Low-energy Impact Research Articles

Highly sensitive single-molecule detection of macromolecule ion beams.

The analysis of proteins in the gas phase benefits from detectors that exhibit high efficiency and precise spatial resolution. Although modern secondary electron multipliers already address numerous analytical requirements, additional methods are desired for macromolecules at energies lower than currently used in post-acceleration detection. Previous studies have proven the sensitivity of superconducting detectors to high-energy particles in time-of-flight mass spectrometry. Here, we demonstrate that superconducting nanowire detectors are exceptionally well suited for quadrupole mass spectrometry and exhibit an outstanding quantum yield at low-impact energies. At energies as low as 100 eV, the sensitivity of these detectors surpasses conventional ion detectors by three orders of magnitude, and they offer the possibility to discriminate molecules by their impact energy and charge. We demonstrate three developments with these compact and sensitive devices, the recording of 2D ion beam profiles, photochemistry experiments in the gas phase, and advanced cryogenic electronics to pave the way toward highly integrated detectors.

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.

MgO Nanoparticles Obtained from an Innovative and Sustainable Route and Their Applications in Cancer Therapy.

This paper aimed to evaluate the biological damages towards diseased cells caused by the use of MgO nanoparticles (NPs). The NPs are produced by a calcination process of a precursor, which is an aqueous suspension of nanostructured Mg(OH)2, in turn synthesized following our original, time-energy saving and scalable method able to guarantee short times, high yield of production (up to almost 10 kg/week of NPs), low environmental impact and low energy demand. The MgO NPs, in the form of dry powders, are organized as a network of intercrystallite channels, in turn constituted by monodispersed and roughly spherical NPs < 10 nm, preserving the original pseudo hexagonal-platelet morphology of the precursor. The produced MgO powders are diluted in a PBS solution to obtain different MgO suspension concentrations that are subsequently put in contact, for 3 days, with melanoma and healthy cells. The viable count, made at 24, 48 and 72 h from the beginning of the test, reveals a good cytotoxic activity of the NPs, already at low MgO concentrations. This is particularly marked after 72 h, showing a clear reduction in cellular proliferation in a MgO-concentration-dependent manner. Finally, the results obtained on human skin fibroblasts revealed that the use MgO NPs did not alter at all both the vitality and proliferation of healthy cells.

Effect of Absorption and Polarization Potentials in The Distorted Wave Calculation of Positron Impact Excitation of Autoionizing State of Rubidium

This study focuses on the scattering of positrons and rubidium atoms. We utilized the distorted wave approach to compute the cross sections and alignment parameter from near excitation threshold up to 1500 eV. Our system employed Clementi and Roetti (1974) multi-zeta Roothan-Hatree-Fock wave. We employed a complex distortion potential comprising static, absorption, and polarization terms to calculate cross sections and the alignment parameter. Our results were compared with other available studies, and we found that including polarization and absorption potentials significantly affected the cross-sections and the alignment parameter, especially at low-impact energies. These two potentials enhanced the accuracy of both the cross-section and alignment parameter results.

INFLUENCE OF ENVIRONMENTAL CONDITIONS ON MECHANICAL PROPERTIES OF PERSONAL PROTECTIVE EQUIPMENT

The aim of this study was to determine the influence of environmental conditions on changes inthe mechanical properties of personal protective equipment (PPE). The paper includes a review ofthe literature on the subject as well as results of own research. The focus was on ageing, abrasionand service conditions. In addition, the effect of direct exposure of the equipment to harmful andhazardous factors specific to the operating environment was considered. The following personalprotective equipment (and/or materials used in their manufacture) was reviewed: special clothing,firefighter boots and firefighter helmet. Ageing processes, abrasion and operating conditionsdegrade the mechanical properties of PPE. The rate of degradation varies depending on thematerial used. Direct exposure to a humid environment degrades the properties of materials usedin the manufacture of firefighter helmets. The strength of the materials used in the manufactureof head protection and firefighter’s boots decreases when exposed to elevated temperatures. Incontrast, the shock absorption capacity of whole helmets when exposed to elevated and hightemperatures with low impact energy becomes improved. The puncture resistance of firefighterboots under reduced temperature exposure was found to be higher.

On the importance of nano-oxide control in laser powder bed fusion manufactured Ni-based alloys to enhance fracture properties

In this study, a series of Ni-Cr-Mo based alloys (IN625, C22 and NA282), sourced from various powder suppliers and having varying oxygen concentrations (200 ppm to 800 ppm), were printed under similar conditions using laser powder bed fusion (LPBF). Nano-oxides in the range of 20–50 nm were observed in each alloy in the as-printed state, albeit with different number densities. Room temperature tensile tests and liquid nitrogen (LN2, -196 °C) Charpy impact tests were performed to assess the mechanical response of each alloy. The IN625 and C22 samples showed considerably lower impact energy values than the NA282, as well as lower room temperature post-necking tensile elongations, despite showing similar yield strengths and strain hardening behaviours. Fracture surface dimple sizes were shown to correlate with nano-oxide particle spacings. Nano-oxides were found in the middle of most dimples on fracture surfaces suggesting that the nano-oxides are the sites of void nucleation during fracture, despite being only 20–50 nm in size. The precursor metal powders were identified as the primary origin of the nano-oxide particles. This study highlights the critical, detrimental role that nano-oxides, typically present in LPBF metals, have on the fracture properties of these materials. In the case of the Ni-Cr-Mo alloys examined here, limiting oxide formation is critical to achieving optimal fracture properties.

Circular economy and sustainable agri-food systems

In recent times, scientists and economic policy authorities have been promoting viable solutions to address global emergencies related to human-caused climate change. In particular, there is a growing demand for renewable energy sources, technological innovation and energy-saving systems, and ecological and environmental sustainability of natural resources and the territory. At the center of this global effort, an increasingly significant role seems to be destined for the agricultural sector and agro-energy production systems due to the potential benefits in terms of production costs. However, the interest in non-conventional and low-impact energy sources requires an in-depth investigation not only of the advantages, in terms of availability and economic efficiency, but also of the impact on the environment and the quality of the landscape, as well as on the aspects of the overall intervention that must be adopted to allow the supply of agricultural products to the market. Given this scenario, the broad agro-energy issue would be incomplete without exhaustive economic sustainability analyses, which serve as operational decision support tools to measure the cost-effectiveness of investments in agro-energy production and its use. This study presents a methodological proposal to evaluate the economic convenience of energy investments for the production of renewable energy which represents a trade-off between food and non-food production to promote effective and efficient solutions for the allocation of resources. The results of the research must be read to make the agricultural company competitive, not forgetting that it is called upon to produce agricultural products for the market.

Ageing effect on the low-velocity impact response of 3D printed continuous fibre reinforced composites

This paper aims to analyse the low-velocity impact performance of 3D printed continuous carbon fibre reinforced composites manufactured by fused deposition modelling. Moreover, the effect of ageing on the impact properties and visual damage is studied. This evaluation is crucial for understanding the long-term behaviour and durability of these materials, enabling better design and engineering decisions in various applications where impact resistance is paramount. Low-velocity impact tests were conducted on specimens aged 1, 7, 15 and 30 days. An instrumented drop-weight testing machine was employed for the tests. The dimensions and layup sequence of the composite specimens were designed following the recommendations outlined in the ASTM D7136/D7136M standard for unidirectional composite tapes. Results showed that the initial elastic part slightly reduces with age. In addition, the severity of visual damage in the specimens clearly varied with age. The older specimens present the less visible damage but also the lower impact energy absorption.

Life cycle assessment for producing monocrystalline photovoltaic panels: a case study of Brazil

ABSTRACT Energy generation from photovoltaic panels provides for clean, renewable, low environmental impact energy. However, such characteristics are only related to products already in operation, as they do not apply to their production process. In this study, Life Cycle Analysis (LCA) was conducted to quantify 11 environmental impacts caused by the production of monocrystalline silicon photovoltaic panels in Brazil, considering raw material extraction, material processing, construction, and part production. The LCA showed that the photovoltaic panel production process has several environmental impacts that can be minimized by implementing changes to the production chain, especially to reduce the generation of greenhouse gases which contribute to global warming. It was observed that the solar cell production stage contributes to the environmental impacts the most, especially to those referring to abiotic depletion (84%) and to all stratospheric ozone layer depletion (62%). The potential impacts estimated were 9.43 × 10−2 kg Sbeq and 5.34 × 10−4 kg CFC-11eq, respectively. With relation to global warming, Greenhouse Gases (GHG) were emitted with a corresponding value of 3.23 × 103 kg CO2 eq, it was caused by CO2, CH4, HFC-134a, nitrous oxide, HFC-23, CFC-13 gases. To reduce impact per unit of production, it is suggested that the monocrystalline silicon panel production be substituted for polycrystalline, and more incentives be provided to increase large-scale panel production, making it cheaper.

Two modes of contact‐time reduction in the impact of particle‐coated droplets on superhydrophobic surfaces

AbstractReducing the contact time during droplet impact is essential for many scientific and industrial applications, such as self‐cleaning, anti‐icing, heat transfer, and condensation. This paper reports contact‐time reduction by coating droplets with micro–nano hydrophobic particles. Such particle‐coated droplets are known as liquid marbles (LM). LM impact on superhydrophobic surfaces reveals two different modes of contact‐time reduction. For lower impact energies, the reduced adhesion of LM with the surface is responsible for a reduction of up to 21%. Contact‐time reduction in this regime is found to be independent of particle size but dependent on the solid fraction of LM. However, a fragmentation‐based contact‐time reduction is observed for larger particle sizes and higher impact energies. Here, the reduction is as high as 65%. Such fragmentation occurs because the spreading LM lamella breaks when its thickness becomes similar to particle dimensions. Our findings reveal the potential of LM as a novel approach to reduce contact time during droplet impact, with implications for various scientific and industrial applications.

Experiment and Numerical Simulation on Damage Behavior of Honeycomb Sandwich Composites under Low-Energy Impact

It is well-established that the honeycomb sandwich composite structures are easily prone to damage under low-energy impact. Consequently, it would lead to a dramatic decrease in structural load-bearing capacity and a threat to overall safety. Both experimental and numerical simulations are carried out to investigate the impact damage behavior of honeycomb sandwich composite specimens. The damage mode, damage parameters, and contact force-time curves of three types of panel materials with T300, T700, and T800 are obtained under different impact energies of 10 J, 20 J, and 40 J by the drop-weight impact experiment. Moreover, digital image correlation (DIC) tests are used to measure the deformation and strain of the lower panel. The experimental results reveal that the degree of damage increases with increasing impact energy. Particularly, the T300 panel specimen exhibits visible fiber fracture when subjected to an impact energy of 40 J. The impact process involves matrix cracking, fiber fracture, and delamination of the upper panel occurring first, followed by immediate crush damage to the honeycomb core and, finally, slight fiber damage to the lower panel. Due to its higher strength, the T800 panel specimen exhibits the highest damage resistance compared to the T700 and T300 panel specimens. To consider the microscopic failure criteria and various types of contact during the impact process, a finite element model of honeycomb sandwich composites is established, and numerical simulation analysis of low-energy impact is performed to determine the damage mode, damage size, and contact-force curves. Comparative analysis demonstrates good agreement between the simulation and experimental results. The findings of this study provide valuable technical support for the widespread application of honeycomb sandwich composites in the aviation field.

Effect of different underhead shot-peening and lubrication conditions on high-strength screws undergoing multiple tightenings

This study investigates the effect of shot-peening on the bearing friction coefficient of 42CrMoV grade 14.9 screws. An experimental campaign was conducted on a tribological testing rig, investigating the combined effects of shot peening treatments, lubrication conditions, and number of tightenings on the frictional coefficient. A first set of tests was performed, considering the same shot-peening conditions as in a previous study to highlight the role of different material. A second campaign was carried out, adjusting the process parameters to enhance the tribological response. Small shots and high-impact energy are suitable for tightening with lubricant, whereas, in dry conditions, larger shots and lower-impact energy lead to particularly low friction coefficients that are well aligned to those achievable when using lubricants.

Low energy impact behavior of unidirectional and cross-ply flax/epoxy laminates and comparison with similar glass/epoxy laminates

Unidirectional (UD) and cross-ply flax and glass fiber reinforced composites (FFRC and GFRC)are tested under four out-of-plane low velocity impact loads. A hybrid flax reinforcement was used, denoted UD-mat, which is made of a UD layer of continuous flax fibers bound to a flax fiber mat layer. For the mat binder, two types of short flax fibers are considered: unmodified fibers and refined ones. The laminates made ofrefined fibers show the highest permanent and maximum displacements. Moreover,the peak load for the unidirectional FFRC with refinedfibers is lower than that with unmodified fibers, for example it is 25% lower at 11 J. When comparing with flax fiber laminates, the absorbed energy and energy absorption ratio are on average 40% lower for glass laminates but less damage is observed. Several failure modes are observed in the flax laminates, while the main failure of the glass/epoxy laminates is delamination.

A phenomenological understanding of the novel design of hierarchical structure for 1 GPa ultrahigh strength and high toughness combination low alloy steel

In the present study we propose a novel design of hierarchical structure with the aim to obtain high strength of 1 GPa and low temperature toughness in a heavy low alloy steel plate by intercritical quenching and tempering (IQ&T). The hierarchical microstructure consisted of bimodal prior austenite grains with complex microstructure obtained via intercritical quenching from 810 °C and tempering at 500 °C. The large size grains with average diameter of ∼22 μm consisted of tempered martensite and fine intercritical ferrite. While the surrounding fine grains with average diameter of ∼12 μm consisted of tempered lower bainite and tempered lath martensite. Ultra-high yield strength of 998 MPa and tensile strength of 1059 MPa were obtained for the novel hierarchical microstructure steel, which was similar to the conventional quenched and tempered (Q&T) steel. Whereas, the low temperature impact energies at both −40 and −80 °C were ∼100% higher for the hierarchical microstructure steel than the conventional Q&T steel. The significant improvement of low temperature toughness is attributed to the synergistical effect of hierarchical microstructure. The fine intercritical ferrite in large grains increased the plastic deformation ability during impact and was beneficial for formation of dimples, and the surrounding fine grains offered high density of large mis-orientation grain boundaries to deflect crack propagation, leading to high impact energy at low temperature.

Design and characterization of functional TiO2–lignin fillers used in rotational molded polyethylene containers

In this study, new TiO2–lignin hybrid systems were synthesized and characterized by various methods, including non-invasive backscattering (NIBS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), elemental analysis (EA) and zeta potential analysis (ZP). The weak hydrogen bonds between the components, as shown on FTIR spectra, proved the production of class I hybrid systems. TiO2–lignin systems were found to display good thermal stability and relatively good homogeneity. These newly designed hybrid materials were used to produce functional composites via rotational molding in a linear low-density polyethylene (LLDPE) matrix at 2.5 % and 5.0 % loading by weight of the fillers, namely, TiO2, TiO2–lignin (5:1 wt./wt.), TiO2–lignin (1:1 wt./wt.), TiO2–lignin (1:5 wt./wt.) and pristine lignin, creating rectangular specimens. The mechanical properties of the specimens were measured via compression testing and by low-energy impact damage testing (the drop test). The results showed that the system containing 5.0 % by weight of TiO2–lignin (1:1 wt./wt.) had the most positive effect on the container's compression strength, while the LLDPE filled with 5.0 % by weight of TiO2–lignin (5:1 wt./wt.) demonstrated the best impact resistance among all the tested composites.

Mass–Energy Profiles Obtained by Quantum Chemical Computing Applied in Mass Spectrometry: A Case Study with Identification of a Group of Acetalized Monosaccharide Isomers

Accurate modeling of small molecules substantially reduces the logistical effort and time consumption to discover and then obtain chemicals with various applications. Molecular stereochemistry is fundamentally involved in the intermolecular interactions that give rise to biological activity. Establishing the configuration of the asymmetric carbon in diastereomers can be decisive in drug design. In the presented analytical technique, on the basis of quantitative structure–fragmentation relationship (QSFR), mass–energy profiles obtained by electron ionization mass spectrometry (EI-MS) for analytes are used, along with some profiles for candidate structures calculated by quantum chemical (QC) methods. Our paper establishes the analytical conditions that lead to the best matching scores of such profiles corresponding to the actual structures for some isomers of acetalized monosaccharides. The optimization was achieved by group validation of five analytes, using four independent variables: the QC method, the descriptor of calculated energy, the impact energy of electrons, and the descriptor of experimental energy. The true structures were obtained using experimental profiles obtained at low electronic impact energies, and profiles were calculated using the DFT (B3LYP/6-31G) and RM1 QC methods. The double quantification of the ionic mass and the energy that generates it, for only a few primary ions of the mass spectrum, even allows the differentiation of acetalized diastereomers.

Experimental evidence to understand mechanical causes of retinal detachment following blunt trauma

PurposeThis study aimed to perform an in vitro experiment to simulate retinal detachment caused by blunt impact, and provide experimental evidence to understand mechanical causes of traumatic retinal detachment. MethodsThe experiment was conducted on twenty-two fresh porcine eyes using a bespoke pendulum testing device at two energy levels (0.1J for low energy and 1.0J for high energy). We examined dynamic forces and mechanical responses to the impact, including global deformations, intraocular pressure changes and the energy absorption. Another set of twenty-two eyes underwent pathological examination immediately after being subjected to blunt impact. Twelve additional intact eyes were examined as controls. All pathological sections were scored to indicate whether retinal detachment had occurred. ResultsA dynamic variation in intraocular pressure was detected following impact and exhibited an approximate sinusoidal oscillation-attenuation profile. The peaks of impact force were 12.9 ± 1.9 N at low-energy level and 34.8 ± 9.8 N at high-energy level, showing a significant difference (p < 0.001). The positive and negative peaks of intraocular pressure were 149.4 ± 18.9 kPa and −10.9 ± 7.2 kPa at low-energy level, and 274.5 ± 55.2 kPa and −35.7 ± 23.7 kPa at high-energy level, showing significant differences (p < 0.001 for both levels). Retinal detachments were observed in damaged eyes while few detachments were found in control eyes. The occurrence rate of retinal detachment differed significantly (p < 0.05) between the high- and low-energy impact groups. ConclusionsThis study provided experimental evidence that shockwaves produced by blunt trauma break the force equilibrium and lead to the oscillation and negative pressure, which mainly contribute to traumatic retinal detachment.

Effect of V, Nb, and Ti microalloying on low–temperature impact fracture behavior of non–quenched and tempered forged steel

In this study, three kinds of non-quenched and tempered forged steels with V, V–Nb and V–Nb–Ti microalloying elements were designed. The microstructure and low–temperature impact fracture behavior of the three steels were comprehensively compared and analyzed. The results showed that the addition of Nb and Ti elements can significantly refine the grains and form precipitated particles to improve the strength of the steel. The fracture behavior of the three steels types at a low temperature of −28 °C was dominated by brittle cleavage fractures. V–Nb–Ti steel exhibited the worst low–temperature impact toughness. The SEM analysis result showed that coarse (V, Nb, Ti) (C, N) particles present in the steel acted as local cleavage initiation sites. No cleavage fracture caused by (V, Nb) (C, N) particles occurred in the V–Nb steel. The results showed that the high impact energy (70.4 J) at room temperature and low ductile–brittle transition temperature (DBTT, −20 °C) of the V–Nb steel were mainly attributable to the grain refinement of Nb. The micron–sized coarse (V, Nb, Ti) (C, N) particles were the main factor responsible for the low impact energy (35.5 J) at room temperature and high DBTT (−7 °C) of V–Nb–Ti steel and can act as the local cleavage initiation sites to dominate the cleavage fracture at low temperature and decrease the impact toughness.

Mechanical behaviour for aeronautical structures with embedded electric cables under low energy impact

The work focuses on the mechanical strength of composite structures with embedded electrical functionalities submitted to low energy impact. This material is defined for aeronautical applications as multilayers of glass fibre composite with flat electrical cable layers embedded. The main question is about the damage involved by the low energy impact, and its influence on the electrical cables layer performances. The impact leads to failure with no external signs of damage and insulation degradation. The dynamic experimental campaigns are carried out on drop tower tests with hemispherical tool. localized damage mechanisms at conductor interfaces are observed and a finite element model is performed. A link between impact energies and loss of electrical performance of multifunctional samples is established.

Piezoresistive Behavior of a Conductive Polyurethane Based-Foam for Real-Time Structural Monitoring.

Smart flexible materials with piezoresistive property are increasingly used in the field of sensors. When embedded in structures, they would allow for in situ structural health monitoring and damage assessment of impact loading, such as crash, bird strikes and ballistic impacts; however, this could not be achieved without a deep characterization of the relation between piezoresistivity and mechanical behavior. The aim of this paper is to study the potential use of the piezoresistivity effect of a conductive foam made of a flexible polyurethane matrix filled with activated carbon for integrated structural health monitoring (SHM) and low-energy impact detection. To do so, polyurethane foam filled with activated carbon, namely PUF-AC, is tested under quasi-static compressions and under a dynamic mechanical analyzer (DMA) with in situ measurements of its electrical resistance. A new relation is proposed for describing the evolution of the resistivity versus strain rate showing that a link exists between electrical sensitivity and viscoelasticity. In addition, a first demonstrative experiment of feasibility of an SHM application using piezoresistive foam embedded in a composite sandwich structure is realized by a low-energy impact (2 J) test.