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Showing papers on "Shock (mechanics) published in 2021"


Journal ArticleDOI
TL;DR: In this paper, the exact wave structures to the Gilson-Pickering equation (GPE) were obtained in single and combined behavior like shock, singular, shock-singular, singular periodic waves and periodic rational function by utilizing integration norms.
Abstract: This article possesses new exact wave structures to the Gilson–Pickering equation (GPE) that describes the prorogation of waves in plasma physics. The solutions are achieved in single and combined behavior like shock, singular, shock-singular, singular periodic waves and periodic as well rational function by utilizing innovative integration norms namely ( G ′ G 2 )-expansion method and expansion function method (EFM). Moreover, under the suitable choice of involved parameters 3-, 2-dimensional, and their corresponding contour plots are also sketched. The obtained results show that the applied computational schemes are straightforward, efficient, concise and can be utilized for more complex physical phenomena in various fields of sciences. The reported results are helpful to understand the studying of wave propagation and are also vital for numerical and experimental verification in plasma physics.

74 citations


Journal ArticleDOI
Lu Haifei1, Zhao Wang1, Jie Cai1, Xu Xiang1, Kaiyu Luo1, Wu Liujun1, Jinzhong Lu1 
TL;DR: In this article, the effects of laser shock peening on the hot corrosion behavior of the selective laser melted (SLMed) Ti6Al4V titanium alloy were investigated and the results indicated that the SLMed specimen exhibited a significantly lower hot corrosion resistance in comparison to the SLM-LSPed specimen.

59 citations



Journal ArticleDOI
TL;DR: In this article, an external instrument is taken to be correlated with the target structural shock and to be uncorrelated with other shocks of the model (the instrument is exogenous).

54 citations


Journal ArticleDOI
TL;DR: In this article, a putative jet launched from the merger of a binary neutron star (BNS) or a neutron star-black hole (NSBH) merger occurring at the migration trap in an active galactic nucleus (AGN) disk would be choked.
Abstract: Neutron star mergers are believed to occur in accretion disks around supermassive black holes. Here we show that a putative jet launched from the merger of a binary neutron star (BNS) or a neutron star–black hole (NSBH) merger occurring at the migration trap in an active galactic nucleus (AGN) disk would be choked. The jet energy is deposited within the disk materials to power a hot cocoon. The cocoon is energetic enough to break out from the AGN disk and produce a bright X-ray shock breakout transient peaking at ∼0.15 days after the merger. The peak luminosity is estimated as , which can be discovered by the Einstein Probe from . Later on, the nonrelativistic ejecta launched from the merger would break out the disk, powering an X-ray/UV flare peaking at ∼0.5 days after the merger. This second shock breakout signal may be detected by UV transient searches. The cocoon cooling emission and kilonova emission are outshone by the disk emission and are difficult to detect. Future joint observations of gravitational waves from BNS/NSBH mergers and associated two shock breakout signatures can provide strong support for the compact binary coalescence formation channel in AGN disks.

52 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of the incident shock Mach number (Ma) on the ignition delay times in two reflectors are systematically investigated, and the conical reflector creates an abrupt pressure rise in the apex, resulting in a 64.5% increase in the reflected shock velocity compared with the planar reflector.

44 citations


Journal ArticleDOI
01 May 2021-Fuel
TL;DR: In this article, the same coal samples were tested for ultrasonic inspection, stereomicroscopic imaging and nuclear magnetic resonance (NMR) after different cold shock times, and the macroscopic damage was studied by ultrasonic wave; the changes of mesoscopic pores and fractures were studied by stereoscopic microimaging and digital image processing.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of lattice distortion and chemical short-range order (CSRO) on the shock wave propagation, defect evolution, and the cavitation process are explored to distinguish the unique shock properties of MEA.

38 citations


Journal ArticleDOI
TL;DR: Triply periodic minimal surfaces as discussed by the authors are cellular structures that naturally inspired continuous non-self-intersecting surfaces similar to bone microstructure with controllable mechanical properties, which are called 3-minimal surfaces.
Abstract: Triply periodic minimal surfaces are cellular structures that naturally inspired continuous non-self-intersecting surfaces similar to bone microstructure with controllable mechanical properties. In...

36 citations


Journal ArticleDOI
TL;DR: In this paper, the feasibility and effectiveness of thin additive manufactured hybrid metal/composite lattice structures as lightweight shock absorbing devices for application to structural key components in impact events was investigated.

36 citations


Journal ArticleDOI
TL;DR: In this article, the high-order partial differential equation (PDE) of thin cylindrical shells is derived from the Flugge shell theory, and the vibration response of the cylinear shell system is obtained by the wave propagation method.

Journal ArticleDOI
TL;DR: By using the multivariate analysis technique, the analytic forms of the reliability functions for systems under cumulative shock model and extreme shock model are derived and the random point method in Monte Carlo simulation and vector program in Matlab are applied.

Journal ArticleDOI
TL;DR: In this paper, an experimental methodology was designed to study the effects of turbulent flow and shock/boundary-layer interaction (SBLI) on the postflutter response of a thin, buckled panel.
Abstract: An experimental methodology was designed to study the effects of turbulent flow and shock/boundary-layer interaction (SBLI) on the postflutter response of a thin, buckled panel. The approach combin...

Journal ArticleDOI
TL;DR: This study develops generalized reliability models for multi-component systems, where each component is subject to two dependent competing failure processes, i.e., a soft failure process caused jointly by internal performance degradation and an incremental damage due to effective external shock sets.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the mechanisms and generation conditions of the retardation of fatigue crack propagation (FCP) in Ti-17 titanium specimens and found that significant retardation occurs in specimens at high values of residual stresses, small peening gap distances, and lower externally applied loads.


Journal ArticleDOI
15 Apr 2021-Fuel
TL;DR: In this article, a numerical study of the spray collapse process that occurs under flash-boiling, gasoline-direct-injection conditions was performed. And the results agreed qualitatively well with the experimental data of propane available from the literature and revealed the model's ability to capture the near-nozzle shock structures witnessed in the experiments.

Journal ArticleDOI
TL;DR: In this article, shock loading takes materials from ambient conditions to extreme conditions of temperature and nonhydrostatic stress on picosecond timescales, and the fast loading results in tem...
Abstract: Shock loading takes materials from ambient conditions to extreme conditions of temperature and nonhydrostatic stress on picosecond timescales. In molecular materials the fast loading results in tem...

Journal ArticleDOI
TL;DR: In this paper, a self-consistent model of plasma pressure versus time is proposed to predict the aluminum target's behavior under laser shock using mechanical simulation software, which can be used to predict aluminum targets' behavior under LASer adhesion test.
Abstract: Optimization of the laser shock peening (LSP) and LASer Adhesion Test (LASAT) processes requires control of the laser-induced target's loading. Improvements to optical and laser technologies allow plasma characterization to be performed with greater precision than 20 years ago. Consequently, the processes involved during laser-matter interactions can be better understood. For the purposes of this paper, a self-consistent model of plasma pressure versus time is required. The current approach is called the inverse method, since it is adjusted until the simulated free surface velocity (FSV) corresponds to the experimental velocity. Thus, it is not possible to predict the behavior of the target under shock without having done the experiments. For the first time, experimental data collected in different labs with the most up-to-date laser parameters are used to validate a self-consistent model for temporal pressure-profile calculation. In addition, the parameters characterizing the plasma (temperature, thickness and duration) are obtained from the ESTHER numerical code, together with the amount of ablated matter. Finally, analytic fits are presented that can reproduce any pressure-temporal profiles in the following domains of validity: Intensities, I, ranging from 10 to 500 GW cm-2 and pulse durations, T pul, between 5 and 40 ns for the direct-illumination regime at 1053 nm, I ranging from 1 to 6 GW cm-2 and T pul between 10 to 40 ns in the water-confined regime at 1053 nm, and I from 1 to 10 GW cm-2 and T pul between 7 and 20 ns in the water-confined regime at 532 nm. These temporal pressure profiles can then be used to predict the aluminum target's behavior under laser shock using mechanical simulation software.

Journal ArticleDOI
TL;DR: Results of the comparison verify that the proposed evaluation method not only reduces the number of calculations required, but also improves the severity evaluation accuracy.

Journal ArticleDOI
TL;DR: It is found that the lump is the most stable while the shock wave is the least stable under the same perturbation among the breather, lump and shock waves.
Abstract: Investigation is conducted on a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid mechanics and plasma physics. By virtue of the homoclinic-test, ansatz and polynomial-expansio...

Journal ArticleDOI
TL;DR: In this article, the authors investigated the low-frequency unsteady motions behind a backward-facing step in a turbulent flow at and are investigated using a well-resolved large-eddy simulation.
Abstract: The low-frequency unsteady motions behind a backward-facing step (BFS) in a turbulent flow at and are investigated using a well-resolved large-eddy simulation. The instantaneous flow field illustrates the unsteady phenomena of the shock wave/boundary layer interaction (SWBLI) system, including vortex shedding in the shear layer, the flapping motions of the shock and breathing of the separation bubble, streamwise streaks near the wall and arc-shaped vortices in the turbulent boundary layer downstream of the separation bubble. A spectral analysis reveals that the low-frequency behaviour of the system is related to the interaction between shock wave and separated shear layer, while the medium-frequency motions are associated with the shedding of shear layer vortices. Using a three-dimensional dynamic mode decomposition (DMD), we analyse the individual contributions of selected modes to the unsteadiness of the shock and streamwise-elongated vortices around the reattachment region. Gortler-like vortices, which are induced by the centrifugal forces originating from the strong curvature of the streamlines in the reattachment region, are strongly correlated with the low-frequency unsteadiness in the current BFS case. Our DMD analysis and the comparison with an identical but laminar case provide evidence that these unsteady Gortler-like vortices are affected by fluctuations in the incoming boundary layer. Compared with SWBLI in flat plate and ramp configurations, we observe a slightly higher non-dimensional frequency (based on the separation length) of the low-frequency mode.

Journal ArticleDOI
TL;DR: In this paper, the laser shock peening method effectively enhanced the surface mechanical properties of pure copper, and the laser overlap percentage played a key role in improving surface mechanical property of the pure copper.

Journal ArticleDOI
06 Jan 2021-Polymer
TL;DR: In this paper, the phase segregated microstructure of polyurea is used to study its shock response using molecular dynamics simulation. But the authors focus on the soft domain and do not consider the hard domain.

Journal ArticleDOI
TL;DR: In this paper, the authors conducted large-scale molecular dynamics simulations of ballistic impact tests on ultrathin aluminum and polyurea layers and their multilayer arrangements to investigate the energy absorption and deformation mechanisms at the nanoscale.


Journal ArticleDOI
J.Z. Lu1, K.N. Xue1, Lu Haifei1, F. Xing, K.Y. Luo1 
TL;DR: In this paper, Li et al. showed that columnar dendrites in the surface layer with a depth of 0.28 mm were transformed into refined equiaxed dendrees after laser shock peening and the residual stress was completely converted from tensile state into compressive state.

Journal ArticleDOI
TL;DR: In this article, a V-shaped piezoelectric vibration energy harvester (V-PVEH) with impact stopper is proposed for low-frequency vibration and shock energy harvesting.
Abstract: Broadband low-frequency vibration and shock energies are ubiquitous such as biomechanical motion, which can be harvested to power wearable electronics. This paper proposes a compact design of V-shaped piezoelectric vibration energy harvester (V-PVEH) with impact stopper. To demonstrate V-PVEH having high power density, Euler beam model is proposed for qualitative comparison between V-PVEH and cantilevered piezoelectric vibration energy harvester (C-PVEH). FEA model in COMSOL for V-PVEH structure design is proposed especially for the stress check. Modal analysis, two bimorphs connection style, tip mass thickness, and acceleration amplitude are discussed in the experimental vibration validation. A peak voltage of 11.5 V at a low resonant frequency of 12 Hz and a maximum power of 0.442 mW are shown in experiments under the excitation of 0.1 g. A lumped parameters model with nonlinearity analysis for impact induced broadband and shock input is discussed comprehensively. The stopper design in V-PVEH can not only limit the vibration amplitude and prevent overload, but also form broadband of 8−15 Hz and generate large voltage output of 5−19 V when impact occurs at an acceleration of 0.4 g. Except for resonating excitation, biomechanical shock energy harvesting with ultra-low frequency of 1 Hz is testified for wearable V-PVEH to charge a 10 μF capacitor to 10 V in 5 s by stamping feet. Above all, V-PVEH with stopper is believed to show good performance in broadband low-frequency vibration and biomechanical shock energy harvesting.

Journal ArticleDOI
TL;DR: In this paper, the nonlinear frequency response of graphene/piezoelectric sandwich nanoplates under the electric voltage exerted on the layer and a shock force pulse was investigated.
Abstract: The nonlinear frequency response of graphene/piezoelectric sandwich nanoplates under the electric voltage exerted on piezoelectric layer and a shock force pulse is the objective of the present pape...