In this paper, we propose an approach for diagnostics and prognostics of damaged aircraft structures, by combing high-performance fatigue mechanics with filtering theories. Fast & accurate deterministic analyses of fatigue crack propagations are carried out, by using the Finite Element Alternating Method (FEAM) for computing SIFs, and by using the newly developed Moving Least Squares (MLS) law ...

The finite displacement formulation of a quadrilateral element containing an embedded displacement discontinuity is presented. The formulation is based on the kinematically optimal technique, and some known defects of this technique are addressed. Lagrange multipliers are adopted to ensure the correct crack closure prior to initiation. Six additional degrees of freedom in each element allow the...

Debonding of films attached to substrates as well as fibers embedded in matrices typically involves initiation, steady-state propagation and a final transient as the debond converges on an edge or another debond. The emphasis in this paper is on the mechanics of the transient. Under most circumstances, a converging debond crack is characterized by an energy release rate that approaches zero, ca...

In this study, the effect of confining pressure on the crack growth behavior in a highly filled elastomer was investigated. The material under investigation contains 86% by weight of hard particles embedded in a rubbery matrix. The specimens were tested at a constant strain rate under a confining pressure. Two confining pressures, 3.45 MPa and 6.9 MPa, and two types of loading, monotonically in...

Polarimetric optical fibre sensors have been embedded within the 0° ply and close to the 0/90 interface of transparent cross-ply GFRP coupons. The coupons have been subjected to an increasing quasi-static load so that transverse ply cracks initiate and propagate across the coupon. Crack accumulation has been monitored using the optical output signal from the polarimetric sensor, strain measurem...

The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. Th...

Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heat...

Self-healing polymers, based on microencapsulated dicyclopentadiene and Grubbs' catalyst embedded in the polymer matrix, are capable of responding to propagating fatigue cracks by autonomic processes that lead to higher endurance limits and life extension, or even the complete arrest of the crack growth. The amount of fatigue-life extension depends on the relative magnitude of the mechanical ki...

Fatigue cracking is one of the most common failure modes of various load-bearing structures. Even though sensors of many different types have been developed for crack detection, very few can monitor crack growth with a high sensitivity. This paper presents an antenna sensor that is capable of monitoring the growth of fatigue cracks with a sub-millimeter resolution. According to microstrip patch...

The phenomenon of ageing structures has focused attention on the problem of multiple-site damage (MSD) and wide spread fatigue damage (WFD). In isolation each ̄aw or crack may be safe. However, the cumulative e€ect of multiple, interacting cracks may signi®cantly degrade the damage tolerance of the structure. This paper presents an overview of a new ®nite element alternating technique algorithm...