Accession Number:

AD0692516

Title:

A FAILURE STRESS CRITERION FOR A POLYETHYLENE BALLOON FILM,

Descriptive Note:

Corporate Author:

NEW YORK UNIV BRONX DEPT OF AERONAUTICS AND ASTRONAUTICS

Report Date:

1968-07-01

Pagination or Media Count:

31.0

Abstract:

As part of a study of stresses and deformations of balloon films, safe stress levels for polyethylene balloon films are established. Various methods for the determination of the yield point and yield stresses are reviewed and their applicability to balloon films are discussed. In the present paper a safe stress level is considered as the one at which the material sample which creeps will not fail within a specified time interval. Creep tests were conducted with cylindrical samples that were pressurized and additionally loaded by a dead weight axial load. It was found that within a narrow range of stresses, the deformation vs. time curves change from those of uniform creep to curves which show a highly accelerated rate of deformation. The stress values at which this abrupt transition takes place are considered as the failure stresses. Using this new failure criterion a safe stress chart for 2 mil StratoFilm is presented and its applicability in design and analysis of high altitude balloons is discussed. Author

Subject Categories:

  • Lighter-than-air Aircraft
  • Plastics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE