Accession Number:

ADA191267

Title:

Bimodular Behavior and Crack Closure in Compression in a Brittle Material,

Descriptive Note:

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA MATERIALS SCIENCES LAB

Personal Author(s):

• Feldman, L. A.

Report Date:

1987-09-30

Pagination or Media Count:

22.0

Abstract:

A vibrating beam method was used to determine the elastic modulus of graphite rods. The frequency and apparent modulus were determined as a function of compressive end loading. Following fracture of the rod, the frequency and apparent modulus were decreased. At a compressive and loading of about 0.83 MPa 120 psi, crack closure was sufficient for the fractured rod to behave similarly in vibration to the unfractured rod. Thus, the fractured material behaves in a bimodular fashion and crack closure can be achieved to enable unimpeded stress transfer across the fracture surface during vibration. Keywords Bimodular behavior, Elastic modulus measurements, Graphite, Microcracking and modulus.

Descriptors:

• *BRITTLENESS
• *COMPRESSIVE PROPERTIES
• *CRACKS
• *GRAPHITE
• CLOSURES
• FRACTURE(MECHANICS)
• MICROCRACKING
• MODULUS OF ELASTICITY
• RODS
• STRESSES
• VIBRATION
• ACOUSTIC SIGNALS
• ROCK
• CERAMIC MATERIALS
• ACOUSTIC RESONATORS
• BEAMS(STRUCTURAL)
• CROSS SECTIONS

Subject Categories:

• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE