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Abstract Love wave propagation through smart materials is an interesting research area due to its possible applications in seismic acoustic wave (SAW) devices. Apart from existing research, we considered sinusoidal diversity in the piezomagnetic materials under the effect of an impulsive point source to elucidate the hidden characteristics of Love wave behavior. As a two-dimensional problem, the governing equations of motion are laid down for the proposed model and deduced by Fourier transformation. The frequency relation is derived by using prescribed boundary conditions and the well-known properties of Green’s function. The obtained frequency relation is deduced into the conventional form of the Love wave dispersion, validating the proposed model. The fundamental mode along with two higher-order modes of Love wave dispersion is investigated analytically to demonstrate the parametric effects on frequency curves. Analytical findings recommended that the functional gradient parameters, piezomagnetic constants, magnetic permeabilities, and amplify gradient parameters affected the phase velocity of the Love wave extensively. This finding suggested that it is important to take into account the suppressing effects of the parameters when manufacturing transducers and piezomagnetic sensors to achieve better performance. Moreover, the outcomes of this study may be considered to secure the high performance of the SAW devices. [ABSTRACT FROM AUTHOR]

The characteristics of synchronous and phase difference bubble pairs in axisymmetric configuration near a boundary are investigated experimentally by the spark discharge method. Their destructive forces on nearby boundaries are measured using a polyvinylidene fluoride sensor. The bubble pair interactions and deformed features in the boundary vicinity are dissimilar to those in bulk water. Moreover, significant discrepancies between in-phase and out-of-phase pair interactions and their intensities of impulses are also witnessed. The interbubble distance (η), stand-off distance from the boundary (γ), and phase offset (τ) are crucial parameters affecting the shape evolutions and impulsive forces. From the qualitative analysis of sensor acquisition and high-speed imaging, it is observed that bubble periods are either prolonged or shorter than their corresponding isolated single cavity according to different parameters and arrangements. Additionally, the strongest impingements are produced by in-phase pairs. The impulses of phase difference bubble pairs are remarkably lower than in-phase pairs and even lower than a single bubble in some arrangements.

This paper describes 2-D numerical simulations of velocity and pressure fields generated by non-breaking waves on a vertical breakwater with a recurved parapet wall. The influence of the geometrical characteristics of the parapet is investigated. An impulsive pressure force is identified and discussed with respect to the pure vertical wall case. This force is generated by the seaward flow confinement induced by the surging wave crest. We refer to this impulsive impact as “confined-crest impact”. A large part of the vertical wall is affected by an impulsive increase in pressure caused by pulsating wave, compared to the case where the parapet is completely vertical. The maximum values of the impulsive pressures are localized under the recurved parapet. The total force increase on the entire structure may be significant when compared to the pure vertical wall case. [ABSTRACT FROM AUTHOR]

The introductory textbooks on classical mechanics are extremely brief in addressing impulsive forces and the concept of impulse. This can be explained by the emphasis on the study of physical situations in which the applied forces are all constant or position dependent, but constant in time, which is the class of the so-called conservative forces. When the impulsive forces are referred to, they are generally illustrated by a quick blow on a ball, as in golf, tennis or baseball. The focus is still to turn the time dependent force into a constant average force, whose impulse is equivalent to the real force. This paper proposes a simple experiment that consists in applying with the fingers an impulsive force on a smartphone and record the time dependence of the force through its internal accelerometer. This technology allows obtaining the values of the speed during the applied impulsive force by iterating the data extracted of acceleration and time. Some interesting aspects neglected in books emerge from this analysis, such as the lack of symmetry of the applied impulsive force, the possibility of modeling the full interaction without appeal to the concept of average force and calculating impulse directly by impulse and linear momentum theorem. As a consequence of the experiment, it is also possible to obtain the kinetic friction coefficient between the smartphone and the horizontal surface. [ABSTRACT FROM AUTHOR]

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• In-phase and out-of-phase tandem bubbles are created by a spark-induced method near the vertical boundary. • Bubble shape evolutions and impact forces are analyzed by using a high-speed imaging system and PVDF film sensor. • Collapse time of single bubbles, in-phase pairs, and antiphase pairs are discussed. • Impulsive forces result from different inter bubble distances, and temporal separations are investigated. The characteristics of synchronous and phase difference bubble pairs in axisymmetric configuration near a boundary are investigated experimentally by the spark discharge method. Their destructive forces on nearby boundaries are measured using a polyvinylidene fluoride sensor. The bubble pair interactions and deformed features in the boundary vicinity are dissimilar to those in bulk water. Moreover, significant discrepancies between in-phase and out-of-phase pair interactions and their intensities of impulses are also witnessed. The interbubble distance (η), stand-off distance from the boundary (γ), and phase offset (τ) are crucial parameters affecting the shape evolutions and impulsive forces. From the qualitative analysis of sensor acquisition and high-speed imaging, it is observed that bubble periods are either prolonged or shorter than their corresponding isolated single cavity according to different parameters and arrangements. Additionally, the strongest impingements are produced by in-phase pairs. The impulses of phase difference bubble pairs are remarkably lower than in-phase pairs and even lower than a single bubble in some arrangements. [ABSTRACT FROM AUTHOR]

We consider a dynamic problem of interaction of a plane penny-shaped crack with thin elastic interlayer connecting two identical elastic half spaces. The crack is located in one of the half spaces perpendicularly to the interlayer and the crack faces are subjected to the action of impulsive tensile forces. The thin interlayer is modeled by the conditions of imperfect contact of the half spaces. By using the Fourier transformation with respect to time, we reduce the problem to a Helmholtz-potential-type boundary integral equation for the function of dynamic crack opening displacements. As a result of the numerical solution of this equation and transition to the originals, we get the time dependences of mode-I stress intensity factors in the vicinity of the crack for various types of dynamic loads, ratios of the elastic parameters of the half spaces and the interlayer, and the distance between the crack and the interlayer. [ABSTRACT FROM AUTHOR]

A new variational space-time formulation is used to treat elastodynamic problems with impulsive loads that propagate at fast velocities, as blasts or explosions. Based on the new formulation, a new family of fully variational time integration algorithms for elastodynamic problems is formulated. In the framework of this new family of algorithms, a conditionally stable time integration algorithm of the 6th order and the variational treatment of impulsive forces propagating at high speeds are developed. The time integration algorithm is based on Hermite's polynomials, with independent field of velocities, and discontinuous time derivative of the displacement field. Numerical examples are performed to test the computational efficiency of the new approach to treat fast dynamic impulsive forces. [ABSTRACT FROM AUTHOR]

The article discusses the influences of soft tissue motion on skeletal loads during impacts. Soft tissue motion takes place as an impulsive loads which are applied to the skeletal system. It has been presented that the wavelike motion of muscles can minimize the loads acting on the musculoskeletal system.