Mechanical Standpoint Research Articles

Dual‐Ion Co‐Insertion Engineering for Kinetics Enhancement and Stress Regulation in Cu3VS4 Toward Durable Magnesium/Lithium Hybrid Batteries

AbstractRechargeable magnesium batteries (rMBs) have tremendous development prospects in the field of energy storage, however, the strong electrostatic interactions induced by divalent Mg2+ give rise to the sluggish diffusion kinetics. Herein, the dual ion co‐intercalation strategy is proposed to expedite ion migration in Cu3VS4, achieving elevated specific capacity, transcendent rate capability, and ultra‐stable cycling capability. Kinetic analyses combined with DFT calculations indicate that the dual‐ion co‐insertion can fast charge transfer, reduce the diffusion barrier of Mg2+and optimize the reaction kinetics. Finite element simulations quantitatively verify that dual ion co‐intercalation contributes to alleviating magnesiation/lithiation‐induced stress in the shell layer and maintains structural integrity from a mechanical standpoint. Ex situ characterizations profoundly illustrates the multistep magnesium/lithium storage mechanisms and the evolution of structure. The proposed cation co‐intercalation strategy not only holds promise in opening new insights for high‐performance, continuously stable rMBs, but also provides inspiration for multivalent battery systems.

Investigation of the Bonding Performance and Microstructure of MOC Binders for SiO2 as Rock-like Composites.

The heterogeneity of natural rocks complicates the study of carbon sequestration within these materials and raises concerns about the reproducibility of experimental results. Consequently, identifying appropriate rock-like materials has become critical. This research examined the impact of various factors-humidity, binder content, curing period, and cold pressure-on the bond strength of magnesium oxychloride cement (MOC) through orthogonal testing. The tests utilized a molar ratio of MgO to MgCl2-6H2O to H2O of 7:1:18. Both X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to analyze the hydration reactions of MOC and to explore the correlation between the microstructure of the SiO2-MgO-MgCl2 system and its bonding characteristics. The findings indicated that a 5% relative humidity enhances the 7-day bond strength of MOC. Moreover, increasing the curing humidity to 60% relative humidity supports the ongoing hydration of the strength-contributing phases. A binder content ranging from 15% to 25% proved optimal, yielding samples with superior strength and stiffness. While cold pressing initially enhances the bonding properties of MOC, solution loss during the process adversely affects its long-term bonding characteristics. From a mechanical standpoint, the silica-magnesium oxide-magnesium chloride system demonstrates exceptional early strength and resilience, positioning it as a promising rock-like material system.

In-plane and out-of-plane anisotropy in the optical and dielectric properties of YBa2Cu3O7-x superconducting film

YBa2Cu3O7-x (YBCO) is a crucial aspect of research in the field of superconducting applications, where its high anisotropy is generally undesirable in strong power transmission. However, from a dialectical perspective, a thorough investigation of material anisotropy can offer an additional degree of freedom to tune potential properties and design innovative devices. This work employed pulsed laser deposition to fabricate a high-quality YBCO thin film (Tc = 89 K) and used the Mueller matrix spectroscopic ellipsometer (MMSE) to determine the complete dielectric tensor of the YBCO film across the ultraviolet to near-infrared spectrum (245–1000 nm), enabling a comprehensive, quantitative study of the optical anisotropy of YBCO. It provided optical constants and dielectric function spectra for different axes. We found that YBCO exhibits birefringence and dichroism both in-plane and out-of-plane. By combining standard critical point (SCP) analysis and first-principles calculations, we identified specific interband transitions related to SCP in the YBCO dielectric spectra, revealing the physical essence of anisotropic optical transitions from a quantum mechanical standpoint. Temperature-dependent studies of the transitions and optical constants were conducted. The work fills a partial void in the optical parameters of the anisotropy of YBCO and holds relevance for understanding the origins of copper-based high-temperature superconductivity.

Simplified Formula for Nominal Force at Critical Welds in the Lower Chord Node of a Novel Bracket-Crane Truss Structure

In the realm of practical engineering, engineers commonly employ rod system models for modeling and analysis, which consequently precludes them from calculating the nominal forces exerted on welds at intricate nodes. This paper addresses the design challenges of the innovative bracket-crane truss structure by proposing a simplified nominal force calculation formula for critical welds of the integrated node. This study commences with the establishment of the frame model and ABAQUS multiscale models, utilizing engineering project drawings and data, followed by a verification of the similarities between the two simulation methods. This similarity of outcomes provides a foundation for directly using the computational results from the frame model in future calculations of the forces at the weld locations. From a mechanical standpoint, this paper derives nominal force calculation formulas for horizontal and vertical welds at critical locations for three node types. Additionally, a formula for calculating nominal shear forces in vertical welds at the end plate of support nodes is introduced. The applicability of these derived formulas is subsequently validated, ensuring their efficacy in accurately capturing relevant forces at critical locations. The presented nominal force calculation formula serves as a valuable tool for optimizing the design and guaranteeing the structural integrity of the integrated node within this distinctive engineering context.

Devices for Gait and Balance Rehabilitation: General Classification and a Narrative Review of End Effector-Based Manipulators

Gait and balance have a direct impact on patients’ independence and quality of life. Due to a higher life expectancy, the number of patients suffering neurological disorders has increased exponentially, with gait and balance impairments being the main side effects. In this context, the use of rehabilitation robotic devices arises as an effective and complementary tool to recover gait and balance functions. Among rehabilitation devices, end effectors present some advantages and have shown encouraging outcomes. The objective of this study is twofold: to propose a general classification of devices for gait and balance rehabilitation and to provide a review of the existing end effectors for such purposes. We classified the devices into five groups: treadmills, exoskeletons, patient-guided systems, perturbation platforms, and end effectors. Overall, 55 end effectors were identified in the literature, of which 16 were commercialized. We found a disproportionate number of end effectors capable of providing both types of rehabilitation (2/55) and those focused on either balance (21/55) or gait (32/55). The analysis of their features from a mechanical standpoint (degrees of freedom, topology, and training mode) allowed us to identify the potential of parallel manipulators as driving mechanisms of end effector devices and to suggest several future research directions.

Preliminary Analysis and Optimization via CFD of a Liquid Hydrogen Pressure Regulating Piston Valve

Due to their high reliability and precision, piston valves are frequently used for pressure regulating applications. Particularly in the aerospace industry, where cryogenic fluids such as liquid hydrogen are frequently used, the design and operation of piston valves become crucial. The current state of advancement of this technology in the cryogenic field is still in its early stages, owing to the difficulties in designing such complex systems in harsh environments. This justifies the need for further in-depth studies and analysis using CFDs tools and predictive models. In order to ensure an optimal and efficient use of a piston pressure regulating valve in cryogenic environment, it is necessary to understand the strengths and limitations of this technology in an extreme thermal and mechanical condition. The presented work concentrates therefore on a preliminary analysis and optimization of a piston valve operating in liquid hydrogen flow field, for pressure regulating applications. Particular focus will be dedicated to the overall dynamics of the main body of the piston, in terms of robustness and controllability of the desired response of the system. The dynamics of the piston within an extremely low-viscous flow, as well as the thermodynamic and fluid dynamic aspects of the valve system, will be discussed. Simulations of the flow field will be performed through CFD tool, crossing the results with the dynamics of the simulated system response through and implemented Simulink model. The obtained results will be then critically analysed in order to suggest possible optimization of the valve in the locations where the system is most affected from a thermal and mechanical standpoint.

Influence of PLA impregnation on the performances of vegetable fibers for lime-based composites

In recent years, the application of inorganic lime-based Textile Reinforced Mortar (TRM) for repairing existing masonry structures has gained a relevant interest due to the strong compatibility between masonry elements and the strengthening composite. In addition, several research groups worldwide have recently focused on the possible use of natural fibers for replacing the traditional reinforcement (e.g., steel, fiberglass, basalt, PBO, aramid, carbon, etc.) generally employed for TRM composites. As a matter of fact, the natural fabrics (easily available and biodegradable) present comparable resistance to conventional fabrics, good compatibility with the lime-based mortars and elastic modules compatible with masonry elements. On the other hand, it has been also demonstrated that one of the most relevant aspects on their possible application is related their long-term and durability performances which can be mitigated with coating and impregnation treatments. In this context, the present paper presents the preliminary result of an experimental research aimed at investigating the influence of a biodegradable coating system (PLA - polylactic acid) applied to different types of natural fibers (made of flax and jute) on the resulting performances either from the physical and mechanical standpoint. The results demonstrate a significant improvement of the observed performance of natural fibers that can be more properly employed for the production of natural TRM composites.

Study on Mechanism of Static Blasting-Induced Hard Rock Fracture Expansion

How to deal with hard rock cheaply and safely is a pressing issue in today’s coal mining. Weakening fractures of hard rock have always been a significant concern in China’s coal mine engineering. In this study, mechanical derivation, laboratory experiments, and numerical simulation research methodologies are used to evaluate the fracturing process of the static crushing agent (SCA). From a mechanical standpoint, the mechanism of fracturing hard rock by a crushing agent is investigated. It is assumed that single-hole fracturing is separated into three stages: the microfracture stage, the fissure development stage, and the breaking stage. The swelling and fracturing properties of SCA were quantitatively analyzed. It was found that the swelling pressure of SCA increased with the increase in pore diameter, and the range of the swelling pressure was 43.5 MPa to 75.1 MPa. SCA exhibited a delayed fracture initiation, but the rate of breakage was relatively high. The cracking effect of a single-hole specimen under no peripheral pressure was simulated using PFC2D, and the results were consistent with experimental observations. The internal dynamic effect, crack extension, distribution characteristics, and the development law of double-hole expansion pressure were analyzed for double-hole specimens with different hole diameters, hole spacings, and circumferential pressures. It was observed that the cracking effect was positively correlated with the pore diameter, while the pore spacing and surrounding pressure were negatively correlated. The size of the expansion pressure was negatively correlated with the pore diameter, while the pore spacing and surrounding pressure were positively correlated.

Thermo-viscoelastic multiscale homogenization of additively manufactured short fiber reinforced polymers from direct microstructure characterization

Short fiber reinforced polymers (SFRPs) processed by Fused Filament Fabrication (FFF) show great promise for applications requiring high weight-specific mechanical properties, such as aerospace. However, the unique morphology created by the printing process and the relationship between processing parameters and part behavior is not sufficiently well understood, making structural analysis a largely empirical task. The limited ability to predict the effective viscoelastic properties and their thermal dependence is a problem from a mechanical design standpoint and is an obstacle to the widespread adoption of SFRPs made by FFF. In this work, those properties are evaluated using high-resolution imaging of physical samples, enabling the accurate prediction of time-dependent stress–strain relations across different temperatures. Multiscale homogenization is performed considering individual components (fibers, pores, matrix) at the microscale, and the regular pattern created by the printing process at the mesoscale. The efficiency of the Fast Fourier Transform (FFT) based homogenization procedure is leveraged to allow for large Representative Volume Element (RVE) sizes, which are required due to the complexity of real microstructures. The predicted thermo-viscoelastic behavior is validated against creep-recovery data of specimens printed from 30 wt% short carbon fiber reinforced poly-ether-ether ketone (PEEK), and the experimental data can be predicted within 3% mean relative error for axial loading, both at 21°and 120 °C. Imaging data and pre-processed RVEs as well as original source code are made publicly available.

Assessment of different manufacturing techniques for the production of bioartificial scaffolds as soft organ transplant substitutes.

Introduction: The problem of organs' shortage for transplantation is widely known: different manufacturing techniques such as Solvent casting, Electrospinning and 3D Printing were considered to produce bioartificial scaffolds for tissue engineering purposes and possible transplantation substitutes. The advantages of manufacturing techniques' combination to develop hybrid scaffolds with increased performing properties was also evaluated. Methods: Scaffolds were produced using poly-L-lactide-co-caprolactone (PLA-PCL) copolymer and characterized for their morphological, biological, and mechanical features. Results: Hybrid scaffolds showed the best properties in terms of viability (>100%) and cell adhesion. Furthermore, their mechanical properties were found to be comparable with the reference values for soft tissues (range 1-10 MPa). Discussion: The created hybrid scaffolds pave the way for the future development of more complex systems capable of supporting, from a morphological, mechanical, and biological standpoint, the physiological needs of the tissues/organs to be transplanted.

Effects of Apical Barriers and Root Filling Materials on Stress Distribution in Immature Teeth: Finite Element Analysis Study

PurposeA finite element analysis (FEA) study was performed to determine whether the material of apical barrier used for root apexification and/or the use of canal reinforcement affect the stress distribution in an endodontically treated immature permanent tooth in order to infer in which clinical scenarios a fracture is more likely to occur based on the ultimate tensile strength threshold of dentin. Methods and MaterialsAn extracted human immature mandibular premolar was selected as the reference model and scanned by micro-computed tomography (micro-CT). The digital model was segmented and converted to STL (Standard Tessellation Language) using Simpleware Scan-IP and exported in IGES (Initial Graphics Exchange Specification) to Ansys 19. Six experimental models were designed with different combinations of composite, mineral trioxide aggregate (MTA), and Biodentine (BIO). Using FEA, a static 300 N load at a 135 angle with respect to the axis of the tooth was applied to each model and von Mises stress values (MPa) were measured at the sagittal, apical 8-mm, 5-mm, 2-mm, and 1-mm levels. ResultsIn all regions examined, the control (NT model) had lower stress in the root compared WITH experimental models. At the mid-root level, models with composite, MTA, and BIO reinforcement exhibited lower stresses in the root dentin than those with pulp or gutta-percha. BIO models had equal or greater average von Mises stress values than those of MTA models in all regions. Both, MTA and BIO, caused increases in stress of surrounding root dentin, with BIO causing a greater increase than MTA. ConclusionsStress distribution in immature permanent teeth treated by apexification is affected by the types of materials used. Root dentin's stress was lower when the mid-root canal was reinforced by composite, MTA, or BIO, which provided similar stress reduction to the root dentin. MTA is a more favorable apical barrier material from a mechanical standpoint because it induces less stress on apical root dentin than BIO.

Artificial Intelligence for Power Electronics in Electric Vehicles: Challenges and Opportunities

Abstract Progress in the field of power electronics within electric vehicles has generally been driven by conventional engineering design principles and experiential learning. Power electronics is inherently a multidomain field where semiconductor physics and electrical, thermal, and mechanical design knowledge converge to achieve a practical realization of desired targets in the form of conversion efficiency, power density, and reliability. Due to the promising nature of artificial intelligence in delivering rapid results, engineers are starting to explore the ways in which it can contribute to making power electronics more compact and reliable. Here, we conduct a brief review of the foray of artificial intelligence in three distinct subtechnologies within a power electronics system in the context of electric vehicles: semiconductor devices, power electronics module design and prognostics, and thermal management design. The intent is not to report an exhaustive literature review, but to identify the state of the art and opportunities for artificial intelligence to play a meaningful role in power electronics design from a mechanical and thermal standpoint, as well as to discuss a few promising future research directions.

Embedded Instrumentation System Using Acquisition Mechanism for BLDC-Powered Electric Vehicle

The primary component of an electric vehicle is the electric motor. In order for the motor to operate properly, some measurement and data acquisition are required for monitoring and controlling its performance. For this purpose, an embedded system is developed and attached to the vehicle. This paper presents the design and implementation of an embedded instrumentation system that includes a data acquisition device, data processor, and data display. A complete prototype-scale electric vehicle was developed and equipped with an embedded instrumentation system. A Brushless DC (BLDC) motor is employed as prime-mover taking power from a 10-Ah Battery. The input parameter is determined by the vehicle’s throttle opening, and the output variables are measured and processed. For the purpose of data acquisition, the system relies on Arduino and Raspberry Pi as processing and monitoring devices. The data and information are displayed on the vehicle dashboard to indicate the real-time vehicle performance and some related information. These include speed, power, motor temperature, distance achieved, and estimated distance that can still be reached with the remaining battery capacity. The data and information are graphically and numerically displayed, which would be useful for steering that enhances system efficiency. The system was tested in the lab and real system, where it demonstrated fine accuracy. The average deviations of the electrical data displayed in the instrumentation system with those given by the standard meter are 0.25 Volt, 0.03 Amp, and 0.43 Watt for voltage, current, and power, respectively. From a mechanical standpoint, the average deviations of speed and torque are 1.2876 km/h and 1.218*10-4 Nm, respectively. The contributions of this research are the development of a complete system to be operated in real conditions, and validation of the displayed information with standard measurement and manual calculation.

Unmoved movers: a very simple and novel form of indeterminism

It is common knowledge that the Aristotelian idea of an unmoved mover (Primum Mobile) was abandoned definitively (from a mechanical standpoint, at least) with the advent of modern science and, in particular, Newton’s precise formulation of mechanics. Here I show that the essential attribute of an unmoved mover (in a non-trivial sense, and in the context of infinite systems theory) is not incompatible with such mechanics; quite the contrary, it makes this possible. The unmoved mover model proposed does not involve supertasks, and (perhaps precisely for this reason) leads both to an outrageous form of indeterminism and a new, accountable form of interaction. The process presents a more precise characterization of the crucial going-to-the-limit operation (which will admittedly require further development in future research). It has long been acknowledged in the existing literature that, theoretically, in infinite Newtonian systems, masses can move from rest to motion through supertasks. Numerous minor variations on the original schemes have already been published. Against this backdrop, this paper introduces three significant additions: 1) It formulates for the first time a limit postulate for systematically addressing infinite systems; 2) It shows that an Aristotelian unmoved mover (with no supertask) is possible in systems of infinitely many particles that interact with each other solely by contact collision; 3) It shows how interaction at a distance can emerge in systems of infinitely many particles (at relative rest) that interact with each other solely by contact.

Evaluation of test methods for fracture resistance of high modulus asphalt binders from rheological and mechanical perspectives

High modulus asphalt binder (HMAB) has excellent rutting resistance but it might have premature cracking concerns due to its high stiffness. In this study, the intermediate temperature fracture performance of six HMABs was evaluated from a rheological and mechanical standpoint. The linear amplitude sweep (LAS) test, Glover-Rowe (G-R) parameter, and pure linear amplitude sweep (PLAS) test were employed for the rheological characterization, while the binder fracture energy (BFE) test and the double-edge notched tensile (DENT) test were implemented to investigate mechanical performance. The results show that HMABs have lower cracking resistance than conventional asphalt binders, and this was due to the insufficient ductility of their internal polymer networks. Of the five test methods, the PLAS, BFE, and DENT tests are highly recommended for evaluating the cracking resistance of HMABs at intermediate temperatures.

Design of Planetary Gear Train for Geared Rotary Actuator

Geared Rotary Actuators are mechanically operable devices widely used in the aerospace industry so that controlled motion can be provided to secondary flight control surfaces. Their usage can be seen in a variety of applications including powered hinges for aircraft structural movements, they support aerodynamic loads in addition to the surface hinge moment, as an actuator in a linked mechanism where they supply actuation torque. Mostly GRAs are situated along with the bay door drives, and also can be used for controlling leading or trailing edge movements of the aircraft. They receive Power Drive Unit (PDU) torque via assembly of shafts and joints. From a mechanical standpoint, the GRAs can be termed as epicyclical gear reducer or compound planetary gearbox. In this work, the governing criteria and mathematical equations used to characterize GRA are discussed. SOLIDWORKS is used for part modeling of GRA. More focus will be on the speed reduction ratio calculation, determination of strength, and overall Factor of Safety (FOS) of the torque transmission unit. Thus an attempt is made to obtain the best performance parameters to meet the desired requirements of Geared Rotary Actuator.

Design and Validation of a Device Attached to a Conventional Bicycle to Measure the Three-Dimensional Forces Applied to a Pedal.

Knowledge of the forces applied to the pedals during cycling is of great importance both from the point of view of improving sporting performance and medical analysis of injuries. The most common equipment for measuring pedal forces is usually limited to the study of forces in the sagittal plane. Equipment that measures three-dimensional forces tends to be bulky and to be incorporated into bicycles that are modified to accommodate it, which can cause the measurements taken to differ from those obtained in real pedalling conditions. This work presents a device for measuring the 3D forces applied to the pedal, attachable to a conventional bicycle and pedals, which does not alter the natural pedalling of cyclists. The equipment consists of four gauges located on the pedal axis and two on the crank, controlled by a microcontroller. Pedal forces measurements were made for six cyclists, with results similar to those shown in the literature. The correct estimation of the lateral-medial direction force is of great interest when evaluating a possible overload at the joints; it will also allow a comparison of the effectiveness index during pedalling, showing the role of this component in this index from a mechanical standpoint.

Feature Lines Modification Based on As-Stiff-As-Needed Surface Deformation

Aesthetic surface mesh modification, guided by a deforming feature line, is still a challenging task. Whereas most existing surface deformation methods work well when the new surface is stretched or isometrically deformed, in case of areas subjected to compression, unwanted bulging may appear. This configuration typically appears when a designer slides a feature line along the input surface. In this paper, we present a new approach for feature line modification solving the surface bulging problem. We consider physically-based deformation methods applied to surface meshes and characterize configurations that produce compression loading from a mechanical standpoint. Then, the deformation area is decomposed into two sub-domains with a boundary modification of the one subjected to compression loading. Thus, during a subsequent deformation, this sub-domain no longer undergoes a compression loading but rather a traction loading, which ultimately prevents bulging. This transformation looks like a retraction of this surface area and a corresponding processing pipeline is set up.Our feature line modification method is intuitive to use and runs interactively, making it attractive to be used during design reviews in immersive environments. Industrial examples and comparisons with state-of-the-art physically-based deformation methods validate the proposed approach.

The differential effects of time and usage on the brand premiums of automobiles

We investigate how the status and functional benefits of cars’ brands lose value over time. Theoretically, we show that brands with a higher status, or that appeal to status-conscious consumers, exhibit steeper price decline over time. Empirically, we take advantage of the phenomenon of twin cars – pairs of car models that are nearly identical from a structural and mechanical standpoint, but that are sold under differing brand names – to disentangle the effects of physical wear and tear, which should impact both the premium brand and the corresponding standard brand similarly; and time-related price decline, which should affect each brand differently. The main result is that a premium car’s price declines much faster than that of the corresponding standard car (controlling for physical condition, mileage, and initial price). This result suggests that status declines faster than do functional attributes, and status seekers tend to replace their cars earlier.

Green Composites Based on PLA and Agricultural or Marine Waste Prepared by FDM.

Three dimensional-printability of green composites is recently growing in importance and interest, especially in the view of feasibility to valorize agricultural and marine waste to attain green fillers capable of reducing bioplastic costs, without compromising their processability and performance from an environmental and mechanical standpoint. In this work, two lignocellulosic fillers, obtained from Opuntia ficus indica and Posidonia oceanica, were added to PLA and processed by FDM. Among the 3D printed biocomposites investigated, slight differences could be found in terms of PLA molecular weight and filler aspect ratio. It was shown that it is possible to replace up to 20% of bioplastic with low cost and ecofriendly natural fillers, without significantly modifying the processability and the mechanical performance of the neat matrix; at the same time, an increase of surface hydrophilicity was found, with possible positive influence on the biodegradability of such materials after disposal.