The resonance phenomenon observed in Rayleigh wave scattering from surface-breaking cracks has been investigated using Freund's results on reflection of Rayleigh waves from an infinite crack edge. To model the crack as a section of acoustic waveguide, resonances are treated as standing waves in the length and depth directions. The model takes both faces of the crack into consideration, and this...

Residual compressive stress can improve fretting fatigue strength. In this paper, the effects of residual stress on fretting fatigue of Al 2024-T351 alloy specimens are studied using a numerical approach. The extended finite element method combined with the cyclic cohesive zone model is adopted to model fretting fatigue crack growth behavior. It is shown that residual stress changes the frettin...

16 This paper presents a novel large-area strain sensing technology for monitoring fatigue cracks in 17 steel bridges. The technology is based on a soft elastomeric capacitor (SEC), which serves as a 18 flexible and large-area strain gauge. Previous experiments have verified the SEC’s capability to 19 monitor low-cycle fatigue cracks experiencing large plastic deformation and large crack openin...

We present a modeling technique for the interaction of an elliptical-shape crack in a metal with an open-ended waveguide. The crack is first modeled by an appropriate number of short rectangular waveguides. The mode-matching technique is then used to calculate the scattering matrix of the new segmented waveguide structure. The probe reflection coefficient of the dominant mode is finally calcula...

Rotor crack detection method by using multi-vibration signals gathered at the basements is presented in this paper. The finite element software ANSYS is applied for analyzing the vibration response characteristics of the basement to determine sensor configuration. Feature fusion for time-domain statistics of multiple sensors is performed by using the support vector machine to diagnose the depth...

With the characteristics of ANN’s strong capability on nonlinear approximation, a new method by combining an artificial neural network with back-propagation learning algorithm and modal analysis via finite element model of cracked rotor system is proposed for fast identification of crack fault with high accuracy in rotating machinery. First, based on fracture mechanics and the energy principle ...

Seasonal cracking of the soil matrix results in poor estimates of runoff and infiltration by simulation models due to the changing soil storage conditions. In this study, soil surface elevation changes were measured every two weeks and soil crack volume was calculated for a two-year period at the USDA-Agricultural Research Service, Riesel Y-2 watershed in central Texas. Soil anchors were placed...

In this paper, the stress intensity factor (SIF) variations along an arbitrarily developing crack front, the non-planar fatigue-crack growth patterns, and the fatigue life of a round bar with an initially straight-fronted surface crack, are studied by employing the 3D symmetric Galerkin boundary element method-finite element method (SGBEM-FEM) alternating method. Different loading cases, involv...

When a propagating cleavage front encounters a high-angle grain boundary it first penetrates through the grain boundary stably. With increasing penetration depth the resistance of the grain boundary rises, resulting in the well-known R-curve. When the balance between the rates of the energy release rate and the grain boundary resistance is reached, the crack advance becomes unstable and the gra...