Out-of-plane properties
This paper summarizes three areas of research which were performed to characterize out-of-plane properties of composite materials. In the first investigation, a series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. Failures were significantly different between the 2D materials and the 3D weaves. The 2D materials delaminated between layers due to out-of-plane tensile stresses while the 3D weaves failed due to the formation of radial cracks between the surface plies caused by high circumferential stresses along the inner radius. The strength of the 2D textile composites did not increase relative to the tapes. Final failure in the 3D weaves was caused by a circumferential crack similar to the 2D materials and occurred at a lower bending moment than in other materials. The early failures in the 3D weaves were caused by radial crack formation rather than a low through-the-thickness strength. The second investigation focused on the development of a standard impact test method to measure impact damage resistance. The only impact tests that currently exist are compression after impact (CAI) tests which incorporate elements of both damage resistance and damage tolerance. A new impact test method is under development which uses a quasi-static indentation (QSI) test to directly measure damage resistance. Damage resistance is quantified in terms of the contact force to produce a unit of damage where a metric for damage may be area in C-scan, depth of residual dent, penetration, damage growth, etc. A final draft of an impact standard that uses a QSI test method will be presented to the ASTM Impact Task Group on impact. In the third investigation, the impact damage resistance behavior of a variety of textile materials was studied using the QSI test method.
- Research Organization:
- NASA Langley Research Center, Hampton, VA (United States)
- OSTI ID:
- 188456
- Report Number(s):
- N-96-17705; NASA-CP-3311-PT-2; NAS-1.55:3311-PT-2; L-17532B; NIPS-96-06187; CONF-9412106-; TRN: 9617707
- Resource Relation:
- Conference: Mechanics of textile composites conference, Hampton, VA (United States), 6-8 Dec 1994; Other Information: PBD: Oct 1995; Related Information: Is Part Of Mechanics of Textile Composites Conference; Poe, C.C.; Harris, C.E.; PB: 433 p.
- Country of Publication:
- United States
- Language:
- English
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