Prediction and Control of Processing-Induced Residual Stresses in Composites. Part 2. AS4/PEEK Composite

Abstract

Residual stresses in symmetric cross-ply laminates were monitored by measuring the dimensionless curvature. The cooling rate was found to have a significant influence on the amount of residual stress in graphite/PEEK (APC-2) laminates. The transverse strain due to crystallization was not negligible and must be considered when predicting residual stresses for cooling rates of 75 deg C/min and lower. The stress-free temperature for O3/90(3) APC-2 laminates decreases with increasing cooling rate. Successive unconstrained heating/cooling provided the necessary environment for less stress relaxation allowing the specimens to move toward an equilibrium stress-free temperature (SFT) of 328 deg C. The SFT for any heating cycle was found to be equivalent to the previous cooling cycle SFT. The SFT is strongly dependent on geometrical constraint during thermal cycling because of the stress relaxation.

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 1989
Accession Number
ADA223696

Entities

People

  • H. T. Hahn
  • K. J. Schulte

Organizations

  • Pennsylvania State University

Tags

Communities of Interest

  • Air Platforms
  • Space

DTIC Thesaurus Topics

  • Biomedical And Dental Materials
  • Composite Materials
  • Geometry
  • Glass Transition Temperature
  • Heat Of Fusion
  • Laminates
  • Material Degradation Processes
  • Materials
  • Materials Processing
  • Materials Science
  • Materials Testing
  • Mechanical Properties
  • Mechanical Working
  • Mechanics
  • Resins
  • Thermoplastic Resins
  • Transition Temperature

Fields of Study

  • Materials science

Readers

  • Combustion science or combustion engineering.
  • Marine Mammal Biology
  • Structural Health Monitoring of Composite Structures.