Interaction between fast crack and two-media interface

Milios

1980

Int J Fract

A study of the behaviour of cracked composite specimens under dynamic tensile load was undertaken. The crack propagation in the two-phase epoxy resin specimens was studied by the method of high speed photography along with the optical method of caustics.Our investigation was concentrated both on the dependence of the maximum crack propagation velocity and the stress intensity factor at the crack tip upon the different material combinations of the composite, as well as on the role of the interface again in regard to the crack propagation and the singular stress field concentrations at the crack tip.The results show that, under a given value of the applied dynamic load and given notch dimensions, the stress intensity factor at the crack tip and the crack propagation velocity in each phase of the composite is highly dependent on the material characteristics of each phase and on the existence of a stable interface between the two phases.More concretely, it was proved that the interface plays the role of a "barrier" to the crack propagation. Indeed, the crack propagates with a certain maximum velocity in the first phase of the composite and then stops momentarily when it reaches the interface, thus attaining later in the second phase a new maximum velocity.The maximum velocity and the stress intensity factor in the second phase of the composite specimens strongly depend on the material characteristics of the first (notched) phase and are also highly influenced by the crack arrest process itself.The crack propagation and the stress field concentrations at the crack tip in the first phase of the composite specimens is mainly independent from the material characteristics of the second phase of the composite specimens.

Section: Ps Theocaris and J Miliosmentioning

confidence: 94%

Section: Ps Theocaris and J Miliosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic crack propagation in composites

Milios

1980

Int J Fract

“…Also, the crack propagation process in bi-phase plates has been investigated by Sereda et al. [2], again by means of dynamic photoelasticity. Theocaris and Milios [5] have studied the influence of both the mesophase layer between main phases and the material characteristics of each phase, in biphase plates consisting of different materials, on the stress distribution around the crack tip [4].…”

Section: Introduction He Behaviour Of Cracks Propagating Through the mentioning

confidence: 98%

Crack Propagation and Bifurcation in Fiber-Composite Models-II: Hard-Soft-Hard Sequence of Phases

Journal of Reinforced Plastics and Composites

Papadopoulos

1986

An experimental study of the influence of a soft-fiber inclusion and the mesophase layer surrounding it in a hard-soft-hard bi-phase representative volume element (RVE), on the fracture and bifurcation processes in both phases was undertaken. The influence of the mechanical properties of each phase and the effect of the external loading-rate on the crack propagation velocity and the initiation of the crack bifurcation was studied by using highspeed photography and dynamic caustics. It was shown that the propagating crack tended to bifurcate either in the hard or in the mesophase layer, and the bifurcation of the crack depended strongly on the strain rate, the elastic modulus and the Poisson ratio of the phases, as well as on the extent of the mesophase layer, which relies upon the degree of adhesion between phases.

“…[2], again by means of dynamic photoelasticity. This investigation, though, dealt only with the variation of the K,-value of the stress intensity factor in the component phases and did not confront the problem of a crack interacting with an interface.…”

Section: Introduction He Study Of the Behaviour Of A Transverse Crackmentioning

confidence: 99%

Crack Propagation and Bifurcation in Fiber-Composite Models: I. Soft-Hard-Soft Sequence of Phases

Journal of Reinforced Plastics and Composites

Siarova

Papadopoulos

1986

The influence of the hard fiber and the mesophase layers in a soft-hard-soft combination of a biphase plate subjected to a dynamic tensile load, on the fracture mode and bifurcation process in both phases was investigated. It was assumed that the soft matrix envelops the hard-fiber layer of the plate, so that this plate constitutes a meridianal section of a representative volume element of a unidirectional fiber composite.The influence of the mechanical properties of either phase on the crack propagation velocity and the initiation of crack bifurcation was studied by using high-speed photography and dynamic caustics.The results showed that the propagating crack tended to bifurcate either in the brittle or in the mesophase layer under certain conditions of velocity of propagation. It was shown that bifurcation of a propagating crack depends on the elastic moduli and Poisson's ratios of the phases, as well as on the extent of the mesophase layer, which depended on the adhesion quality of phases.