The numerical simulation results utilizing the Peridynamics (PD) method reveal that initial crack and propagation of tunnel concrete lining structure agree with experimental data compared to Japanese prototype test. load model takes into account cracking process distribution segment under influence local bias pressure thickness. In addition, preset cracks section form on is studied. This study ...

An advanced, waveform based acoustic emission (AE) system was used to study the initiation of transverse matrix cracking in cross-ply graphite/epoxy (gr/ep) composites. The AE signals were detected with broad band, high fidelity sensors, and digitized for analysis. Plate wave propagation analysis was used to discriminate noise signals from those generated by cracks. The noise signals were confi...

Hydraulic turbine runner has a complex structure, and traditional location methods can't meet its requirement. This paper describes a source location of cracks in turbine blades by combining kernel independent component analysis (KICA) with wavelet neural network (WNN). The research shows that the location accuracy of WNN combined with KICA feature extraction is the best comparing with the resu...

The method of identification of cracks-like defects in coated pipes is proposed. A cross section of the pipe, reinforced by inner annular coat and the magnetic field propagation of permanent magnets modelled. The identification of several geometric parameters of defects is carried out. Investigated the influence of different geometric parameters of the defects on the performance of neural netwo...

Dynamics of amorphization and fracture in SiSe 2 nanowires are studied using the molecular-dynamics method. We find that fracture is initiated in an amorphous region at the nanowire surface. Local amorphization propagates across the nanowire while multiple cracks start at the boundaries of the amorphous region. Results for the time evolution of amorphization, crack propagation, and fracture are...

Ultrasonic crack detection and sizing is an essential tool in determining the asset integrity of pressure vessels and piping. Conventional UT shear wave methods have proved to be time consuming, requiring high skill levels and frequently resulting in unreliable and inconsistent data. Phased array UT technology can provide novel solutions to these problems with reliable results, imaging of the c...

Certain results of numerical simulations obtained by the use of the spectral finite element method in time domain are presented by the authors. They were selected in order to show the effectiveness of the spectral finite element method for investigation of problems associated with propagation of guided elastic waves in a wind turbine laminated composite blade. Results of these simulations were ...

This paper presents an overview of Laser Shock Processing and then discusses how the process can be extended to treat fastener holes on aging aircraft. The process is used to treat localized fatigue-critical areas by developing deep residual compressive stresses to inhibit the initiation and propagation of fatigue cracks. This feature can be applied to fastener holes in aircraft structures to d...

The motivation for this paper is the need to detect radial fatigue cracks in a shaft/bearing assembly (as shown in Fig. 1), using guided circumferential waves. To do so, wave propagation in a layered cylinder must be understood. In order to accurately detect the crack, the dispersion relationship for guided circumferential waves must be known; this enables the selective generation of specific w...

We present a new mechanism--discovered using molecular dynamics simulations--that leads to complete healing of nanocracks. This mechanism relies on the generation of crystal defects known as disclinations by migrating grain boundaries. Crack healing by disclinations does not require any compressive loads applied normal to the crack faces and even occurs under monotonic tensile loading. By closi...