Resistance Force Research Articles

Dynamic response of piles embedded in granular soil to lateral impacts

Soil-embedded vehicle barriers, such as W-beam guardrail systems, play a pivotal role in transportation safety, mitigating the risks associated with vehicular collisions with roadside hazards. The efficacy of these barriers greatly depends on the pile-soil system's kinetic energy dissipation capability during vehicular impacts. However, a comprehensive understanding of how soil strength, embedment depth, and impact velocity collectively govern the dynamic behavior of the pile-soil system remains a gap in current research. This study explores the dynamics of lateral impacts on piles embedded in various granular soils. The process of dynamic lateral impact and interaction between the pile and the soil was modeled using the Updated Lagrangian Finite Element Method (UL-FEM). A damage-based element erosion algorithm was incorporated into the model to accommodate severe mesh distortions and element entanglements of the soil material brought by the pile impact. Validation against well-documented large-scale physical impact tests ascertained the model's fidelity. Our findings elucidate the significant differences in resistive forces between piles in strong versus weak granular soils – notably, the former exhibited resistive forces roughly double their weaker counterparts under equivalent embedment depths and varied impact velocities. Intriguingly, a stiff pile in weak soil necessitates nearly double the embedment depth to match the energy dissipation of its strong-soil counterpart. Furthermore, the study discerned consistent depth of rotation point ranges for piles embedded in distinct soil strengths, regardless of embedment depth and impact velocity.

The influence of imbalances on the dynamic characteristics of the laboratory centrifuge HERMLE Z306

Laboratory centrifuges are used in various industries. During operation, vibrations occur that lead to resonant frequencies, which in turn impair functionality. This paper presents an overview of the computational model of the HERMLE Z306 laboratory centrifuge used in medical laboratories to separate mixtures of different fractions to determine the dynamic characteristics. The zones of stable operation of the centrifuge and the influence of the rotation speed on the natural frequencies are analytically determined. Experimental results are presented with the influence of imbalances on the dynamic characteristics of the HERMLE Z306 centrifuge. As a result of the modeling, the amplitude-frequency characteristics are determined and a Campbell diagram is constructed. Objective: Modeling of dynamic processes in laboratory centrifuges by studying the influence of imbalances on the quality of mixture separation. Determination of zones of stable operation of the centrifuge.Purpose: Construction of amplitude-frequency characteristics of the centrifuge, determination of zones of stable operation of the laboratory centrifuge during separation and Campbell diagram showing the dependence of natural frequencies on the rotation speed of the HERMLE Z306 centrifuge. This diagram makes it possible to determine the resonance zones. Methods of implementation: Based on the use of the Lagrange equation of the second kind, a model is obtained that makes it possible to determine the zones of stable operation of the centrifuge. Using experimental equipment, determine the frequency response of the centrifuge and analyze the Campbell diagram to determine the resonance zones.Results: The zones of stable operation of a laboratory centrifuge were analytically determined. The amplitude-frequency characteristics of the HERMLE Z306 centrifuge were constructed, the trajectories of the free end of the shaft were built taking into account the corresponding imbalances, and the resonance zones were experimentally determined. Conclusions: Experimental studies have shown that the free end of a laboratory centrifuge shaft moves along a surface whose shape and, accordingly, the path of movement depend on both the angles of rotation and translational movement that arise as a result of deformations of elastic supports. The analytical and experimental studies made it possible to identify unstable modes and thereby determine the areas of the centrifuge's operating modes. The separation process will be stable if the roots of the equation have a negative real part, and moreover, the motion will be asymptotically stable in the presence of resistance forces. An experimental technique for determining the dynamic parameters of the centrifuge has been developed. On its basis, the effect of the rotation speed on the natural frequencies was determined.

A GFDM based computational model for the analysis of tunnels under gravitational loadings

Based on an impedance relation, a new computational model is developed for the analysis of tunnels under gravitational loading. The shape of tunnel is arbitrary. The impedance matrix, representing the soil resistance, is evaluated through integration of the equations of elasticity by generalized finite difference method (GFDM). The rigidity matrix of tunnel ring is constructed by using two types of elements: plate and shell elements. The equations of these elements are evaluated through integration of the equations of higher order plate and shell theories again by GFDM. These element equations accommodate not only axial and bending deformations, but, also shear deformations in the ring. In the study, the rotational joint deformation is simulated through the use of rotational spring model and the slippage is considered by modifying the impedance matrix so that the tangential soil resistance force between the ring and soil medium vanishes. Some numerical results are presented, in nondimensional forms, for circular and square tunnels where the following three cases are considered for circular tunnels: a) the soil medium is infinite, the change in σv (vertical (in situ) compressional stress) in the vicinity of tunnel is disregarded b) the soil medium is infinite, the change in σv is taken into account c) the soil medium is halfspace (HS). In connection with the case of (a), a comparison is presented for the ring flexibility curves of radial displacement and section forces of circular ring with those reported in literature. In view of the interpretations of the results and comparisons, we think, the proposed model may be used reliably in the analysis of tunnels.

Two-phase flow visualization experiments in variable-aperture fractures: The correlation between flow structure, displacement efficiency and relative permeability

The correlation of flow structure, displacement efficiency and relative permeability for two-phase flow in variable-aperture fractures is critical for many fractured rock applications. A systematic visualization method for two-phase flow experiments was developed and four transparent variable-aperture fracture samples were duplicated by epoxy casting method. A total of 112 times two-phase flow experiments of nitrogen displacing water under various gas flow rates were performed and the corresponding results of images and pressure data during flow process were recorded and analyzed based on optical principles. On the basis of the competition between capillary resistance and inertia force of gas, the flow structure can be generally divided into four states including capillary resistance dominant (CR) state with few flow paths in two lateral sides without fingering flow, competitive (CP) state with the occurrence of clear fingering flow phenomenon, inertia force of gas dominant (IF) state showing more chaotic gas distributions, and steady (SD) state that has few changes in flow paths. The growth of displacement efficiency is greatly affected by the four transition states, in which the increment of displacement efficiency in Frac-1 that has gone through the three states of flow structure approaches 30%, and that of Frac-2 and Frac-3 are about 15%, while Frac-4 with little change of flow structure is less than 10%. As a consequence, the relationship between saturation and relative permeability of gas becomes steeper from Frac-1 to Frac-4 with greater deviation from X, V–C and Corey models due to the smaller variation range of gas saturation, and an improved v-type model is obtained where the exponent n shows a positive correlation to fracture mean aperture.

Estimation of vehicle tire effective rolling radius and vertical wheel/road contact force

In a vehicle, knowledge of physical wheel/road contact parameters is valuable for the design of dynamic control and active safety systems. In this paper, a new method is designed to estimate the effective rolling radius and the vertical wheel/road contact force using an extended Kalman filter and the Pacejka magic formula. Moreover, it allows the estimation of the longitudinal force, the rolling resistance force, and the longitudinal slip. The method is designed in four blocks. First, a comparison with other research is carried out to validate both the controller and quarter-vehicle model blocks. Then, the blocks of the extended Kalman filter and the Pacejka magic formula are applied to estimate all parameters. The relative mean estimation errors are calculated, and the results show that the developed method is capable of estimating all parameters simultaneously and in real-time with satisfactory accuracy.

Numerical simulation of transpiration cooling in porous nose cone under hypersonic conditions

Transpiration cooling in a two-dimensional porous nose cone under hypersonic flow have been numerically investigated. The numerical model intricately captures the interaction between compressible and incompressible flows in the boundary layer and the phase change of coolant within porous region. The validation of numerical method is performed by comparing the simulation results with experimental data. The simulation results are in reasonable agreement with the experimental data. The results show that the increase of blowing ratio can effectively improve the cooling efficiency of transpiration cooling，where the blowing ratio represents the mass flow rate ratio between the coolant of porous region and the mainstream free flow. Such as, the average cooling efficiency rises from 0.33 to 0.86 when the blowing ratio increases from 0.0459% to 0.2753%. Although the porous resistance force increases as the particle diameter and porosity decrease, the effect of these parameters and solid material of porous region on the cooling efficiency are marginal.

Comparative analysis between multi-strain probiotics and antibiotic as starter feed supplement of poultry on growth performance, serum metabolites and meat quality

The unobstructed use of antibiotics in poultry production has emerged as a major driving force of antibiotic resistance and public health hazard, particularly in developing countries. This study aimed to determine the functional roles of lyophilized native probiotic based starter feed on performance, selective serum metabolites and meat quality of poultry. A total of 90 day-old birds (30 broilers, 30 layers and 30 ducks) were used as experimental birds which were divided into three treatment groups for each kind of bird. Isolated native probiotic strains from chicken intestine were used to prepare lyophilized probiotic samples. Growth performances were measured manually, serum biochemicals analysis were carried out using diagnostic kits, and meat quality was determined through Kjeldahl method and Soxhlet method. When compared to groups receiving antibiotics, the introduction of lyophilized probiotics in starter feed significantly (P<0.05) increased body weight gain, feed intake, and feed conversion ratio. The birds' serum calcium and protein levels likewise exhibited a similar pattern. Comparing the groups receiving antibiotics, the protein content of the meat revealed significant (P<0.05) variations. Significant (P<0.05) reduced level of serum total cholesterol, triglycerides and fat content in meat was observed when compared to antibiotic-fed group. It is possible to conclude that lyophilized probiotics have a significant positive impact on growth performance, serum metabolites and meat quality. The findings of the study could open up new avenues for the application and adoption of native probiotic-based poultry feeds as an alternative to antibiotic-based poultry feeds among stakeholders.

Effects of Mosquito-Imitated Microneedle’s Reciprocating Rotations on Puncture Resistance Forces—Evaluations by Puncturing Experiments and Nonlinear FEM Analyses—

Development of a low-invasive microneedle is currently desired in the medical field to mitigate the patients’ stress and pain. We have paid attention to mosquitoes that puncture the skin without giving humans no feelings of pain. We have observed mosquitoes and found that when their proboscis punctures human skin, they make the following three behaviors: apply tension to human skin; rotate their proboscis; vibrate their proboscis. In our previous studies, we developed a bundled set of three microneedle imitating the mosquito’s proboscis and experimentally proved the usefulness of their alternate vibrations, which is one of the mosquito’s puncturing behaviors. However, the setting of three needles with proper clearances from each other was difficult, making their driving system too complex to practically use it. Therefore, we have developed a simplified microneedle by reducing the number of needles from three to two or one. This paper has focused on the effects of the rotations of a single needle. Using our developed microneedle with a diameter of 90 µm and the thinnest commercial microneedle with a diameter of 180 µm, we evaluated the effect of reciprocating rotation, one of the mosquitoes’ puncturing behaviors, by puncture experiments using artificial skin and nonlinear finite element method (FEM) analysis. As a result, it was found that the reciprocating rotation suppresses the puncture resistance force and the skin deflection.

Drive Characteristics of Air-Cylinder-Type Artificial Muscle in Annular Bending

Air cylinders are actuators that slide a piston inside cylinders by applying air pressure. We propose an air-cylinder-type artificial muscle that can be flexibly bent by using a flexible tube for the cylindrical part. The actuator output was a string connected to a piston. When the air-cylinder-type artificial muscle bends, the inner wall of the tube and the string come into contact, causing output fluctuations owing to friction. In this study, we investigated the output when an artificial muscle was bent. After describing the structure of the air-cylinder-type artificial muscle, the measurement results of the resistance force at each part of the actuator are presented. A theoretical output inspired by the capstan equation was derived, and its validity was verified by comparison with experimental results.

A Delicate Balance: Iraq’s Security Culture Between Iran and the United States

Iraq’s leaders are working to modernise its national-security institutions, and to manage the challenges arising from multiple subnational armed groups. The main groups, the Kurdish Peshmerga and the largely Shia Popular Mobilisation Units, or Hashd, are linked to the armed forces, but enjoy considerable autonomy. Iraq also has militias linked to region-wide resistance forces with ties to Iran. The Gaza war has triggered dozens of lethal encounters between these groups and the 2,500 US troops in Iraq, leading Baghdad to renegotiate the terms of security cooperation with Washington. Even if US and NATO forces leave Iraq, the Iraqi government will work to balance its relations with Tehran and Washington. Iraq therefore has a role to play in determining how the region finds a new equilibrium after the Gaza war. Iraq’s emerging security culture also provides an important case study of a country in transition from authoritarian rule.

A new approach to transformation of micro analysis into macro analysis of forces to study the dynamic behaviour of riverbank morphology

ABSTRACT Due to complex nature of the riverbank erosion and owing to action of wide variety of forces on the particles, it is an uphill task for the researchers to find a general approach to riverbank failure mechanism. Here, a planar failure-block of right-angled trapezoidal shape spanning to the tension crack has been considered. Transformation of inter-particle microscopic forces into macroscopic forces has been made to analyse the stability of the block. Stability of the failure block is a function of the bank erosion rate in terms of the escape velocity. Moreover, varying free surface water level has been investigated to study the dynamic behaviour of the bank. With the increasing number of base particles in the tension crack from 10 to 100, escape velocity increases by 8.47% as the water level rises and 10.74% as it falls. Similarly, the increase in escape velocity with free surface water level height from 0 to full height of the tension crack is 39.4% as the water level rises and is 48.4% as water level falls. Rising water level increases hydrostatic confining pressure force, which is a resistive force. This increases the escape velocity continuously leading to greater stability of the mass.

Development of the rolling extrusion rock bolt with constant resistance and large deformation

With the increasing excavation depth of underground engineering, engineering problems such as large deformation and rock burst caused by high geo-stress brings new challenges to the excavation and reinforcement of surrounding rock in deep underground engineering. The traditional rock bolt is prone to brittle fracture under high geo-stress due to its low elongation. Therefore, this work aims to develop a novel energy-absorbing bolt with constant resistance and large displacement to reinforce the surrounding rock with a risk of large deformation or rockburst. The novel energy-absorbing bolt refereed as rolling extrusion rock bolt (RE bolt) is mainly consists of sleeve tube with a variable cross-section, energy absorption slider with steel balls embedded, steel bar connected with the energy absorption slider. The rolling extrusion is adopted to produce the resistance force of the RE bolt, which avoids the sudden attenuation of resistance force and the abrasion of the energy absorption slider. The static pull test is conducted to study the resistance force and deformation characteristics of the RE bolt with different specifications. Results imply that the RE bolt has higher resistance force, larger deformation capacity and energy absorption capacity. The work of this study provides an effective solution for the reinforcement of surrounding rock in deep rock engineering.

Quantitative analysis on resistant forces at oil-surfactant-rock interfaces with dynamic wettability characterization

Adhesion of oil at rock surface plays an important role in the liberation of oil from micro-/nano-pores, especially for heavy oil that has extremely high viscosity. Although molecular dynamics simulation is widely used to study the interfacial interaction for some specific oil-water-rock systems, experimental measurements provide more realistic and reliable evidence. In this work, we propose a dynamic wettability characterization method to indirectly measure resistant forces at oil-surfactant-rock interfaces, including frictional force, wettability hysteresis force, and viscous force, which are parallel with the oil-solid interface. The adhesive force, which is normal to the oil-solid interface is calculated through measurement of work of adhesion. The results show that work of adhesion instead of contact angle can better describe the adhesion of oil at solid surface. The effect of surfactant concentration on work of adhesion is different for water-wet and oil-wet surfaces. Moreover, average viscous forces are calculated through force analysis on oil drops moving along solid surface in different surfactant environments. It is found that viscous force has a magnitude comparable to the frictional force during the movement, while the wettability hysteresis force is negligible. On the other hand, the adhesive force calculated from the work of adhesion is also comparable to the viscous force. Therefore, both the resistant forces parallel with and normal to the oil-solid interface should be minimized for the liberation of oil from rock surface. This work proposes a simple method to evaluate the wetting capability of different surfactants and measure the adhesive force between heavy oil and rock surfaces indirectly, which provides insight into the adhesion of heavy oil at rock surface and would be valuable for the development of surfactant-based oil recovery methods.

Modeling and performance analysis of a lithium‐ion battery pack with an electric vehicle power‐train for different drive cycles and highway conditions

AbstractLithium‐ion cell chemistries are favored in the automotive sector, as they enable electric vehicles (EVs) to compete with traditional gasoline‐powered vehicles in terms of performance, range, and cost. The life and performance of these packs depend upon the Battery management system which monitors and controls the pack. The modeling, simulation, and analysis of a lithium‐ion battery pack that closely resembles an actual automobile battery are the focus of this paper. Real cells that are commercially available and specifically developed for automotive applications are modeled in the simulation environment. The cell characterization and formation of pack topology with heat exchange are addressed. A commercial electric car's power train model and EV dynamics are used in the simulation environment to test the modeled battery pack over various drive cycles. The performance analysis is upscaled by considering different aspects like resistive forces while driving, ambient temperature, initial conditions while the vehicle starts, etc. The battery manufacturer can verify the battery's performance under different load conditions, with a high degree of similarity to real‐world scenarios. The simulations are conducted on MATLAB/Simulink 2021b software.

Head-Up Haptic Display Using Dual-Mode Haptic Actuator for Vehicles

Driving assistance modules are important components to improving driver safety in driving environments, which can create overloaded multisensory information. This paper introduces the concept of a head-up haptic display that assists drivers in keeping their visual attention focused, and then offers a haptic actuator that may be used as the main component in the head-up haptic display. We selected magneto-rheological elastomer (MRE) as the base material and adopted a porous structure to reduce its initial stiffness. Furthermore, we fabricate a haptic actuator based on an MRE having a porous structure (pMRE) and a solenoid. The current to the solenoid generates a magnetic field that causes the pMRE to stiffen, thereby increasing the resistive force. As soon as the current input is removed, the pMRE becomes soft again. We simulated the solenoid coil and the magnetic path to further maximize the magneto-motive force generated by the solenoid coil and experimentally optimized the pMRE. We showed that the proposed haptic actuator creates not only a sufficient resistive force but also vibration to generate various haptic sensations. Moreover, we constructed a head-up haptic display using four haptic actuators and demonstrated the possibility of utilizing a new user interface to increase driving safety.

Relative elongation of raw cotton fibers as a result of feathers adhesion and action of tensile forces

The change in the relative elongation of raw cotton fibers as a result of feathers adhesion and the influence of tensile forces is studied. The dependence of the relative elongation of fibers on tensile forces is obtained, taking into account other significant factors. For experimental studies of different varieties of cotton, a test bench is made to determine the resistance forces of the elastic element of the raw material. Keywords:raw cotton, relative elongation, tension, resistance force, elastic element rasulov.ruzimurad@mail.ru

Development of a system for controlling a diamond drilling mode in terms of rock fault resistance

Relevance. Resistance to rock-cutting elements in rock destruction largely determines the effectiveness of drilling results. Information about the drag coefficient allows you to correctly and timely adjust the intensity of a drilling tool impact on the bottom of the well. To control the force contact of the drilling tool cutters with the bottom of the well, it is necessary to have a methodological apparatus that allows determining the rock destruction mechanism, taking into account the resistance forces. The existing methods for selecting combinations of diamond drilling mode parameters according to the known RPI index or according to the criterion of energy intensity of rock destruction N/vm , where N is the bottomhole power to overcome the resistance during rock destruction at the bottom hole; vm – mechanical drilling speed, have a number of disadvantages. They consist, for example, in occurrence of tool wear or the need to obtain a bottomhole power value in the current time mode, which is difficult under modern drilling conditions. Therefore, the study of rock resistance to destruction by a diamond cutter, based on application of the full factorial experiment method with obtaining mathematical models of factors and their graphical interpretation in combination with process control systems using computer technology in the current time mode, is a relevant topic. The disclosure of this topic will determine the direction of increasing technical and economic indicators of drilling. Aim. To develop a methodological apparatus that allows determining the mechanism of rock destruction taking into account the resistance forces to ensure optimal control of diamond drilling. Objects. Mechanism of rock resistance to destruction by a diamond cutter. Methods. Analysis, analytical research, full factorial experiment. Results. The paper presents an analytical analysis of the possibility of controlling drilling modes in order to achieve the greatest effect from drilling by estimating the drag coefficient as a function of the intensity of destruction or deepening per one revolution. Based on the analytical studies and the mode of drilling control by a computer in the real time mode, the authors have proposed a method for selecting the parameters of the drilling mode according to a given optimal value of the resistance index during drilling, and a way for its automatic implementation.

Effect of Hydration Forms and Polymer Grades on Theophylline Controlled-Release Tablet: An Assessment and Evaluation.

Drug release from controlled release delivery systems is influenced by various factors, including the polymer's grade and the drug's hydration form. This study aimed to investigate the impact of these factors on the controlled release of theophylline (THN). This research compares the monohydrate form found in branded products with the anhydrous form in generic equivalents, each formulated with different polymer grades. Quality control assessment was conducted alongside in vitro evaluation, complemented by various analytical techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, thermal analyses using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed. Quality control assessments demonstrated that the generic tablets exhibited lower average weight and resistance force compared to the branded ones. In vitro tests revealed that generic tablets released contents within 120 min, compared to 720 min for the branded counterpart. Characterization using XRD and SEM identified disparities in crystallinity and particle distribution between the three samples. Additionally, the thermal analysis indicated consistent endothermic peaks across all samples, albeit with minor variations in heat flow and decomposition temperatures between the two products. This study demonstrated that variations in polymer grade and hydration form significantly impact THN release.

DLP‐Printable Porous Cryogels for 3D Soft Tactile Sensing

AbstractThree‐Dimensional (3D) printed porous materials hold the potential for various soft sensing applications due to their remarkable flexibility, low density, and customizable geometries. However, developing versatile and efficient fabrication methods is crucial to unlock their full potential. A novel approach is introduced by combining Digital Light Processing (DLP) 3D printing and freeze‐drying to manufacture deformable cryogels featuring intricate morphologies. Photocurable hydrogels based on Poly(3,4‐ethylenedioxythiophene)Polystyrene sulfonate (PEDOT:PSS), Polyethylene glycol Diacrylate (PEGDA) and Ethylene Glycol (EG) are successfully printed and lyophilized. In this way, porous cryogels with tailorable properties are achieved. Microporosity varies from 68% to 96%, according to the chemical composition. Ultra‐soft cryogels with a compressive modulus of 0.13MPa are fabricated by adding a reactive diluent. As a result of the cryogelation process, which effectively removes water from the hydrogels, microporous structures with details as fine as 100 µm are obtained. The achieved freedom of design is exploited to fabricate resistive force sensors with a honeycomb lattice morphology. The sensitivity and the working range of the sensors can be tailored by tuning the size of the cells, paving the way for sensors with programmable architectures that can meet diverse requirements.

Optical Myography-Based Sensing Methodology of Application of Random Loads to Muscles during Hand-Gripping Training.

Hand-gripping training is important for improving the fundamental functions of human physical activity. Bernstein's idea of "repetition without repetition" suggests that motor control function should be trained under changing states. The randomness level of load should be visualized for self-administered screening when repeating various training tasks under changing states. This study aims to develop a sensing methodology of random loads applied to both the agonist and antagonist skeletal muscles when performing physical tasks. We assumed that the time-variability and periodicity of the applied load appear in the time-series feature of muscle deformation data. In the experiment, 14 participants conducted the gripping tasks with a gripper, ball, balloon, Palm clenching, and paper. Crumpling pieces of paper (paper exercise) involves randomness because the resistance force of the paper changes depending on the shape and layers of the paper. Optical myography during gripping tasks was measured, and time-series features were analyzed. As a result, our system could detect the random movement of muscles during training.