The Use of Ultrasound to Investigate Rough Surface Contact Phenomena

Drinkwater, Bruce W.; Dwyer-Joyce, R. S.; Robinson, Alice M.

doi:10.1007/978-1-4615-4791-4_187

Cited by 7 publications

(2 citation statements)

References 9 publications

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“…This model has been used in conjunction with ultrasonic measurements to investigate the interfacial stiVness of solid±solid contacts in several other systems [10,11].…”

Section: Quasi-static Spring Modelmentioning

confidence: 99%

Measurement of the stiffness of joints in a graphite brick assembly

Robinson

Drinkwater

Dwyer-Joyce

et al. 2001

Proceedings of the Institution of Mechanical Engineers, Part C:

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Large, dry-contacting assemblies of graphite blocks are a feature of many nuclear reactors, and the seismic response of these structures is dependent on both the bulk and surface properties of the blocks. The nature of the interblock interface will in¯uence the load±de¯ection relationship of the blocks, which is important in understanding the response of the structure to seismic loading. The stiVness of this interface is dependent on surface roughness eVects.In this paper, ultrasonic re¯ection coeYcient measurements are used to investigate the stiVness distribution of this interface under various loading conditions. A low-frequency quasi-static spring model of the interface was adopted. This allowed the interfacial stiVness to be determined as a function of applied load, frequency, surface roughness and graphite composition. Cyclical loading of the graphite±graphite interface has also been carried out. This has shown that there is only a slight plastic deformation under normal loading, and also is indicative of a degree of intersurface adhesion at the interface. Direct measurement of the load±de¯ection relationship of an entire brick was also carried out which, in conjunction with the ultrasonic measurements, suggests that it is the eVect of macroscopic surface features rather than microscopic roughness that is the dominant interfacial contribution to brick-tilting stiVness. NOTATION d half-depth of the brick face (m) E Young's modulus (Pa) F force (N) h height of the brick (m) I second moment of area (m 4 ) K interfacial stiVness per area (Pa/m) l half-width of the brick face (m) p local contact pressure (Pa) p nom nominal contact pressure (Pa) R ultrasonic re¯ection coeYcient R a centre-line average roughness (m) u average interfacial separation (m) W total weight of the brick (N) x distance along the brick face from the centre of the edge (m) x 0 position along the brick face at which contact with the substrate is lost (m) z acoustic impedance (kg/m 2 s) ¬ ratio of interfacial stiVness per area to root of pressure (Pa 1=2 /m) ¡ torque applied to the brick (N m) brick de¯ection (m) angle of tilt of the brick (rad) ! ultrasonic angular frequency (rad/s) IMPORTANCE OF GRAPHITE±GRAPHITE INTERFACESThe cores of many commercial nuclear reactors contain large assemblies of graphite blocks which are used to moderate the fast neutrons in the reaction. Fuel and control rods are positioned in holes in this assembly. These blocks are typically around 1 m high and are arranged in arrays ten or more layers high. The bricks cannot be physically constrained into a ®xed matrix owing to the extreme irradiation and heat-induced deformation they undergo, but instead ®t together withThe MS was

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“…This model has been used in conjunction with ultrasonic measurements to investigate the interfacial stiVness of solid±solid contacts in several other systems [10,11].…”

Section: Quasi-static Spring Modelmentioning

confidence: 99%

Measurement of the stiffness of joints in a graphite brick assembly

Robinson

Drinkwater

Dwyer-Joyce

et al. 2001

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

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“…Equations (10) and (11) may yet be used to model the rough contact interface between two solids. 4,21,24,25 In this case, the matrix K is proportional to the interfacial contact area between the solids. We emphasize here that the formulation presented bellow is applicable within all these three different contexts mentioned above.…”

Section: B Adhesion Interfacesmentioning

confidence: 98%

Scattering of ultrasonic waves by heterogeneous interfaces: Formulating the direct scattering problem as a least-squares problem

Leiderman

Castello

2014

The Journal of the Acoustical Society of America

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An analytic-numerical method to simulate the interaction of time-harmonic ultrasonic waves with imperfectly bonded layered structures is presented. In the proposed formulation, elastic layers may be either isotropic or anisotropic and adhesion interfaces are replaced by equivalent continuous distribution of normal and transversal springs. In addition, adhesion imperfections are allowed to be localized in space and are modeled by a corresponding local reduction in spring constants. The resulting direct scattering problem is formulated as a least-squares problem and solved accordingly. The formulation was extended for three different cases: Scattering from imperfectly bonded half-spaces, scattering from imperfectly bonded layered structures and scattering from imperfectly bonded layered plates immersed in acoustic fluid, and numerical simulations corresponding to each one of these cases are presented. The simulations indicate that the method is capable of capturing the scattering resulting from the interaction of ultrasonic waves with defective bonds as well as indicate that ultrasound has the potential of revealing the presence of defective bonds and interfacial heterogeneities.

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Identifying the ultrasonic inspecting fields that most strongly interact with adhesive bonding defects

Leiderman

Junqueira

Castello

et al. 2018

J Braz. Soc. Mech. Sci. Eng.

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We propose a systematic modelling procedure to identify the harmonic ultrasonic incident fields that most strongly interact with adhesive bonding defects in submerged multilayer plates. In principle, these are also the optimal choices for the interrogating fields in inverse methods for interfacial stiffness estimation. We model the adhesive bonding with the aid of the spring boundary conditions and model the bonding defects by a reduction in the spring constants. As part of the proposed procedure, we use the invariant embedding technique to compute the reflection coefficient at the top of the immersed laminates. The main advantage of this technique is its unconditional numerical stability even for evanescent waves at high frequencies. The developed algorithm is equally well suited to treating isotropic as well as anisotropic layers. We illustrate the application of the proposed procedure simulating the inspection of a three-layer isotropic plate and a 16-ply anisotropic composite laminate used in the aeronautical industry. In the simulations, we identify the frequencies and angles of incidence that will most strongly interact with bonding defects.

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The Use of Ultrasound to Investigate Rough Surface Contact Phenomena

Cited by 7 publications

References 9 publications

Measurement of the stiffness of joints in a graphite brick assembly

Measurement of the stiffness of joints in a graphite brick assembly

Scattering of ultrasonic waves by heterogeneous interfaces: Formulating the direct scattering problem as a least-squares problem

Identifying the ultrasonic inspecting fields that most strongly interact with adhesive bonding defects

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