Laser-scanning structural health monitoring with wireless sensor motes

Evolution of Slip Morphology and Fatigue Crack Initiation in Surface Grains of Ni200

“…Fatigue crack initiation occurs when the slipband width to spacing ratio increases to a value of 0.5 to 1 for Ni200. Thus, the evolution of roughness of a fatigued surface may potentially be used as a damage precursor or indicator to prognosticate fatigue crack initiation from a surface, as demonstrated by Buckner et al [5] on machined surfaces of Waspaloy. A region of high surface roughness may indicate a region where cyclic deformation and slipband formations are prevalent.…”

“…For structural components, the machined surfaces may be sufficiently rough to obscure the detection of surface roughness due to persistent slipbands or extrusions. Such a concern was alleviated by recent work by Buckner et al, [5] who successfully obtained surface roughness measurements on machined surfaces of Waspaloy* with and without fatigue. Significant differences were observed in the bidirectional reflectance distribution (BRDF) signal levels of the pristine and fatigued machined surfaces.…”

“…[4] Thus, the surface roughness induced by cyclic slip has been considered a fatigue damage precursor to crack initiation and used in fatigue crack prognostics. For example, Buckner et al [5] have applied a laser scattering technique to measure the surface roughness of a fatigued surface. Such a technique can potentially be used as a structural health monitoring system if the surface roughness can be directly related to fatigue life.…”

“…Such a technique can potentially be used as a structural health monitoring system if the surface roughness can be directly related to fatigue life. [5] The processes responsible for the formation of persistent slipbands, extrusions, and fatigue cracks in surface grains are well established, as described in several reviews. [1,2,6] A number of mechanistic models have been proposed to describe the initiation of fatigue cracks at slipbands or extrusions.…”

Non-contact based structural damage assessment using stochastic subspace identification and finite element model updating.

“…Wireless sensor interface, data processing subsystem, wireless transceiver and power supplier need to be encompassed to achieve wireless data acquisition (Dorvash 2013). Different wireless techniques have been used in structural health monitoring (Buckner et al 2008;Grosse and Krüger 2006;Mascarenas et al 2010). A typical wireless sensor network is shown in Figure 2.4.…”