Compression strengths of advanced composites from a novel mini-sandwich beam

Journal Article · Mon Apr 01 00:00:00 EST 1991 · SAMPE Quarterly (Society of Aerospace Material and Process Engineers); (United States)

OSTI ID:5457967

Crasto, A S; Kim, R Y ^[1]

---

1. Univ. of Dayton, OH (United States)

The intrinsic compression strength of advanced composites is difficult to measure, as the results often depend on the loading geometry and test conditions. Slight variations in specimen geometry can result in an eccentricity of the applied load with consequent specimen buckling. Complex test fixtures and specimen geometries have therefore been developed to avoid such premature failure under compressive loading. In spite of this, there is a large variation in reported strengths for some composites (notably those of intermediate-modulus carbon fibers), and failure strains are also significantly lower than those of the individual filaments. To better approximate the intrinsic composite compressive strength, a novel symmetric mini-sandwich beam was designed for testing. The beam has a composite skin (of variable thickness) on both sides of a neat resin core (of same material as the composite matrix). Unidirectional mini-sandwich specimens of AS4 and S-glass fibers in an epoxy matrix and AS4 in a PEEK matrix were tested in direct axial compression and four-point flexure. Failure occurred predominantly in the specimen gage section, at composite stresses and strains substantially higher than observed in corresponding tests on all composite-coupons. This paper discusses the fabrication and testing of these beams and analyzes the resulting compressive data and failure modes.

• OSTI ID: 5457967
• Journal Information: SAMPE Quarterly (Society of Aerospace Material and Process Engineers); (United States), Vol. 22:3; ISSN 0036-0821
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
COMPOSITE MATERIALS
COMPRESSION STRENGTH
MECHANICAL TESTS
CARBON FIBERS
CONSTRUCTION
DESIGN
EPOXIDES
EXPERIMENTAL DATA
FAILURE MODE ANALYSIS
FIBERGLASS
GEOMETRY
IMAGES
MEASURING INSTRUMENTS
STRAINS
TEST FACILITIES
DATA
FIBERS
INFORMATION
MATERIALS
MATERIALS TESTING
MATHEMATICS
MECHANICAL PROPERTIES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TESTING
360603* - Materials- Properties
420500 - Engineering- Materials Testing