Mechanical Model Research Articles

Research on dynamic performance and mechanical model of a novel magnetorheological shear thickening damper with adaptive variable damping gap

Abstract Magnetorheological shear thickening fluid (MRSTF) is an intelligent composite material, which shows considerable potential in semi-active vibration control. However, the current research is mostly limited to the study of the rheological properties of materials, and there is still a lack of damper structures that can effectively utilize the dual-control characteristics of MRSTF. In this paper, a novel damper structure with adaptive adjustable damping gap length is proposed. Its unique design integrates an adaptive internal damping gap that changes with the movement of the piston and an external gap controlled by the magnetic field, providing a relatively wide range of current-controlled damping force and reliable adaptive adjustment capabilities. Based on the M-S shear stress constitutive model and structural characteristics, the mechanical model is derived from the force balance of the micro-element, and verified by performance test and curve fitting. The effectiveness of the new damper structure proposed in this paper is verified by dynamic performance test. The results show that the damper has a wide range of current controlled damping force at low speed and reliable adaptive adjustment capability at high speed. Finally, the accuracy and universality of the modified mechanical model of damper are verified by curve fitting method. All these studies can offer an effective guidance for further application of MRSTF in the field of semi-active vibration control.

Electromagnetic Field and Variable Inertia Analysis of a Dual Mass Flywheel Based on Electromagnetic Control

The moment of inertia of the primary flywheel and the secondary flywheel in a dual mass flywheel (DMF) directly affects the vibration damping performance in an automotive driveline. To enable better minimization of vibration and noise by changing the moment of inertia of the DMF to adjust the frequency characteristics of the automotive driveline, a new variable inertia DMF structure is proposed by introducing electromagnetic devices. The finite element simulation model of the electromagnetic field of an electromagnetic device is established, the electromagnetic field characteristics in the structure are analyzed, and the variation in the electromagnetic force under different air gaps and current conditions is obtained. The electromagnetic force test system of the electromagnetic device is constructed, and the validity of the finite element simulation analysis of the electromagnetic field of the electromagnetic device is verified. A mechanical model of the electromagnetic device is established to analyze the characteristics of the displacement of the moving mass in the structure as well as the variation in the moment of inertia of the DMF at different rotational speeds and currents. The maximum adjustable proportion of its moment of inertia can reach 15.07%. A torsional model of the automotive driveline is established to analyze the effect of variable inertia DMF on the resonance frequency of the system under different currents. The results show that the electromagnetic device introduced in the DMF can realize the active adjustment of the moment of inertia and enable the resonance frequency to decrease with increasing rotational speed, which expands the idea of optimizing the vibration damping performance of the DMF and provides a reference for better control of the torsional vibration of the automobile or other mechanical transmission systems.

Study of Microstructural Evolution and Strain Analysis in SiOx/C Negative Electrodes Using In‐situ X‐ray Tomography and Digital Volume Correlation

Increasing the silicon content in batteries is expected to enhance their capacity. However, its implementation comes with challenges, as silicon exhibits a large volumetric expansion. This is a significant factor contributing to the decreased lifespan of these batteries, one of the critical degradation mechanisms from a mechanical perspective is the delamination of electrode structure. The cyclability of these anodes is noted to be influenced by the interaction between the binder and particles during battery cycling. The heavy local strain experienced by particles in these electrodes often leads to binder failure, resulting in particle detachment, or delamination over multiple cycles. A good understanding of the local evolution of the strain is essential in advancing the mechanical modelling of the degradation mechanism and in realizing the complete potential of silicon‐based electrodes. In this work, in situ global and local strain measurements were performed by combining synchrotron tomography with Digital volume correlation (DVC). The measurements showed that there is significant local strain in these electrodes which can lead to delamination. In addition to this, the spatial variability of the composite electrodes was characterized by estimating the characteristic length to strain, which can be used to replicate the strain field and model the delamination.

Design and Experiment of an Inter-Row Weeding Machine Applied in Soybean and Corn Strip Compound Planting (SCSCP)

To address the lack of specialized machinery for the mechanical weeding of SCSCP in the Huang Huai Hai region, this study designs a mechanized inter-row weeding machine for SCSCP. The machine features a reciprocating weeding shovel and an adaptive contouring mechanism for cultivation and soil loosening. This paper details the machine’s principles by analyzing the geometric relationship and mechanical model between the corresponding profiling quantities, which determine the relevant parameters for adaptive contouring to ensure stable operation on undulating ground. Furthermore, by optimizing the design of the weeding shovel’s reciprocating motion mechanism, combining EDEM simulation with the weeding shovel–soil interaction, it has been determined that, at various PTO shaft speeds, the optimal weeding efficacy is achieved with a blade-type weeding shovel structure when operating at a forward speed of 3.5 km/h. Field experiments were conducted with different PTO shaft speeds and weeding depths, using weeding and seedling injury rates as performance indicators. The results showed that, based on the optimal speed, the PTO shaft speed is 760 r/min, the operating depth is 3–5 cm, and the average row weeding rate is 90.4%. The average soybean and corn seedling injury rate is 3.4% and 4.2%, meeting the technical requirements for mechanical weeding.

Investigating the impact of corrosion on behavior and failure modes of reinforced concrete slabs: An experimental and analytical study

Corrosion of steel reinforcement significantly reduces the load-carrying capacity of reinforced concrete (RC) flat slabs, making them more vulnerable to punching shear failure. This type of failure can lead to sudden and catastrophic collapse of the structure. Despite its critical implications, research on this topic remains limited, and a mechanical model to estimate the load-displacement behavior of RC flat slabs with corroded reinforcements is currently lacking. In this paper, experimental work on corroded RC slabs under punching shear loading was conducted. To investigate the impact of corrosion on the structural behavior of reinforced concrete (RC) flat slabs, eight specimens, including both corroded and uncorroded controls, were subjected to load testing. The study focused on key performance indicators including punching shear strength, stiffness, crack patterns, failure modes, and energy dissipation capacity. Additionally, an analytical study based on the newly developed Critical Shear Crack Theory (CSCT) was conducted to understand the behavior of corroded RC slabs. Experimental results indicated a significant reduction in the punching shear strength of corroded slabs. Moreover, as corrosion progressed, a notable shift in failure mode from punching shear to flexural failure was observed. The proposed CSCT model demonstrated good agreement between the experimentally obtained and analytically predicted load-displacement curves.

ANALYTICAL DESCRIPTION AND ALGORITHM OF CALCULATIONS OF MECHANICS OF STRUCTURES WITH BERNOULLI – EULER BEAMS USING SCAS KIDY

The problems of developing a universal analytical description and algorithm for automatic computer calculations of dynamics, statics and kinetostatics of mechanical models of structures including a beam lattice are considered. This can be calculations of transient processes, steady-state free and forced oscillations, determination of equilibrium positions and stress-strain states under static and dynamic loads, etc. The structure itself can be flat or spa- tial, stationary or moving on a plane or in space. Various instruments and devices can be attached to it. Arbitrary connections can be taken into ac- count. It is shown how it is possible to succinctly, using a special language for preparing computer data, analytically describe a part of a structure rep- resenting a beam lattice. Based on the theory of elasticity of Bernoulli-Euler beams, 2 forms of the canonical representation of the potential energy of an elastic beam are obtained. This makes it possible to introduce into the language of description of mechanical models of the special computer algebra system KiDyM (SCAS KiDyM) a new beam element, for which the position of the coordinate systems associated with the extreme sections is indi- cated. The positions of these sections are determined by lattice nodes, like solid bodies. Angular and linear coordinates of such solid bodies give gen- eralized coordinates of the mechanical model. An algorithm has been developed for the formation of elements adopted to describe mechanical models in SCAS KiDyM. Thus, the elastic structure of the mechanical model is formed. Using the available tools in this program, equations of dynamics and statics are automatically constructed, that is, a mathematical model is formed, and dynamic and static calculations can be carried out. The proposed method is demonstrated in detail on the example of calculating the deformation of an elastic lattice, with is the basis of a UAV (unmanned aerial vehi- cle). The results are compared with calculations using the ANSYS program

Peanut Pickup Combine Harvester Seedling Vines Crushing Mechanism Performance Enhancement and Pilot Studies

Aiming at the current peanut pickup combine harvester seedling vines crushing mechanism operation qualified seedling length rate is low, the impurity rate is high, and the seedling vines crushing mechanism is optimized design. On the basis of the material characteristics of peanut seedling vines, taking the crushing mechanism as the research carrier, the interaction mechanism of the seedling vine mechanism was analyzed. Establish the mechanical model and motion trajectory model in the crushing process, simulate the peanut seedling vines crushing process based on the discrete element method, analyze the influence of the cutter shaft rotational speed, movement speed, and bending angle on the crushing of peanut seedling vines, and establish the regression model, and the results of the research show that the influence factors in the main order of priority are: knife shaft speed > movement speed > bending angle The optimal parameter combination is knife shaft speed 2171.94 r/min, movement speed 0.79 m/s, and bending angle 45°. According to the field test conditions, it is determined that the knife shaft rotational speed of 2170 r/min, movement speed of 0.8 m/s, and bending angle of 45° can make the peanut seedling vines crushing mechanism of the work performance to achieve a qualified seedling length rate of 97.292%, the rate of impurity content of 2.746%, and the error with the predicted value is less than 2%, which indicates that this study can provide a reference for the optimal design of the seedling vines crushing mechanism of the peanut pickup combine harvester.

Research and analysis of rock breaking mechanical model of single-roller PDC compound bit

In order to improve wear resistance and rock breaking efficiency of single-roller bit, a new type of bit, single-roller PDC compound bit is designed. The mechanical model of interaction between PDC teeth and rock of single-roller PDC compound bit is established, and the theoretical calculation formula of resultant force and torque generated by interaction between PDC teeth and rock on cone and bit is obtained. The rock-breaking experiment on the single-roller PDC compound bit are carried out. The results show that with the increase of front inclination angle, the axial force and radial force of PDC teeth decrease greatly at first and then tend to be stable, while the tangential force of PDC teeth decreases at first and then increases slightly; the axial force, radial force and tangential force all increase with the increase of the cutting depth; the maximum values of the three forces all appear at the position of the combined effect of the maximum cutting depth and the minimum front inclination angle. The maximum value of moment [Formula: see text] and [Formula: see text] both appear at the minimum value of h C and δ, while the maximum value of moment [Formula: see text] appears at the minimum value of δ. In order to reduce the acting moment generated by PDC cutter on the roller, the PDC cutter at different position heights can be designed with different front inclination angles. The rock breaking experiment results show that compared with the common single-roller bit, the single-roller PDC compound bit has higher rock breaking efficiency and better development prospect. When drilling in hard limestone, the single-roller PDC compound bit is more energy-efficient under higher WOB.

Microscopic analysis of relaxation behavior in nonlinear optical conductivity of graphene

Abstract We produce a general formalism to study the interband dynamical optical conductivity in the nonlinear regime of graphene in the presence of a quantum bath comprising phonons and electrons. When a quantum solid of graphene is subjected to an intense electric field in the optical frequency range, the observation of a nonlinear response is facilitated by formulating a quantum master equation of the density operator associated with the Hamiltonian encapsulated in a spin-boson model of dissipative quantum statistical mechanics. Our results reveal the nonlinear steady-state regime's population inversion and decoherence. The present method enables us to investigate further the nonlinear interband optical conductivity of pristine and gapped graphene characterized by a single dimensionless parameter at finite temperatures. The effects of different bath spectra for phonons and electrons are examined in detail. {\color{red} The temperature dependence of conductivity reveals that changing temperature can enable us to make the transition from the linear to the nonlinear regime for fixed optical field parameters.} Interestingly, a fascinating switching-like behavior is observed for the low-temperature optical conductivity of the gapped graphene while we vary the energy gap as well as the frequency of the externally applied field. Although our general formulation can address a variety of nonequilibrium responses of the two-band system, it also facilitates a connection with the phenomenological modeling of nonlinear optical conductivity.

Fundamental mechanical relations of open-cell metal foam composite materials with reticular porous structure

The compressive behavior is one of the most fundamental mechanical properties for engineering materials. In this paper, the octahedral structure model of porous materials is used to evolve the mechanical analysis model under compressive loading for the porous composite materials, which are resulted from reticular metal foams with pore struts presenting multilayered structure. Starting from this analysis model, some fundamental mechanical relationships, including those of the safe load-bearing and overall strength, have been deduced for these porous composite materials. The compressive strength has been characterized for the porous composite body, corresponding to the overall failure caused by the prior breakage of the strut core and by the prior breakage of the strut shell, respectively. The nickel foam products manufactured on the production line of enterprise were used to make porous composite materials by coating the pore struts with epoxy resin, and the metal foam composite material was obtained with the composite pore-struts of metal/resin multilayered structure. Using this porous composite material for compression experiments, it is found that the experimental data match well with the mathematical relationship from the present theoretical model. The results verify the feasibility of this analysis model and the practicality of the relevant mathematical relationship.

Explore the feasibility of using spot-scanning proton arc therapy for a synchrotron accelerator-based proton therapy system - A simulation study.

The aim of this study was to evaluate the feasibility and plan quality of spot-scanning proton arc therapy (SPArc) using a synchrotron-accelerator-based proton therapy system compared to intensity-modulated proton therapy (IMPT). Five representative disease sites, including head and neck, lung, liver, brain chordoma, and prostate cancers, were retrospectively selected. Both IMPT and SPArc plans are generated with the HITACHI ProBEAT PBS system's minimum MU constraints and physics beam model. The SPArc plans are generated with 2.5° sampling frequency. The static delivery time was simulated based on the previously published synchrotron delivery sequence model, and the dynamic delivery time was simulated using a proton arc gantry mechanical model integrated with the synchrotron delivery sequence. Both dosimetric plan quality and delivery efficiency are evaluated. A superior plan quality is reached compared with the IMPT plans generated for the same disease site. However, a relatively prolonged static and dynamic delivery time post new challenge, as static time increased by 49.22% and dynamic time 59.10% on average. This study presents the first simulation results of delivering the SPArc plans using a synchrotron-accelerated proton therapy system. The result shows its feasibility and limitations, which could guide future development.

Топологические изоляторы в электронных и спинтронных устройствах

Background: Topological insulators (TIs) are materials with distinctive features, including insulating interiors and conducting surface states protected by time-reversal symmetry. These features make TIs extremely promising for electrical and spintronic device applications, where manipulating electron spin without charge transfer is advantageous. Objective: This study aims to investigate of TIs to improve the performance and efficiency of electrical and spintronic devices. We look at the special qualities of TIs that may be used to improve device functionality, such as reduced power consumption and higher operational speed. Methods: To investigate electron transport behaviour on the surfaces of different TIs, we used a mix of quantum mechanical models and experimental settings. Devices based on bismuth telluride (Bi2Te3) and thallium arsenide (TlAs) were built to test their performance in real-world applications. Results: TI devices showed considerable gains in spin transport efficiency and thermal stability compared to conventional materials. Spintronic devices based on TIs demonstrated a 50% reduction in energy usage and a 30% improvement in data processing speed. Conclusion: Including topological insulators in electrical and spintronic devices offers a promising path to more efficient and speedier technologies. Future research should concentrate on the scalable integration of TIs into commercial devices and the discovery of novel materials with topological insulating characteristic.

A coupled model for precipitation strengthening in Mg-Zn alloys

A recently developed precipitation model is coupled to an original mechanical model to predict the strength evolution in Mg-Zn alloys during aging. The proposed models consider the strengthening effects of rod and plate-shaped precipitates on the most important deformation mechanisms in Mg alloys: basal slip, prismatic slip, and twinning. It is found that shearing of rod precipitates dominates the strengthening on basal slip at early aging stages, while the bypass mechanism dominates medium and over-aging stages. On prismatic planes, the bypass of rod precipitates dominates across all aging stages. The influence of different precipitate arrangements and aspect ratios on modelling results is also discussed. The strengthening from plate-shaped precipitates is found to be very poor for the studied slip modes. While for twinning, the strength evolution is nicely represented by bypassing of rod-shaped precipitates. The evolutions of tensile and compressive yield strength during aging are well predicted by considering the hardening on prismatic and twinning planes, respectively.

Low frequency vibration monitoring of wind turbine tower based on optical fiber sensor and its potential for internet of things

Among all renewable energy sources, wind energy is a cost-effective alternative energy source. The majority of wind turbines are built in harsh environments due to their power generation characteristics, which is one of the prime reasons resulting in frequent failures of wind turbine. Among various failures, the vibration of wind turbine tower cannot be ignored because it is a precursor of the failure of the wind turbine. The electrical vibration sensors have the problems of power supply and electromagnetic interference for the condition assessment of wind turbine tower. A vibration sensor based on optical Fabry-Perot (F-P) interference principle with high sensitivity is designed, fabricated and characterized to further meet the requirements of vibration detection of wind turbine tower. The mechanical simulation model of the diaphragm and optical vibration platform is constructed to verify the sensing characteristic of the F-P optical fiber vibration sensor (OFVS). The experiment results indicate a resonant frequency of the F-P OFVS of 223 Hz, an output sensitivity of 122.22 mV/m·s−2 at 10 Hz, and a horizontal output of less than 6 %. In addition, the designed F-P OFVS possesses the superiorities of compact structure, passive and excellent anti-electromagnetic interference, and has a wide application prospect in the vibration detection of the wind turbine tower.

Evaluation of Mechanical Response during Nano Scale Contact for Contact Mechanics Model of Fatigue Wear

Evaluation of Mechanical Response during Nano Scale Contact for Contact Mechanics Model of Fatigue Wear

Advancements in Subchondral Bone Biomechanics: Insights from Computed Tomography and Micro-Computed Tomography Imaging in Equine Models.

This review synthesizes recent advancements in understanding subchondral bone (SCB) biomechanics using computed tomography (CT) and micro-computed tomography (micro-CT) imaging in large animal models, particularly horses. Recent studies highlight the complexity of SCB biomechanics, revealing variability in density, microstructure, and biomechanical properties across the depth of SCB from the joint surface, as well as at different joint locations. Early SCB abnormalities have been identified as predictive markers for both osteoarthritis (OA) and stress fractures. The development of standing CT systems has improved the practicality and accuracy of live animal imaging, aiding early diagnosis of SCB pathologies. While imaging advancements have enhanced our understanding of SCB, further research is required to elucidate the underlying mechanisms of joint disease and articular surface failure. Combining imaging with mechanical testing, computational modelling, and artificial intelligence (AI) promises earlier detection and better management of joint disease. Future research should refine these modalities and integrate them into clinical practice to enhance joint health outcomes in veterinary and human medicine.

Topology optimization for precipitation hardening in ferroelectric material

AbstractRecent studies have shown that precipitation hardening effectively enhances the mechanical quality factor of ferroelectric material. In this work, Li‐doped , a material system with elliptical precipitates is investigated. We present a mechanical model to determine energetically stable precipitate shapes by minimizing the total energy, consisting of elastic and interface energy. Furthermore, we investigate the influence of external loads on the precipitate topology. Correct elastic constants as well as lattice misfits for the simulation are provided. The shapes determined from finite element simulations agree well with observed results.

Tracking the 2007–2023 magma-driven unrest at Campi Flegrei caldera (Italy)

Understanding and managing unrest at a volcano include i) ascertaining the magmatic distribution and migration, and ii) tracking the evolution of the shallow plumbing system. Here we use multi-technique geodetic data, mechanical models, and petrological simulations to define both aspects for the ongoing (2005-present) unrest at Campi Flegrei caldera, Italy. Results show a deformation source exhibiting progressive widening and shallowing, from 5.9 to 3.9 kilometres. Concurrently, a deeper tabular source at 8 km depth experiences limited but constant deflation. Petrological calculations explain inflation of the shallower source resulting from the rise of 0.06 to 0.22 cubic kilometres of magma from depth ≥8 kilometres. Our analysis provides strong evidence that magma ascent to depths shallower than 8 kilometres is the ultimate driver behind the ongoing unrest. This merging of geodetic and petrological approaches to track the evolution of a plumbing system better constrains magma ascent at volcanoes experiencing unrest.

Microstructure-Dependent Macroscopic Electro-Chemo- Mechanical Behaviors of Li-Ion Battery Composite Electrodes

The rapid development of the electric vehicle industry has created an urgent need for high-performance Li-ion batteries. Such demand not only requires the development of novel active materials but also requires optimized microstructure of composite electrodes. However, due to complicated heterogeneous electrode microstructure, there still lacks a relationship between the electrode microstructure and the macroscopic electro-chemo-mechanical performance of the battery. In this study, electrochemical and mechanical multi-scale models are developed in order to account for the influence of the heterogeneous microstructure on the macroscopic mechanical and electrochemical behavior of the battery. It is found that porosity and particle size are two important parameters to characterize the microstructure that can affect the macroscopic mechanical and electrochemical behavior. The models developed in this study can be served as designing guidelines for the optimization for the Li-ion battery composite electrodes.

Cyclic response of unsaturated weathered red mudstone: Experimental investigation and a cyclic model

The mechanical properties and constitutive model of unsaturated soils under cyclic loading are crucial for understanding the behavior of foundations and slopes subjected to dynamic motions such as earthquakes and traffic loading. In this study, multilevel strain-controlled cyclic simple shear tests of unsaturated weathered red mudstone (WRM) were conducted. The detailed investigation focused on cyclic responses, including shear stress-strain behavior and volume change, strain-dependent secant shear modulus and damping ratio, and stress–dilatancy behavior. This study revealed the significant influences of the degree of saturation and vertical stress on these responses, with the initial static shear stress mainly affecting the shear stress-strain behavior and volume changes at the initial loading stage. Based on the experimental observations, a cyclic constitutive model was proposed for unsaturated WRM. The model incorporates a slightly revised Davidenkov model and Masing criterion to generate shear stress-strain hysteresis loops with or without initial static shear stress. Additionally, a stress-dilatancy equation was included to capture the volume changes during cyclic loading. The proposed model was verified by comparing representative test data and calculation results, demonstrating the excellent performance of the proposed model in modeling the main features of unsaturated WRM under cyclic loading.