Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi

Zhukovsky Moscow, Russia

Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi

Zhukovsky Moscow, Russia

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Matvienko Y.G.,Russian Academy of Sciences | Pisarev V.S.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Eleonsky S.I.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi
Frattura ed Integrita Strutturale | Year: 2013

New experimental technique for a determination of the stress intensity factor (SIF) and T-stress values is developed and verified. The approach assumes combining the crack compliance method and optical interferometric measurements of local deformation response on small crack length increment. Initial experimental information has a form of in-plane displacement component values, which are measured by electronic speckle-pattern interferometry at some specific points located near a crack tip. Required values of fracture mechanics parameters follow from the first four coefficients of Williams' series. A determination of initial experimental data at the nearest vicinity of notch tip is the main feature of the developed approach. That is why it is not necessary to involve complex numerical models, which include global geometrical parameters, loading and boundary conditions of the object under study, in a stage of experimental data interpretation. An availability of high-quality interference fringe patterns, which are free from rigid-body motions, serves as a reliable indicator of real stress state around a crack tip. A verification of the technique is performed by comparing experimental results with analogous data of FEM modelling. Experimentally determined mode I SIF for DCB specimen with end crack is in 5 per cent agreement with the numerically simulated case. Proposed approach is capable of estimating an influence of the notch radius on fracture mechanics parameters. Comparing SIF and T-stress obtained for U-notches of different radius both in actual and residual stress field confirms this statement.


Eleonsky S.I.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Matvienko Yu.G.,Russian Academy of Sciences | Odintsev I.N.,Russian Academy of Sciences | Pisarev V.S.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi
19th European Conference on Fracture: Fracture Mechanics for Durability, Reliability and Safety, ECF 2012 | Year: 2012

New experimental technique for a determination of the stress intensity factor and the non-singular T-stress in the case of narrow notches is developed. The approach is based on combining the crack compliance method and optical interferometric measurements of local deformation response as a result of crack length increment. Initial experimental information has a form of in-plane displacement component values, which are measured by electronic speckle-pattern interferometry at some specific points located near the crack tip. The first four coefficients of Williams' formulation can be thus derived. A determination of initial experimental data in immediate neighbourhood of the notch tip is the main feature of the developed approach. In this case, it is not necessary to use complex numerical models which are connected with geometrical parameters and loading conditions of the object under study in a stage of experimental data interpretation. Moreover, an availability of high-quality interference fringe patterns, which are free from rigid-body motions, serves as a reliable indicator of real stress state in the vicinity of the notch tip. Proposed approach gives the unique capability for an estimation of the effect of the notch tip radius on fracture mechanics parameters. A confirmation of this fact is based on the investigation of U-notch increment for two notch radius (0.3 mm and 0.15 mm) in the same residual stress field. The values of the stress intensity factor and the Tstress are calculated for notches of different length. A difference in maximum values of KI and T-stress is equal to 20% and 30%, respectively.


Pisarev V.S.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Eleonsky S.I.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Chernov A.V.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi
Experimental Mechanics | Year: 2015

Novel method for a determination of residual stresses in orthotropic composite plates based on local displacement measurements by electronic speckle-pattern interferometry is developed and verified. The values of hole diameter increments in principal residual stress directions serve as initial experimental deformation. The technique is based on analytical solution of S.G. Lekhnitsky, which describes a stress concentration along the edge of central open hole in rectangular orthotropic plate under one-axis tension in arbitrary direction. A situation when principal directions of residual stresses coincide with principal axes of anisotropy is considered. The relations, which connect initial experimental data with residual stress components, are unequivocally solution of the properly posed inverse problem. An availability of interference fringe patterns, a quality of which is high enough for reliable recognizing of fringe orders at the hole edge immediately, is the essential experimental foundation of the approach developed. The accuracy of the proposed method has been assessed by two different ways. The results of residual stresses determination in rectangular composite plate are presented. © 2015, Society for Experimental Mechanics.


Pisarev V.S.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Dzuba A.S.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi | Chernov A.V.,Central Aerospace Hydrodynamics Institute Named After Prof Ne Zhukovsky Tsagi
28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012 | Year: 2012

New experimental technique for a determination of the stress intensity factor and the nonsingular T-stress is developed, verified and implemented. The approach is based on combining the crack compliance method and optical interferometric measurements of local deformation response on small crack length increment. Initial experimental information has a form of in-plane displacement component values, which are measured by electronic speckle-pattern interferometry at some specific points located near the crack tip. The first four coefficients of Williams' formulation can be thus derived. A determination of initial experimental data in immediate neighbourhood of the notch tip is the main feature of the developed approach. In this case, it is not necessary to use complex numerical models which are connected with geometrical parameters and loading conditions of the object under study in a stage of experimental data interpretation. Moreover, an availability of high-quality interference fringe patterns, which are free from rigid-body motions, serves as a reliable indicator of real stress state in the vicinity of the notch tip. Experimental verification is performed on a base of investigation of end crack growth in trapezium contoured DCB specimen. Distributions of SIF and T-stress for cracks propagating in residual stress fields near FSW joints of two different types are constructed.

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