Dynamic Shock Research Articles

Research on Ni-WC Coating and a Carbide Solidification Simulation Mechanism of PTAW on the Descaling Roll Surface

The descaling roll is a critical component in a hot-rolling production line. The operating conditions are significantly impacted by water with high-pressure and dynamic shocks caused by high-temperature steel slab descaling. Roll surfaces often experience wear and corrosion failures. This is attributed to a combination of high temperatures, intense wear, and repeated thermal, mechanical, and fluid stresses. Production costs and efficiency are significantly affected by the replacement of descaling rolls. Practice shows that the use of plasma cladding technology forms high-performance coatings. Conventional metal surface properties can be significantly improved. In this study, a Ni-WC composite coating was prepared on the descaling roll surface by plasma-transferred arc welding (PTAW) technology. The microstructure and phase composition of the welding overlay were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that the WC hard phase added to the molten pool dissolves, and subsequently M7C3 and W2C phases are formed. To further explore the morphological evolution mechanism of the hard phase, numerical simulations were performed using a phase-field method to model M7C3 phase precipitation. The evolution from nucleation, rod-like growth, to eutectic structure formation was revealed. Experimental and simulation results show high consistency, validating the established phase-field model. In this study, a theoretical foundation for designing and preparing high-performance coatings is provided.

Resistive Heating and Thermal Decomposition of an Additively Manufacturable Electrically Conductive Explosive

AbstractThe ability to transmit electrical signals through high explosive charges without using dense metal conductors could enable continuous monitoring of explosive charges with internally embedded sensors. With the sensor materials themselves being energetic, the impact on the intended detonation performance of the charge can be minimized. Embedded sensors enable real time, in‐situ measurements of conditions relevant to ageing assessments. Additionally, dynamic material property sensing can provide detonation performance data, enabling measurement of dynamic shock position. One proposed method to allow for electronic signal transfer through high explosives is to use electrically conductive explosive composites consisting of an electrically conductive polymer binder mixed with high explosive crystals. These conductive energetic pathways also serve as independently reactive elements and can provide additional functionality via dynamic sensor removal through resistive heating and subsequent decomposition. This work discusses the resistive heating of a previously developed, poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based, electrically conductive extrudable explosive composite. Experimental samples of the conductive explosive material were subjected to a range of direct current applications and the resulting heating and decomposition of the material is discussed.

Dynamic response mechanism of layered coatings under impacts: Insights from the perspective of stress wave

Precision machining operations often lead to the failure of protective coatings on cutting tools due to common issues such as cracking, delamination, and peeling from cyclic impacts. While material selection and structural design are crucial for enhancing impact resistance, they primarily focus on static performance with limited consideration from the dynamic sights. This paper presents a novel dynamic design method for coatings, viewed through the lens of stress waves. We investigate the propagation behavior of stress waves in TaN/TiN and CrN/TiN coatings with layered structures. Our findings indicate that the attenuation of stress waves is dominated by the physical properties on both sides of the interface and the stride length. For interfaces with similar physical properties, the attenuation of stress waves is insensitive to the stride length, while for interfaces with different physical properties, the attenuation is regulated by the ratio of single-layer thickness to the full width at half maximum of the stress wave. These insights offer a strategy for extending the life of coatings and improving process safety under dynamic shocks.

The rebound law of micro-particle on amorphous alloys under high impact velocities

Compared to their crystalline counterparts, amorphous alloys due to disordered structures are expected to have higher elasticity of deformation. However, in this work, we use the micro-ballistic impact technique to show a smaller dynamic redound of micro-particles on a Zr-based amorphous alloy than that on its corresponding polycrystalline target. We find that the two alloys follow the same rebound law of micro-particle under low impact velocities, but with increasing impact velocity the amorphous alloy exhibits a faster decrease in rebound velocity of micro-particle. This lower rebound results from the easier activations of shear banding in glassy structures, thus contributing to more significant energy dissipation during the micro-particle impact. Further analyses imply that the amorphous alloys and their crystalline counterparts are more favorable in shock wave and projectile protection, respectively. This work is useful in the understanding of the dynamic elasticity and shock energy dissipation of amorphous alloys under micro-particle impacts.

Experimentally induced troilite melt pervasion in chondritic analog materials: A study for FeNi‐FeS darkening in chondrites

AbstractIron sulfide and metal melt veins in chondritic materials are associated with advanced stages of dynamic shock. The shock‐induced residual temperatures liquefy the sulfide component and enable melt distribution. However, the distribution mechanism is not yet fully understood. Capillary forces are proposed as agents of melt distribution; yet, no laboratory experiments were conducted to assess the role that capillary forces play in the redistribution of iron sulfide in post‐shock conditions. To investigate this further, we conducted thermal experiments under reducing conditions (N2(g)) using dunitic fragments, suitable chondritic analog materials that were doped with synthesized troilite (stoichiometric exact FeS). We observed extensive iron sulfide (troilite) migration that partially resembles that of ordinary chondrites, without the additional influence of shock pressure‐induced fracturing. The iron sulfide melt infiltrated grain boundaries and pre‐existing fractures that darkened the analog material pervasively. We also observed that the iron sulfide melt, which mobilized into grain boundaries, got systematically enriched in Ni from the surrounding host olivine. Consequently, FeNi metal fractionated from the melt in several places. Our results indicate that capillary forces majorly contribute to melt migration in the heated post‐shock environment.

Dynamic thermal shock resilience of functionally graded materials: An adaptive phase-field approach

This work presents a phase field model for dynamic fracture under thermo-mechanical loads to analyze functionally graded material (FGM). Coupled governing equations are derived by minimizing the total energy consisting of kinetic energy and elastic strain energy, along with the energy due to the external heat source. To overcome the computational expense associated with the standard finite element analysis for implementing the phase field model, an adaptive approach based on the quadtree algorithm is employed that enhances computational efficiency while preserving accuracy. The hanging nodes within the element are treated as polygonal elements. The governing equations are solved using a staggered solution algorithm, following a hybrid phase field implementation strategy. The notch location, temperature variation, and gradation profile of FGM are carefully examined and investigated using numerous examples. It is observed that these parameters significantly influence the behavior of FGM. The results align well with the existing literature, validating our methodology within the examples explored. Additionally, the computational efficiency of adaptive meshing techniques is assessed, demonstrating the significant reductions in computational overhead while preserving accuracy and versatility in handling multi-physics fracture scenarios.

Cylindrical compression of thin wires by irradiation with a Joule-class short-pulse laser

Equation of state measurements at Jovian or stellar conditions are currently conducted by dynamic shock compression driven by multi-kilojoule multi-beam nanosecond-duration lasers. These experiments require precise design of the target and specific tailoring of the spatial and temporal laser profiles to reach the highest pressures. At the same time, the studies are limited by the low repetition rate of the lasers. Here, we show that by the irradiation of a thin wire with single-beam Joule-class short-pulse laser, a converging cylindrical shock is generated compressing the wire material to conditions relevant to the above applications. The shockwave was observed using Phase Contrast Imaging employing a hard X-ray Free Electron Laser with unprecedented temporal and spatial sensitivity. The data collected for Cu wires is in agreement with hydrodynamic simulations of an ablative shock launched by highly impulsive and transient resistive heating of the wire surface. The subsequent cylindrical shockwave travels toward the wire axis and is predicted to reach a compression factor of 9 and pressures above 800 Mbar. Simulations for astrophysical relevant materials underline the potential of this compression technique as a new tool for high energy density studies at high repetition rates.

Modeling and identification of hysteresis of marine damper considering shock environment based on evolutionary sparrow search algorithm

The mechanical properties of marine dampers are usually highly nonlinear in order to adapt to dynamic and shock environments. The dampers are subjected to dynamic and shock tests and the hysteresis curves are found to be rate-dependent and asymmetric. To be able to describe the dynamic hysteresis and shock hysteresis, a rate-dependent generalized Prandtl-Ishlinskii (RDGPI) model is proposed based on the generalized Prandtl-Ishlinskii (GPI) model, which is a hybrid of the GPI model and the radial basis function (RBF) neural network. Due to the large number of parameters in the model, thus aiming to improve the effect of parameter identification, an evolutionary sparrow search algorithm mixed with sparrow search algorithm and differential evolutionary algorithm is proposed. Compared with other algorithms, sparrow search algorithm is verified to have ideal optimization effect and convergence speed, and it is not easy to fall into the local optimum. Finally, the RDGPI model is experimentally verified, and the results show that the prediction error of the RDGPI model for dynamic hysteresis is within 0.06 kN, and the prediction error for shock hysteresis is within 0.8 kN, which is capable of describing the rate-dependent characteristics of the damper hysteresis. And it has a very good generalization ability, which makes it very suitable to be used in the modeling of the mechanical characteristics of the marine damper.

Ab initio simulation of the dynamic shock response of single crystal and lightweight multicomponent alloy

The dynamic response of shock wave impact on single crystal aluminium and lightweight multicomponent alloy Al-Cu-Li-Mg is simulated by using the combination of Ab initio Molecular Dynamics (AIMD) and Multi-Scale Shock Technique (MSST), with the analysis carried out at the atomic/electronic levels. The simulation is verified by comparing the particle velocity of single crystal obtained in this work with the data in literature. The shock compression process not only involves the migration of atoms, but also is related to electronic transition. Two stages could be found in the shock compression process: oscillatory compression of the crystal cell and oscillatory migration of the atoms. The crystal structure of the multicomponent alloy could be disordered even at low shock speed, due to the difference in the ability to migrate between different kinds of atoms. As the sample is shock-compressed, the contribution proportion of crystal orbitals shows a sharp decrease for D orbital, while it increases significantly for S orbital and P orbital. The electron structure shows a quicker response to the shock wave compression process than the crystal structure. The orbital contribution from P orbital of the crystal is mainly due to the P orbital of Al atoms, while the orbital contribution from D orbital of the crystal is mainly due to the D orbital of Cu atoms. Total Density of States (TDOS) is mainly contributed by the Projected Density of State (PDOS) of Cu atoms in the occupied state of energy levels, while it is close to the PDOS of Al atoms in the non-occupied state of energy levels.

Fabrication and structural characterisation of ZrC-W cermet by spark plasma sintering: Application in ballistical projection

This paper describes the effect of addition of tungesten (W) when was introduced into ZrC composite forming ceramic metal-composite (MMC) and (FGMS) to improve the fracture toughness (KIC) and hardeness (Hv) of the composite ceramic-metal. ZrC and ZrC with addition of 20 % of tungesten (ZrC-W) were prepared by vacuum sintering FAST-SPS-FCT technology at the temperatures in the range of 1700–1800 °C for 400 s under pressure of 50 Mpa. Microtructural properties were investigated by X-ray diffraction and energy-dispersive spectrometry in addition scanning electron miroscopy. The investigations shows that the phase separation of the as-sintered ZrC and ZrC-20 wt%W into two phases: ZrC (dark) and (C)W (bright) indicating that the as-sintered (ZrC)W was thoroughly decomposed in tree phases ZrC, W2C and WC. The effect of the W is already illustrated. X-ray diffraction and energy-dispersive spectrometry results indicate that bright grains are W, (W)C and dark ZrC solid solution. The relative density increases with the reinforcement by W into ZrC. Fully dense ZrC and ZrC-20 vol% W ceramic metal-composite with a relative density of more than 98.8 % were obtained. The Vickers hardennes (HV), fracture toughness (KIC) and Raman spectroscopy will be performed in the near future. In addition, ballistic performance (dynamic properties by projectil persing resistance) . A finite element simulation will used to optimise the vol% W addition to obtain better mechanical properties and ballistical performance. The Analyzer of the termo-mechanical evolution within the volume of ZrC and ZrC-W specimens subjected to FAST-SPS-FCT platform (thermo-mechanical modeling under ABAQUS). Also, the ballistic performance will be evaluated using the Rosenberg model and compared with the experimental results in order to better understand the dynamic shock behavior of ceramic metal-composite (ZrC and ZrC-W) by the projectile that to be applied for body armor.

Closed-Loop Control of Dynamic Oblique Shock with Arc Plasma

The fluctuations caused by the dynamic shock wave and its interaction with the boundary layer bring formidable challenges for aerodynamic design and stable control of supersonic aircraft. The mechanism of closed-loop control for dynamic oblique shock stabilizing with arc plasma is numerically studied. Two types of dynamic oblique shocks are formed in supersonic airflow by a compression ramp rotation and incoming Mach number variation, respectively. A closed-loop controller is established to connect the arc plasma deposited power with the pressure ratio across the dynamic shock by using the proportional-integral method. It realizes the shock pressure ratio stabilized in the desired target value with a local overshoot appearing at the initial excitation and a more stable flow downstream of the oblique shock during excitation state for both types of dynamic shock control. The effects of arc plasma length and ramp rotating speed on the closed-loop control for the dynamic shocks induced by ramp rotation are further discussed. Results show that the arc plasma with longer length is more favorable to the dynamic oblique shock control with lower energy consumption and total pressure loss. The pressure ratio fluctuation is increased at higher ramp rotation speed, but its standard deviation is still limited to 0.3% of the desired target value during excitation state.

Dynamic convergent shock compression initiated by return current in high-intensity laser–solid interactions

We investigate the dynamics of convergent shock compression in solid cylindrical targets irradiated by an ultrafast relativistic laser pulse. Our particle-in-cell simulations and coupled hydrodynamic simulations reveal that the compression process is initiated by both magnetic pressure and surface ablation associated with a strong transient surface return current with density of the order of 1017 A/m2 and lifetime of 100 fs. The results show that the dominant compression mechanism is governed by the plasma β, i.e., the ratio of thermal pressure to magnetic pressure. For targets with small radius and low atomic number Z, the magnetic pressure is the dominant shock compression mechanism. According to a scaling law, as the target radius and Z increase, the surface ablation pressure becomes the main mechanism generating convergent shocks. Furthermore, an indirect experimental indication of shocked hydrogen compression is provided by optical shadowgraphy measurements of the evolution of the plasma expansion diameter. The results presented here provide a novel basis for the generation of extremely high pressures exceeding Gbar (100 TPa) to enable the investigation of high-pressure physics using femtosecond J-level laser pulses, offering an alternative to nanosecond kJ-laser pulse-driven and pulsed power Z-pinch compression methods.

Investigation into the stability of synthetic goethite after dynamic shock compression

Investigation into the stability of synthetic goethite after dynamic shock compression

Measuring real money demand in Cambodia: an ARDL approach to cointegration

The findings obtained through the ARDL approach to cointegration indicate that real income, consumer price index, and interest rate are cointegrated with real money demand. In terms of the estimated results derived from the long-run model, it is observed that real income has a statistically significant positive impact on real money demand, while the general price level and interest rate have a negative impact. The short-run dynamic model, known as the error correction model, demonstrates that all explanatory variables collectively account for the growth rate of real money balances. In the short-run, the growth rate of real income exhibits a positive relationship with the demand for real money, whereas the inflation rate and changes in interest rate have a significant negative effect on the demand for real money balances. The estimated slope coefficient of the short-run dynamic model, which measures the speed of adjustment, is projected to be 60.67%. This outcome suggests that the real money balance model takes no more than two quarters to adjust towards long-run equilibrium in response to short-run dynamic shocks. Stability tests, such as the CUSUM and CUSUMSQ tests, indicate that the real money demand function in Cambodia remains stable in the long-term. The findings derived from this study provide empirical evidence in favor of the quantity theory of money.

Reliability modeling and warranty optimization for products with self-healing under a dynamic shock environment

As modern products evolve in intelligence, self-healing mechanisms have been gaining prominence in the field of reliability. In actual operation, the performance of a product is inevitably influenced by external environments and user interactions. However, existing warranty studies often overlook these factors, leading to oversimplifications in product reliability modeling. This paper offers a comprehensive and realistic view of the product failure process by integrating the dynamic shock environment, inherent self-healing property, and post-sale consumer utilization. The constructed reliability evaluation model accounts for fatal and non-fatal shocks with a dynamic time-varying failure threshold. We introduce the concept of self-healing trigger/delay time, considering a generalized self-healing process. The approximate product reliability is derived, and its accuracy is validated using Monte Carlo simulations. Then, derived from real-world practices, we propose a novel two-stage warranty policy which combines lemon law principles with preventive maintenance. By minimizing the expected cost rate throughout the warranty service period, a preventive maintenance schedule optimization model is developed from the manufacturer's perspective. Finally, a numerical case is presented to reveal the influences of different factors on product reliability and demonstrate the existence of the optimal solution.

Inverse design of the radiation temperature for indirect laser-driven equation-of-state measurement

The theoretical design for the time profile of radiation temperature plays an important role in indirect laser-driven equation-of-state measurement, which severely relies on a large number of radiation hydrodynamic simulations. In this work, we provide a concise data-driven method for optimizing the radiation temperature profile, which combines a time-varying Volterra model with an improvement achieved by data generation via radiation hydrodynamic simulations utilizing random perturbations in a skew normal distribution as inputs. We find that the time-varying Volterra model can be used to investigate the time-dependent relationship between the radiation temperature and the key physical quantities of interest, such as shock-wave velocity and ablation drive pressure. With this method, we realize the inverse designs of the radiation temperature profiles for planar dynamic shock and ramp compressions according to the desired shock-wave velocity and drive pressure, respectively, which shows the advantage of practical application in experiments.

A novel dynamic grey multivariate prediction model for multiple cumulative time-delay shock effects and its application in energy emission forecasting

Energy emission systems are often influenced by external information and policy shock. However, conventional grey models ignore the existence of the impact of multiple shock events and cumulative time-delay effects, which are crucial for achieving accurate forecasts. From a dynamic perspective, we aim to establish a multivariable grey prediction model considering the impact of multiple shock events, namely MSGTDM(1,N) model. Specifically, to accurately describe the impact of different types of external shocks on the system, three kinds of nonlinear dynamic shock functions are designed, including growth dynamic shock function, decline dynamic shock function, and slope dynamic shock function. Based on this, multi-dimensional instantaneous shock utility terms and cumulative time-delay utility terms are constructed to accurately measure shock effects. And Whale Optimization Algorithm is employed to determine the optimal parameters of the shock functions through comprehensive comparative analysis. The findings affirm the MSGTDM(1,N) model's higher predictive accuracy and validity. Consequently, the forecast results of China's carbon emissions from coal and natural gas consumption in 2022–2025 provide a reliable basis for adjusting the energy structure and implementing the “dual-carbon” policy effectively.

Sustainability of Existing Phase of Extruded Fiber-Reinforced Polylactic Acid under Dynamic Shock Loading Conditions

Sustainability of Existing Phase of Extruded Fiber-Reinforced Polylactic Acid under Dynamic Shock Loading Conditions

Enhancing the efficiency of gas sensing on perovskite BaTiO3 nanoparticles using dynamic shock wave flow environment

The effect of nonlinear dynamic shock waves on perovskite BaTiO3 nanoparticles (NPs) is investigated using a table top pressure-driven shock tube (Reddy Tube) for ammonia gas sensing applications with the Mach number of 2.2. In general, shock waves are a nonlinear high-pressure phenomenon characterized by high dynamic pressure and temperature. Raman and powder X-ray diffraction (XRD) methods were utilized to evaluate the molecular and structural characteristics of the BaTiO3 (BTO) NPs under the influence of dynamic shock waves. The surface absorption was assessed using UV- diffuse reflectance spectroscopy (UV-DRS). XRD data shows that BaTiO3 NPs crystallized in tetragonal crystal structure with P4mm space group and stable throughout the shocks, without undergoing any phase change. The average particle size of the control BaTiO3 was 31 nm, while those of shocked BaTiO3 were 62 nm (100 shocks) and 55 nm (200 shocks), demonstrating the significant change in morphology and showing that particles have irregular spherical morphology and are agglomerated by shock wave loaded conditions. Moreover, BaTiO3 nanoparticles were shocked after being tested with various concentrations of different gases at a temperature of 200°C. Under shock loaded conditions, the heightened sensing response for ammonia gases was between 5 and 20 ppm; also, sensing properties such as sensitivity, response, and recovery time indicated that BaTiO3 nanoparticles are a good potential ammonia gas sensing material for real-time sensor applications with enhanced characteristics.

Dynamic shock wave processing on β-MnMoO4 ceramic micro-sized crystals and its structure-morphology-property relations

In the present work, we perform a few shock-wave-processing experiments on typical ceramic materials of β-MnMoO4 (P2/c) by the exposure of 0, 100 and 200 shocks, respectively, and investigated their structural, optical and morphological features to materialize the effect of shock waves. Under shocked conditions, the title sample does not undergo any crystallographic phase transitions of either to α or to ω phases. However, several modifications are noticed in the mother phase such that the diffraction intensity ratio of (1-11)/(111) is found to have increased with respect to the number of shock pulses and the observed values are 0.85, 1.07 and 1.36 for the exposure of 0, 100, 200 shocks, respectively. Under the 200-shocked condition, the sample's intensity ratio is found to be closely matched to the standard pattern of the test sample with the P2/c space group. In morphological aspects, the control sample's wolframite structure has slight morphological deformations whereas the 200-shocked sample has an almost ideal morphology of the wolframite structure. Optical property results demonstrate a slight enhancement of the optical transmittance in the UV–Visible and NIR regions along with a blue shift at the 200-shocked condition. The above-mentioned analytical results reveal that the applied shock waves have effectively induced the thermal softening process, reducing the lattice and surface stresses on the test sample. A detailed discussion on the triangle relation of the structure-morphology-property of the control and shocked samples is provided.