Degree Of Bending Research Articles

Design and Optimization of Electromagnetically Driven End-Effector

The excellent flexibility and plasticity of a flexible robotic hand enable it to grip objects of various shapes and sizes. Currently, most of the flexible robotic hand fingers on the market use pneumatic drives. However, the unstable power of the pneumatic drive can cause the object gripped by the finger to slip. Additionally, the pneumatic pump can create noise pollution. To address these issues, a flexible end-effector is designed using an electromagnetic coil as the power source. The electromagnetic-driven end-effector has high precision and fast response, without the need for external devices. It only requires controlling the current to control the magnetic force of the electromagnet, thereby controlling the degree of end-effector bending. The finite element simulation is used to analyze the impact of the structural parameters of the end-effector on bending degree. And the optimal basic parameters of the end-effector are determined. Under the same intensity of the current, when the bottom layer thickness is 5 mm, end-effector knuckle spacing is 4 mm, the maximum angle of end-effector bending is reached.

Scanning electron microscopy imaging of multilayer-doped GaN: Effects of surface band bending, surface roughness, and contamination layers on doping contrast

Dopant profiling by a scanning electron microscope possesses great potential in the semiconductor industry due to its rapid, contactless, non-destructive, low cost, high spatial resolution, and high accuracy characteristics. Here, the influence of plasma and wet chemical treatments on doping contrast was investigated for a multilayered p-n GaN specimen, which is one of the most promising third-generation wide bandgap semiconductors. Angle-resolved x-ray photoelectron spectroscopy and atomic force microscope were employed to characterize the degree of surface band bending, surface roughness, gallium oxides, and hydrocarbons on the surface of GaN. N2 and air plasmas were unable to remove the surface contamination layers, although the degree of surface band bending was suppressed. In contrast, wet chemical methods offer superior capability in removing contamination layers; however, the surface roughness was increased to varying degrees. Notably, NH4F solution is capable of improving the doping contrast. The underlying mechanism was elucidated from the perspective of surface band bending, surface roughness, and contamination. The findings reported here will provide a feasible solution for effective characterization of semiconductor materials and devices.

Enhanced photoelectrocatalytic CO2 reduction to CO via structure-induced carrier separation in coral-like CuBi2O4-Bi2O3

Significant carrier recombination has severely limited the development of the most potential photoelectrocatalytic CO2 reduction reaction (PEC-CO2 RR). Herein, coral-like CuBi2O4-Bi2O3 photocathodes are prepared using the strategy of the construction of heterojunction to improve the efficiency of carrier separation. As expected, its faradic efficiency of CO (FECO) at the lower potential (0.1 V vs. RHE) is 86.03 %, which is about 1.49 times higher than that of the original CuBi2O4 film. The increased catalytic activity of CuBi2O4-Bi2O3 can be attributed to the high surface area of the distinctive coral-like structure of Bi2O3, which enhances light absorption efficiency. Additionally, the higher degree of band bending in CuBi2O4-Bi2O3 and the built-in electric field can speed up the transport rate of electrons, slow down the recombination of photogenerated electrons with holes and extend the lifetime of photogenerated electrons, allowing electrons to continuously participate in the reaction. This study proposes a novel strategy to optimize the efficiency of photoelectrocatalytic CO2 reduction by CuBi2O4-based photocathodes.

The evolution of flexibility and function in the Fc domains of IgM, IgY, and IgE.

Antibody Fc regions harbour the binding sites for receptors that mediate effector functions following antigen engagement by the Fab regions. An extended "hinge" region in IgG allows flexibility between Fab and Fc, but in both the most primitive antibody, IgM, and in the evolutionarily more recent IgE, the hinge is replaced by an additional domain pair in the homodimeric six-domain Fc region. This permits additional flexibility within the Fc region, which has been exploited by nature to modulate antibody effector functions. Thus, in pentameric or hexameric IgM, the Fc regions appear to adopt a planar conformation in solution until antigen binding causes a conformational change and exposes the complement binding sites. In contrast, IgE-Fc principally adopts an acutely bent conformation in solution, but the binding of different receptors is controlled by the degree of bending, and there is allosteric communication between receptor binding sites. We sought to trace the evolution of Fc conformational diversity from IgM to IgE via the intermediate avian IgY by studying the solution conformations of their Fc regions by small-angle X-ray scattering. We compared four extant proteins: human IgM-Fc homodimer, chicken IgY-Fc, platypus IgE-Fc, and human IgE-Fc. These are examples of proteins that first appeared in the jawed fish [425 million years ago (mya)], tetrapod (310 mya), monotreme (166 mya), and hominid (2.5 mya) clades, respectively. We analysed the scattering curves in terms of contributions from a pool of variously bent models chosen by a non-negative linear least-squares algorithm and found that the four proteins form a series in which the proportion of acutely bent material increases: IgM-Fc < IgY-Fc < plIgE-Fc < huIgE-Fc. This follows their order of appearance in evolution. For the huIgM-Fc homodimer, although none are acutely bent, and a significant fraction of the protein is sufficiently bent to expose the C1q-binding site, it predominantly adopts a fully extended conformation. In contrast, huIgE-Fc is found principally to be acutely bent, as expected from earlier studies. IgY-Fc, in this first structural analysis of the complete Fc region, exhibits an ensemble of conformations from acutely bent to fully extended, reflecting IgY's position as an evolutionary intermediate between IgM and IgE.

Variants of Mutual Arrangement of Parts of Human Pancreas According to Computed Tomography Data

INTRODUCTION: With development of methods of diagnosis and surgical treatment of diseases of hepatopancreato-biliary region, there is increasing interest in and necessity to search for various methods of studying organs of this zone. Compared to the earlier methods of studying topographic anatomy, the method of computed tomography (KT) permits to work with a wide scope of lifetime data of human anatomy. We did not find enough information in the literature about peculiarities of the shape, size and position of pancreas in the horizontal projection. AIM: To study the peculiarities of the shape, size and position of the pancreas using contrast-enhanced CT data. MATERIALS AND METHODS: The work was based on the available archive of examination of organs of the abdominal cavity by CT method with contrast in patients (n = 31) without pathology of the hepatopancreatobiliary zone, gastrointestinal tract, spleen, kidneys and spine. Measurements were performed based on the horizontal projection of scans. The length was determined by measuring the organ in parts. The degree of curvature of the pancreas shape was determined by constructing the central axis of the organ and measuring the angles formed by it. The obtained data were subjected to statistical processing. RESULTS: According to increase in the length of the organ, three groups were formed. Different degrees of the organ bending were identified. Upon that, no clear correlation was found with skeletopy data, age and gender and parametric data of the upper part of the abdominal cavity. CONCLUSION: Owing to the developed method of measuring angles between parts of the pancreas, a range of mutual arrangement of the head and body, body and tail of the gland in the horizontal projection was obtained. Our data complement the anatomy of the pancreas and can be considered as a promising resource for further study of the features of syntopy and blood supply of the organs of the upper part of the abdominal cavity.

Structural response of glass fiber-polymer composite bending-active elastica beam under long-term loading conditions

Bending-active elastica beams represent structural members which are initially installed as straight beams and then bent into arched shapes by applying horizontal displacements to one support. Designing such members for permanent structures made of fiber-polymer composites involves complex viscoelastic responses, which have not yet been thoroughly investigated. An experimental investigation of medium-scale bending-active elastica beams, consisting of pultruded glass fiber-polymer composite profiles, was thus conducted to investigate the long-term structural behavior of such members under imposed sustained bending and axial compression. The results revealed that viscoelastic responses are based on an interaction of stress relaxation and creep with their effects increased with increasing bending degree and time of exposure to sustained strains and stresses. The imposed horizontal displacement to one of the supports to maintain the bent beam shape induced sustained bending stresses in the beam. Beneficial relaxation of these stresses occurred with relaxation predicted to reach 12 % during a targeted 50-year design service life. Furthermore, the likelihood of the curved beam exhibiting in-plane deformations under sustained stresses enabled creep to occur simultaneously, with associated in-plane creep deformations and strength reduction. While creep deformations remained insignificant, progressive creep rupture occurred at highest bending degrees, exhibiting sequential creep rupture in the outer combined mat layers, delamination, crack opening and final fiber failure. Creep rupture can be prevented by postponing crack initiation in the combined mat layer beyond the targeted design service life. This can be achieved by limiting the bending degree to 50 % of the bending degree at which short-term crack initiation occurs.

Sign To Speech Conversion And Home Automation Control Using Smart Gloves

In today's world, there are many new technologies changing the way we do things. One interesting technology is the home automation system. It helps people control things in their homes from far away, making life more comfortable, saving money, and being easy to use. But some people find it a bit tricky to use these systems well. To make it simpler for everyone, we can use something called a flex sensor-based home automation system. This system lets you control things by moving your hands, which is really helpful for older people or those who might find it a bit hard to move. It's also great for people who haven't had much learning. And if we add voice help, it becomes even easier. This way, people who are in bed or dealing with physical problems can use it too. This makes technology not just cool but helpful for everyone in different situations. In this paper, we explore the integration of flex sensors onto hand gloves to facilitate a dynamic interaction between hand movements and technological outputs. The flex sensors, akin to miniature potentiometers, are strategically affixed to the fingers, registering changes in value corresponding to the bending action. As the finger bends, the sensor's resistance alters, influencing the output in an inversely proportional manner. This innovative system allows for nuanced control, where specific angles of finger bending lead to calibrated adjustments in output, demonstrating a responsive and intuitive interface between human gestures and technology. The implementation of flex sensor- based gloves introduces a versatile means of capturing and translating hand movements into actionable data. The project leverages the concept of resistance modulation to precisely interpret the degree of finger bending, creating a reliable framework for diverse applications such as gesturecontrolled devices or assistive technologies for individuals with limited mobility. The abstracted communication between human hand gestures and technology opens avenues for accessible and intuitive interfaces, promising potential applications across various domains.

Biomimetic soft actuator: Rapid response to multiple stimuli with programmable control

Stimuli-responsive soft actuators have attracted increasing attention in multiple fields since they exhibit unique advantages in safe interaction with humans and adaptability to dynamic environments. However, the study of untethered stimuli-responsive soft actuators has been limited by the slow response speed, irreversible deformations or inability in responding to multiple stimuli. Taking inspiration from the growth process of lotus leaves, we propose a novel design for an untethered soft actuator comprising graphene oxide (GO) and polyethylene (PE), which shows sensitive response to multiple stimuli, including moisture, light, heating, cooling, and elective volatile organic compounds (VOCs), and exhibits significant deformation at a rapid rate (up to 90.5°/s). The high sensitivity of the actuators enables them to be powered by the neglected energy in daily life instead of requiring specialized energy sources, paving the way for the green and sustainable development in soft robotics. In addition, the bending modes and bending degrees of actuators can be programmed to meet the personalized needs of complex three-dimensional structures. Based on GO/PE actuators, a variety of multi-stimuli-responsive intelligent devices have been developed to demonstrate their application potential in arts, bionics, soft robotics and wearable devices, including interesting WordArt, Chinese paper-cut art pieces, artificial iris, soft crawling robots and a smart cloth unit with adjustable breathability.

Intermolecular Bending States and Tunneling Splittings of Water Trimer from Rigorous 9D Quantum Calculations: I. Methodology, Energy Levels, and Low-Frequency Spectrum.

We present the computational methodology that enables the first rigorous nine-dimensional (9D) quantum calculations of the intermolecular bending states of the water trimer, as well as its low-frequency spectrum for direct comparison with experiment. The water monomers, treated as rigid, have their centers of mass (cm's) at the corners of an equilateral triangle, and the intermonomer cm-to-cm distance is set to a value slightly larger than that in the equilibrium geometry of the trimer. The remaining nine strongly coupled large-amplitude bending (angular) degrees of freedom (DOFs) enter the 9D bend Hamiltonian of the three coupled 3D rigid-water hindered rotors. Its 9D eigenstates encompass excited librational vibrations of the trimer, as well as their torsional and bifurcation tunneling splittings, which have been the subject of much interest. The calculations of these eigenstates are extremely demanding, and a sophisticated computational scheme is developed that exploits the molecular symmetry group of the water trimer, G48, in order to make them feasible in a reasonable amount of time. The spectrum of the low-frequency vibrations of the water trimer simulated using the eigenstates of the 9D bend Hamiltonian agrees remarkably well with the experimentally observed far-infrared (FIR) spectrum of the trimer in helium nanodroplets over the entire frequency range of the measurements from 70 to 620 cm-1. This shows that most peaks in the experimental FIR spectrum are associated with the intermolecular bending vibrations of the trimer. Moreover, the ground-state torsional tunneling splittings from the present 9D calculations are in excellent agreement with the spectroscopic data. These results demonstrate the high quality of the ab initio 2 + 3-body PES employed for the DOFs included in the bound-state calculations.

Gradient-doped BiVO4 Dual Photoanodes for Highly Efficient Photoelectrochemical Water splitting.

Bismuth vanadate (BiVO4) is regarded as a promising photoanode candidate for photoelectrochemical (PEC) water splitting, but is limited by low efficiency of charge carrier transport and short carrier diffusion length. In this work, we report a strategy comprised of the gradient doping of W and back-to-back stacking of transparent photoelectrodes, where the 3-2 wt.% W gradient doping enhances charge carrier transport by optimizing the band bending degree and back-to-back stack configuration shortens carrier diffusion length without much sacrifice of photons. As a result, the photocurrent density of 3-2% W:BiVO4 photoanode reaches 2.20 mA cm-2 at 1.23 V vs. hydrogen electrode (RHE) with a charge transport efficiency of 76.1% under AM 1.5G illumination, and the back-to-back stacked 3-2% W:BiVO4 photoanodes achieves a photocurrent of 4.63 mA cm-2 after loading Co-Pi catalyst and anti-reflective coating under AM 1.5G illumination, with long-term stability of 10 hours.

Influence of brick laying height on biomechanical load in masons: Cross-sectional field study with technical measurements.

Work-related musculoskeletal disorders (WMSDs) located in the low back and neck/shoulder regions are major concerns for both workers, workplaces, and society. Masons are prone to WMSD, because their work is characterized by repetitive work and high physical workload. However, the knowledge on the physical workload during bricklaying is primarily based on subjective measurements. This cross-sectional field study with technical measurements aimed to quantify physical workload in terms of muscular activity and degree of forward bending during bricklaying at different working heights among masons, i.e., knee, hip, shoulder, and above shoulder height. Twelve male (36.1±16.1 years) experienced masons participated in a cross-sectional field study with technical measurements. Surface electromyography from erector spinae longissimus and upper trapezius muscles and an inertial measurement unit-sensor placed on the upper back were used to assess the physical workload (level of muscle activation and degree of forward bending) different bricklaying heights. Manual video analysis was used to determine duration of work tasks, frequency, type, and working height. The working heights were categorized as 'knee', 'hip', 'shoulder', and 'above shoulder'. The 95 percentiles of the normalized Root Mean Square (RMSn) values were extracted assess from erector spinae and trapezius recordings to assess strenuous level muscle of muscle activation. The RMSn of dominant erector spinae muscle increased from hip- to shoulder height (from 26.6 to 29.6, P < 0.0001), but not from hip to above shoulder height and decreased from hip to knee height (from 26.6 to 18.9, P < 0.0001). For the dominant trapezius muscle, the RMSn increased from hip- to shoulder- and above shoulder height (from 13.9 to 19.7 and 24.0, respectively, P < 0.0001) but decreased from hip- to knee height (from 13.9 to 11.5, P < 0.0001). Compared to hip height (27.9°), an increased forward bending was detected during bricklaying at knee height (34.5°, P < 0.0001) and a decreased degree of forward bending at shoulder- and above shoulder height (17.6° and 12.5°, P < 0.0001, respectively). Based on technical measurements, bricklaying at hip height showed the best compromise between muscular load and degree of forward bending. This study contributes to the development of the work environment for masons and can help guide preventive initiatives to reduce physical workload.

High elongation, low hysteresis, fatigue resistant gel electrolyte for supercapacitor and strain sensor

With the arrival of the era of the Internet of Everything and the popularization of flexible wearable devices, energy supply devices serving flexible wearable devices have also become a research hotspot. Hydrogels are gaining ground in the field of flexible energy supply devices, especially supercapacitors, which have attracted wide attention due to the advantages of fast charging/discharging, high power density, and stability. However, flexible supercapacitor inevitably undergoes varying degrees of deformation during use, and their service life decreases dramatically with the prolongation of use. Therefore, the fabrication of a flexible supercapacitor that can be assembled from hydrogel electrolyte and is fatigue-resistant and stable has become a promising research direction. In this study, we constructed a gel electrolyte with high stretchability, low hysteresis, high stability, and fatigue resistance by designing a dual network structure, and assembled it into a supercapacitor. The device has many excellent features, providing a surface capacitance of 100 mF/cm2, a power density of 0.19 mW/cm2, and an energy density of 425 μWh/cm2 at a frequency of 1 mA/cm2. More importantly, it also exhibits superb stability when subjected to varying degrees of bending and compression. In addition, the gel electrolyte can detect small changes of the human body and quickly and sensitively convert motion signals into electrical signals, showing great potential as a flexible wearable device. This study provides an effective strategy for designing gel electrolytes with low hysteresis and high stability for wider application in flexible electronic devices.

Molecular Analysis of Changes in DNA Binding Affinity and Bending Extent Induced by the Mutations on the Aromatic Amino Residues in Cren7.

Proteins from Crenarchaeal organisms exhibit remarkable thermal stability. The aromatic amino acids in Cren7, a Crenarchaeal protein, regulate protein stability and further modulate DNA binding and its compaction. Specific aromatic amino acids were mutated, and using spectroscopic and theoretical approaches, we have examined the effect of the mutation on the structure, DNA binding affinity, and DNA bending ability of Cren7. The mutants were compared to the structure and function of wild-type (WT) Cren7. The reverse titration profiles were analysed by a noncooperative McGhee-von Hippel model to estimate affinity constant (Ka) and binding site size (n) associated with binding to the DNA. The biolayer interferometry (BLI) measurements showed that the binding affinity decreased at higher salt concentrations. For theoretical analysis of the extent of DNA bending, radius of gyration and bending angle were compared for WT and mutants. The time evolution of order parameters based on the translational and rotational motion of tryptophan residue (W26) was used for the qualitative detection of stacking interactions between W26 of Cren7 and DNA nucleobases. It was observed that the orientation of W26 in F41A favored the formation of a new lone pair-lone pair interaction between DNA and Cren7. Consequently, in thermostable proteins, the aromatic residues at the terminus maintain structural stability, whereas the residues at the core optimize the degree of DNA bending and compaction.

Ultralow Power, Cleft Size-Adjustable and pH-Sensitive Hyaluronic Acid (HA) Biodevices for Acid-Sensing Ion Channels Emulation.

The burgeoning implantable biodevices have unlocked new frontiers in healthcare, promising personalized monitoring strategies tailored to specific needs. Herein, hyaluronic acid (HA) is harnessed to create fully biocompatible, acidity-sensitivity and cleft-adjustable neuromorphic devices. These HA-biodevices exhibit remarkable sensitivity to pH variations, effectively mimicking biological acid-sensing ion channels (ASICs) through protonation reactions between electronegative atoms and hydrogen ions, even at ultralow driving voltage (5mV). They can monitor joint cartilage acidity by tracking changes in proton concentration and successfully diagnose the onset of arthritis. Furthermore, by adjusting the synaptic device's cleft distance, which determines responsiveness, power efficiency and plasticity, HA-based neuromorphic devices can be tailored to meet the unique demands of various implantation sites, providing both high-sensitivity and low-heat dissipation, thus broadening their application scopes. Moreover, the HA-biodevices maintain stable performance across various bending degrees, up to a curvature radius of 7.5mm, with flexibility and deformation resilience enabling installation on joints of varying curvatures. The combination of all-biocompatibility, high sensitivity, low heat dissipation, ultralow low power (2 pW), and extraordinary deformation tolerance paves the way for the development of versatile, multipurpose medical monitoring devices with immense potential in the field of healthcare.

Development of Dynamic Four-Dimensional Printing Technology for Patterned Structures by Applying Microcellular Foaming Process.

Four-dimensional (4D) printing adds the dimension of time to 3D-printed specimens, causing movement when external stimuli are applied. This movement enables applications across various fields, including the soft robotics, aerospace, apparel, and automotive industries. Traditionally, 4D printing has utilized special materials such as shape-memory polymers (SMPs) or shape-memory alloys (SMAs) to achieve this movement. This study explores a novel approach to 4D printing by applying microcellular foaming processes (MCPs) to 3D printing. This study primarily aims to design and fabricate patterned specimens using common materials, such as PLA, through 3D printing and to analyze their dynamic behavior under various foaming conditions. To demonstrate the potential applications of this technology, the degree of bending was measured by controlling the patterning and foaming conditions. The 3D-printed specimens with microcellular foaming exhibited predictable deformations owing to the asymmetric expansion caused by differential gas saturation. The results confirm that 4D printing can be realized using conventional materials without the need for smart materials and can introduce foaming processes as a new external stimulus. This study highlights the potential of combining 3D printing with microcellular foaming for advanced 4D printing applications.

Ultraviolet photodetector improvement based on microspheres

Owing to the ideal optical cavity structure, the microsphere has always played a significant role in micro/nano optoelectronic devices for its high light-confined ability and large surface-volume ratio, which have been applied in lots of areas including intracellular lasers, tunable lasers, and so on. Furthermore, the microsphere cavity will be a useful and efficient means to improve the photodetector (PD) performance by enhancing the light absorption efficiency and light energy in the arrays. Herein, the wide-bandgap semiconductor microspheres are introduced in the PD, which are synthesized by a simple and universal hydrothermal method. The sensitive ultraviolet PD is constructed and obtained with a metal-semiconductor-metal type device structure. The oxide defect concentration in the ZnO microspheres is modulated through thermal treatment to improve the performance, including higher photo-to-dark current ratio near 600, responsivity of 7.6✕10−5 A/W, detectivity of 4.6✕107 Jones, and response speed. Moreover, the microspheres fabricated flexible device presents great detecting performance with different bending degrees. The results display the excellent prospect of semiconductor microspheres to flexible ultraviolet high-performance PDs, which possess the broad and potential development prospect in flexible even on-chip optoelectronic devices.

Tribovoltaic nanogenerators based on n-n and p-p semiconductor homojunctions

Tribovoltaic nanogenerators (TVNGs) usually consist of two heterogeneous materials with disparate Fermi levels. However, TVNGs based on two same semiconductors with uniformed Fermi levels have been rarely reported, as they are believed to lack the sufficient potential difference necessary to drive tribo-induced carriers’ separation and collection, resulting in minimal or negligible electricity production. Here, tribovoltaic nanogenerators based on two homojunction semiconductors (H-TVNGs) with the same doping concentration are proposed and designed. The H-TVNGs were demonstrated to be driven by abundant surface states introduced through laser cutting at the slider boundaries and surfaces, which further lead to the bending of interface energy bands. Upon two sliders of different sizes (with different degrees of band bending) come into contact, the built-in electric field at the interface will be established and drive tribo-induced carriers, leading to the production of a direct-current (DC) electrical signal. The performance of H-TVNGs could be effectively amplified or regulated by many factors, including laser cutting power, semiconductor surface roughness, slider shape, and the interface media, etc. These compelling findings reveal innovative physics in tribovoltaic effect, offer special insights for designing high-performance TVNGs, and provide effective strategies for device output optimization.

Identification of force chains in wet coal dust layer and the effect of porosity on three-body contact stiffness

Aiming at the three-body contact problem of mechanical rough surface containing wet coal dust interface, the three-body contact model of rough surface containing wet coal dust interface is constructed by comprehensively considering the contact deformation of rough surface and contact characteristics of wet coal dust, and based on the crushing theory. By analysing the contact force, load-bearing particle size and adjacent contact angle thresholds of the wet coal dust layer, the force chain identification criterion is formulated. Finally, quantitative calculations of the force chain characteristics are performed to reveal the effect of different initial porosities on the three-body contact stiffness, which is verified experimentally. The results of the study show that the average contact force of the wet coal dust layer can be used as the force chain contact force threshold, the average particle size can be used as the force chain particle size threshold, and the force chain angle threshold is determined by the particle coordination number. As the initial porosity decreases, the number, length and stiffness of force chains in the wet coal dust layer increase significantly, and the stiffness reaches a maximum value of 2.007 × 108 pa/m at the moment of downward pressure to stabilisation, while the trend of force chain bending varies in the opposite direction, and its minimum bending degree decreases to 20°. The maximum relative error between the simulation and experimental results of three-body contact stiffness is 9.64%, which proves the accuracy of the force chain identification criterion and the quantitative calculation of three-body contact stiffness by force chain.

Comprehensive crashworthiness simulation analysis of a large aircraft fuselage barrel section in various crash scenarios

To utilize computational techniques in investigate and evaluate the crashworthiness of typical fuselage section of a large transport aircraft in various crash scenarios, the finite element model of fuselage section was modeled and validated based on the vertical drop test of fuselage section at 6.02 m/s. The crash simulation analysis in various crash scenarios (such as concrete ground, soft soil grounds and water) were further conducted based on the validated model of fuselage section, and the crash response characteristics (deformation and failure mode, acceleration response and occupant injury risk, energy-absorbing characteristics) were analyzed and compared. The results show that the finite element model can accurately simulate the unrolling failure mode (three plastic hinges failure mode) of fuselage section and the failure of the connections of cargo floor crossbeams and fuselage frames, and it is in good agreement with the test results in terms of impact velocity and acceleration response. In the case of various soft soil grounds impact scenarios, the partial impact energy is absorbed by the soft soil ground, resulting in slightly different failure modes of fuselage section and a reduction in the peak acceleration. The water-entry impact failure mode of fuselage section is consistent with the rigid ground impact failure mode, the overall deformation degree of fuselage section decreases, but the degree of bending and upturning of fuselage frames increases with the increasing of the water-entry impact velocities The safety of occupants can be effectively protected in the soft soil ground and water-entry impact scenarios. The unrolling failure mode of fuselage section can be changed to the flattening failure mode (multiple plastic hinges failure mode) through the reasonable design to avoid the rupture of cargo floor crossbeams, and the more crash energy can be absorbed due to the production of more plastic hinges for the flattening failure mode, and the crashworthiness of fuselage section can be significantly improved.

Mechanical properties and bonding mechanism on interfaces containing work-hardening surface layer of roll-bonded 6061 Al/Q235 steel composite plates

The film theory is widely accepted as a bonding mechanism of metallic laminate composites (MLCs). It states that the fresh metal contact after the rupture of the surface film is an important condition for the bonding of MLCs. However, the bonding performance and mechanisms at the interfaces containing surface films have not been sufficiently investigated. In this study, steel–aluminium composite plates were used to study the bonding state, elemental diffusion behaviour, and mechanical properties of the bonding interface between the steel-side work-hardened surface layer (WHSL) and the aluminium matrix. The results indicate that the Al and Mg atoms inside the Al matrix can diffuse to about 100–150 nm into the WHSL (Fe3O4) and undergo selective oxidation, thus generating Fe0.1MgAl2O4 particles during annealing. However, the Fe atoms in the WHSL cannot diffuse into the aluminium matrix, thereby preventing the WHSL–Al interface from generating intermetallic compounds and maintaining beneficial bonding properties after long-term annealing. Additionally, compared to the steel–aluminium composite plate without a WHSL, the steel–aluminium composite plate with a WHSL exhibited a superior bonding performance. It also demonstrated an elongation increase of 28.67%, the mechanism of this increased elongation was also studied. Under the same degree of bending, the composite plates with WHSL maintained a stable bonding state and formed a unique interface deformation mode around the WHSL–Al interface after bending, which are highly desirable bending properties.