Impact Kinetic Energy Research Articles

Experimental and Numerical Investigation of Striker Shape Influence on the Destruction Image in Multilayered Composite after Low Velocity Impact

The paper presents results obtained by experimental and numerical research focusing on the influence of the strikers’ geometry at the images of the destruction created in hybrid composite panels after applying impact load. In the research, the authors used four strikers with different geometry. The geometries were designed to keep the same weight for each of them. The composite panels used in the experiment were reinforced with aramid and carbon fabrics. An epoxy resin was used as a matrix. The experiments were carried with an impact kinetic energy of 23.5 J. The performed microscopy tests allowed for determination of destruction mechanisms of the panels depending on the geometry of the striker. The numerical calculations were performed using the finite element method. Each reinforcement layer of the composite was modeled as a different part. The bonded connection between the reinforcement layers was modeled using bilateral constraints. That approach enabled engineers to observe the delamination process during the impact. The results obtained from experimental and numerical investigations were compared. The authors present the impact of the striker geometry on damage formed in a composite panel. Formed damage was discussed. On the basis of the results from numerical research, energy absorption of the composite during impact depending on the striker geometry was discussed. It was noted that the size of the delamination area depends on the striker geometry. It was also noted that the diameter of the delamination area is related to the amount of damage in the reinforcing layers.

Modeling and Analysis of Pneumatic Cushioning Systems Under Energy-Saving Measures

Pneumatic cylinder drives are widely used in automation technology—mainly for two reasons: They are cheap to acquire and easy to handle. At the same time, it is well known that there is a significant potential of energy savings when changing the control pattern from a standard scheme toward a task-specific scheme. In order to maintain a reliable operation and low wear of pneumatic cylinders, it is essential not to exceed the manufacturer’s specifications on kinetic impact energy at stroke end. Lowering the kinetic impact energy is typically done either by external shock absorbers (increasing the acquisition cost and requiring installation space) or internal solutions, i.e., pneumatic cushioning systems. In this article, we give a comprehensively identified and validated model extension to common modeling approaches for pneumatic cylinder drives regarding pneumatic end cushioning systems. Based on this model, we analyze, optimize, and evaluate the potential and applicability of energy-saving control strategies for pneumatic cylinder drives in the context of internal pneumatic cushioning systems. The results illustrate the large savings potential and point out which strategy is best to use for a specific application. Note to Practitioners —This article addresses the topic of energy efficiency of pneumatic drives, which are widely used in automation technology due to their low cost and high reliability. It is well known that pneumatic drives are often oversized and cause waste of energy. By changing the valve hardware and control pattern, energy savings of more than half of the compressed air consumption can be achieved as demonstrated in many scientific works. One main barrier to using such energy-saving strategies in practice is the concern about losing robustness. In this article, we analyze the influence of energy-saving strategies on impact velocity and the functionality of internal cushioning systems. By this, the robustness issue is addressed from two sides: the kinetic energy that needs to be absorbed at stroke end, and the kinetic energy that can be absorbed by internal damping systems. From a practical point of view, this contribution motivates and helps one to decide on the choice of energy-saving measures for pneumatic drives.

Experimental and theoretical study on steel long-rod projectile penetration into concrete targets with elevated impact velocities

To have a better understanding of behaviors of projectiles and concrete targets during impacts at different velocities, experiments and analysis of medium carbon steel long-rod projectiles impact on concrete targets have been carried out in this paper. The impact mechanics of projectiles and concrete targets has been investigated for impact velocities in range of 500 m/s to 1700 m/s covering three penetration regimes. Based on the observation of the residual projectiles and penetration depths, a deforming model has been proposed to investigate the deformable process of projectiles. Furthermore, deforming penetration model was established based on a rigid penetration model and the projectile deformation parameters, which was validated by the experimental results. The applicability of existing eroding penetration models penetration into concrete were validated and discussed based on the experimental results. At last, the eroding penetration model was further justified and improved by taking the deforming penetration regime into consideration. Influence of projectile and target strength on penetration process were investigated based on the theoretical model. Results show that the crater diameter and depth are linearly proportional to the impact velocity, while the volume of the crater and the initial impact kinetic energy of the projectile have a linear relationship. The calculated diameters of residual projectiles and Depth of Penetration (DOP) with a board range of impact velocities are in good agreement with experimental results. It is noted that the strength of projectiles and concrete targets have significantly influences on DOPs and critical velocities.

Enhancing the Energy Absorption Characteristics of Multi-Cell Square Tubes under Lateral Impact

Thin-walled tubular components have been broadly utilized in energy absorption applications, to improve the crashworthiness of the structure and to mitigate the impact kinetic energy through progressive plastic buckling. The extensive usage of cylindrical tubes as impact energy attenuators is owing to their superior crashworthiness behaviour, easy fabrication, less cost, and light-weight efficacy. The current paper examines the lateral impact behaviour of thin-walled aluminum multi-cell square tubes of different configurations using numerical simulations. These non-linear impact simulations were performed on multi-cell square tubes using finite element ABAQUS/CAE explicit code. From the overall results obtained, the crashworthiness performance of multi-cell square tubes of various configurations were compared. Moreover, multi-cell square tube of first type were recognized as most prominent for better energy absorption. This type of tubes was found to be effective one to improve the lateral crashworthiness performance

Impact Degassing of H2 on Early Mars and its Effect on the Climate System

AbstractImpacts on early Mars can produce H2 and CH4 in the thermal plume. In a thick CO2 atmosphere, collision‐induced absorptions between CO2‐H2 and CO2‐CH4 can boost the greenhouse effect. We construct a simple model of the impact history of Mars and show that for a variety of impactor types and CO2 surface pressures >0.5 bars, postimpact surface temperatures due to H2 alone can exceed the melting point of water for much longer periods of time than from the dissipation of the heat derived from the impactor's kinetic energy. This longer timescale is set by hydrogen escape rather than radiation to space. Cumulatively, the Noachian surface may have been above the melting point of water for millions of years by this mechanism. These greatly extended postimpact warm environments may have played a larger role in the erosion and mineralogy of the surface than previously thought and may partly explain some of the observed fluvial features.

Hypervelocity impact damage behavior of B4C/Al composite for MMOD shielding application

In order to improve the survivability of in-orbit spacecraft against the hypervelocity impact (HVI) of space debris, the lightweight B4C/Al composite is fabricated by the pressureless presintering and Al infiltration in vacuum and applied as the bumper of Whipple shield configuration. The HVI tests ranging from 3 km/s to 6.5 km/s are carried out to assess the shield performance of B4C/Al bumper. The fitting line of the ballistic limit for the B4C/Al bumper is obtained, and its critical projectile size can be improved by about 20% in comparison to the conventional Al alloy Whipple shield configuration. Based on the damage features of bumper and rear wall, the B4C ceramic phase of B4C/Al composite is the key reason to break the projectile into smaller fragments or liquid droplets of debris cloud. The Al plastic phase with three-dimensional network enhances the toughness of B4C/Al composite bumper, which plays an important role in avoiding structural failure caused by shock waves. Hence, the impact kinetic energy of debris cloud is obviously dispersed, and the subsequent impact damages on real wall are alleviated accordingly. The primary investigation provided theoretical and technical instructions for the design and application of B4C/Al composite in MMOD shield configuration.

Impact-sliding wear behaviors of 304SS influenced by different impact kinetic energy and sliding velocity

Abstract Wear behaviors of materials in nuclear power stations are very complex, because they are rarely subject to just pure impact or sliding wear. This study uses a self-made impact-sliding wear test rig to study the influences of impact kinetic energy and sliding velocity on the energy absorption, mechanical response, interface deformation, and damage behavior of nuclear-grade 304 stainless steels (304SS). The results show that an increase in impact velocity causes an increase in absorbed energy, impact force, and friction force, while lowing the friction coefficient. The friction force and friction coefficient increase with an increase in the sliding velocity, whereas no obvious change is seen in impact force and absorbed energy. The dominant wear mechanism in test samples were delamination failure and friction oxidation. Furthermore, numerical study was performed to explain the effect of velocity on the mechanical response of 304SS.

Restitution modeling in vibration-dominated impacts using energy minimization under outward constraints

Impact models can involve either detailed simulation or approximate net-impulse prediction. Net-impulse approaches map pre-impact to post-impact states without solving differential equations. Net-impulse approaches are seldom used for predicting restitution in vibration-dominated impacts with explicit accounting of vibrations. Here we study impacts of Hertzian balls on four different Euler-Bernoulli beams, with uniform and nonuniform cross sections as well as different boundary conditions. For each beam, initial detailed simulations using modal coordinates are used to compute restitution values for different ball masses and contact locations. Subsequently, a simple method is proposed for approximately predicting the restitution level, given colliding mass and vibration mode information. The key idea is to minimize post impact kinetic energy subject to various linear inequality constraints. These constraints include both fundamental restrictions as well as new outward or rebound-enhancing constraints that constitute the main novelty of the approach. The new approach, referred to as Energy Minimization under Outward Constraints (EMOC), requires solution of a quadratic optimization problem, yields a unique solution using readily available routines, and has three fitted parameters. These parameters, in our examples, are constant for all ball masses and contact locations for a given beam. Physical impossibilities like interpenetration or energy increases are never predicted for any parameter values. Upon parameter fitting, the match between full numerical solution and EMOC is good on average, with key qualitative trends captured correctly. No comparable net-impulse model exists in the vibroimpact literature.

Modernization of the device for milling of fastening details

Purpose. Reducing of impact kinetic energy of the clamping device by changing of control system parameters.Object of research. Clamping device for milling of fastening details, supplied with a pneumatic actuator. Direct and reverse motion of a stock are realized by air supply to the top or bottom pneumocylinder space, which is controlled by electrovalves.Methods of research. Operation cycle of the clamping device has been divided into three steps: air supply, pause in air supply, renewal of air supply for clamping of a stock. Stock speed decreases during a pause because of friction forces in a sealant. Variation of step durations allows to control final stock speed at the moment of impact. The mathematical model of stock movement has been designed, taking into account the transitory termination of pressure supply. Stock movement was considered at isothermal process at the second step. Gravity and friction forces were considered as well. The corresponding nonlinear differential equation has been solved numerically by the Euler method. Result accuracy has been provided by use of very small integration step, that at a modern level of develop­ment of computer facilities does not cause additional problems. Optimal step durations for direct and reverse motion were calculated by successive approximation method.Results. Impact kinetic energy has been reduced approximately 15 times with response time increase 1.5 times by optimizing of control system parameters. Increase of operation time at a direct motion from 18 ms to 27 ms has no practically significant influence on productivity.Practical value. A new mathematical model of the rod movement that have been designed gives an opportunity to find the optimal parameters of clamping device control system by means of a computer. Research practical value has been caused by the improvement of device dynamic characteristics without additional capital investments.

Encapsulation with an interfacial liquid layer: Robust and efficient liquid-liquid wrapping

HypothesisWe developed an impact driven liquid-based encapsulation method by utilizing the fundamental thermodynamic tendency of a suitable three-liquid combination towards formation of a core-shell structure. ExperimentsStable wrapping is achieved by impinging a core drop from a vertical separation on an interfacial liquid film floating on a host liquid bath. The resulting interfacial dynamics is captured using a high-speed camera. Several combinations of impact height and interfacial film thickness are investigated for a quantitative description of the phenomena. FindingsThe stability and integrity of the liquid encapsulating layer are confirmed both experimentally (by analyzing the under-liquid wetting signature) and theoretically (by equilibrium thermodynamic analysis). Effect of viscous dissipation on the dynamics is explained and a consequent theoretical threshold for minimum allowable drop size is provided. A non-dimensional experimental regime is also constructed for successful encapsulation in terms of impact kinetic energy and interfacial layer thickness. Additionally, the encapsulating layer is shown to protect the core drop even when the core and host liquids are miscible. The demonstrated method is simple to implement yet robust, offers flexibility regarding varying both the size and the material properties of the core and shell liquids and consistently produces stable monodispersed encapsulated drops in an ultrafast manner.

Water droplet impact energy harvesting with P(VDF-TrFE) piezoelectric cantilevers on stainless steel substrates

Harvesting energy from ambient environmental sources using piezoelectric transducers has seen a tremendous amount of interest from the scientific community in recent times. The practicality of energy scavenging technology looks set to see continued relevance, with decreasing power demands of electrical systems, such as wireless sensor networks, allowing such technology to progressively act as an energy source to drive and sustain them independently. In light of this, there is a growing opportunity for piezoelectric materials to prolong, or even replace, battery powered sensor systems positioned in remote or difficult to reach areas. It has been demonstrated that falling water droplets of millimetric-scale diameter can impart forces of over a thousand times their resting weight upon surface impact. As such, the potential for utilising piezoelectric transducers to drive sensor systems, by converting the kinetic impact energy of falling water droplets into useful electrical energy, is investigated. The key parameters that affect the efficiency of energy transfer between incident water droplets and piezoelectric cantilever structures made of stainless steel foil coated with the lead-free piezoelectric material P(VDF-TrFE) are investigated. A peak power output of 28 nJ achieved from the impact of a 5.5 mm diameter droplet upon a single energy harvesting transducer illustrated that, for droplets of diameter 3.1–5.5 mm impacting from heights between 0.5 and 2.0 m, it is desirable to utilise piezoelectric transducer beams of bending stiffness in the range of 0.067–0.134 N m−1 in order to achieve good energy transfer efficiency. Although the active electrode area was constrained in order to maintain consistency between samples, reducing the peak energy output, the achieved results correspond to a 15.9 J m−3 energy density, representing the significant energy transfer efficiency achievable through appropriate transducer mechanical tailoring to the excitation source.

Super-robust and frequency-multiplied triboelectric nanogenerator for efficient harvesting water and wind energy

Mechanical energy in ambient, such as water wave, wind, vibration, and human activities, is a green energy that is widely distributed and universally achievable. However, this type of energy has ultra-low frequencies and variable amplitudes, so it is rather challenging to collect them at high efficiency. Here we report a pendulum inspired triboelectric nanogenerator (P-TENG), which could not only boost the output frequency multiple times using a pendulum structure, but also hugely improve the harvesting efficiency through a transformation of impact kinetic energy into potential energy. The P-TENG also has ultrahigh sensitivity and active response to mechanical triggering from a random direction and superior durability for long time operation. A single trigger from the environment, the P-TENG shows a continuous electrical output for 120 s at a frequency of 2 Hz, and its output energy of which is 14.2 times larger than the energy of conventional free-standing TENG. Owing to the air gap between the triboelectric layer and electrodes and the mechanism of electrostatic induction, the P-TENG can work with little frictional resistance and surface wearing, largely enhancing its robustness and durability. The network of P-TENGs was successfully demonstrated to scavenge water wave or wind energy as sustainable power sources. Given the features of exceptional output performance, unprecedented robustness and universal applicability resulting from distinctive mechanism and structure, the P-TENG is a promising method to efficiently harvest energy from the ambient environment with possibility contributing to the blue energy.

Improving impact wear resistance of Ti-6Al-4V alloy treated by laser shock peening

Abstract The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.

The Influence of Sinusoidal Oscillating Water Flow on Sprinkler and Impact Kinetic Energy Intensities of Laterally-Moving Sprinkler Irrigation Systems

Laterally-moving sprinkler irrigation systems under low pressure experience problems including small spraying range, low uniformity, surface runoff, and low water utilization rate. To solve these problems, experiments were carried out on a laterally-moving sprinkler irrigation system using a Nelson D3000 sprinkler (Nelson Irrigation Co., Walla Walla, WA, USA) under low pressure, sinusoidal oscillating water flow. The sprinkler intensity and impact kinetic energy intensity distribution were investigated for sprinklers both static and in motion. The test data were used to calculate combined sprinkler intensity and impact kinetic energy intensity uniformity for different nozzle spacings, and were compared with constant water pressure test results. It was found that sinusoidal oscillating water flow can effectively increase spraying range, as well as reducing the peak value of the sprinkler intensity and impact kinetic energy intensity. Within an optimal range of amplitude and nozzle spacing, sinusoidal oscillating water flow significantly improves the combined sprinkler intensity, impact kinetic energy intensity uniformity, and the spraying quality of laterally-moving sprinkler irrigation systems under low pressure conditions. When the average water pressure is 100 kPa, the optimal range of amplitude of sinusoidal oscillating flow applied to the laterally-moving sprinkler irrigation system is 50–60 kPa. When the amplitude is 50 kPa, the optimal nozzle spacing is 3.5–4 m; when the amplitude is 60 kPa, the optimal nozzle spacing is 3.5–4.5 m. The related parameters can provide a reference for the application of sinusoidal oscillating water flow in laterally-moving sprinkler irrigation systems.

Numerical analysis on impact response of ultra-high strength concrete protected with composite materials against steel ogive-nosed projectile penetration

In order to investigate the impact behaviours of ultra-high strength concrete (UHSC) target protected with high-toughness lightweight energy absorption composite materials against the projectile penetration thoroughly, a numerical study using LS-DYNA is conducted at impact velocities between 540 m/s and 810 m/s. The major compositions of FE models are the same as those of experimental specimens which include steel wire mesh reinforced concrete (SWMRC) plates, UHMWPE fibre laminates, aluminium foam sheets and the protected UHSC. Numerical results involving depth of penetration (DOP), impact crater (exfoliated) diameter of SWMRC plates, localized damage and ballistic deviation of the projectiles are obtained and then compared with experimental data, where the numerical results show reasonable agreement with the test results. Based on the validated FE models, the projectile penetration process and the energy evolution between the target and the projectile are studied. In addition, a parametric analysis is conducted to investigate the influence of the arrangement order for present composite materials on DOP and impact resistance of reinforced UHSC target, as well as the ballistic deviation and deformation of the projectile. Results of this study indicate that for the current UHSC target, firstly, the ballistic deviation and projectile deformation are two important factors affecting the impact resistance of the target; secondly, the fibre laminates play a major role in the projectile ballistic deviation and the impact kinetic energy of the projectile is mainly absorbed by the concrete matrix, multilayer steel wire meshes and different densities of foam sheets.

Study on the abrasive wear behavior of laser shock peening Ti-6Al-4V titanium alloy under controlled cycling impact

The impact wear behavior of Ti-6Al-4V alloy treated with laser shock peening (LSP) and without treatment were investigated under sand environment using an independently developed impact wear tester. The dynamic response, interface response, and wear mechanism under different impact kinetic energies and during wear evolution were analyzed. ANOVA analysis results show that LSP has no significant effect on mechanical properties and wear resistance of Ti-6Al-4V alloys under the same test conditions. When the impact kinetic energy was relatively low or number of the impact cycles was relatively small, the worn surface was significantly higher than the original surface. When the impact kinetic energy was relatively high or the number of impact cycles was relatively large, the center of wear scars was a pit, and the edge of wear scars was higher than the original surface. Experimental results also showed that the absorbed energy was closely related to the wear of the material during the impact-abrasive wear. The greater the loss of material was, the more energy was absorbed. The impact wear mechanism under the sand condition was mainly plowing, micro-cutting, extrusion spalling, and press-in particle on the surface of the specimens.

Space Weathering Induced Via Microparticle Impacts: 1. Modeling of Impact Velocities and Flux of Micrometeoroids From Cometary, Asteroidal, and Interstellar Origin in the Main Asteroid Belt and the Near‐Earth Environment

AbstractThe processes of alteration of airless bodies exposed to the space environment are referred to be as “space weathering.” Multiple agents contribute generally to space weathering, to an extent that depends on the specific location of the surface within the solar system. Typical space weathering agents encountered in the solar system are solar radiation, solar wind and cosmic rays, magnetospheric plasma (e.g., at Jupiter or Saturn), and cosmic dust. The effect of space weathering is generally assessed by measuring the surfaces optical properties, for example, by near‐infrared spectroscopy. The alteration of the surfaces is due to a cumulative effect over time of all agents. We investigate in this paper the contribution of micrometeoroid (dust) bombardment on different asteroids, by using the Interplanetary Micrometeoroid Environment Model for the interplanetary dust populations and a simplified model of interstellar dust dynamics. We quantify, for different representative asteroids (main belt and Near Earth Objects [NEOs]), the particle cumulative flux, mass flux, impact velocity, and the kinetic impact energy deposited. This work is primarily intended to support laboratory work investigating the effect of energy deposition onto sample surfaces, as well as astronomical observations of optical properties of asteroid surfaces.

Impact cratering on a granular bed by hydrogel spheres having intermediate property between solid and liquid.

We investigated the low speed impact on a granular bed by a hydrogel sphere and especially focused on the resultant crater diameter. Though the crater diameter depends only on the impact kinetic energy for the solid sphere impact cratering, it also depends on the elastic energy for the hydrogel sphere. The hydrogel sphere impact cratering is classified into two dynamics: small and large indentation of the sphere. For the small indentation, the crater diameter is proportional to the 1/4 power of the energy for ejecting granular materials, which is calculated by substituting the elastic energy stored in the sphere from the impact kinetic energy. Considering the force balance between the inertial force and the indentation, we derived the relation between the impact kinetic energy, Young's modulus, and the crater diameter. In the large limit of Young's modulus, the relation leads to the 1/4 power law observed in solid sphere impact. The dependency of Young's modulus on the crater diameter for the large indentation of the sphere is larger than the impact with small indentation.

Multifunctional triboelectric nanogenerator towards impact energy harvesting and safeguards

The widespread impact kinetic energy always causes injury and property loss in daily life. Conventional safeguarding systems protect human beings by passively insulating and dissipating impact energy but have ignoring exploring them. Triboelectric nanogenerator (TENG) proves to be a favorable device in harvesting mechanical energy but shows no protection property. Thus, developing novel safeguarding material with energy-harvesting performance is essential in future generation personal security field. Here, a multifunctional TENG capable of collecting impact kinetic energy with safeguarding property is reported by assembling Al foil with hybrid polymer matrix. The matrix is fabricated by incorporating polytetrafluoroethylene (PTFE) nano-particles into shear stiffening (SST) gel and polydimethylsiloxane (PDMS). The optimized TENG (6 mm) after introducing 1% PTFE nano-fillers into hybrid polymer attains the maximum electrical voltage, current and output power of 44.20 V, 8.84 μA and 390.73 μW, respectively. More importantly, SST/PDMS/PTFE-based TENG generates an instantaneous power density of 135.57 μW/m2 under low velocity impact. The impact force simultaneously decreases from 1971.90 to 839.72 N, exhibiting a remarkable safeguarding property. Finally, a wearable TENG-based electronic skin can capture external impact energy into electrical energy, resist the impact and precisely map force distribution which demonstrates promising application in next generation smart wearable systems.

Effect of ultrasonic surface rolling process on impact-sliding wear behavior of the 690 alloy

Various impact-sliding wear behaviors commonly occur among steam generator tubes and their supporters. The main purpose of this study is to investigate the effect of ultrasonic surface rolling process (USRP) on the impact-sliding wear behavior of Inconel 690 alloy tubes. A self-made two-dimensional cycling impact-sliding wear test rig was developed to realize multiple wear patterns by changing motion parameters in both impact and sliding directions. Tests were carried out under different impact and sliding velocities. Results indicated that USRP reduced the impact kinetic energy absorption rate, friction coefficient and increased the wear resistance of Inconel 690 alloy. These can be attributed to the USRP which decreased the grain size of 690 alloy, resulting in the increase of micro-hardness and compressive residual stress.