Compared with continuous elements, discontinuous elements advance in processing the discontinuity of physical variables at corner points and discretized models complex boundaries. However, computational accuracy is sensitive to positions element nodes. To reduce side effect node position on results, this paper proposes employing partially compute time-domain boundary integral equation 3D elasto...

Marchenko methods are based on integral representations which express Green's functions for virtual sources and/or receivers in the subsurface terms of reflection response at surface. An underlying assumption is that inside medium wave field can be decomposed into downgoing and upgoing waves evanescent neglected. We present a new derivation function circumvents these assumptions, both acoustic ...

Abstract Elastodynamic equations have been formulated with Newton's second law of motion, Lagrange's equation, or Hamilton's principle for over 150 years. In this work, contrary to classical continuum mechanics, a novel strategic methodology is proposed formulating general mechanical using the energy conservation. First, based on principle, equations, and elastodynamic equation motion are deriv...

Experimental studies were performed using high-fidelity broadband Glaser-NIST conical transducers to quantify stress waves produced by the elastic collision of a tiny ball and a massive plate. These sensors are sensitive to surface-normal displacements down to picometers in amplitude, in a frequency range of 20 kHz to over 1 MHz. Both the collision and the resulting transient elastic waves are ...

The FETI-DP domain decomposition method is extended to address the iterative solution of a class of indefinite problems of the form (K−σM)x = b, and a class of complex problems of the form (K − σM + iσD)x = b, where K, M, and D are three real symmetric positive semi-definite matrices arising from the finite element discretization of either second-order elastodynamic problems or fourth-order pla...

In this paper, we first recall the general assumptions and results arising in mortar methods applied to elastostatics [Woh01]. By extension to the curved interfaces case of the ideas from Gopalakrishnan and Brenner [Gop99, Bre03, Bre04], and from the introduction a generalized Scott and Zhang interpolation operator [SZ90], we prove the independence of the coercivity constant of the broken elast...

We summarize recent evidence that models of earthquake faults with dynamically unstable friction laws but no externally imposed heterogeneities can exhibit slip complexity. Two models are described here. The first is a one-dimensional model with velocity-weakening stick-slip friction; the second is a two-dimensional elastodynamic model with slip-weakening friction. Both exhibit small-event comp...

Ultrasonic spectrum analysis is used to study the frequency and angular behavior of diffracted longitudinal waves from elliptical cracks with arbitrary orientation in diffusion bonded titanium alloy. The aspect ratio of the cracks (ratio of major to minor axis) ranged from l to 8 and the bandwidth of the input signal was such that the scattering diameter was ka > l. The experimental data are an...

Microcracking in composite laminates is a known precursor to the growth of inter-ply delaminations and larger scale damage. Microcracking can lead to the attenuation of ultrasonic waves due to the crack-induced scattering. 3D elastodynamic finite integration technique (EFIT) has been implemented to explore the scattering of ultrasonic waves due to microcracks in anisotropic composite laminates....

In the present work a new concept for a shear horizontal ultrasonic wave transducer based on piezoelectric fibre patch (PFP) technology is presented. In this type of sensor two separate fibre layers with opposite polarization are tilted by ±45° relative to the electrode fingers. Numerical 3-D simulations based on the Elastodynamic Finite Integration Technique (EFIT) show that with this new PFP ...