High Impact Energy Research Articles

The relationship between repeated impacts and CAI strength of sandwich structure considering different impactor shape in individual impact

Sandwich structures are susceptible to repeated impact loads, and each individual impact is not nearly identical to the previous one, especially for repeated impacts under different impactor shapes such as hail impact. Therefore, the repeated impact behavior using different impactor shape in individual impact of polymethacrylimide (PMI) foam sandwich structure is studied and discussed through experiments and finite element (FE) simulations in this paper. The representative mechanical characteristics such as impact responses, damage modes, and energy absorption are investigated until penetration occurs, and the mechanism of impact damage accumulation between impact events with different impactor shapes is revealed. Besides, the compression after impact (CAI) strength is utilized to assess the residual strength of sandwich structure under repeated impacts. It indicates when the contact area between the specimen and impactor is larger, it can result in a higher impact force, a shorter contact duration, and potentially reduce the extent of damage. The matrix damage is the main damage mode, and the proportions of matrix tension and compression are nearly constant, with a ratio of approximately 2:1. In addition, the proportion of the impact energy absorbed by foam core increases as the number of impacts increases. When the impact energy is low, the CAI strength is sensitive to the number of impacts, the shape of impactor, and the sequence of impactors, but the similar phenomenon does not occur at higher impact energy. The present study provided a series of experimental and numerical results, which could be utilized as design reference guidance in the designing of composite sandwich structures.

Prediction of nano metal matrix composites based on hybrid approach

AbstractThis manuscript proposes a hybrid method to predict the optimal nano‐metal matrix composites. The proposed hybrid technique is the wrapper of the Fire‐Hawk Optimizer (FHO) and Spiking Neural Network (SNN). Commonly it is known as FHO‐SNN method. The main objective of the proposed method is to improve the method parameters for better enhancement in mechanical properties. FHO approach is used to improve the process parameters of stirring squeeze casting method. The SNN predicts optimal parameters. Moreover, the problem based on the casting is reduced. By then the proposed hybrid technique performance is performed in the MATLAB platform and associated with various existing approaches. The proposed system shows the high tensile strength, impact energy and hardness compared with other existing methods.

SOLID PARTICLE AIRJET EROSION AND CORROSION BEHAVIOR OF AA6063 ALUMINUM ALLOY

Aluminum alloy 6063 has excellent mechanical properties and it is used in automotive industries. This research focuses on solid particle airjet erosion behavior in different input parameters such as mass flow rate of 2, 3, and 4 gm/min, impingement angle of 30[Formula: see text], 60[Formula: see text], and 90[Formula: see text] and erodent velocity of 100, 150, and 200 m/s. The alumina erodent is mixed with an airjet which acts as an impingement fluid jet. Taguchi was utilized for investigating the influence of the process parameter on erosion rate, and ANOVA was performed to evaluate the parameter contribution. The impingement velocity is the most significant parameter to reduce the erosion rate rather than the impingement angle and the mass flow rate. The increase in velocity of the impingement fluid jet accelerates the erosion rate due to the high kinetic energy impact. The desirability approach is used to optimize the input parameters. At 99% confidence levels, the models were considered significant. The importance of the factor is increased by a reduced [Formula: see text]-value. From the overall analysis, the optimum conditions of solid particle airjet erosion are impingement angle of 90[Formula: see text], erodent velocity of 100 m/s and erodent flow rate of 2 gm/min. Utilizing the cyclic sweep approach, corrosion behavior and NaCl solution are involved in the test of AA6063. As the corrosion current density increased, the corrosion potential became more positive.

Investigating the effectiveness of CFRP strengthening in improving the impact performance of RC members

Rising global rail infrastructure expansion has increased accidents involving train derailments. Reinforced concrete (RC) elements require impact-resistance enhancement to prevent structural damage or failure. While extensive research has analyzed CFRP-strengthened concrete columns under dynamic loading, further understanding of CFRP's impact on RC members is needed. Considering dynamic factors, this study investigates CFRP-RC components' performance under asymmetric impact. Components wrapped in one, four, or six CFRP layers underwent high-energy asymmetric lateral impact testing to obtain deflection-time curves. Results showed that multiple CFRP layers significantly improved impact resistance by increasing plateau force, reducing maximum deflection to 42%, and shortening duration. Longitudinal-circumferential bonding conferred better reinforcement than other arrangements. However, multiple CFRP layers increased fracture susceptibility due to severe concrete damage. An equation was derived from dynamic equilibrium principles. Finite element modeling validated experimentally was used to simulate lateral impact. Impact force, deflection, and bending moment over time were compared. Impact resistance, flexural capacity, plastic deformation, and energy absorption were also examined. Internal force distribution and development were analyzed. A simplified calculation estimated maximum deflection. CFRP reinforcement methods' effects were examined. Results indicate CFRP elevates plateau impact force and average bending moment while significantly decreasing deflection and duration, greatly enhancing impact resistance and flexural bearing capacity.

Economic Aspects of Mechanical Pre-Treatment’s Role in Precious Metals Recovery from Electronic Waste

Printed circuit boards (PCBs) make up 3 to 5% of all electronic waste. The metal content of spent PCBs can reach 40%. They usually contain valuable metals, such as Ag, Au, and Pd, as well as other metals such as Cu, Sn, Pb, Cd, Cr, Zn, Ni, and Mn. However, the metallic part of a whole PCB is 40–60% including the Cu layers between the fiberglass–polymer layers. The paper describes the economics of the valuable metal (Ag, Au, Pd)-containing concentrate preparation from a raw PCB. We considered the influence of the pre-treatment method of PCBs before the extraction of valuable metals on the extraction self-cost change. The disintegration method is based on the high-energy impact of the particles of the material to be ground, thus causing the separation of the metallic components of the PCB. In the course of the work, single and double direct grinding using the method of disintegration was studied. For the calculation, the test batch of 10,000 kg of two types of PCB was taken for estimation of the self costs and potential profit in the case of complete valuable metals (Ag, Au, Pd) plus Cu extraction. It was shown that from 10,000 kg of studied PCB, it is possible to obtain 1144 and 1644 kg of metal-rich concentrate, which should be further subjected to electro-hydrochlorination for metals leaching. The novelty of this research lies in the fact that a technical and economic analysis has been carried out on a newly developed combined technology for processing electronic waste. This included mechanical processing and electrochemical leaching with the help of the active chlorine that is formed in situ. The real (not specially selected or prepared) waste PCBs were used for the process’s economical efficiency evaluation. The main findings showed that despite the high content of Cu in the studied PCBs, the commercial value was insignificant in relation to the total income from the Ag, Au, and Pd sale. A correlation was established between the self-cost decrease after separative disintegration of PCBs by metal content increase (by specific metals such as Au, Ag, Pd, and Cu) with the metal potential yield after extraction.

Evaluation of corrugated core configuration effects on low-velocity impact response in metallic sandwich panels

Abstract Sandwich panels are used as body components of vehicles in many sectors, such as defense, aircraft, and aviation, due to their advanced mechanical properties and lightness. This study aims to investigate the effect of core configurations on mechanical performance and deformation behavior of metallic sandwich panels under low-velocity impact loading. For this purpose, metallic sandwich panels having monolithic and sliced core configurations were first produced. Low-velocity impact tests were carried out using varying energy levels (20, 40, 60 J) to examine how the intensity of influence affects the deformation of the sandwich panel. The perforation and deformation behavior on the upper surface plates of sandwich panels were evaluated. Experimental results showed that the core design significantly affects the impact behavior of sandwich panel samples. The sliced core configuration produced approximately 10 % more maximum contact force and absorbed 14 % more impact energy at high-impact energy levels. Additionally, the sliced core configuration delayed core collapse of the core in deformation situations where complete perforation does not occur.

Design method for crash attenuation embankments reinforced with geosynthetics

One valid solution for attenuating the crash of a traveling train or truck against buildings and infrastructures is to build a reinforced soil embankment approx. perpendicular to the direction of the vehicle. Such reinforced embankment shall be designed for crash attenuation to absorb even very high impact energy, based on the mass, the size, and the speed of the impacting vehicle. The Authors present a new analytical design method which consider the effect of all the variables playing a role in the resistance to penetration on the uphill face and the resistance to extrusion on the downhill face, in order to finally compute approximate yet consistent values of the penetration depth and of the extrusion length; hence the designer can quickly try different solutions and finally select the best combination of design variables which afford to respect all design limits and Factors of Safety.

Microtextures on quartz grain surfaces in the Bay of Bengal shoreline sediments, Bangladesh: Implications for sediment transport process and depositional environment

SEM and SEM-EDS studies of quartz grains in the shoreline sediments of the Bay of Bengal, Bangladesh were carried out to evaluate the mode of origin, paleoclimate, and depositional environment. A total of 38 microtexture types were identified, which were grouped into mechanical (23 features), mechanical/chemical (6 features), and chemical (9 features) origins. The morphology of quartz grains in the shorelines was dominantly sub-angular to sub-rounded in shape, which represents robust energy conditions, short residence time, low weathering, and nearby sediment provenance. The microtextures of mechanical origin such as straight and curved scratches, pits, broken edges, and crescent-shaped features were relatively abundant in the eastern site samples (Section-I) indicating high-energy, fluvial, and beach environments. The abundance of V-shaped marks and smooth surfaces of quartz grains indicate high-velocity storm conditions and/or high-energy impact events. The well-rounded outline, low relief with dish-shaped depressions, mechanically upturned plates, and arcuate steps were also observed on quartz grain surfaces. These features suggest that they were developed during an aeolian process in the beach berm environment. Etching, solution/irregular pits, and differential relief on quartz grains were somewhat elevated in the western site samples (Section-III), reflecting that these microtextures were associated with a subaqueous collision and humid climates in the fluvial and nearshore environments. Quartz grains in all sections represented microtextures of high energetic subaqueous environment as well as wind events. However, the absence of corrosion channels and high density of voids in the quartz grains revealed low degree of weathering.

Experimental investigation on low-velocity impact behavior of glass, Kevlar, and hybrid composites with an elastomeric polyurethane matrix

Low-velocity impacts represent a critical dynamic condition for engineering structures. Combining two reinforcing fibers in a single matrix, i.e., hybridization, is considered a feasible way to improve composite performance. In this context, this paper presents an experimental work on composites with Kevlar and glass fabrics and a novel thermoset polyurethane matrix. The coupons are manufactured by vacuum infusion technique and low-velocity impact tests are carried out. First, the impact behavior of Kevlar and glass laminates of different thicknesses is assessed, and then impact tests are performed on different configurations of hybrid laminates, both symmetric and non-symmetric. For the non-symmetric specimens, impact tests were conducted on both sides of the stack. Load vs displacement curves are reported along with absorbed energy. To investigate the damage mechanism, the front, back, and cross-section views of the specimens are analyzed, and features related to the stacking sequences are discussed. Thermographic analyses are carried out on the impacted specimens to further analyze damage. The failure mechanisms are different from traditional epoxy composites and a hybridization effect is reported. The results evidence that the hybrid coupons are viable for structural applications, being capable of absorbing high-impact energies, in particular, non-symmetric hybrid laminates outperformed the Kevlar, glass, and symmetric ones, absorbing roughly 15% less energy for the highest energy impact.

Quantum-mechanical four-body versus semi-classical three-body theories for double charge exchange in collisions of fast alpha particles with helium targets

AbstractWithin the two-channel distorted wave second-order perturbative theoretical formalism, we study capture of both electrons from helium-like targets by heavy nuclei as projectiles at intermediate and high impact energies. The emphasis is on the four-body single-double scattering (SDS-4B) method and the three-body continuum distorted wave impact parameter method (CDW-3B-IPM). The SDS-4B method deals with the full quantum-mechanical correlative dynamics of all the four interactively participating particles (two electrons, two nuclei). The CDW-3B-IPM is a semi-classical three-body independent particle model (one electron, two nuclei), using a combinatorial calculus to describe double capture by a product of two uncorrelated probabilities, integrated over impact parameters. Both theories share a common feature in having altogether two electronic full Coulomb continuum wave functions. One such function is centered on the projectile nucleus in the entrance channel, whereas the other is centered on the target nucleus in the exit channel. These two methods satisfy the correct initial and final Coulomb boundary conditions in the asymptotic region of scattering, at infinitely large inter-particle separations. Yet, it is presently demonstrated that most of the available experimental data on total cross sections for the double capture from helium by alpha particles distinctly favor the SDS-4B method. This is especially true at intermediate energies. Such energies are critically important in versatile applications under the general umbrella of ion transport in matter, including thermonuclear fusion (plasma physics) and ion therapy (medicine).

Влияние высокоэнергетического воздействия при плазменной резке на структуру и свойства поверхностных слоёв алюминиевых и титановых сплавов

Introduction. Plasma cutting of various metals and alloys is one of the most productive processes for obtaining workpieces, especially when using reverse polarity plasmatrons. The use of plasma cutting in the production of workpieces of large thicknesses potentially allows to increase the productivity of the process. In the domestic industry plasma cutting equipment of foreign production is widely used, which poses the problem of import substitution of manufactured products and equipment with the corresponding parts of Russian companies. For this reason, at present the Institute of Strength Physics and Materials Science together with the company "ITS Siberia" develops plasma cutting equipment on reverse polarity currents. At the same time, in order to determine the peculiarities of influence of parameters and modes of plasma cutting process on the structure of metal in the cutting zone, it is necessary to conduct comparative studies on different metals and alloys. Aim of the work: is to identify the characteristics of the influence of high energy impact on the structure and properties of surface layers of aluminum and titanium alloys during plasma cutting using a plasma torch operating with reverse polarity currents. The research methods are optical metallography, microhardness measurement and laser scanning microscopy of the surface after plasma cutting. Results and discussions. The conducted researches show a wide range of possibilities to adjust the process parameters of plasma cutting of aluminum alloys AA5056 and AA2124, and titanium alloy Grade2. For the alloys used in this work there are optimal values of process parameters, deviations from which lead to various violations of cut quality. Aluminum alloys show a tendency to significant de-strengthening in the cutting zone, which is associated with the formation of a large crystalline structure and large incoherent secondary phases with simultaneous depletion of the solid solution with alloying elements. Titanium alloys are characterized by quenching effects in the cutting zone with increasing microhardness values. Oxides are also formed in the surface layers despite the use of nitrogen shielding gas. In the alloy Ti-4Al-1Mn, in the previously conducted works, the formation of oxide films with high hardness is not noted, while in the Grade2 alloy at cutting in the surface layers oxides are formed sharply increasing the values of microhardness of the material up to values of about 15 GPa. This situation can complicate mechanical processing of titanium alloys after plasma cutting. The obtained results indicate a rather low value of the allowance for further machining after plasma cutting of aluminum and titanium alloys.

Low-velocity impact-resistance of aramid fiber three-dimensional woven textile-reinforced thermoplastic-epoxy composites

The development of impact-resistant composite materials for protective applications such as helmet and body armor has attracted considerable attention. In this study, a novel aramid fiber-woven thermoplastic-epoxy composite was developed. Furthermore, three types of woven textiles, namely three-dimensional (3D) orthogonal-woven (3DOW), 3D angle-interlock woven (3DAIW), and two-dimensional plain-woven (2DPW) textiles, were used as reinforcement structures. To study the effect of the woven structure, impact energy, and damage repairment on impact-resistance performance of these composites, low-velocity drop-weight impact tests with various impact scenarios, such as single-impact, repeated-impact, as well as multiple-impact with hot-press damage repairment, were conducted. The results revealed that the woven structure exhibited an obvious effect on the composite impact-resistance performance and failure modes when subjected to specific impact scenarios. For the single-impact scenario, especially under high impact energy levels (10 and 20 J), the 3DOW structure exhibited superior impact-resistance performance as well as damage tolerance, followed by 3DAIW and 2DPW structures. Furthermore, 3DOW achieved superior impact-resistance to the other two structures for the 10-J repeated-impact scenario. The 3DAIW structure, in which debonding or delamination as well as severe resin cracks dominated, achieved superior impact-resistance to multiple impacts with damage repairment.

Incidence of cervical spine injuries in paediatric patients and their outcome in tertiary care hospital

Objective: The incidence of mortality after cervical trauma in the pediatric population is very high. The purpose of this study was to determine the treatment given, morbidity and mortality of patients with cervical spine injuries, and their outcome after 6 months of management which includes both surgical and conservative treatment. Materials & Methods: A prospective study was conducted at Lady Reading Hospital, Peshawar with a total number of patients n = 187 included in our study. Patients were stratified according to their age, mortality, mechanism of injury (fall, motor vehicle accident, bicycle injuries, &sports-related injuries), level of cervical spine injury, presence of neurologic deficit, presence of bony injury (fractures, &dislocations), ligamentous injuries & SCIWORA. The primary outcome was the functional status at 6 months following treatment. Results: There were 78 females and 109 males. In comparison to the lower cervical spine (C3 – C7), which was involved in 86 patients (46%), the higher cervical spine level (C0 – C2) was involved in 101 patients (or 54%). The most frequent cause of cervical spine injuries in the older age range was a history of a fall, followed by a motor vehicle accident. Among the treatment groups, mortality was highest in patients who underwent surgery. Conclusion: Younger age groups, higher cervical spine levels, and mechanisms of injury such as high energy impact trauma were independent risk factors for increased mortality. Compared to incomplete neurological abnormalities, a complete neurological disability increases mortality.

Evaluation of Simulated Heat Affected Zone of Molybdenum- and Niobium Alloyed Ultra-High-Strength Steels

Gleeble 3800-thermomechanical simulator was used to simulate the heat affected zone of quenched and tempered 0.16 wt.% C steels with variation of molybdenum-and niobium contents. The purpose of the study was to evaluate the effect of alloying content on the properties of the coarse-grained zone of HAZ region (CGHAZ) and partially re-austenitised inter-critical zone (ICHAZ) with two different t8/5 times (5 s and 15 s). Results showed that Mo and Nb decreased the amount of softening in the HAZ-region, especially with longer t8/5 -time (15 s). 0Mo steel had mixed microstructure of bainite and martensite in the CGHAZ region with t8/5 time of 15 s, which led to higher degree of softening compared to other steels. Shorter t8/5 time of 5 s produced martensitic microstructure in CGHAZ region in all cases leading to higher hardness values. Impact energy values at-40 °C were at least 34 J/cm2 in all cases. Highest hardness values in the ICHAZ-region were achieved in the case of 0.5Mo steel. Also, at-40 °C impact energy values of ICHAZ were at least 34 J/cm2 in all cases, however Mo-free steel achieved clearly higher impact energies in ICHAZ region, which is result from softer microstructure with relatively low hardness compared to other steels. Overall, it can be concluded that longer t8/5 time can be used, which corresponds to higher heat input in welding, if Mo and/or Nb alloying is used.

Numerical analysis of rubberized engineered cementitious composite (RECC) RC beams under impact loads

The environmental hazards of unrecycled rubber products and the current movement of developing more sustainable materials shed the light on utilizing recycled rubber as aggregates in concrete. The use of recycled scrab tire rubbers as aggregates in concrete can not only reduce environmental damages but also enhance the concrete’s dynamic mechanical properties such as an increase in the overall compression strain at failure and the material’s fracture energy. Previous research has investigated using rubber aggregates in concrete for reinforced concrete (RC) structural elements under static loads. However, this study aims to utilize the improved dynamic properties of concrete with rubber to resist impact loads on beams. This article presents a novel numerical investigation of the static and impact loading response of rubberized engineered cementitious composite (RECC) beams. A three-dimensional (3D) non-linear finite element (FE) model was constructed to analyze the behavior of conventional concrete (NC), crumb RECC, and powder RECC beams under impact loads. The study employs an accurate FE model that captures the non-linear behavior of RECC materials, including their properties in compression and tension, and the strain rate effect. Moreover, the strength and toughness of concrete beams can be improved by using a hybrid section of NC and RECC. Therefore, in the current study, the behavior of crumb or powder RECC layers in compression or tension sides of NC beams was studied under impact loads as well as the effect of low-impact energy, high-impact energy and the impactor nose type (hemispherical and flat-nose cylinder) on RECC beams. The outcomes of the FE model demonstrated good agreement with the available experimental results from the literature. The dynamic response of RECC beams was analyzed using FE model outputs, including time histories of impact forces, reaction forces, internal forces (shear force and flexural moment), mid-span displacements, and dissipated energy. Results indicated that RECC enhanced the performance of RC beams under impact loads. The tension performance of RC beams under impact loads was enhanced by using RECC on the tension side or in full depth since RECC limited flexural cracks and improved flexural capacity. In Comparison with NC Beams, the RC beams mid-span displacement was reduced and the energy dissipation capacity of concrete was improved when using RECC under low and high impact energies. CRECC on the compression side or in full depth improved the distribution of impact force on the NC and reduced compression damage.

Bimodality in zircon oxygen isotopes and implications for crustal melting on the early Earth

Zircons from the oldest dated felsic crust, the Acasta Gneiss Complex, Canada, provide key information that may help understand the generation of crust on our nascent planet. When screened to eliminate grains with secondary alteration by measuring relative hydration (Δ16O1H/16O), primary ≥ 3.99 Ga zircon cores show δ18O of 5.88 ± 0.15 ‰, at the extreme upper (heavy) range for mantle values. Another early (≥3.96 Ga) zircon component indicates distinctly different, primary light δ18O values (δ18O ≤ 4.5 ‰). This bimodality in ancient zircon oxygen isotopes implies partial melting of both deep (lower crustal) and shallower (near surface) source rocks, responsible for felsic crust production on the early Earth. A similar bimodality in zircon δ18O is recognised in data from other ancient cratons, albeit at different times. Although alternative (uniformitarian) interpretations may also satisfy the data, the tempo of this bimodality matches models of planetary high-energy impact flux, consistent with a fundamental role for bolide impacts in the formation of crustal nuclei on the early Earth.

Mathematical Modeling of Collisional Heat Generation and Convective Heat Transfer Problem for Single Spherical Body in Oscillating Boundaries

The application of high-energy ball milling in the field of advanced materials processing, such as mechanochemical alloying and ammonia synthesis, has been gaining increasing attention beyond its traditional use in material crushing. It is important to recognize the role of thermodynamics in high-energy processes, including heat generation from collisions, as well as ongoing investigations into grinding ball behavior. This study aims to develop a mathematical model for the numerical analysis of a spherical ball in a shaker mill, taking into account its dynamics, contact mechanics, thermodynamics, and heat transfer. The complexity of the problem for mathematical modeling is reduced by limiting the motion to one-dimensional translation and representing the vibration of the vial wall in a shaker mill as rigid boundaries that move in a linear fashion. A nonlinear viscoelastic contact model is employed to construct a heat generation model. An equation of internal energy evolution is derived that incorporates a velocity-dependent heat convection model. In coupled field modeling, equations of motion for high-energy impact phenomena are derived from energy-based Hamiltonian mechanics rather than vector-based Newtonian mechanics. The numerical integration of the governing equations is performed at the system level to analyze the general heating characteristics during collisions and the effect of various operational parameters, such as the oscillation frequency and amplitude of the vial. The results of the numerical analysis provide essential performance metrics, including steady-state temperature and time constant for the characteristics of temperature evolution for a high-energy shaker milling process with a computation accuracy of 0.1%. The novelty of this modeling study is that it is the first to obtain such a high accuracy numerical solution for the temperature evolution associated with a shaker mill process.

The relationship between the impact position interference and CAI strength of composite sandwich structures under double impacts

Sandwich structures are susceptible to multiple-impacts, and such multiple-impacts will typically occur at certain distances from each other. Therefore, the influence of five different distances between impact positions (DBIP) and three impact energies on compression after impact (CAI) strength are considered and discussed for honeycomb sandwich structure with composite face sheets in this paper. By comparing two typical impact characteristics, i.e., maximum impact force and displacement, the trend of CAI strength shows a turning-point, which is closely related to the size of the impactor. However, high impact energy (15 J) leads to damage in the bottom face sheet during the second impact, and the presence of damage in both top and bottom face sheet reduces CAI strength, resulting in the turning point of CAI strength not exist. It was observed that there is obvious buckling failure, and some cracks along the width direction from the impact point to the edge after CAI. To provide a more comprehensive understanding of double impacts and CAI behavior, a finite element (FE) model considering different DBIP is developed. In addition, the predicted fraction of energy absorbed by top face sheet, honeycomb core, and bottom face sheet is also obtained to reveal the relationship between the impact position interference and CAI strength.

Development of a high-energy centrifuge model impact hammer for pile-driving

The offshore wind energy industry continues to expand rapidly around the world in response to the demand for clean energy. Research to investigate monopile performance under cyclic lateral loading needs to replicate the installation process as well as the cyclic loading regimes. This has provided the impetus for the development of model pile driving hammers for use in geotechnical centrifuges. This paper presents a new model-scale centrifuge impact hammer that is capable of in-flight driving of large-diameter piles into dense sediments with the flexibility of varying the energy during a test for a more controlled installation. The new hammer is activated by a pair of rotating cams, improving on the pneumatically activated hammer developed in the 1980s, giving greater energy and much better reliability. This paper provides full details of the hammer, together with data obtained at 80g acceleration, driving prototype 4 m wide (50 mm in model scale) piles into dense, dry sand to depths of over 20 m (over 5D) in <1000 blows.

High performance shape-adjustable structural lithium-ion battery based on hybrid fiber reinforced epoxy composite

High performance shape-adjustable structural batteries with both excellent electrochemical performances and mechanical properties, and compatible with conventional batteries and composite processing techniques, are highly attractive for next generation electrical vehicles and electrical aircrafts. Herein, a high-performance structural lithium-ion battery composite (SLBC) is developed by encapsulating commercial-available battery core materials with hybrid fiber reinforced epoxy composite laminate shells, which can be assembled into desired irregular shapes with the conventional vacuum bagging technique. Firstly, the laminate shell layout with the combination of glass fiber woven fabric (GFWF) and carbon fiber woven fabric (CFWF) is designed and optimized. Meanwhile, a PET film is employed to wrap the battery core materials, which enables processing of the SLBC with liquid electrolyte in ambient condition. The SLBC obtained demonstrates both prominent mechanical (flexural strength of 211.7 MPa and flexural modulus of 7.7 GPa) and electrochemical properties (an initial discharge capacity of 98.5 mAh/g at 0.2C, a high energy density of 314.5 Wh kg−1, and a good cycling performance) owing to the hybrid design of CFWF and GFWF as well as a sealed environment to guarantee the battery operate well. Impressively, the in-situ mechano-electrochemical measurements are assessed under the out-of-plane compressive stress and the flexural stress conditions. These results show that the SLBC under loading can maintain stable electrochemical performance even at a high out-of-plane compressive stress of 20 MPa and a high flexural stress of 150 MPa. Furthermore, the SLBC can also maintain the excellent discharge capacity when subjected to a high impact energy, which is promising in next generation electrical vehicles. Finally, the wave-like SLBC fabricated demonstrates the effectiveness in withstanding loads and driving electric fan simultaneously, which is promising in next generation electrical vehicles..