Un modèle de sources ďémission acoustique pour ľanalyse de ľémission continue et de ľémission par salves II. Vérifications expérimentales

Rouby, P.; Fleischmann, P.; Duvergier, C.

doi:10.1080/01418618308245258

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…The wave will then be proportional to the expansion rate of the radius d(t') and, for the dislocation loop, to the radius by a(t') and for the microcrack and shear decohesion, to the area by a(t') 2. These results are in agreement with those of other authors [3,4].…”

Section: Sl(t)=ss(t)dt and S2(t)=ssl(t)dtsupporting

confidence: 83%

“…The distance r is the one measured here on the compact tension specimen (about 10mm-40mm). For r, the values generally observed for a volume source are in the range about 0.1 ~ts-0.3 ~ts [4,5,9,15], but smaller values than 0.1 ~ts [15] and larger values up to 21as [16] were also reported for this source. The relativistic limit of the expansion rate of the radius is c, for a dislocation loop [17] and cR, i.e.…”

Section: Applications For a Tensile Source And A Shear Sourcementioning

confidence: 92%

“…By assuming that the wave is emitted only at this point, the expression of u,. Another form of this expression, where the moment tensor (here its time derivative /~/k~(t')) appears, is [2] Io I with ~Vlkt(t') = 2~zbni vjcijkta(t')a(t'), (4) or after integration…”

Section: Expansion Of a Dislocation Loopmentioning

confidence: 99%

“…It can be expected that the dynamic theory of dislocations will be an appropriate means to calculate these waves and to determine the parameters of their source by analysis of the waves. This was done for seismic sources such as faults [2], and, at the microscopic scale, for acoustic emission sources such as dislocations, microcracks, local creation of free surfaces by shear (denoted here by shear decohesion) [3,4,5,6,7,8,9], and local formation of a new phase [10].…”

Section: Introductionmentioning

confidence: 99%

“…The moment tensor of the source can be determined from this representation [2]. When the dislocation loop is not sufficient to describe the stress field, complementary results from linear elastic fracture mechanics are used [3,4,5,9]. The wave displacement (wave) is calculated generally in 2 dimensions by the Green's function formalism for an unbounded medium.…”

Section: Introductionmentioning

confidence: 99%

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Acoustic emission sources modelled by dislocations

Tirbonod

1992

Int J Fract

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Acoustic emission sources representing dislocations and cracks under tensile forces, shear forces or a combination of these forces are modelled by a single circular dislocation loop and by a continuous distribution of such loops. The medium is assumed to be linear, elastic isotropic, homogeneous and unbounded. The quasistatic and the point source approximations are assumed. The wave displacement induced by the expansion of a loop and of a continuous distribution of loops is calculated for a tensile and a shear source on the basis of the dynamic dislocation theory by using the Green's function formalism. The wave is given in terms of L-, SV-and SH-waves as a function of the expansion law of the source and is calculated in a simple case. The wave form, radiation pattern and the diameter of the source are calculated; the influence of the expansion time of the source and of the distance between the source and the observation point is discussed. The results are used to check the assumptions of linearity and elasticity. They are compared with experiments and applied to characterise the source from measurements.

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Section: Sl(t)=ss(t)dt and S2(t)=ssl(t)dtsupporting

confidence: 83%