of gas pipe. The experimental parameters that were varied were stress, notch depth, temperature, and material. Quantitative measurements were made with an optical microscope fitted with a filar objective, a strain guage extensometer, a thermocouple, timer, and a digital data collector.

Descriptors :   *POLYETHYLENE, *FAILURE(MECHANICS), *BRITTLENESS, *DUCTILITY, *PIPES, *PHASE TRANSFORMATIONS, MECHANICAL PROPERTIES, MICROSCOPES, OPTICAL EQUIPMENT, MANUFACTURING, NOTCH SENSITIVITY, PIPELINES, NATURAL GAS, CREEP STRENGTH, INDUSTRIAL ENGINEERING, LIFE EXPECTANCY(SERVICE LIFE), STANDARDS, THERMOCOUPLES, YIELD POINT, RATES, STRESSES

Subject Categories : Plastics
      Pumps, Filters, Pipes, Tubing, Fittings & Vlvs

Distribution Statement : APPROVED FOR PUBLIC RELEASE