Crack-fiber interactions at frictional interfaces: Experimental observations and computational simulation

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:175310

Larson, M C ^[1]

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1. Tulane Univ., New Orleans, LA (United States)

This three-dimensional experimental and computational investigation lends insight into the influence that a frictionally constrained interface has on the progress of a quasi-statically propagating matrix crack. Understanding this localized interaction holds implications for enhancing the global toughness of brittle fibrous composites containing small matrix fractures. The experiments, captured on videotape, show the real-time propagation of fractures toward and around cylindrical frictional interfaces. Modified double cleavage drilled compression specimens containing inclusions are employed as a model composite. The degree of interference permits control over the frictional shear constraint at the fiber/matrix interfaces as characterized by the Frictional Grab. This measure is based on the nominal, pre-existent compression, (e.g. a thermal setting stress), the critical stress intensity of the cracked matrix, a Coulomb friction coefficient, and the fiber size. The cases highlighted clearly show the crack retardation near a frictionally constrained interface as compared to a monolithic material and a material containing a void. Computational simulations demonstrate the effectiveness of using the surface integral method to represent the matrix cracks and the coupled interfacial sliding zones. This approach offers particular advantages in that only surfaces need to be discretized, and the kernel of the singular integral governing equation is physically meaningful for fracture characterization. An iterative scheme determines the interfacial frictional tractions; embedded crack-tip singularities govern the crack propagation. The explicit modeling of the progress of the matrix crack as it engulfs individual fibers reveals the degree of localized matrix toughening.

• OSTI ID: 175310
• Report Number(s): CONF-950686--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
CRACK PROPAGATION
FIBERS
FRICTION
INCLUSIONS
INTERFACES
SHEAR