Analysis of the hygrothermal effects and parametric study of the edge crack torsion (ECT) mode 3 test layups
- National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center
A shear deformation theory including residual thermal and moisture effects is developed for the analysis of either symmetric or asymmetric laminates with midplane edge delamination under torsional loading. The theory is based on an assumed displacement field that includes shear deformation. The governing equations and boundary conditions are obtained from the principle of virtual work. The analysis of the [90/({+-}45){sub n}/({+-}45){sub n}/90]{sub s} edge crack torsion (ECT) Mode 3 test layup indicates that thee are no hygrothermal effects on the Mode 3 strain energy release rate because the laminate, and both sublaminates above and below the delamination, are symmetric layups. A further parametric study reveals that some other layups can have negligible hygrothermal effects even when the sublaminates above and below the delamination are not symmetric about their own midplanes. However, these layups may suffer from distortion after the curing process. Another interesting set of layups investigated is a class of antisymmetric laminates with [{+-}({theta}/{theta} {minus} 90){sub 2}/{theta}]{sub n} layups. It is observed that when n takes on even numbers (2 and 4), both hygrothermal and Mode 1 effects can be neglected. From this point of view, these layups provide a way to determine the Mode 3 toughness between two dissimilar layers. However, when n takes on odd numbers (1 and 3), both hygrothermal and Mode 1 effects may be strong in these layups. In particular, when {theta} equals 45{degree}, the layups are free from both hygrothermal and Mode 1 effects irrespective of n.
- OSTI ID:
- 566525
- Report Number(s):
- CONF-950569-; TRN: IM9805%%175
- Resource Relation:
- Conference: 6. ASTM symposium on composites: fatigue and fracture, Denver, CO (United States), 16-18 May 1995; Other Information: PBD: 1997; Related Information: Is Part Of Composite materials: Fatigue and fracture (sixth volume); Armanios, E.A. [ed.]; PB: 579 p.; ASTM special technical publication 1285
- Country of Publication:
- United States
- Language:
- English
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