Transverse Microcracking in Celion 6000/PMR-15 Graphite-Polyimide
Abstract
The effects of room temperature tensile loading and five thermal loadings, in the range -3200F (-l960C) to 6250F (33o0C), upon the development of transverse microcracks (TvM) in Celion 6000/PNR-05 graphite-polyimide laminates wire investigated. Microcracks were observed using a replicating technique, microscopy and x-ray. The mechanical or thermal load at which microcracking initiates and the ply residual stresses were predicted using laminate analysis with stress- and temperature-dependent material properties. TVM density as a function of tensile load was predicted using the multiple cracking theory proposed by Garrett, Parvizi and 8aile>. It has been shown that TVM density and the load to initiate microcracking are functions of the type of loading and the laminate configuration. Generally1 cross-ply laminates exhibit higher TVM density after thermal loading than do quasi-isotropic laminates, but the converse is true for tensile loading. Cross-ply laminates attain a saturation TVM density prior to failure, but the TVM density .f quasi-isotropic laminates continues to increase until failure. Edge effects have a significant influence on the development of TVM, and TVM present at the free edge of a laminate extend across the entire width of the laminate. All laminates considered in this investigation were free of cracks after curing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1979
- Accession Number
- ADA306031
Entities
People
- Carl T. Herakovich
- J. S. Mills
- John G. Davis Jr.
Organizations
- Virginia Tech