Intense Dynamic Loading Research Articles

Thermodynamically consistent phase-field model for pressure-induced multiphase phase transformation of metals under intensive dynamic loading

Understanding the pressured-induced multiphase phase transformation (MPT) of metals at high strain rate is of great technical and scientific interest. Despite of several decades of studies, the pressured-induced MPT of metals at high strain rate is far from well understood because the deformation at high strain rate is so complex that present in situ diagnostic techniques or atomistic simulations cannot provide the details of the MPT at high strain rate. In the current work, a multiphase phase-field (MPF) model for the dynamic phase transformation (PT) of metals is developed, in which the volume fraction of each phase is chosen as the order parameter. The driving force of the MPT consists of the Gibbs free energy, the gradient energy and the penalizing energy. In particular, a smooth and normalized interpolation function is introduced to establish the Gibbs free energy at the multiphase junction. With the aid of this interpolation function, the explicit forms of the kinetics equation and constitutive relations of the MPT at the multiphase junction are also derived. It is demonstrated that the model satisfies all seven criteria of a consistent MPF model. Compared to previous models, the thermodynamic stability of this model is improved significantly. When applied to address the MPT of bismuth subjected to ramp-wave loading (RWL), the model can quantify the connection between the microstructural evolution of multiple phases and the experimentally measured multiwave structures.Moreover, new insights concerning the MPT-related thermodynamic paths of bismuth at elevated temperatures and the metastable phase during dynamic MPT are gained.

Analysis and evaluation of suitability of high-pressure dynamic constitutive model for concrete under blast and impact loading

Concrete demonstrates complex dynamic mechanical behaviors under the influence of blast or impact loads, and there are inherent limitations in experimental and theoretical methods when dealing with highly nonlinear problems. As computational technologies and mechanics continue to evolve, it is possible to conduct high-fidelity simulations of the transient response of concrete structures subjected to intense dynamic loads. Such simulations play a crucial role in revealing the propagation laws of stress waves, the progression of damage, the mechanisms of structural failure, and in conducting protective engineering design. An accurate concrete material model is essential for conducting numerical studies. This article reviews the development of high-pressure dynamic constitutive models for concrete in recent years from both experimental research and theoretical modeling perspectives, focusing on the analysis and evaluation of the modeling methods and main shortcomings of the equation of state(EOS), strength model, and damage model. Using single-element numerical simulations under a single loading path and numerical calculations of engineering cases under complex loading paths, a systematic analysis and comparison were conducted on the predictive capabilities of the HJC, RHT, KCC, and CSC models, as well as the newly developed Kong-Fang and Yan-Chen models. It pointed out the impact of high-pressure mechanical behavior of concrete and the cumulative effect of damage under hydrostatic pressure on the calculation results. Finally, a discussion was conducted on the inherent flaws, applicability, and research difficulties of local constitutive models of concrete in the finite element method. This provides a reference for the selection and research of constitutive models when conducting numerical analysis of the blast and impact resistance of concrete structures.

Elastodynamic behaviors of steady moving straight dislocation within thin nano film

The elastodynamic dislocation behaviors are of great interest for understanding the performances of structural alloys under intense dynamic loading conditions. The formation, propagations, and interactions of dislocations (such as injected dislocation, accelerating dislocation, steady moving dislocation at high constant speed) are quite different from static dislocations. For steady-moving dislocation within the isotropic infinite medium, the effects of surface and interface on steady-moving dislocations within limited space are still known. In this paper, we investigate the elastodynamic image stress simulation of steady moving dislocation within film of limited thickness at constant speed using Eigenstrain theory, Lorentz transformation, and steady dynamic equilibrium equations. We propose an efficient solution method that involves complex Fourier series, transforming partial differential equations into ordinary differential equations, and ultimately into a set of algebraic equations in spectral space. The effects of dislocation speed and position near the free surface on the image stress of steady-moving climbing and gliding dislocations within the thin film are examined. The results show that relativistic effects are significant for certain dislocation configurations and stress components, whereas other stress components are less sensitive to relativistic effects near the transonic speed region.

Cooperative competition between melt-phase and void during micro-spallation and recompression

Dynamic tensile (micro-spallation) fracture and subsequent recompression in a molten state is the key physical process for metallic materials undergoing multiple intense dynamic loadings. However, there still lacks in-depth analysis of the complete evolution process from damage accumulation to recompression, as well as the influence of damage history on subsequent deformation and fracture. In the present work, the mechanism of cooperative competition evolution between the melt-phase and voids has been proposed as a new perspective to investigate damage evolution. Various important physical phenomena discovered in larger-scale MD simulations of molten aluminum can be self-consistently explained according to the proposed mechanism, such as the rate-dependence of spall strength and the pressure oscillation. The recompression-after-damage and second fracture process are discussed in detail to analyze the damage history effect. Under the present framework, two theoretical models have been proposed from the perspective of void and melt-phase evolution, respectively. The proposed models agree well with the simulation results and provide a comprehensive understanding of the damage evolutionary characteristics.

Dynamic mechanical behaviors of pearlitic U71MnG rail steel: Deformation mechanisms and constitutive model

Pearlitic rail steels with excellent mechanical and wear properties are widely employed for high-speed railways. During the service period, the presence of track irregularities, switches, as well as crossings can cause intense dynamic loadings, which accumulate the severe deformation of rails, and sometimes even facilitate crack initiation and failure. Knowledge of the dynamic mechanical response and damage behaviors of the rail steels is therefore important for the service performance estimation of railways. In this study, the pearlite U71MnG rail steel was deformed using a split Hopkinson pressure bar (SHPB) apparatus to reach a wide range of strain rates and temperatures. Microstructures including the grain morphology, deformation characteristic of cementite lamellae, dislocation substructures in ferrite lamellae, and phase transformation at pearlite colony boundaries were characterized. Based on the microstructural observations, the rate-controlling strengthening mechanism and temperature-dependent softening mechanism of the steel were revealed when the process for the dynamic loading-induced cementite decomposition at boundaries was discussed. In consideration of the athermal deformation mechanism, thermally activated mechanism, and viscous-drag effect, a physically based constitutive model was proposed to describe the dynamic mechanical response of the pearlite rail steel. The predicted flow stresses were found to be consistent with the experimental one for all strain rates and temperatures.

DYNAMIC MECHANICAL AND STATIC ANALYSIS OF KEVLAR FIBER REINFORCED EPOXY COMPOSITES INCORPORATED WITH EGG SHELL PARTICLE

Research on composite material has been carried out stringently by using various reinforcing elements in the matrix with an intend to replace traditional monolithic materials eventually. In this regard, the Calcium-rich egg shell, which is abundantly available as a solid waste, can be used as a possible filler material for reducing material cost, improving processability, and refining the requisite properties of composite for specific applications with simultaneous reduction of the waste. In this study, the static and dynamic mechanical characteristics of eggshell particle-filled Kevlar/epoxy composites have been investigated. Through stirring with the aid of an Ultrasonicator, different weight percent of NaOH-treated eggshell particles (0, 10, 20 wt. %) of 90 micron sizes are mixed with epoxy to fabricate the composite using the traditional hand-layup method. In comparison to the hybrid composites, the mechanical properties of Kevlar/epoxy (0 wt. % filler) composite demonstrate superior tensile and flexural strength and modulus. However, when the Thermogravimetric analysis (TGA) and the Dynamic mechanical analysis (DMA) are accomplished for evaluating the thermal deterioration and viscoelastic characteristics, the hybrid composites demonstrated improvement in overall damping properties including storage modulus and loss modulus along with the thermal stability characteristics. Also, the elongation before failure is more for composite with 10 wt. % (71%) as well as 20 wt.% (18%) filler content with substantial improvement in Inter Laminar Shear Strength. Thus, the presently prepared composite is recommended for weight-sensitive and high-performance engineering applications under elevated temperatures and intense dynamic loading.

Theory and Practice of Determining the Dynamic Performance of Traction Rolling Stock

In the interaction of the rolling stock and the upper structure of the railway track, intense dynamic loads occur. They have a destructive effect both on the parts of the rolling stock and on the elements of the superstructure of the track. In order to develop a durable, rational and reliably functioning design of cars and locomotives with good dynamic properties and good indicators of the impact of rolling stock on the railway track, along with theoretical computational studies, experimental studies are also required, which are usually the final stage in the design and implementation of rolling stock or the modernization of existing ones, such as locomotives and wagons, in order to improve their strength and dynamic performance. This article presents the results of field tests to determine the dynamic performance of the type CKD6e diesel locomotive. The description of the preparation of the CKD6e shunting locomotive for testing is given. An analysis of the dynamic performance of a diesel locomotive during the passage of turnouts, on a straight section of the track and in a curve with a radius of 400 m, was carried out. The studies performed showed that the minimum value of the stability factor against wheel derailment on a straight section of the track is significantly higher than the standard value. The experimentally obtained ratio of frame forces to the static load from the wheelset on the rails, the coefficients of vertical dynamics of the first and the second stages of suspension and the coefficient of stability against derailment of the wheel from the rail were registered on the track section in a curve with a radius of 400 m meet the current requirements. A calculation scheme and equations of vertical oscillations are proposed, an analysis is carried out according to the graphs of movements of bogies and a locomotive body when moving along irregularities of different lengths at different speeds.

Inverse dynamics method in properties estimation of residual stiffness of multi-story buildings

The present paper considers methods and algorithms for determining the values of horizontal stiffness of multi-story buildings based on experimental laser measurements of their natural vibrations. The developments findings are used in determining the residual stiffness of various structures in a certain operation period, subjected to intensive dynamic loading. No need for a close inspection of buildings associated with the inevitable dismantling of enclosures and emptying of the buildings is considered as an advantage of such methods for determining the stiffness parameters of buildings. Direct method for determining the horizontal stiffness of buildings by means of specified displacements and corresponding forces in their elements implies fixing of tension elements in specified nodes – mass centers of structures. However, in some cases, they fail to be implemented. The suggested approach demonstrates its potential in the inspection of a large residential area consistent of buildings under different operating conditions, thus requiring the development of an action plan to ensure the functionality of the structures. In addition, the paper demonstrates that using the dynamic low-size models in the estimation of stiffness parameters implies determining the principles of forming the types of such models.

Role of Shear on Strength and Damage Evolution in Soda-Lime Glass Under High Dynamic Pressures

Abstract Silica glasses, such as soda-lime glass (SLG), have found wide ranging applications in engineering due to their excellent optical properties, high strength, and relatively low cost. In such applications, SLG may be subjected to intense dynamic loading due to high/hyper-velocity impact and therefore necessitates understanding of the dynamic shear strength and kinetics for the development of constitutive models. However, while several investigations have generated Hugoniots for silicate glasses, none appear to have measured shearing resistance at pressures above ∼ 20 GPa. In this study, the role of pressure and strain rate on the shearing resistance of soda-lime glass is explored using sandwich configuration high pressure-pressure shear plate impact (HP-PSPI) experiments. These experiments are conducted at pressures ranging from 14 to 42 GPa and strain rates of 105 − 106 s−1, and analyzed using finite element simulations incorporating a modified Johnson–Holmquist (JH-2) material model. The yield strength of SLG is observed to decrease as a function of pressure, which is reminiscent of the evolution of shear strength in granular media at high pressures. This observation suggests a probable shear-induced damage progression from intact material to granular matter in SLG at high pressures.

An elastoplastic damage constitutive model for capturing dynamic enhancement effect of rock and concrete through equivalent stress history

The strength enhancement effect of rock and concrete under dynamic loading is one of the significant response characteristics differing from quasi-static loading. Typically, current dynamic constitutive models describe this phenomenon by adopting strain/stress rate dependent functions. In this study, a novel elastoplastic damage constitutive model that captures the dynamic strength increase through the equivalent stress history is developed by coupling the incubation characteristic time (ICT) criterion and the unified strength theory (UST). Specifically, the ICT criterion substitutes the stress history for the strain/stress rate to predict dynamic yield strength of rock and concrete. And the equivalent stress expressed by the UST provide an appropriate selection of the stress history in the ICT criterion under complex stress states. Furthermore, based on the non-associated plastic flow rule and the plastic-damage evolution law, combined with the equation of state, the proposed constitutive model is established and implemented numerically. The dynamic stress-strain curves of granite were reconstructed by a series of numerical tests on a single element, which verified the accuracy of the proposed constitutive model and the reliability of the numerical algorithm by comparing the experimental data. The proposed model was applied to the numerical simulation of dynamic compression-shear tests on inclined sandstone specimens loading by the split Hopkinson pressure bar (SHPB) and fragmentation experiments of single borehole granite specimens under blast loading, respectively. And the experimental dynamic crack patterns on the specimen surface captured by high-speed cameras match the simulated damage distribution well. In addition, several common concrete constitutive models and the proposed model were employed to simulate the dynamic response of reinforced concrete beams under near-field blast loading. The damage patterns and the mid-span residual displacement calculated numerically by the proposed model are more consistent with the experiments than other concrete models. As a conclusion, the proposed model, coupled the ICT criterion and the UST, provides a new perspective and paradigm for characterizing the responses of rock and concrete subjected to intense dynamic loads.

A plastic-damage material model for foam concrete under blast loads

Foam concrete is a prospective material in defense engineering to protect structures subjected to intense dynamic loadings such as impact and blast through wave impedance mismatch as well as energy absorption. In the near-field of intense dynamic loadings, the foam concrete is always suffered from a high-pressure stress state associating with complex failures such as pore collapse, shear fracture and tensile fracture. A well-established material model is needed to capture above-mentioned behaviors. In this paper, a plastic-damage material model for foam concrete is proposed focused on its mechanical behavior under high pressures. Firstly, a closed form yield function, a partially-associative flow rule and a new piecewise hardening law are introduced. The yield function is composed of a fracture function describing the mechanical behavior due to microcracks and a continuous cap function describing the mechanical behavior due to pores. The partially-associative flow rule is used to avoid the overestimation of plastic strain induced by the classical associative flow rule. In particular, a new piecewise hardening law is proposed instead of frequently-used exponential ‘‘crush curve’’, which is flexible for fitting test data and can capture the experimentally-observed increase of unloading bulk modulus with increase of pressure. The rate dependency of yield surface is considered to capture the strain-rate effect of foam concrete. And then three independent damage indexes with clear physical background are proposed to describe irreversible degradation caused by microcrack growth and pore collapse. The shear damage caused by shear cracks, tensile damage caused by tensile cracks, and hydrostatic compression damage caused by pore collapse, are separately identified and proposed in the framework of continuum damage mechanics. The proposed model is embedded into the LS-DYNA through the subroutine of user-defined material model. Its performances for predicting complex failures under various stress states at a Gaussian point level are numerically evaluated using a single element, and further used to predict blast response of foam concrete. All the numerical predictions agree with test data well.

Elastic effects on the dynamic plastic deflection of pulse-loaded beams

Beams under intense dynamic pulse loading may experience large elastic-plastic deformation. Despite numerous studies have been conducted based on the rigid-perfectly plastic idealization of material, it is of great interest in both theoretical modeling and practical application to characterize and evaluate the effect of elastic deformation on the dynamic behavior of structures. This paper is aimed to examine the range of applicability of rigid-plastic theoretical solutions on large deflection of beams in response to dynamic pulse loading. The energy ratio R and the characteristic time ratio are first precisely defined by referring to the characteristics of a “plastic string”, which represents the ultimate status of beams under very large deformation. Based on the recently published complete solutions on the dynamic response of fully-clamped and simply-supported rigid-plastic beams subjected to uniformly distributed rectangular pressure pulse, the discrepancies in final deflection and in saturated impulse of the rigid-plastic theoretical predictions from the elastic-plastic simulation results are evaluated and analyzed. It is revealed that if the energy ratio R>5 (with no limitation to the pulse duration), the rigid-plastic solutions can provide reliable predictions on final deflection and saturated impulse for the usage in engineering design. Then, the effects of the key dimensionless parameters related to the energy ratio R (e.g., the structural and material parameters as well as the loading one) on the discrepancies in final deflection and in saturated impulse are thoroughly examined. Finally, a unified dimensionless stiffness is identified to characterize the combined effect of structural and material parameters. For the cases of ζ≤1.581, which represent most of the practically used beams, 1/(2R) and 1/(3R) could provide upper bounds to the absolute value of the discrepancy in final deflection for fully-clamped and simply-supported beams, respectively.

Molecular Dynamics Study on Hugoniot State and Mie-Grüneisen Equation of State of 316 Stainless Steel for Hydrogen Storage Tank.

To promote the popularization and development of hydrogen energy, a micro-simulation approach was developed to determine the Mie-Grüneisen EOS of 316 stainless steel for a hydrogen storage tank in the Hugoniot state. Based on the combination of the multi-scale shock technique (MSST) and molecular dynamics (MD) simulations, a series of shock waves at the velocity of 6-11 km/s were applied to the single-crystal (SC) and polycrystalline (PC) 316 stainless steel model, and the Hugoniot data were obtained. The accuracy of the EAM potential for Fe-Ni-Cr was verified. Furthermore, Hugoniot curve, cold curve, Grüneisen coefficient (γ), and the Mie-Grüneisen EOS were discussed. In the internal pressure energy-specific volume (P-E-V) three-dimensional surfaces, the Mie-Grüneisen EOSs show concave characteristics. The maximum error of the calculation results of SC and PC is about 10%. The results for the calculation deviations of each physical quantity of the SC and PC 316 stainless steel indicate that the grain effect of 316 stainless steel is weak under intense dynamic loads, and the impact of the grains in the cold state increases with the increase in the volume compression ratio.

Numerical simulation of the behavior of enstatite up to 1.4 TPa

An accurate description of the effect of extreme pressure and temperature on the physical properties of materials is required to understand the structure and composition of the mantle of the Earth and similar planets. One of such materials is enstatite MgSiO3, which causes increased interest in the investigating of its behavior under intense dynamic loads. It is proposed to consider the shock-wave loading of enstatite as a mixture of quartz oxides SiO2 and MgO periclase in an equal stoichiometric ratio based on experimental data in which decomposition of magnesium silicates was observed. Calculations are performed using a thermodynamically equilibrium model that takes into account the phase transitions of the components. Phase transitions of SiO2 and MgO are taken into account when modeling high-energy effects on enstatite. The results are compared with the data obtained on the basis of shock-wave loading experiments, as well as with calculations based on the PREM model performed based on the results of seismic exploration. Keywords: equation of state, phase transitions, quartz oxide, periclase oxide, enstatite.

Численное моделирование поведения энстатита до 1.4 TPa

An accurate description of the effect of extreme pressure and temperature on the physical properties of materials is required to understand the structure and composition of the mantle of the Earth and similar planets. One of such materials is enstatite MgSiO3, which causes increased interest in the investigating of its behavior under intense dynamic loads. It is proposed to consider the shock-wave loading of enstatite as a mixture of quartz oxides SiO2 and MgO periclase in an equal stoichiometric ratio based on experimental data in which decomposition of magnesium silicates was observed. Calculations are performed using a thermodynamically equilibrium model that takes into account the phase transitions of the components. Phase transitions of SiO2 and MgO are taken into account when modeling high-energy effects on enstatite. The results are compared with the data obtained on the basis of shock-wave loading experiments, as well as with calculations based on the PREM model performed based on the results of seismic exploration.

Dynamic load assessment of building structures

The questions of the theory and practice of testing structures with dynamic loads are presented. A concrete example of testing a structure on its physical model by dynamic load is clearly shown. Some information necessary for statistical processing of research results is given. Building structures are exposed to the intensive dynamic loads. The existing methods and regulatory requirements should consider the loss of strength subject to dynamic impacts. The dynamic load types will show what needs to be more focused on during the construction. Building structures should be designed to stay out of the resonance band during the use. Nowadays, the construction of new industrial complexes and modernization of factories is widely developing. Increased production, leads to increased loads, including load-bearing structures of buildings and structures, namely there are dynamic effects from a large number of machines and mechanisms. Dynamic loads are very varied in nature. They include impacts associated with natural phenomena, such as seismic shocks and wind gusts, as well as dynamic impacts of technological and accidental origin. The most important characteristic determine behavior of buildings and structures under the action of external dynamic load, and are frequency, and nature of vibration. All methods for calculating wind and seismic loads are based on determining these parameters. The purpose of this paper is to demonstrate the effects of dynamic loads on strength, durability, rigidity and crack resistance of building structures; to develop measures for mitigating oscillations; to verify the design performance of commercialized and exploited structures by the frequency and attenuation intensity of natural oscillations. The scientific novelty in this paper is that experiments were conducted to assess the dynamic stability and deficient dynamic stability using the “soil-to-building”.

Stiffness contributions of ballast in the context of dynamic analysis of short span railway bridges

Railway bridges are subjected to intensive dynamic loading. In structural calculations, the resulting response is estimated by dynamic calculations. As the basis of these calculations, the system's natural frequencies are to be numerically determined. Various studies have shown that a discrepancy between these measured natural frequencies and the numerical determination often occurs for short-frame bridges. In common practice, the ballast is assumed to be non-contributing to the global structural stiffness. In some cases, rheological models are developed to consider possible ballast stiffnesses based on small-scale model tests. The resulting spring-damper models are based on empirical values and are not directly related to the material behaviour of ballast.This paper discusses the ballast stiffness at the material level using relationships known from soil dynamics. The research shows that the material properties of the ballast can be determined in terms of stress and shear strain dependence. An equivalent ballast stiffness can be determined and considered in dynamic calculations for a known stress state and corresponding superstructure accelerations. The paper presents an approach for determining vertical and horizontal ballast stiffness according to shear strains and superstructure accelerations.This developed approach is validated by experimental tests using a small-scale bending beam and accompanying numerical calculations.Furthermore, a parameter study shows that the stiffness of the ballast does not contribute significantly to the global bending stiffness. Thus, the first bending natural frequency is hardly influenced by the ballast track.

Micro-damage evolution under intensive dynamic loading and its influence on constitutive and state equations for nanocrystalline NiTi alloy through molecular dynamics

In this study, to comprehensively reveal the damage mechanisms of NiTi alloys, molecular dynamics (MD) simulations were applied to examine the void evolution process under uniaxial and triaxial intensive dynamic loading. A single-crystal model was first used in the MD simulations. The calculation results revealed that the single-crystal NiTi model exhibited a similar damage response to brittle fracture. The corresponding damage mechanism was the rapid growth and coalescence of voids inside the material. Meanwhile, the defect influence was also examined for the single-crystal model, and the reduction effect of the ultimate stress value due to the stress concentration was analyzed quantitatively by the MD simulations. In addition, a polycrystalline model of NiTi was used in the MD simulations. Compared with the single-crystal model, the polycrystalline model showed an evident plastic stage under uniaxial loading due to dislocation slip. The MD simulation proved that the dislocations accumulated on the grain boundaries, which led to a stress concentration effect on the grain boundaries and sequentially resulted in void generation. However, the propagation and coalescence of voids were hindered by the grain interactions, which resulted in a ductile damage behavior inside the material. Based on this mechanism, the grain size influence was also studied in the MD simulations. It was discovered that the grain size effect in the damage stage resulted in a damage ductility enhancement with the decrease in the average grain size value. Finally, based on the relationships between the stress-strain curve, void fraction, and damage behavior, novel constitutive and state equations were proposed with damage terms to consider the void evolution process during the damage stage. The prediction results showed good agreement with the MD simulation data.

ДИНАМИЧЕСКИЙ РАСЧЕТ ЖЕЛЕЗОБЕТОННЫХ БАЛОК НА ПОДАТЛИВЫХ ОПОРАХ ЗА ПРЕДЕЛАМИ УПРУГОСТИ

Protective structures of civil defense are designed from the condition of perception of short-term dynamic loads. In this case, the supporting structures can be deformed in the plastic stage. To reduce the forces and displacements of the bearing elements under intense dynamic loading, the active methods of protecting structures are used. The flexible supports in the form of collapsible inserts of annular section is one of such methods. The paper considers the change in displacements and forces of the elastic-plastic reinforced concrete beams, depending on the compliance of support fastenings. Based on the theoretical studies, an algorithm for the dynamic calculation of reinforced concrete beams with cracks was developed, with which the calculation of structures was performed under various conditions of deformation of yielding supports. The calculations showed that the use of yielding supports deformed only in the elastic stage can have both a positive and a negative effect on the operation of structures. In this case, there may be the areas of ωθ values in which there is an increase in the dynamic coefficient of the structure on yielding supports relative to the beams on non-displaceable supports. The greatest efficiency of using the yielding supports is achieved when they work at the plastic stage without transition to the hardening stage.

Structural phase transition and amorphization in hexagonal SiC subjected to dynamic loading

Understanding the dynamic behavior of silicon carbide (SiC) at extreme conditions is critical for applications such as coatings and armor. Revealing the plasticity and phase transition in SiC under intensive dynamic loading is among the key concerns. However, the effects of polytypes in SiC as well as the various loading conditions on its dynamic material responses are still not well understood. Here we carry out a series of large-scale molecular dynamics (MD) simulations to explore the inelastic responses of hexagonal SiC subjected to shock and ramp compression along the [0001] direction. The shock responses present three regimes sequentially as the shock particle velocity is increased from 0.5 km/s to 6 km/s: a single elastic wave, a multi-wave structure consisting of an elastic-plastic wave followed by two consecutive phase transition waves, and finally, an overdriven structural phase transformation wave. The original wurtzite structure is observed to transform into a 6-coordinated rock salt structure through a 5-coordinated intermediate structure. Furthermore, slip along the <112‾0> direction on the (0001) plane causes multiple stacking faults and amorphization when subjected to intense shock compression. The effects of temperature and strain rate on the material responses of hexagonal SiC are decoupled by performing ramp loading simulations. The results reveal that a lower temperature rise impedes atomic motion while a lower strain rate promotes it, highlighting a competitive effect. Besides, due to the limited availability of slip planes, dynamic compression can lead to the formation of nanograins in hexagonal SiC, and nanograins refinement with increasing shock intensity is observed. These results provide important insights into the deformation of SiC polytypes under extreme conditions and promote the understanding of the dynamic properties of hexagonal structure covalent materials.