Effects of Moisture, Residual Thermal Curing Stresses and Mechanical Load on the Damage Development in Quasi-Isotropic Laminates.
Abstract
This investigation demonstrates how the maximum moisture absorbed (that is the wet condition) in O/+ or - 45/9O sub s and 0/90/+ OR -45 sub s laminates fabricated from T3OO/52O8 significantly alters the dry stress state and subsequent damage development along the laminate free edge. Emphasis is placed on using reasonable approximations for wet, dry, and out-of-plane elastic properties since these properties are required to predict the damage free stress state at the laminate edge. Classical laminate theory and a finite element model were used to predict stress states prior to the first formation of damage. Crack patterns characteristic of the laminate in a wet or dry condition were also predicted using a shear lag model. Development of edge damage was recorded and observed during the test by transferring an image of the damage from the edge surface on to a thin acetate sheet (replica technique), such that the damage imprinted on the ecetate sheet could be immediately viewed on a microfiche card reader. Moisture was shown to significantly alter the interior and edge dry stress states due to swelling and a reduction of elastic properties. Moisture also reduces the transverse strength in the 90 deg plies such that the first formation of damage in a wet 0/+ OR -45/90 sub s laminate is a simultaneous occurrence of delaminations and transverse cracks in the 90 deg plies. A model was developed in order to predict changes in first ply failure laminate loads due to differences in stacking sequence together with a wet or dry environmental condition.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1980
- Accession Number
- ADA301677
Entities
People
- D. R. Tenney
- R. D. Kriz
- W. W. Stinchcomb
Organizations
- Virginia Tech