Maximum Lateral Force Research Articles

Hydrodynamics of a three-dimensional self-propelled flexible plate

The hydrodynamics of a three-dimensional self-propelled flexible plate in a quiescent flow were simulated using the immersed boundary method. The clamped leading edge of the flexible plate was forced into a prescribed harmonic oscillation in the vertical direction but was free to move in the horizontal direction. Several types of trapezoidal plates were simulated by changing the shape ratio (S = Wt/Wl), where Wt is the trailing edge width and Wl is the leading edge width. The aspect ratio was fixed at AS = (Wl + Wt)/2L = 0.4, where L is the length of the plate. To explore the hydrodynamics of a rectangular plate (S = 1.0), the average cruising speed (ŪC), the input power (P¯), and the swimming efficiency (η) were determined as a function of the flapping frequency (f). The kinematics of the plate, the maximum angle of attack (ϕmax), and the mean effective length (L¯eff) were examined to characterize the hydrodynamics, including the peak-to-peak amplitude (At/A) and the Strouhal number (St=fAt/Ūc). Next, the effect of S on the hydrodynamics was explored for 0.1 ≤ S ≤ 3.0. The swimming efficiency was found to be the highest at S = 0.5. The maximum thrust (Ft,max) of S = 0.5 decreased by 15% compared to that of S = 1.0, and the maximum lateral force (Fl,max) decreased by more than 50%. The velocity field behind the plate and the vortical structures around the plate were visualized. The influence of the tip vortex on the swimming efficiency was examined.

New Lateral Force Distribution for Seismic Design of Structures Based on Seismic Demand Ratio

The design of earthquake-resistant buildings starts with defining the maximum lateral earthquake forces or their resultant. The amount of these forces depends on various factors, including coefficient of system behavior which depends on over strength and its ductility. In this study, a method is proposed in order to design an earthquake-resistant system in which the distribution of lateral forces is adjusted based on equal distribution of the seismic demand ratio in structural elements for the optimum use of seismic capability of the structure. To this end, three types of 4-, 7-, and 10-story structures are Applied. Firstly, the above-mentioned structures are designed based on gravity loads and consequently analyzed based on linear and nonlinear dynamic analyses, applying the accelerograms of some major earthquakes. Pursuant to that, the average loading ratio to the allowed capacity of the elements of each story in linear analysis and the average ratios of plastic rotations to the allowed capacity of elements in nonlinear analysis are applied as the modified shear ratio in the Iranian National Seismic Code. On that account, the new lateral loading distribution is measured and identified. Based on this new distribution, the above-mentioned structures are designed and their seismic behaviors are identified, applying linear and nonlinear dynamic analyses of the same accelerograms. The findings indicate an ameliorated seismic behavior of the beams and the columns. Moreover, the distribution of the seismic demand ratios attains more uniformity along the height of the structures.

SPH-Based Analysis on the Lateral Response of Pipe Culverts in the Flowing Process of Liquefied Sand

This study proposes a solid-fluid-coupled Smoothed Particle Hydrodynamics model to investigate the behavior of pipe in the liquefied sand after failure. In this model, the liquefied soil is simulated as a Bingham fluid material combined with the equivalent Newtonian viscosity. Then the pipe culvert is treated as an elastic solid material, and the culvert-soil interaction is assumed as the solid-fluid coupling force. Verification has been conducted through a dam-break model to demonstrate the accuracy of simulating the flow behavior of liquefied sand. At the same time, the applicability of the SPH simulation in the two-phase-coupled force has been checked compared with previous researches. After that, parametric studies are performed on the lateral force and movement of pipe culverts in the flowing sand. The derived results demonstrate that the culvert size and buried depth are the significant factors when estimating the maximum lateral force of culvert-soil system, while the slope angle severely affects the run-out distance of culvert and the velocity of flowing sand.

Seismic performance of a repaired thin steel plate shear wall structure

A multi-ribbed grid of channels can effectively restrain the deformation of an embedded steel plate shear wall, improving the elastic stiffness of the overall structure while enhancing its energy dissipation capacity. Aone-bay, two-story specimen was tested under low cycle reversed loading in two stages. After being damaged in Stage I, the structure was repaired by anchoring the multi-ribbed channel grid. The structure was then loaded to destruction. To investigate the changes in performance of the structure due to reinforcement, comparison and analysis of the structure were conducted for the two stages. The results indicate that in the elastic stage, when the repaired structure is in its normal service state, the deformation of the steel plate is effectively restrained, and the elastic stiffness and energy dissipation capacity is improved. In the elastic-plastic stage, the failure mode of the structure is reasonable, and the hysteresis loop is full as the multi-ribbed channel grid effectively restrains the pinching phenomenon. Based on the results of the experiment, finite element models were established. According to the finite element analysis, the yield load, initial stiffness, and maximum lateral force bearing capacity of the repaired structure improved significantly.

Measurement and calculation of lateral trapping strength of focused beams generated by a two-dimensional ultrasound array

This study is aimed at developing a method to controllably manipulate kidney stones in the human body using a single ultrasound source. Calculation and measurement of the lateral force on a sphere using various acoustic beams (vortex and radially-varying phased beams) were compared. A 256-element, 1.5-MHz array was used to synthesize the beams. Spheres of 1–6 mm (6 < ka < 20) diameter made of glass, ceramic, or brass were positioned on an acoustically matched platform at the focus rigidly attached to the transducer by a frame. The transducer and platform were rotated to the angle at which the trapped sphere fell. The acoustic power was <9 W and was adjusted by the duty cycle (10–60%) to control the range of the trapping angle. Maximum temporal average intensity ISPTA was 46.5 W/cm2. The acoustic force was calculated numerically as in Sapozhnikov and Bailey [JASA, 133, 616 (2013)] and the angle calculated with static force equilibrium equation. Good agreement between calculation and measurement was observed, with an average error in angle measured of 11.3%. The maximum lateral forces were 80% of the axial radiation force and 52% the gravitational force. [Work supported by NIH P01-DK043881, K01-DK104854, R01EB7643, and RBBR 17-02-00261.]

Hinge Moment Coefficient Prediction Tool and Control Force Analysis of Extra-300 Aerobatic Aircraft

This paper presents the development of tool that is applicable to predict hinge moment coefficients of subsonic aircraft based on Roskam’s method, including the validation and its application to predict hinge moment coefficient of an Extra-300. The hinge moment coefficients are used to predict the stick forces of the aircraft during several aerobatic maneuver i.e. inside loop, half cuban 8, split-s, and aileron roll. The maximum longitudinal stick force is 566.97 N occurs in inside loop while the maximum lateral stick force is 340.82 N occurs in aileron roll. Furthermore, validation hinge moment prediction method is performed using Cessna 172 data.

Evaluation of vehicle-based tyre testing methods

The demand for reduced development time and cost for passenger cars increases the strive to replace physical testing with simulations. This leads to requirements on the accuracy of the simulation models used in the development process. The tyres, the only components transferring forces from the road to the vehicle, are a challenge from a modelling and parameterization perspective. Tests are typically performed on flat belt tyre testing machines. Flat belt machines offers repeatable and reliable measurements. However, differences between the real world road surface and the flat belt can be expected. Hence, when using a tyre model based on flat belt measurements in full vehicle simulations, differences between the simulations and real prototype testing can be expected as well. Vehicle-based tyre testing can complement flat belt measurements by allowing reparameterization of tyre models to a new road surface. This paper describes an experimental vehicle-based tyre testing approach that aims to parameterize force and moment tyre models compatible with the standard tyre interface. Full-vehicle tests are performed, and the results are compared to measurements from a mobile tyre testing rig on the same surface and to measurements on a flat belt machine. The results show that it is feasible to measure the inputs and outputs to the standard tyre interface on a flat road surface with the used experimental setup. The flat belt surface and the surface on the test track show similar characteristics. The maximum lateral force is sensitive to the chosen manoeuvres, likely due to temperature differences and to vibrations at large slip angles. For tyre models that do not model these effects, it is vital to test the tyres in a manoeuvre that creates comparable conditions for the tyres as the manoeuvre in which the tyre model will be used.

Evaluation of adhesion strength between amorphous splat and substrate by micro scratch method

A micro scratch test was performed to evaluate the adhesion strength of plasma sprayed Fe-based amorphous splats deposited on a mirror polished steel substrate preheated at different temperatures. The lateral force (LF), penetration depth (PD) and acoustic emission (AE) signals were recorded to reflect the dislodging process of the splats. The debonding mechanism and the adhesion strength of the individual splat were discussed in details. The results indicate that the adhesion strength of splat was prone to be higher on fully preheated substrate due to sufficient spreading time and good wettability at the droplet/substrate interface. The scratch process contains three stages, i.e., scratching on the bare substrate towards the splat (stage I), contacting and dislodging the splat (stage II), moving away from the splat (stage III). The maximum lateral force (MLF), PD as well as AE signal in stage II vary a lot both in value and range of influenced distance with the increment of substrate preheating temperature. The projected cone areas and residuals onto the scratch can qualitatively reflect the bonding status of splat, whereas the ratio of adhesion force to splat area can quantitatively characterize the adhesion strength of the splat.

Experimental cyclic response assessment of partially grouted reinforced clay brick masonry walls

As part of an ongoing research project into the seismic response of partially grouted reinforced masonry (PG-RM) walls, this article presents the analysis of the experimental results of eight full-scale walls that were tested in laboratory under cyclic lateral loading. All walls tested were constructed using multi-perforated clay bricks and horizontally reinforced with ladder-type bed-joint reinforcement. Three design parameters were investigated in this research: wall aspect ratio, axial load level, and horizontal reinforcement ratio. The combined effect of these variables on shear response of the walls tested is analyzed and discussed. In addition, the accuracy of four shear expressions available in the literature is assessed against the experimental results obtained. The study has confirmed that a rise in the horizontal reinforcement ratio may lead to an increase in lateral capacity of PG-RM walls, although this effect would be more remarkable for square and slender walls. The results obtained also suggest that the influence of axial load level becomes more relevant as the aspect ratio decreases. In addition, moderate values of displacement ductility, ranging from 2.5 to 5.5, were estimated from a bilinear idealization. At the level of maximum lateral force, the average drift level for all walls tested in this experimental program ranged between 0.2 and 0.62%. Finally, the research also confirms the need to review the shear expressions currently available for the design and assessment of this type of walls.

Seismic Performance of Existing R/C Building with Irregular Floor Plan Shape

Bu33333333ilding with irregular floor plan has the eccentricity of force to the centre of building isappears to be more susceptible to deformation and damage when subjected to earthquake movements than with regular floor plan. This study aims to determine the seismic performance of buildings with the irregular floor plan in displacement and drift by service and ultimate performance limit.The object of research is Padang Pariaman public works office building. The evaluation method used non-linear static analysis(Pushover) which is one method to evaluate the seismic performance of the building.Pushover analysis performed by providing a static load in the lateral direction gradually to achieve a specific displacement target. This research is based on SNI-1726-2012, ATC-40 and FEMA 356. The results of the analysis show that the maximum lateral force of 10909.9 kN occurs in step-6 pushover analysis with a displacement of 0.165 m, maximum drift = 0.0705 m and maximum in-elastic drift = 0.025 m.This means the building is included in the IO (Immediate Occupancy) performance level. Although there is damage from small to medium level, still has a big threshold against the collapse, which means the building is safe against the earthquake.

Analysis of the car body stability performance after coupler jack-knifing during braking

ABSTRACTThis paper aims to improve car body stability performance by optimising locomotive parameters when coupler jack-knifing occurs during braking. In order to prevent car body instability behaviour caused by coupler jack-knifing, a multi-locomotive simulation model and a series of field braking tests are developed to analyse the influence of the secondary suspension and the secondary lateral stopper on the car body stability performance during braking. According to simulation and test results, increasing secondary lateral stiffness contributes to limit car body yaw angle during braking. However, it seriously affects the dynamic performance of the locomotive. For the secondary lateral stopper, its lateral stiffness and free clearance have a significant influence on improving the car body stability capacity, and have less effect on the dynamic performance of the locomotive. An optimised measure was proposed and adopted on the test locomotive. For the optimised locomotive, the lateral stiffness of secondary lateral stopper is increased to 7875 kN/m, while its free clearance is decreased to 10 mm. The optimised locomotive has excellent dynamic and safety performance. Comparing with the original locomotive, the maximum car body yaw angle and coupler rotation angle of the optimised locomotive were reduced by 59.25% and 53.19%, respectively, according to the practical application. The maximum derailment coefficient was 0.32, and the maximum wheelset lateral force was 39.5 kN. Hence, reasonable parameters of secondary lateral stopper can improve the car body stability capacity and the running safety of the heavy haul locomotive.

Seismic Behaviour of Composite Steel Fibre Reinforced Concrete Shear Walls

In this paper is presented an experimental study conducted at the “Politehnica” University of Timisoara, Romania. This study provides results from a comprehensive experimental investigation on the behaviour of composite steel fibre reinforced concrete shear walls (CSFRCW) with partially or totally encased profiles. Two experimental composite steel fibre reinforced concrete walls (CSFRCW) and, as a reference specimen, a typical reinforced concrete shear wall (RCW), (without structural reinforcement), were fabricated and tested under constant vertical load and quasi-static reversed cyclic lateral loads, in displacement control. The tests were performed until failure. The tested specimens were designed as 1:3 scale steel-concrete composite elements, representing a three storeys and one bay element from the base of a lateral resisting system made by shear walls. Configuration/arrangement of steel profiles in cross section were varied within the specimens. The main objective of this research consisted in identifying innovative solutions for composite steel-concrete shear walls with enhanced performance, as steel fibre reinforced concrete which was used in order to replace traditional reinforced concrete. A first conclusion was that replacing traditional reinforcement with steel fibre changes the failure mode of the elements, as from a flexural mode, in case of element RCW, to a shear failure mode for CSFRCW. The maximum lateral force had almost similar values but test results indicated an improvement in cracking response, and a decrease in ductility. The addition of steel fibres in the concrete mixture can lead to an increase of the initial cracking force, and can change the sudden opening of a crack in a more stable process.

Exploring the relationship between vertical and lateral forces, speed and superelevation in railway curves

The research described in this paper is based on an experiment which involved running a test train through a curve at various speeds, changing the cant of the curve by tamping and repeating the train runs. The cant was changed due to high wheel wear rates. The curve already had a cant deficiency, and this cant deficiency was subsequently increased by reducing the curve's cant. Assessing the before and after tamping test data validated the existence of the expected relationships between the vertical and lateral rail forces, the speed and the cant. The change in cant had a minimal effect on the magnitude of the vertical forces, although a transfer of loading between the high and low legs did occur. The theory indicates that the 14% reduction in cant in this curve, given all of the other curve characteristics, should have resulted in an increase in the lateral forces. There was, however, a roughly 50% reduction in the maximum lateral forces, after the cant had been reduced, which can be explained from a train dynamics point of view. In addition, there was an increase in safety, due to a reduced derailment ratio at this curve's normal operating speed of 85 km/h. It is not unreasonable to presume that a 50% reduction in the maximum lateral forces could lead to a halving of the wear rate of the rail and wheels in this curve, with similar results to be expected in other curves on the rail network.

Evaluation of the lateral loading caused by aircraft with complex gear configurations turning during taxiing

ABSTRACTThe advent of New Generation Large Aircraft (NGLA), such as the Boeing 747 and Airbus A380, has introduced more complicated landing gears and heavier axle loads. The wheel configurations and loads induce complex mechanical response to the pavement structure particularly during turning movements while taxiing. The objective of this paper is to determine the lateral force on all wheels during turning movements to permit future field measurements and pavement design. The paper documents the use of the velocity instantaneous method to analyse the lateral forces imparted by a B747 and A380 under a moving aircraft. Firstly a multi-wheel landing gear is represented by a single wheel, and then the total lateral force of each landing gear at different velocities is analysed, and the total lateral force of a multi-wheel gear is assigned to each wheel. The results show that both taxiing velocity and nose gear steering angle have an effect on the lateral force during turning at low speed, and an increase in velocity and nose gear steering angle cause a significant increase in the lateral force. The maximum wheel lateral force of A380 is located on the front landing gear without sideslip whereas of the B747 it is located on the inside wheel of the wing landing gear near the center. These positions are recommended as the critical design factor.

Superior-inferior position of patellar component affects patellofemoral kinematics and contact forces in computer simulation

BackgroundAnterior knee pain has been reported as a major postoperative complication after total knee arthroplasty, which may lead to patient dissatisfaction. Rotational alignment and the medial-lateral position correlate with patellar maltracking, which can cause knee pain postoperatively. However, the superior-inferior position of the patellar component has not been investigated. The purpose of the current study was to investigate the effects of the patellar superior-inferior position on patellofemoral kinematics and kinetics. MethodsSuperior, central, and inferior models with a dome patellar component were constructed. In the superior and inferior models, the position of the patellar component translated superiorly and inferiorly, respectively, by 3mm, relative to the center model. Kinematics of the patellar component, quadriceps force, and patellofemoral contact force were calculated using a computer simulation during a squatting activity in a weight-bearing deep knee bend. FindingsIn the inferior model, the flexion angle, relative to the tibial component, was the greatest among all models. The inferior model showed an 18.0%, 36.5%, and 22.7% increase in the maximum quadriceps force, the maximum medial patellofemoral force, and the maximum lateral patellofemoral force, respectively, compared with the superior model. InterpretationSuperior-inferior positions affected patellofemoral kinematic and kinetics. Surgeons should avoid the inferior position of the patellar component, because the inferior positioned model showed greater quadriceps and patellofemoral force, resulting in a potential risk for anterior knee pain and component loosening.

Effect of wavelength of fish-like undulation of a hydrofoil in a free-stream flow

Fish-like undulating body was proposed as an efficient propulsion system, and various mechanisms of thrust generation in this type of propulsion are found in the literature—separately for undulating and pitching fishes/foil. The present work proposes a unified study for undulating and pitching foil, by varying wavelength \(\lambda \) (from 0.8 to 8.0) of a wave travelling backwards over the NACA0012 hydrofoil in a free-stream flow; the larger wavelength is shown to lead to the transition from the undulating motion to pitching motion. The effect of wavelength of undulation is studied numerically at a Reynolds number \(Re=4000\), maximum amplitude of undulation \(A_{max}=0.1\) and non-dimensional frequency of undulation \(St=0.4\), using level-set immersed-boundary-method based in-house 2D code. The Navier–Stokes equation governing the fluid flow is solved using a fully implicit finite-volume method, while level-set equation governing the movement of the hydrofoil is solved using an explicit finite-difference method. It is presented here that the thrust generation mechanism for the low wavelength case undulating \((\lambda =0.8)\) foil is different from the mechanism for the high wavelength pitching foil. With increasing wavelength, mean thrust coefficient of the undulating foil increases and asymptotes to value for the pure pitching foil. Furthermore, the ratio of maximum thrust coefficient to maximum lateral force coefficient is found to be larger for the smaller wavelength undulating foil as compared with the larger wavelength pitching foil.

The effect of the secondary lateral stopper on the compressed stability of the couplers and running safety of the locomotives

This paper aims to study the effect of the secondary lateral stopper on the compressed stability of the couplers in order to improve the running safety of the heavy-haul locomotives. The influence mechanism of the secondary lateral stopper on the compressed stability of the couplers is theoretically analyzed. To verify the effect of the secondary lateral stopper, both the simulation and the field braking tests are conducted. The multi-body dynamic model consists of two eight-axle locomotives, one dummy of freight vehicle and four detailed connected couplers. The field braking tests are conducted on the tangent line using three eight-axle locomotives. The results indicate that decreasing the free clearance and increasing the stiffness of the secondary lateral stopper both have a positive effect. However, when the free clearance decreases from 20 mm to 10 mm, there is no remarkable decrease in the yaw angles of the coupler and the car body, and the maximum lateral force of the wheelset is still out of the standard in the simulation. When the stiffness of the secondary lateral stopper increases by five times, the yaw angles of the coupler and the car body are reduced significantly and the running safety of the locomotives is also enhanced.

Prediction of Allowable Lateral Ground Acceleration (in-Plane Direction) of Confined Masonry Walls Using Ambient Vibration (microtremor) Analysis

Rural houses are recently built using confined masonry walls. The concrete beam and column confining the wall are usually considered to resist lateral loads, such as earthquake load. The Indonesian code requires reinforcement of 12mm diameter in each corner of the beam and column with 8mm diameter of stirrups. Such houses are usually termed of non-engineered structures, i.e buildings which the strength is not technically calculated but is established by the communities based on their experiences. This research was aimed to relate the in plane lateral ground acceleration and the resulting lateral displacement on the top of the wall at the first fundamental frequency. As the wall occasionally breaks at certain lateral drift ratio (H/V ratio), therefore, a prediction of the maximum lateral ground acceleration of the wall due to earthquake shake may also be established. Two wall specimens were made of local masonries with dimensions of 3m x 3m and 0.15 m thick. Lateral loads were applied in several stages and ambient vibrations of the two accelerometers, mounted on the base and on the top of the wall, were also recorded in stages. The maximum lateral force prediction, calculated using allowable lateral ground acceleration, was closely approaching the experiment result and numerical calculation.

EShiver: Lateral Force Feedback on Fingertips through Oscillatory Motion of an Electroadhesive Surface.

We describe a new haptic force feedback device capable of creating lateral shear force on a bare fingertip-the eShiver. The eShiver creates a net lateral force from in-plane oscillatory motion of a surface synchronized with a "friction switch" based on Johnsen-Rahbek electroadhesion. Using an artificial finger, a maximum net lateral force of ±300 mN is achieved at 55 Hz lateral oscillation frequency, and net force is shown to be a function of velocity and applied voltage, as well as the phase between them. A second set of experiments is carried out on a human finger, and a lateral force of up to ±450 mN is achieved at a lateral oscillation frequency of 1,000 Hz. This force is reached at a peak lateral surface velocity of 400 mm/s and a peak applied voltage of 400 V. We develop a simple lumped parameter model of the eShiver, and a time domain simulation of the artificial finger is shown to agree with the experimental results. Three distinct zones of operation are found, which predict the limitations of force generation and which may be used for optimization. The human finger is found to be similar to the artificial finger in its dependence on actuation parameters, suggesting that the same lumped parameter model may be applied, albeit with different parameters. Curiously, the friction force due to Johnsen-Rahbek electroadhesion is found to increase substantially over time as the finger remains in contact with the surface. Considerations for optimizing the performance of the eShiver are discussed.

Multi-directional force–displacement response of underground pipe in sand

A methodology is presented to evaluate multi-directional force–displacement relationships for soil–pipeline interaction analysis and design. Large-scale tests of soil reaction to pipe lateral and uplift movement in dry and partially saturated sand are used to validate plane strain, finite element (FE) soil, and pipe continuum models. The FE models are then used to characterize force versus displacement performance for lateral, vertical upward, vertical downward, and oblique orientations of pipeline movement in soil. Using the force versus displacement relationships, the analytical results for pipeline response to strike-slip fault rupture are shown to compare favorably with the results of large-scale tests in which strike-slip fault movement was imposed on 250 and 400 mm diameter high-density polyethylene pipelines in partially saturated sand. Analytical results normalized with respect to maximum lateral force are provided on 360° plots to predict maximum pipe loads for any movement direction. The resulting methodology and dimensionless plots are applicable for underground pipelines and conduits at any depth, subjected to relative soil movement in any direction in dry or saturated and partially saturated medium to very dense sands.