Simulation Of Impact Research Articles

Embedded finite element modeling of the mechanics of brain axonal fiber tracts under head impact conditions

Investigating and understanding the biomechanical kinematics and kinetics of human brain axonal fibers during head impact process is crucial to study the mechanisms of Traumatic Axonal Injury (TAI). Such a study may require the explicit incorporation of brain fiber tracts into the host brain in order to distinguish the mechanical states of axonal fibers and brain tissue. Herein we extend our previously developed human head model by using an embedded element method to include fiber tracts reconstructed from diffusion tensor images in a host brain with the purpose of numerically tracking the deformation state of axonal fiber tracts during a head impact simulation. The updated model is validated by comparing its prediction of intracranial pressures with experimental data, followed by a thorough study of the effects of element types used for fiber tracts and the stiffness ratios of fiber to host brain. The validated model is also used to predict and visualize the damaged region of fiber tracts during the head impact process based on different injury criteria. The model is promising in tracking the state of fiber tracts and can add more objective functions such as axonal fiber deformation if used in the future design optimization of head protective equipment such as a football helmet.

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Lattice Boltzmann simulation of water droplet impact and freezing on inclined supercooled surfaces with different roughnesses and wettabilities

Water droplet's impact and subsequent freezing on inclined supercooled surfaces, having micro-pillar structures with three different types of wettabilities (hydrophilic, neutral, or hydrophobic) are investigated numerically by a three-dimensional, multi-relaxation time, pseudo-potential liquid-vapor phase-change lattice Boltzmann method. Effects of volume expansion of water at 0 °C as well as the advancing contact angle of the droplet on real rough surfaces are considered in this model. Temporal variations of droplet morphological changes after impact and subsequent freezing on the supercooled inclined surfaces under various wall temperatures are illustrated. Simulation results indicate that after impacting on the supercooled rough inclined surfaces at a given Weber number, a water droplet can form fully penetrated elliptical ice morphologies and stretched stream-like ice morphologies attached on the supercooled surface, or partially and fully rebounding from the supercooled surface depending on the wettability of the surface, the surface inclination, and the degree of supercooling. It is shown that elliptical ice patterns are formed on hydrophilic substrates where droplets do not recoil after spreading, while stream-like ice patterns are mostly formed on neutral substrates where droplets are gradually stretched due to the gravity because droplets are attached on the inclined surface. On the other hand, partial and full rebounds of droplets occur on hydrophobic surfaces having high inclination angle where droplets undergo strong recoiling and rebounding after spreading on rough surfaces. At low degrees of supercooling (i.e., higher substrate temperatures), partial rebounds occur because a portion of the water droplet freezes on the substrate during contact with the supercooled substrate; otherwise, fully rebounding occurs. These results elucidate the effects of wettability, roughness, temperature and inclined angle of the wall on ice morphologies. Additionally, effects of Stefan number (substrate temperature) on the four different ice morphologies of a water droplet (D0 = 100 and Pr = 13.5) after its impact on supercooled inclined rough surfaces at a Weber number of We = 112 (Reynolds number of Re = 164.9) are illustrated.

The influence of particle size and velocity on the wear failure of TiC coated Fe under oil extraction conditions: A molecular dynamics study

The application of titanium carbide (TiC) coatings, renowned for their exceptional tribological properties, holds promise for the research on failure prevention in downhole petroleum machinery. In this study, molecular dynamics was employed to coat TiC layers onto Fe surfaces to enhance wear resistance. The effects of particle size and velocity on the wear and erosion resistance failure of the entire system were investigated through nanoindentation, scratch tests, and particle impact studies. The results indicate that the influence of particle size on the abrasion resistance and erosion resistance of materials is manifested in the load trend and surface atomic morphology. In the plastic damage of materials, an increase in velocity weakens the accumulation of slip faults and rearrangement phenomena among internal atoms, resulting in irregular fluctuations in the load curve. Meanwhile, the high-speed system will dominate the influence on temperature by accelerating atomic motion, leading to different orders of magnitude of wear and high-temperature atoms in impact simulations compared to particle size. This provides significant reference for the study of protective failure of TiC coatings in complex oil machinery service environments.

Binary craters on Ceres and Vesta and implications for binary asteroids

Context. Airless planetary objects have their surfaces covered by craters, and these can be used to study the characteristics of asteroid populations. Planetary surfaces present binary craters that are associated with the synchronous impact of binary asteroids. Aims. We identify binary craters on asteroids (1) Ceres and (4) Vesta, and aim to characterize the properties (size ratio and orbital plane) of the binary asteroids that might have formed them. Methods. We used global crater databases developed in previous studies and mosaics of images from the NASA DAWN mission high-altitude and low-altitude mapping orbits. We established selection criteria to identify craters that were most likely a product of the impact of a binary asteroid. We performed numerical simulations to predict the orientation of the binary craters assuming the population of impactors has mutual orbits coplanar with heliocentric orbits, as the current census of binary asteroids suggests. We compared our simulations with our survey of binary craters on Ceres and Vesta through a Kolmogorov-Smirnov test. Results. We find geomorphological evidence of 39 and 18 synchronous impacts on the surfaces of Ceres and Vesta, respectively. The associated binary asteroids are widely separated and similar in diameter. The distributions of the orientation of these binary craters on both bodies are statistically different from numerical impact simulations that assume binary asteroids with coplanar mutual and heliocentric orbits. Conclusions. Although the identification of binary craters on both bodies and the sample size are limited, these findings are consistent with a population of well-separated and similarly sized binary asteroids with nonzero obliquity that remains to be observed, in agreement with the population of binary craters identified on Mars.

The South Pole‐Aitken Basin: Constraints on Impact Excavation, Melt, and Ejecta

AbstractThe formation and evolution of the South Pole‐Aitken (SPA) basin is critical to relating large impact basin formation and modification to lunar geophysical evolution. Most prior models of the SPA impact were conducted in 2D, making it difficult to compare model output to the 3D crustal structure and ejecta distribution. In order to better constrain the parameters of the SPA impactor and the expected post impact distribution of crust and ejecta, we conducted numerical simulations of the SPA impact in 3D. We tested a wide range of impact parameters and constrained model results with recent geophysical data. We found the crustal structure of the SPA basin is best fit by an oblique impact (30–45°) of a 350–400 km diameter projectile impacting at 12–16 km/s. The impact excavated material from as deep as 80–120 km, and ejecta was deposited in a butterfly pattern with a forbidden region uprange of the impact.

Evaluation of lap belt-pelvis load transfer in frontal impact simulations using finite element occupant models

Objective The goal of this study was to examine the relationship between lap belt tension and force measured at the iliac wing and the effects of model type and torso posture on this relationship. From this analysis, preliminary transfer functions were developed to predict loads applied to the iliac wing as a function of lap belt tension at magnitudes typically measured in sled and vehicle crash tests. Methods A DOE study was conducted to provide a robust assessment of the lap belt-pelvis load relationship under various conditions. The GHBMC, THUMS, and THOR FE models were positioned in upright and reclined postures with several other intrinsic and extrinsic parameters varied for a total of 360 simulations. For the HBMs, instrumentation was developed to measure ASIS load at each iliac wing. Simulations that resulted in submarining were identified and removed from the subsequent development of lap belt-ASIS force transfer functions. Results The GHBMC exhibited submarining more frequently than the THUMS and THOR models. In addition to submarining, there were several cases in which the lap belt remained below the ASIS instrumentation or roped during the model’s forward excursion. These phenomena, particularly prevalent in the THUMS model, also influenced how the lap belt engaged the ASIS instrumentation and were thus eliminated from the transfer function development. Transfer functions relating peak lap belt tension and corresponding ASIS force magnitudes were developed for the GHBMC and THOR models in upright and reclined postures. In the upright posture, the THOR showed a higher level of ASIS load measured for a given level of lap belt tension than the GHBMC; however, in recline the lap belt-pelvis load relationship was similar between the two models. Conclusions The lap belt-pelvis load relationship was found to be affected by model type, posture, the area in which the ASIS instrumentation was defined, and occupant kinematics. This study showed it was possible to minimize the ASIS force by having the lap belt engage low on the pelvis and upper thighs, though further study is needed to determine if this loading mechanism is truly protective from an injury standpoint or an artifact of bypassing the ASIS instrumentation. The transfer function that showed the highest ASIS force measured for a given level of lap belt tension is recommended for future use.

Numerical Study on the Impact Pressure of Droplets on Wind Turbine Blades Using a Whirling Arm Rain Erosion Tester

The leading-edge erosion of a wind turbine blade was tested using a whirling arm rain erosion tester, whose rotation rate is considerably higher than that of a full-scale wind turbine owing to the scale effect. In this study, we assessed the impact pressure of droplets on a wet surface of wind turbine blades using numerical simulation of liquid droplet impact by solving the Navier–Stokes equations combined with the volume-of-fluid method. This was conducted in combination with an estimation of liquid film thickness on the rotating blade using an approximate solution of Navier–Stokes equations considering the centrifugal and Coriolis forces. Our study revealed that the impact pressure on the rain erosion tester exceeded that on the wind turbine blade, attributed to the thinner liquid film on the rain erosion tester than on the wind turbine blade caused by the influence of centrifugal and Coriolis forces. This indicates the importance of correcting the influence of liquid-film thickness in estimating the impact velocity of droplets on the wind turbine blade. Furthermore, we demonstrated the correction procedure when estimating the impact velocity of droplets on the wind turbine blade.

Implementation of three-dimensional contact algorithm in numerical manifold method for the structural impact simulation

Structural impact often accompanies large amounts of contacts and leads to complex mechanical phenomena. In solid mechanics, the numerical manifold method (NMM) is proposed to address problems featuring continuous-discontinuous transitions by utilizing a dual coverage system encompassing both mathematical and physical covers. In the present work, a penalty contact algorithm for 3DNMM based on cover-based contact theory is programmed and applied to impact mechanics problems. The accuracy of the developed contact algorithm is firstly calibrated through free-falling blocks and collision blocks. The influence of contact parameters on contact convergence is systematically studied, and three preliminary criteria for how to set contact parameters are provided. The effectiveness of the contact algorithm is verified by conserving system momentum during block collisions. Subsequently, the contact algorithm is applied to Taylor rod and car-streetlight impact simulation, further confirming its effectiveness in modeling high-speed collisions, large displacements, and large deformations of structures. By comparing the 3DNMM results with those from Abaqus, the contact algorithm developed here performs exceptionally well in solving collision problems and produces results consistent with commercial software. The research results in the present work verify the applicability and accuracy of the proposed contact algorithm in solving structural dynamic impact problems. The present work also provides guidance for contact parameter setting in impact problems.

Peridynamics contact model: Application to healing using phase field theory

This paper presents a contact algorithm in non-ordinary state-based peridynamics (NOSB-PD) framework and its application in healing phase field (HPF) theory. The idea here is to exploit the nonlocality in PD to model the contact between two deformable bodies. The proposed method does not require artificial short-range force or additional degrees of freedom, e.g., Lagrange multiplier, which are often used in the conventional classical and PD contact models. In the regions where contact is likely to take place, neighbor search is performed at every time step and extra particles entering the horizon are identified. These extra particles form artificial bonds which transfer forces only in compression. This feature is essential for rebound simulation. Envisioning surface-to-surface bonding as the opposite process of cracking, we propose an HPF theory to model high velocity impact induced bonding between two material bodies. Here an HPF based bonding criterion is postulated and integrated with the proposed contact algorithm. The solution of the governing equations is obtained using the fourth order Runge-Kutta method. The efficacy of the proposed contact algorithm is demonstrated by simulations of impact and rebound of two plates, two cylinders, and cylinder with rectangular prism and comparing the energy time histories with finite element solutions obtained using ANSYS®. The potential of the proposed HPF theory is demonstrated through simulation of impact of two plates where the plates rebound when the impact velocity is below a critical value, and above that velocity, the plates join with each other.

Finite elements analysis of drop weight impact loading on GLARE-6A

Fibre Metal Laminate (FML) is a damage-tolerant material being opted in modern aerospace industries. FML impact absorbing properties were studied for determining FML response against impact loading. The author contributed by experimentation of drop weight impacts on FML GLARE 6A samples. In this paper, the author reproduced drop weight impact simulation using Finite Element Analysis (FEA). The author modeled GLARE FML, and a simulation of drop weight impact was performed using the explicit dynamics module of ANSYS. The drop weight impact method in Ansys was used to analyse the impact force effect on GLARE FML. Simulation results depicted drop weight impacts measured impact force, velocity, and energy vs time. Maximum deformation of plots was presented.

Advanced feature extraction for the characterization of impact events on composites using multiresolution wavelet-based simulations

The detection and characterization of impact events on composite structures from the induced wave responses, involves many challenges. Coexisting guided waves of high dispersive nature propagate after impact, entailing continuous time variations in their wavenumber, frequency and group velocity content, which complicate the exact estimation of the time-of-flight and the extraction of impact characteristics. A multiresolution finite wavelet domain computational method, combined with appropriate contact laws, is presented to provide enhanced simulation and characterization capabilities of impact events. An explicit multiresolution time integration scheme involves a coarse solution, followed by finer solutions that are sequentially added to the coarse one, until convergence is achieved. The hierarchical character of the approach makes the impact simulation very fast and accurate. Moreover, due to the filtering properties of Daubechies wavelet functions, each resolution component effectively models and isolates specific wavenumber spectra, providing the capability to separate coexisting wave modes, and to overcome difficulties imposed by the dispersive nature of the resultant guided waves. It is demonstrated that the multiresolution simulation can reveal wave characteristics and time-of-flight features that no other traditional single-resolution method can do, and provides the basis for the development of powerful inverse methods that can localize the impact and characterize the impactor parameters. The method is first applied on impacted composite strips and the structural responses of each resolution component are assessed in order to obtain the desired features for impact location estimation and characterization. Finally, the method is implemented on an impacted composite plate structure and the various wave characteristics simulated by the fine components are presented, evincing the advanced features that the proposed method provides.

Microscopic Mechanism and Percolation Model of Dynamic Deposition of Elemental Sulfur Particles in Acidic Gas Reservoirs.

The dissolution of elemental sulfur in acidic gas leads to its precipitation as gas pressure decreases, thereby causing potential damage to the formation due to the deposition of sulfur particles. Previous sulfur deposition prediction models often relied on the solubility of sulfur in acidic gas and the stress state of sulfur particles to determine the occurrence of deposition, thus establishing predictive models. However, in the presence of complex geological conditions, the multiphase flow through porous media and the adsorption of particles on pore throat walls can also influence sulfur particle deposition to some degree. It is well known that sulfur particle deposition during gas reservoir development exhibits instability, with multiple factors influencing the deposited sulfur particles. Particularly noteworthy is the influence of airflow velocity, which can resuspend sulfur particles that are physically adsorbed on pore throat surfaces, thereby reintegrating them into the gas phase. Additionally, the dynamic deposition of larger sulfur particles involves a dynamic process. This study elucidates the dynamic process of sulfur deposition by considering the diverse transport dynamics of sulfur particles. Physical adsorption and desorption behaviors of sulfur particles are determined based on variations in reservoir conditions. The desorption status of sulfur particles with different particle sizes within the formation is established by evaluating the equilibrium between the force exerted on the pore throat wall and the suspension force generated by gas flow. The critical conditions for sulfur deposition in Yuanba gas reservoir were obtained by substituting on-site parameters into calculations. Moreover, a mathematical model is proposed to describe the dynamic deposition and migration of sulfur particles, adopting principles from continuous porous media porous flow theory, fluid flow mass conservation, as well as sulfur particle desorption and migration. The formulated model is solved, and its resulting solution process and outcomes hold significant implications for numerical simulation and predictive assessment of the development impact on gas reservoirs, particularly in later stages.

Numerical simulation of aeration impact on the performance of a-type rectangular and trapezoidal piano key weirs

Numerical simulation of aeration impact on the performance of a-type rectangular and trapezoidal piano key weirs

Probing the Atomic Erosion Wear Characteristics of TiC-Coated Fe in Oil and Gas Drilling Environments.

The titanium carbide (TiC) coating is considered one of the key coating materials to resist erosion wear in oil and gas drilling environments due to its excellent impact and wear resistance. Based on molecular dynamics, the erosion wear resistance of TiC coatings and the pure Fe system in the simulation of nanoindentation, scratch, and particle impact was studied at the microscale. The results indicate that TiC coatings can effectively enhance the load-bearing capacity of the Fe substrate within the critical load range and exhibit low friction characteristics and erosion resistance. However, the protection is lost after the TiC coating cracks, leading to an increase in the tangential force. In addition, when TiC coatings and pure Fe systems exhibit typical erosion characteristics of brittle materials, the TiC coating will significantly reduce the erosion wear of the substrate.

Dynamic mechanical response and constitutive model of (Ti37.31Zr22.75Be26.39Al4.55Cu9)94Co6 high-entropy bulk metallic glass

In this work, the mechanical response and fracture characteristics of (Ti37.31Zr22.75Be26.39Al4.55Cu9)94Co6 high-entropy bulk metallic glass (HE-BMG) were investigated in detail over a wide range of strain rates (10−4–105 s−1). The HE-BMG exhibited a negative strain rate sensitivity under uniaxial compression, with the strength showing more significant rate dependence under dynamic conditions. The shear band behavior translated from the dominance of multiple shear bands propagations under quasi-static compression to the rapid propagation of a single shear band to form cracks under dynamic compression. Under dynamic loading, the shearing velocity increased along an arc-shaped displacement path, and the local stress state on the shear fracture surface shifted from compressive-shear to tensile-shear, accompanied by changes in fracture morphologies. The spall strength of HE-BMG decreased as flyer impact speed increased, while the long-term dependence of spall strength on strain rate may be positive. With the increase of impact speed, the main microstructural features of the spalling surface translated from flat regions accompanied by dimples to cup-cone structures. Furthermore, the complete parameters of the Johnson–Holmquist II (JH-2) model for HE-BMG were obtained based on experimental data. Numerical simulations of planar impact, penetration, and hypervelocity impact are in good agreement with experimental results, demonstrating the validity of the JH-2 model parameters. The current work has important guiding value for the application of HE-BMG in space debris protection.

Topology optimised novel lattice structures for enhanced energy absorption and impact resistance

ABSTRACT This study evaluates topologically optimized lattice structures for high strain rate loading, crucial for impact resistance. Using the BESO (Bidirectional Evolution Structural Optimisation) topology optimisation algorithm, CompIED and ShRIED topologies are developed for enhanced energy absorption and impact resistance. Micromechanical simulations reveal CompIED surpasses theoretical elasticity limits for isotropic cellular materials, while the hybrid design ShRComp achieves theoretical maximum across all relative densities. Compared to TPMS, truss, and plate lattices, the proposed structures exhibit higher uniaxial modulus. Manufactured via fused deposition modeling with ABS thermoplastic, their energy absorption capabilities are assessed through compression tests and impact simulations. The ShRComp lattice demonstrates superior energy absorption under compression compared to CompIED. Impact analyses of CompIED and ShRComp sandwich structures at varying velocities show exceptional resistance to perforation and higher impact absorption efficiency, outperforming other classes of sandwich structures at similar densities. These findings position these new and novel topologies as promising candidates for impact absorption applications.

Multi-stage Johnson–Cook Model for Collision Analysis: Impact Experiments and Simulations

Multi-stage Johnson–Cook Model for Collision Analysis: Impact Experiments and Simulations

Three-Dimensional Lattice Boltzmann Simulations for Droplet Impact and Freezing on Cold Surfaces with a Large Density Ratio

Droplet impact and freezing on solid surfaces are ubiquitous in many natural and engineering processes. Simulating the impacting-freezing process of a droplet is still challenging because it involves the complex multiphase flow and the liquid-solid phase change. This paper establishes a three-dimensional lattice Boltzmann model that considers the effects of contact angle hysteresis and volume expansion to simulate this complex process under realistic conditions. We adopt an enhanced cascaded lattice Boltzmann method to calculate the flow field and a multiple-relaxation-time scheme to solve the liquid-solid phase change model. In addition, a new contact angle model based on the pseudopotential multiphase lattice Boltzmann model is proposed to mimic the contact angle hysteresis. The simulations of droplet impact and freezing on both hydrophobic and hydrophilic surfaces with different surface temperatures and Weber numbers are conducted, and the temporal droplet profile and dimensionless contact length agree well with the experiments, which effectively validates the accuracy and robustness of the present model. Finally, the effects of surface temperatures ( 0 , − 15 , − 30 ∘ C ) and Weber numbers (4.4, 19.2, 40.0, 71.1) on droplet dynamics are also examined.

Insight into compression-rebound behavior of lignocellulose-derived aerogel through finite element modeling based dynamic impact simulation

In this study, lignocellulose-derived aerogel (LA) with compression-rebound was synthesized from liquefied wood through sol-gel polymerization, aging and freeze-drying process. The results presented a gradual increase in the compressive strength, flexural strength, and maximum decomposition temperature of the LA sample with prolonged aging time from 3 to 10 h, demonstrating excellent elasticity and thermal stability. After more than 10 h, the bending strength began to decrease, indicating that the material’s rigidity was greater than its elastic toughness at this time. A nonlinear viscoelastic constitutive model based on the Ogden function and parallel rheological framework showed very high correlation with experimental measurement results, and also demonstrated admirable mechanical properties. These predictions can provide an effective approach for the application of LA in buffer packaging.