An Experimental Investigation of the Stress Levels at Which Significant Damage Occurs in Graphite Fiber Plastic Composites.
Abstract
Significant damage stress levels in HTS/ERLA-2256 graphite epoxy composites were investigated in this research program. In order to do this it was necessary to establish high quality fabrication and inspection techniques for processing flat laminates and tubes and to experimentally characterize the mechanical and physical properties of the composite (lamina and laminate). Two significant damage stress levels were observed in 0/90 sub c laminates and related to the material's mechanical behavior. Empirically modified micro/macro-mechanics techniques and maximum strain theory were used to predict these stress levels as well as other composite properties with reasonable accuracy. These predicted values are used in normalizing the experimental data to one fiber and void volume for direct comparison and statistical analysis. Material design allowables and confidence limits on the composite properties were established and possible application criteria proposed. Significant milestones accomplished during the program include: (1) the development of new processing techniques for the new prepreg version (Fiberite HY-E-131 7B) of the HTS/ERLA-2256 graphite/epoxy material system, (2) development of quality seamless tube fabrication tooling and processing techniques, (3) establishment of improved instrumentation and automated data recording procedures along with semiautomated data reduction methods, (4) development of axial and biaxial tube testing techniques, and (5) the discovery of two significant micromechanical damage stress levels in the 0/90 sub c orientations which cause a change in subsequent loading behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1972
- Accession Number
- ADA307442
Entities
People
- G. C. Grimes
- G. E. Commerford
- G. K. Wolfe
- Philip H. Francis
Organizations
- Southwest Research Institute