A new mixed-mode threshold stress intensity factor is developed using a critical plane-based multiaxial fatigue theory and the Kitagawa diagram. The proposed method is a nominal approach since the fatigue damage is evaluated using remote stresses acting on a cracked component rather than stresses near the crack tip. An equivalent stress intensity factor defined on the critical plane is proposed...

Multiple healing cycles of a single crack in a brittle polymer coating are achieved by microvascular delivery of a two-part, epoxy-based self-healing chemistry. Epoxy resin and amine-based curing agents are transported to the crack plane through two sets of independent vascular networks embedded within a ductile polymer substrate beneath the coating. The two reactive components remain isolated ...

Analyses of dynamic crack growth along interfaces are discussed. The material on each side of the bond line is characterized by an elastic constitutive relation. A cohesive surface constitutive relation that allows for the creation of new free surface is also specified across the bond line. The resistance to crack initiation and the crack speed history are then predicted without invoking any ad...

The T ∗ ε integral was calculated numerically along an extending, tunneling crack front in an 8 mm thick, aluminum three-point bend (3PB) specimen, using a numerical model driven by experimentally obtained surface displacements. The model provided input to a contour integration for the T ∗ ε integral, via the Equivalent Domain Integral (EDI) method with incremental plasticity. Validity of the a...

As a first step towards a new crack healing methodology for cyclic loading, this paper examines two promising crack-tip shielding mechanisms during fatigue of a microcapsule toughened epoxy. Artificial crack closure is achieved by injecting precatalyzed monomer into the crack plane to form a polymer wedge at the crack tip. The effect of wedge geometry is also considered, as dictated by crack lo...

Failure modes in recent earthquakes on lightly reinforced shear walls includes rebar fracture and out of plane buckling of its boundary elements. In latest edition of ACI 318 and also latest amendment of NZS 3101-2006 to avoid rebar fracture in boundary elements, the minimum reinforcement ratio for shear walls is increased. This experimental study investigates that rather than increasing reinfo...

The growth of slant cracks by fretting fatigue of a half plane in contact with a flat rounded pad was studied. The mode I and mode II stress intensity factors for cracks of various lengths and directions were calculated using the semi-analytical method of the distribution of dislocations, and their cumulative effect on the crack growth was investigated using the strain energy density criterion....

In reinforced concrete design, there are situations where transfer of shear across a specific plane needs to be considered. Examples of such situation include corbels, bearing shoes, ledger beam bearing, and a host of connection between precast concrete elements. In this study, the shear transfer behavior of reinforced concrete is investigated experimentally by conducting test on 6 precracked p...

This paper presents a three-dimensional crack initiation analysis in a sidegrooved CT specimen. This is achieved with an endochronic damage model proposed recently by Chow and Chen [ 1,2] and discretized for finite element analysis. The damage model enables the quantification of the progressive damage evolution which would not be otherwise possible using the conventional fracture mechanics anal...