Accession Number : ADA310813

Title :   Effects of Thermal Treatment and Loading Rate Variation on Graphite Bismaleimide.

Descriptive Note : Final rept.,

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Personal Author(s) : Fish, Alice E.

PDF Url : ADA310813

Report Date : APR 1996

Pagination or Media Count : 79

Abstract : In this work, the tensile properties of graphite-reinforced bismaleimide were studied. In particular, specimen design, loading rate variation, and thermal exposure effects were examined on a series of specimens. The purpose of this study was twofold: (1) develop a tensile specimen design that provides consistent, reliable data; and (2) provide a foundation for evaluating the mechanical behavior aspects of this composite system. Several issues associated with tensile design in regard to tensile specimens were considered, including specimen thickness, fiber orientation, specimen shape, tab material selection, and extensometer/strain gage incorporation. The analysis indicated that tab angle played a significant role in the resulting stress-to-failure data. By using a straight-sided specimen, appropriate specimen thickness, carefully fixturing the composite specimen in the wedge grips and using 15 deg tab angles, reliable test data were generated. Mechanical property data, in the form of stress-to-failure values, were generated by the tensile tests. Two thermal treatments, representing certain service conditions, were selected and compared to a base line (as-cured) condition, These thermal treatments were shown to have had an effect on the stress-to-failure results. The data indicated that thermal exposure caused a small reduction in the stress-to-failure values. Subjecting the composite to elevated temperatures resulted in an increased number of microcracks formed within the brittle matrix. Loading rate variation (0.22 mm/sec and 121 mm/sec) did not have a significant effect on the resulting mechanical property data. In order to identify the effects of the variables that were incorporated into the testing, a computer program designed to perform a linear regression analysis was utilized.

Descriptors :   *THERMAL PROPERTIES, *TENSILE PROPERTIES, *GRAPHITE, TEST AND EVALUATION, STRESSES, COMPUTER PROGRAMS, ANGLES, THICKNESS, FIBERS, MECHANICAL PROPERTIES, EXPERIMENTAL DATA, EXPOSURE(GENERAL), COMPOSITE MATERIALS, HIGH TEMPERATURE, LOADS(FORCES), FAILURE, ORIENTATION(DIRECTION), HEAT TREATMENT, REDUCTION, RELIABILITY, BASE LINES, STRAIN GAGES, SPLITTING, LINEAR REGRESSION ANALYSIS, SELECTION, IMIDES, EXTENSOMETERS, MICROCRACKING.

Subject Categories : Organic Chemistry
      Inorganic Chemistry
      Physical Chemistry
      Laminates and Composite Materials
      Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE