Simulation Of Impact Research Articles

Optimal Monetary Policy Framework in an Emerging Market Economy under Sanctions Pressure and Restrictions on Capital Flows

Abstract The study evaluates the effectiveness of monetary policy regimes that can serve as the basis for economic policy strategies in emerging economies. Based on the macroeconomic gap model for Belarus, simulations of the strong shock impact on the economy using different monetary policy regimes have been implemented. The effects of capital flow restrictions on the stabilization capacity of monetary policy regimes have been examined. Given the existing sanctions and internal capital controls, the most preferable regime for Belarus is a flexible inflation targeting. In transforming the economy and political system towards the inclusivity of political and economic institutions, applying a flexible price-level targeting can be considered.

Impact‐Generated Permeability and Hydrothermal Circulation at the Vredefort Impact Structure, South Africa

AbstractThe 2.02 billion year old Vredefort impact structure in South Africa offers a unique opportunity to study large‐scale impact processes on Earth. Vredefort's large size (∼250 km in diameter) and eroded topography provides the opportunity to study the effects of shock physics at depth and post‐formation hydrothermal alteration. In this work, we simulate the formation of the Vredefort structure building upon recent shock physics (iSALE) simulations. We expand those simulations to cover a wider range of input conditions, and compute impact‐driven porosity and permeability. The latter quantities are used to perform fluid mobility simulations (HYDROTHERM). We find that the Vredefort event produced significant impact‐generated porosity (up to 30%) in an annulus from about 50 to 100 km from the center and up to several kilometers in depth. The corresponding estimated permeability (up to 10−12 m2) would have allowed for large scale subsurface fluid flows. Our hydrothermal calculations show that the Vredefort impact event could have generated a complex crustal fluid pattern within the crater rim that lasted for hundreds of thousand years, with localized flow concentration regions, opening a new interpretation for the mobilization and location of the ore deposits in the Witwatersrand basin. The combined approach utilizing impact and hydrothermal simulations constitute a powerful tool to understand geochemical processes at Vredefort, as well as to assess the ability of large impacts to drive crustal chemistry with far‐reaching consequences for the prebiotic evolution of the early Earth.

The Relative Effects of Surface and Subsurface Morphology on the Deflection Efficiency of Kinetic Impactors: Implications for the DART Mission

The Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the moonlet of the binary asteroid 65803 Didymos, on 2022 September 26 and successfully tested a kinetic impactor as an asteroid deflection technique. The success of the deflection was partly due to the momentum of the excavated ejecta material, which provided an extra push to change Dimorphos’s orbital period. Preimpact images provided constraints on the surface but not the subsurface morphology of Dimorphos. DART observations indicated that Dimorphos contained a boulder-strewn surface, with an impact site located between a cluster of large surface boulders. In order to better understand the momentum enhancement factor (β) resulting from the impact, we performed impact simulations into two types of targets: idealized homogeneous targets with a single boulder of varying size and buried depth at the impact site and an assembly of boulders at the impact site with subsurface layers. We investigated the relative effects of surface morphology to subsurface morphology to put constraints on the modeling phase space for DART following impact. We found that surface features created a 30%–96% armoring effect on β, with large surface boulders measuring on the order of the spacecraft bus creating the largest effect. Subsurface effects were more subtle (3%–23%) and resulted in an antiarmoring effect on β, even when layers/boulders were close to the surface. We also compared our 2D axisymmetric models to a 3D rectilinear model to understand the effects of grid geometry and dimension on deflection efficiency computational results.

Fabrication of natural fiber-mixed natural matrix composite-infused indoor air purifier with health impact simulation

The inhalation of airborne particles can endanger the health of any human being. Natural fiber and natural fiber reinforced with natural matrix material are employed in this work to create an indoor air purifier. Various natural fiber and natural composite combinations are used to purify the interior environment by eliminating particulate matter of various sizes and volatile organic chemicals. An air purifier is created using four distinct natural fibers, including hemp, jute, silk cocoon, and coir fibers, as well as neem and aloe vera gel as natural filler materials. An air quality-monitoring instrument is used to validate the performance of the designed natural fiber/natural plant-based filler material-equipped air purifier. Particulate matter of various sizes and volatile organic compounds in the indoor environment are detected at various time intervals. The efficacy of the air purifier is afterward determined in human lungs of various ages utilizing health impact simulation studies. The current product is utilized to effectively purify indoor air by eliminating particulates and volatile organic chemicals.

Social Impact Simulation Including Social Capital, Based on Current Status of Multi-Agent Simulation

Social Impact Simulation Including Social Capital, Based on Current Status of Multi-Agent Simulation

Assessing the Effect of Chest Orientation on Pulmonary Pressure Under Free Field Shock Waves: A Numerical Analysis

Purpose This study explores how thoracic orientation affects lung pressure and injury outcomes from shock waves, building on earlier research that suggested human posture impacts injury severity. Methods A layered finite element model of the chest was constructed based on the Chinese Visual Human Dataset (CVH), which includes the rib layer and intercostal muscle layer. The dynamic response of the chest under 12 different angles oriented shock waves under incident pressures of 200kPa and 500kPa was calculated. The correspondence between lung pressure at different angles, chest wall motion velocity and lung stress, and differences in pressure/stress of lung tissue behind ribs and intercostal muscle were analyzed. Results The dynamic response of the chest can be roughly divided into four processes. High local intrapulmonary pressure areas were primarily in the anterior lobe margin and lung's central region. A 500kPa incident wave at 0° could cause slight lung injury, whereas at 240°, the pressure was non-harmful. Lung tissue pressure and stress induced by chest wall movement were significantly higher behind the intercostal muscles than behind the ribs, with a difference of about 2-3 times. Conclusions This layered model provides a cost-effective tool for large-scale shock wave impact simulations on the chest. Chest wall movement velocity strongly correlates with lung stress distribution. The significant density and sound velocity differences among ribs, intercostal muscles, and lungs cause an acoustic impedance mismatch, leading to “striped bleeding” marks in post-impact lungs. This research enhances understanding of chest and lung injury mechanisms and informs the development of protective measures.

Simulation of Multi-Layered Ballistic-Resistant Armour with Enhanced Energy Absorption Properties

This research focuses on the simulation of ballistic impact on multi-layered ballistic resistant armour. The efficiency of spring-loaded backing plate armour was compared with armour that has solid end plate with a view to introducing a more elastic surface that enhances energy absorption properties. The design consists of three major layers of different materials: fibre cement as the first layer; Kevlar as the second; and a spring-loaded backing plate made of steel as the third layer. SolidWorks was used to model the multi-layered armour and ANSYS Workbench Explicit Dynamics and AUTODYN 3D solver were used to simulate the ballistic impact. The simulation involved testing different configurations of the multi-layered structure. Analysis of the effect of the spring wire diameter on the armour's energy-absorbing characteristics was carried out while keeping the overall weight within the acceptable range. The simulation results for the different configurations were compared and the ballistic-resistant armour designed with a spring-loaded backing plate of 0.40 mm spring wire diameter gave the least deformation. The research suggested an enhanced armour performance using embedded elastic material.

Hypervelocity impact simulations on space structures using various shielding systems

Hypervelocity impact simulations on space structures using various shielding systems

Assessing the Impact of Covid-19 in Mozambique in 2020

Taking advantage of the 2019/2020 Mozambican household budget survey, in the field both before and during the first phases of the Covid-19 pandemic, we assess the impact of Covid-19 on welfare in 2020, aiming to disentangle this impact from the effect of other shocks. Comparing a number of welfare metrics, and applying propensity score matching and inverse probability weighted regression adjustment approaches, we find that consumption levels are significantly lower and poverty rates substantially higher during the first phases of Covid-19 than in the pre-Covid-19 period. Moreover, the impact was greater in urban areas and accordingly in the more urbanised southern region. Non-food expenditures suffered relatively more than food expenditures, likely a coping strategy, while the impact on consumption levels was greater for people working in the secondary and tertiary sectors than for workers in the primary sector, mainly agriculture. Stunting among under-5 children also suffered. Only a limited number of countries have actual, collected in-person, survey data that span across the initial phases of the Covid-19 pandemic. Thus, the present analysis adds value to our understanding of the welfare consequences of Covid-19 in a low-income context, where automatic social safety nets were not in place during the early phases of the pandemic. More specifically, it helps in assessing the results of previous welfare impact simulations, compared to real data. Even though our main findings are broadly in line with existing estimates based on simulations or phone surveys, important differences between the predictions and the actual results emerge. We conclude that it is critically important for Mozambique and its development partners to develop stronger and more targeted policies and tools to respond to temporary shocks.

Simulation for impact of nanofluid spectral splitter on efficiency of concentrated solar photovoltaic thermal system

Nanofluid filter has been applied in current research to boost the efficiency of a concentrated photovoltaic thermal (CPVT) module. Owing to tunable optical features of nanofluid and its greater thermal characteristics, it was utilized as spectral filter and cooling fluid in the present proposed solar system. The mixture of silver and water has been utilized as working fluid and its concentration within the filter and cooling duct are 0.005 and 0.05, respectively. Three dimensional models have been proposed involving spectral distribution of solar irradiation. Also, transmissivity of nanofluid filter has been derived according to empirical models. Two structures have been applied for cooling duct: 1) straight bottom wall; 2) wall with triangular obstacles (semi-wavy wall). As velocity of nanofluid within the filter (Vf) section enhances, the electrical performance increases about 3.4 %. For case 4, with augment of concentration ratio (CR) from 3 to 30, the electrical performance reduces about 13.57 % while thermal performance augments about 5.68 %. When CR=10, utilizing case 4 makes electrical and thermal performance to enhance about 25.09 % and 22.36 % in comparison to case 1. Also, cell temperature decreases about 47.82 % with applying the filter within the second structure of the cooling duct.

SPH–DEM modelling of hypervelocity impacts on rubble-pile asteroids

ABSTRACT Investigating the hypervelocity impact process on rubble-pile asteroids is crucial for understanding the formation and evolution of small celestial bodies, and has important implications for planetary defence. In recent years, numerical simulations have been widely used to model asteroid impacts, as a complement to experimental and theoretical approaches. In particular, the hybrid SPH–DEM framework has been introduced to describe the multistage dynamics involving shock propagation and gravitational re-accumulation. However, the tension between modelling accuracy and computational costs poses significant challenges in rubble-pile impact simulations. In this study, we introduce two distinct particle configurations, i.e. multiple layers of similar-sized surface contact particles and a set of different-sized gravity particles, to efficiently describe the large irregular boulders during long-term evolution. Accordingly, the new transition algorithms are implemented to convert the smoothed particle hydrodynamics (SPH) results into the desired discrete-element method (DEM) configurations. With the proposed method, the complexity of contact computation is reduced from $\mathcal {O}(N)$ to $\mathcal {O}(N^{2/3})$, and the gravity computation is accelerated by about one hundred times while maintaining the same level of resolution. The method is then used to simulate the double asteroid redirection test impact on the rubble-pile asteroid Dimorphos. Our numerical simulations have reproduced the observation results regarding momentum transfer and mass ejection. Moreover, we predict that the impact event will form a final crater larger than 45–68 m in diameter and lead to global resurfacing of the target. The renewed surface and fresh interior will be accessible to the upcoming Hera mission, providing new perspectives on the formation and evolution of the rubble-pile binary asteroids.

Strain rate-dependent failure modelling of impact damage in laminated CFRP structures

This work focuses on the development, implementation, and validation of a constitutive model for unidirectional composites, aiming to numerically simulate impact damage in laminated structures. The model incorporates a failure criterion that accounts for the influence of strain rate on failure initiation and distinguishes between four failure modes. Failure initiation criteria are 3D phenomenological-based criteria according to the previous work of Puck and Schürmann (1998) and Pinho (2006). Additionally, a mesh-objective damage propagation model is implemented to simulate the impact damage. The impact simulations are performed using Abaqus/Explicit, with the constitutive model implemented through the user subroutine VUMAT. Validation of the strain rate effects on failure initiation is performed using strain rate-dependent bi-axial failure curves for IM7/8552 and AS-4/3506. The analyses indicate that the properties governing the strain rate dependence of failure initiation are consistent. Therefore, the hypothesis was tested in which the same strain rate scaling approach could be used for CFRP materials for which only static properties are available. This hypothesis was tested in high and low-velocity impact simulations at laminated IMS60/977–2 CFRP plates. The results demonstrate that the model accurately replicates the experimentally observed impact-induced contact forces and effectively captures the damaged state in the impacted plate.

High-fidelity simulations of low-velocity impact induced matrix cracking and dynamic delamination progression in CFRP beams

A high-fidelity finite element model is constructed to simulate the low-velocity line-impact experiments conducted by Bozkurt and Coker on [05/903]s CFRP beams. The simulations utilize a user-implemented three-dimensional continuum damage model with the LaRC05 criterion for matrix cracking, and a built-in cohesive zone model for delamination in ABAQUS/Explicit. The significant influence of boundary supports on the global impact response leads to proposing a heuristic boundary conditions approach using spring elements that replicate the experiment boundaries. Results then demonstrated an excellent agreement with the experiments in terms of the global impact response, the strain field, and damage pattern and sequence. Simulations reveal intersonic delamination with crack tip speeds around ∼5000 m/s, while the experimental crack speeds were measured as sub-Rayleigh speeds reaching ∼1000 m/s. When a crack tip definition based on the crack tip opening is introduced in the simulations, crack tip speeds in the range of 490–1500 m/s are measured which are within the range of experimental speeds, suggesting that the sliding mode might be physically hidden in the experiments. The potential use of delamination crack tip speeds as a benchmark for refining numerical simulations is demonstrated by increasing the effective interface toughness leading to a decrease in crack tip speeds with no noticeable effect on the global responses.

A progressive damage model associated with dynamic fracture toughness and IFF criterion with a fast search algorithm of fracture angle

This paper presents a quick search algorithm of the fracture angle of inter-fiber fracture (IFF) criterion and a progressive damage model considering the dynamic fracture toughness effect. The fracture angle determination of the IFF criterion is necessary and time-consuming, which has limited its practicality. Therefore, to accurately calculate stress exposure factors under various combinations of stress states, a highly efficient algorithm is needed. In this paper, a novel algorithm using stress tractions on the fracture plane and the golden section search (GSS) is promoted. Through a series of simulation tests, this novel algorithm has been proven to be exact and efficient compared with other two common algorithms, which saves an average of 63.2 % and 28.1 % of the time in 1 million calculations and 2 h 2 min 4 sec and 39 min 2 sec in simulations. Additionally, fracture toughness, which controls material damage evolution process, also has strain-rate effect like elastic modulus and strength. Hence, a new progressive damage model considering the dynamic fracture toughness effect is proposed. The results of dynamic compression and ballistic impact tests and simulations demonstrate the fidelity of the novel damage model.

Discrete element method simulation of rice grains impact fracture characteristics

The fracture of rice grains and other cereals is a common phenomenon during various processes such as seeding, harvesting, and processing. With the objective of elucidating the underlying fracture mechanisms involved, this paper aimed at simulating the fracture of rice grain caused by impacts at different locations on the surface using the discrete element method (DEM) and a bonded particle model (BPM). The aim was to establish an accurate BPM of rice grain using an impact bench test combined with the DEM. To uncover the mechanisms underlying the fracture of rice grains, the fracture process of rice grains at different locations was visualised using impact simulation. The findings demonstrated that this BPM can replicate the fracture behaviour of rice grains. The impact fracture velocity of rice grains varied across different locations, with the highest fracture velocity observed at the centre of the grain, reaching a maximum of 39.5 m s−1. The propagation of cracks played a crucial role in the occurrence of fractures in rice grains. The impact force and kinetic energy were concentrated in the impact zone, resulting in the formation of fracture surfaces in rice grains. The impact toughness of the impact zone in rice grains exhibited a direct correlation with the impact fracture velocity of the rice grains. This study elucidated the fracture mechanism of rice grains and determined the impact fracture velocities at different locations, thereby establishing a reliable foundation for minimising losses in various agricultural stages including seeding, harvesting, and processing.

Development of a Restraint System for Rear-Facing Car Seats

In self-driving vehicles, passengers can set their seats in an unconventional seating position, such as rear-facing. Sitting in such an orientation can increase the risk of whiplash in the head-and-neck system in a frontal impact, as frontal crashes usually have higher severities compared with rear-end crashes. This paper shows that a forward-facing front seat optimised for rear-impact protection needs to be redesigned to be used as a rear-facing seat. In the second and main part of this paper, a restraint system for rear-facing car seats is developed, and frontal impact simulations with 64 km/h of delta-V are used to evaluate its performance. The designed seating system comprises two rigid torso plates, a fixed recliner and an energy absorber under the seat pan. Without using the developed restraint system, the 50th percentile male human model is exposed to neck shear forces exceeding 600 N. With the developed restraint system, neck shear forces are less than 350 N in frontal impacts with 64 km/h of delta-V. Apart from whiplash, the risk of head, chest, lower extremity and lower back injuries are also evaluated. The results confirm that the developed restraint system successfully protects the occupant since all assessment criteria values are lower than the injury assessment reference values.

PV installations and the safety of residential buildings

The dynamic development of the photovoltaic industry entails threats that have a direct impact on the safety of residential buildings. Appropriate design of a PV installation can be a challenge due to the multifaceted nature of this issue. The designer should take into account issues related to the selection of electrical parameters of the installation, adapting lightning and surge protection in accordance with applicable standards, ensure the optimization of the system in terms of efficiency and fire safety and calculate the mechanical stress on the rooftop. Unfortunately, most PV installations in Poland are built without any engineering project, which is allowed by the current law. In this article, we describe the results of simulations of real mechanical loads inflicted from the installation of PV panels on flat roofs for various regions of Poland. We also present the results of the simulation of the thermal impact of hot-spots on the roof surface, which can be a potential source of fire. In addition, we propose changes to the regulations that may increase the safety of PV installations mounted on the roofs of residential buildings.

A kinking-based failure model for engineering simulation of compressive crushing of composite structures

The use of continuum damage models is state of the art for the finite element modelling of progressive damage and failure under compressive loading in composites during e.g. crash and impact simulations. However, after failure initiation the compressive stress is quickly degraded to zero alternatively to a plateau with constant stress and at a certain point the element needs to be deleted due to the damage level or large element deformation. This effectively represent a void in the material which contrasts with reality where a fully formed kink band would be expected to have compressive properties similar to the transverse direction of the ply. To better represent this physical behaviour is here a kinking formulation developed that instead of the common constant stress plateau after initial softening features a stiffening at larger strains. This formulation has been implemented in a commercial FE-code complemented by criteria for kinking initiation and kink band broadening. The results presented show the novelty of the model in that it describes a chain of events starting with initiation of kinking, progressing to the growth of kink bands through the element and finally including an increase in stress that initiate kinking in adjacent elements.

Three-dimensional lattice Boltzmann simulations for droplet impact and freezing on ultra-cold superhydrophobic surfaces

Droplet impact and freezing on cold surfaces is a widely encountered multi-physical phenomenon involving droplet deformation and the liquid–solid phase change. Due to its complexity in nature, it is challenging to simulate the three-dimensional (3D) droplet impact and freezing process. Furthermore, due to the limitation of experimental techniques, it is not easy to experimentally investigate the impact of liquid droplets on ultra-cold superhydrophobic surfaces, which is crucial in some applications. Thus, in the present work, a 3D lattice Boltzmann (LB) method is developed to simulate the droplet impact and freezing on an ultra-cold superhydrophobic surface, in which an enhanced cascaded LB method is used to solve the multiphase flow field, and a multi-relaxation-time scheme is applied to solve the liquid–solid phase change model. The previous experimental results are numerically reproduced, proving that the present model can satisfactorily describe the droplet impact and solidification. The surface temperatures have no significant influence on droplet spreading. However, during the droplet retraction, a rim of ice first appears near the three-phase contact line, and then, the droplet bottom will completely solidify into ice. The occurrence of solidification at the bottom of the droplet will lead the droplet to break at a lower impact velocity, which can only be observed at a high Weber number on the room-temperature superhydrophobic surface. In addition, the effects of surface temperatures and Weber numbers on the evolution of spreading factors and space-averaged heat flux are also quantitatively analyzed in detail.

Safety Analysis of Concrete Barriers Shielding Roadside Obstacles from Impact Simulation Test

Safety Analysis of Concrete Barriers Shielding Roadside Obstacles from Impact Simulation Test