Accession Number : ADA292992

Title :   Failure Analysis for Polycarbonate Transparencies.

Descriptive Note : Final rept. 1 May 92-1 Sep 93,

Corporate Author : ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF CIVIL ENGINEERING MECHANICS AND METALL URGY

Personal Author(s) : Chudnovsky, A. ; Chen, T. J. ; Zhou, Z. ; Bosnyak, C. P. ; Sehanobish, K.

PDF Url : ADA292992

Report Date : MAY 1994

Pagination or Media Count : 45

Abstract : Today polymers are increasingly used in advanced structural applications such as aircraft canopies. However, there are no well established models which could be used by design engineers for predicting time to failure for these materials. Development of adequate criteria for three basic stages of fracture (crack initiation, stable crack growth and dynamic crack propagation) is necessary for the accurate prediction of service lifetime. Part 1 of this report reflects a recent progress in understanding of various failure initiation mechanisms in transparency-grade Polycarbonate (PC). A new fatigue crack initiation map for PC is proposed. Another important stage of the fracture process which may strongly influence the total lifetime is crack propagation. Propagation of a crack surrounded by the process zone is a well-known phenomenon for the PC. The properties of the material in the process zone may strongly influence such critical fracture parameters as lifetime, fracture toughness, etc. The deformation of PC by shear banding at a notch-tip was found very similar to that obtained by cold-drawing of PC. In the Part 2 of this report the tensile cold-drawing (necking) behavior of PC is further examined using simple tensile extension coupled with temperature measurements via an infrared camera. (AN)

Descriptors :   *CRACKING(FRACTURING), *POLYCARBONATES, STRESS STRAIN RELATIONS, STABILITY, LIFE EXPECTANCY(SERVICE LIFE), PREDICTIONS, PARAMETERS, POLYMERS, DEFORMATION, TENSILE PROPERTIES, ACCURACY, TOUGHNESS, GLASS, CRACK PROPAGATION, DUCTILE BRITTLE TRANSITION, SHEAR STRESSES, AIRCRAFT CANOPIES, THERMOPLASTIC RESINS, FATIGUE(MECHANICS), FAILURE(MECHANICS), TRANSPARENCIES, COLD DRAWING.

Subject Categories : Polymer Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE