Materials and mechanics of rate effects in brittle fracture. Progress report, October 1975--October 1976. [PMMA]

Technical Report · Thu Jan 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7232320· OSTI ID:7232320

Burns, S. J.

The slow, isothermal, propagation of cracks was analyzed by introducing the fracture mechanics concepts into molecular rate theory. Relations between thermodynamic variables and measurable quantities such as crack velocities, specimen temperature and crack extension force were derived. The shape and distribution of the rate controlling obstacles were left unspecified in the theory. The theory was applied to published crack propagation data in PMMA and agreement between theory and data is found. A literature survey of crack velocity data in a wide selection of materials including inorganic glasses, ceramics, polymers and metals shows the correlation that the crack extension force is inversely proportional to the crack activation area. In rapid crack propagation, a new technique, measuring the complimentary boundary condition to the applied boundary condition was used to deduce the stress intensity factor and the crack velocity during crack propagation in DCB specimens. The technique is easier to use and gives better results than the electro-potential methods of measuring crack length during rapid fracture. The shear force in a rapidly wedged DCB specimen is multiplied by the square root of the time after the wedge strikes the specimen, this product is nearly constant during fracture, from its slight time dependence we deduce how K/sub ID/ and the crack velocity vary as a function of time. Time is eliminated and K/sub ID/ is plotted versus crack velocity.

• Research Organization: Rochester Univ., NY (USA)
• OSTI ID: 7232320
• Report Number(s): COO-2422-08
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360403* -- Materials-- Polymers & Plastics-- Mechanical Properties-- (-1987)
CARBOXYLIC ACID ESTERS
CERAMICS
CORRELATIONS
CRACKS
ELEMENTS
ESTERS
FRACTURE PROPERTIES
GLASS
KINETICS
MECHANICAL PROPERTIES
METALS
METHACRYLIC ACID ESTERS
METHYL METHACRYLATE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYACRYLATES
POLYMERS
POLYVINYLS
RESEARCH PROGRAMS
SOLIDS