Vertical Dynamic Load Research Articles

Research on the mode switching control of vehicle electromagnetic suspension employing linear motor

An electromagnetic suspension employing linear motor is able to harvest the energy otherwise wasted in the suspension vibration while the vehicle is running on rough road. A switch method of operation modes is put forward to coordinate the contradiction between energy regeneration and vibration isolation. A dynamic model is created to analyse the general properties of energy regeneration suspension under different working modes. Both simulation and experiments are conducted to verify the modelling and advantages. In energy regenerative mode, the dynamic properties of electromagnetic suspension are basically coincident with those of passive suspension, and more than 14 W of electricity is harvested while driving at 20 m s−1 on level C road. In active control mode, the RMS of vehicle body vertical acceleration and tyre dynamic load are decreased by 21.35% and 4.24% respectively, much better than passive suspension, which proves that the mode switching method is simple and effective.

Effects of Work on Shock Absorber and Spiral Springs Against Vertical Loads of Vehicles Burdening the Road Structure

This research aims to examine the effect of vertical dynamic load of vehicles and changes in dimensional barriers on the road surface in its path. Experimentally this fluctuating load is replaced by a pneumatic force change based on the regulation of air pressure on the regulator. The deviations generated by the varying load work are measured by placing a proximity sensor along the spring movement. The amount of vertical load transformation reaches the road surface is measured by using Load cell. Characteristics of vertical dynamic vibration occurring due to several dimensional barriers, U (cm) obtained using mathematical modelling method with 2 DOF suspension system transfer function. The results showed a condition on the body and wheels of vehicles experienced a brief overshot for 0.14 seconds with deviation of 0.178 m. From the graph shows that the rate of deviation that occurs is large enough that Y2d = 1.03 m / s caused by a sudden shock that occurred on the wheels of the vehicle. This condition does not last long that is only duration t = 0.22 s, because the spring reaction force and shock absorber can absorb 45% vibration against the sprung and un-sprung vertical load of the vehicle.

Modeling of Vertical Dynamic Vibration Characteristics on Vehicles Suspension System

Vibrations often interfere with driving comfort for riders and passengers. Variations in loads, especially for four-wheeled vehicles, bumps, hollow road surfaces, and other forms of road damage will greatly affect the vehicle suspension work system. This research aims to (1) further test the effect of vertical dynamic load of the vehicle and change the dimension of resistance on the road surface, (2) the contribution of spring and shock absorber to the load fluctuation of the vehicle. Experimentally these load fluctuations are replaced by pneumatic actuator forces of varying magnitude based on the regulatory pressure of the regulator. The deviations generated by the varying load work are measured by placing a proximity sensor along the spring movement. The vertical dynamic load transformation up to the road surface is measured using a "Load cell" mounted under the wheels of the vehicle. Characteristics of vertical dynamic vibration occurring due to several dimensional barriers, U (cm) obtained using mathematical modeling method with 2 DOF suspension system transfer function. The results showed a condition on the body and wheels of vehicles experienced a brief overshot for 0.14 seconds with deviation of 0.178 m. From the graph shows that the rate of deviation that occurs is large enough that Y2d = 1.03 m / s caused by a sudden shock that occurred on the wheels of the vehicle. This condition does not last long that is only duration t = 0.22 s, because the contribution of springs and shock absorbers that can absorb vibration is 25% to the vibrations caused by the vertical load of the body and the axis of the vehicle.

Vertical dynamic impedance of suction caissons

Nowadays, suction caissons are being increasingly deployed as foundations to support offshore wind turbines (OWTs). Due to the overturning moment induced by waves and wind, vertical forces are the dominating ones acting on these foundations. In this study the dynamic stiffness and damping coefficients of suction caissons embedded in a viscoelastic soil layer over bedrock, subjected to vertical dynamic load were investigated. Numerical analyses of representative 3D finite element models were performed, while the numerical modelling was validated against existing analytical solutions for end bearing piles. The vertical dynamic response of suction caissons was evaluated by considering the effects of the foundation’s geometry, i.e. the slenderness ratio, and the stiffness of the soil layer on the vertical dynamic impedance of suction caissons. Results showed that the overall dynamic response is profoundly affected by the skirt length and by the variation of soil stiffness with depth.Mathematical expressions of the dynamic stiffness and damping coefficients were derived pertaining to foundations with various slenderness ratios and embedded in different soil profiles. The proposed expressions can be implemented in structural models used for the dynamic analysis of the support structure of a wind turbine, taking thus into consideration the effects of soil-structure-interaction.

General solutions of transversely isotropic multilayered media subjected to rectangular time-harmonic or moving loads

This paper presents the general solutions of three-dimensional transversely isotropic multilayered media subjected to a vertical or horizontal rectangular dynamic load by utilizing the analytical layer-element method, and the solutions can be used for both time-harmonic loads and moving ones. Based on the governing equations and constitutive equations of a transversely isotropic elastic body, the analytical layer-element solutions of a single medium layer are derived in the Fourier transformed domain by utilizing the double Fourier integral transform. Taking the continuity conditions between adjacent layer and boundary conditions into account, the global stiffness matrix can be obtained by assembling the interrelated layer elements. The final solutions in the frequency domain are recovered by the inversion of double Fourier integral transform. Numerical examples are given to study the influence of the transversely isotropic character, frequency of load excitation, stratification and the first layer's thickness when the media are subjected to a time-harmonic load, and the influence of the load speed as well as the load depth when the media are subjected to a moving constant load, respectively.

Response of open-end pipe piles to vertical dynamic load considering the effects of soil plug and soil disturbance during driving

This paper presents an analytical solution for the vertical dynamic response of an open-ended pipe pile considering the radial inhomogeneity caused by soil disturbance. The governing equation of the surrounding soil is deduced on the basis of incremental deformations superimposed on an initial finite deformation, i.e. the soil disturbance. The effect of the radial expansion pressure of the soil plug after pile driving is investigated for the first time. By treating the soil plug as the additional mass attached to the pile shaft using the Voigt model, the densification of the soil plug is also considered. A parametric study is performed to illustrate the influence of the expansion pressure of both inner and outer sides of the pile wall and the soil plug on the vertical dynamic response of the pipe pile. The results indicate that the expansion pressure enhances the fluctuation of velocity admittance curves and the peak amplitudes of the reflected signal at both the pile toe and the soil plug top. Wall thickness of the pile influences the dynamic effects of expansion pressure and soil plug on the pile.

Development of a three‐dimensional soil model for the dynamic analysis of end‐bearing pile groups subjected to vertical loads

SummaryThis paper presents a new analytical model for calculating the steady‐state impedance of pile groups subjected to vertical dynamic loads. The derived solution allows considering effects of radially but also vertically propagating soil waves on the soil attenuation function, pile interaction factor, and pile group impedance. The proposed model provides accurate estimates of the soil stress field and of the response of the pile group in the low as well as in the high‐frequency range, unlike earlier solutions based on the plane‐strain model to describe the soil surrounding the piles, which ignores the vertical soil stress gradient. The latter assumption results in underestimating pile group impedance and overestimating radiation damping for frequencies lower than the cutoff frequencies of the system, which are explicitly captured with the proposed solution.

Modular Integrated Longitudinal, Lateral, and Vertical Vehicle Stability Control for Distributed Electric Vehicles

There is a nonlinear coupling relationship between the vehicle in the longitudinal, lateral, and vertical directions, which brings great difficulties to the design of the controller. To tackle the chattering problem, a hierarchical integrated controller for distributed electric vehicle is proposed to improve driving safety, handling stability, ride comfort, and road tracking capabilities. The proposed algorithm has been developed to overcome a major challenge of the conventional method, which can improve only partial dynamic performance of the vehicle. The optimal pre-pointing lateral acceleration model is used to simulate the operator's expected reaction to the vehicle. The body control layer decouples complex problems to achieve multi-target independent tracking through a nonlinear sliding-mode control algorithm, and calculates the expected total body force to meet the upper level instructions. The tire force distribution layer is designed to optimize the function by reducing the tire load ratio and balancing the vertical dynamic load coefficient to improve the vehicle's driving stability and ride comfort. The lower actuator control layer controls the corresponding actuator to achieve the optimal tire force output from the middle layer. Finally, the effectiveness of the chassis integrated control system is verified in CarSim and MATLAB co-simulation.

The results of the study of the rigidity of tires of tractor wheels and its effect on tractor vibrations

The work is devoted to a theoretical study of the rigidity of pneumatic tires of tractor wheels and analysis of its influence on the vertical oscillations of tractors. Mathematical modeling of the patterns of deformation of elastic tractor wheels and soil using experimental data was performed. These experimental data on the patterns of deformation of the studied soils were obtained in our works earlier in field trials, when normal stresses at the contact of the wheels and the soil, as well as the density and humidity of the soil loosened before the wheel passes and after successive wheel passes along the same track were meas-ured. According to the developed computer program, which allows to calculate the rigidity of tires of tractor wheels, one-factor and full factorial computer experiments of three types were carried out. In computer experiments of the first type, the dependence of tire stiffness of a number of elastic wheels under the MTZ-82 tractor on the soil operation from air pressure at different vertical dynamic loads on the axes of the respective tractor wheels was investigated. According to the results of computer experiments of the first type, the regression equations, reflecting the dependencies studied, were found. In computer experiments of the second type, the tire stiffness of various sizes on tire pressure with constant vertical dynamic loads on the axles of the wheels was investigated. According to the results of computer experiments of the second type, the regression equations were found, reflecting the corresponding dependencies. High values of correlation relations for the obtained regression equations indicate a great closeness of relations in the correlation dependences found. In computer experiments of both types, the deviations of the wheel-soil interaction values, found using tire stiffness values obtained by calculation, are within the limits of measurement accuracy of experimental data. Computer experiments of the third type are performed using the experimental data obtained in authors works. The vertical oscillations of the axles of the MTZ-82 tractor for different values of the rigidity of the tires of the front and rear wheels were calculated. The graphs that characterize these fluctuations were built. The results of the study show that with an increase in tire stiffness, the amplitudes of the vertical axes of the tractor axles decrease. This helps to improve the smoothness of the tractor and reduce its sealing effect on the soil. By calculation, it was found out that wheels with 18.4R38 tires are optimal on the rear axle of the MTZ-82 tractor.

Evaluating the effect of the working conditions on the ride comfort and road friendliness of the heavy truck

This study proposes a nonlinear dynamic model of the heavy trucks to evaluate the influence of the various working conditions on the ride comfort and road friendliness of the heavy vehicles based on Matlab/Simulink software. The weighted root mean square (RMS) acceleration responses of the vertical driver’s seat, the cab’s pitch and roll angles, and the dynamic load coefficient (DLC) are chosen as objective functions. The influence of the vehicle velocity and loads on the different road surfaces are evaluated based on the standard ISO 2631-1. The results show that the vehicle’s ride comfort is clearly affected on the road surfaces of ISO level C and D at the range of the vehicle velocity. Especially, the vehicle’s ride comfort is very poor at the velocity of 10-30 m.s-1 on ISO level D. The road friendliness of the vehicle is greatly decreased in the condition of the half-loaded vehicle. Particularly the vertical dynamic wheel loads at 2nd axle strongly affect the road damage at the velocity of 10-30 m.s-1.

Aplikasi Aktuator Pneumatik sebagai Simulator Beban Dinamis Vertikal pada Mekanisme Suspensi Roda Kendaraan Seperempat

Driving comfort for riders and passengers is a keytarget to be achieved. Fluctuations in vehicle loads, bumps,perforated surfaces, and other road damage will greatly affectthe vehicle suspension working system. This study aims tocalculate the vertical dynamic load of the vehicle actually whichoccurs on road construction after through the vehicle wheelsuspension mechanism. The Pneumatic cylinder that was drivenby pressurized air directly weigh on the spring and ShockAbsorber that contained on the wheels of the vehicle. The loadfluctuations of the medium weight category vehicle aredetermined by the regulation of the amount of pressurized airentering into the pneumatic cylinder chamber pushing the pistonand connecting rods. The deviation that occurs duringcompression on the Spring and Shock Absorber, is substitutedinto the vehicle dynamic load equation by taking also themagnitude of the spring stiffness constant, and the fluid or gascoefficient of the damper. The results showed that the magnitudeof the displacement when the compression force worked hassignificantly influenced the amount of vertical dynamic load ofthe vehicle that overlies the road construction. Experimentalresults using pneumatic actuators instead of real dynamic vehicleloads illustrate the characteristics of the relationship betweenwork pressure and dynamic load. If the working pressure of P2(bar) is given great, the vertical dynamic load Ft (N) whichoverloads the structure of the road is also greater. From thegraph shows that shock absorbers have greater ability to reducedynamic load vertically when compared to spring ability.

Analysis of the influence of the main factors on the characteristics of the elastic properties of elastic wheels of tractors

The work is devoted to the theoretical study of the elastic properties of tractor wheels and the analysis of the effect of air pressure in the tires and vertical loads on the wheel axles. According to the developed computer program, which allows to implement the method of calculating the characteristics of the elastic properties of tractor wheels with pneumatic tires proposed in this work, one-factor and complete factor computer experiments of two types were carried out. In computer experiments of the first type, the dependences of the elasticity coefficients of a number of elastic wheels were investigated when operating on the practically non-deformable basis of tractors MTZ-82 and MTZ-142 from the air pressure in the tires at different values of the vertical dynamic loads on the axes of the corresponding wheels of tractors. In computer experiments of the second type, the dependences of the elasticity coefficients and the normal deflection of the wheels with tires of different sizes from the air pressure in the tires at constant values of the vertical dynamic loads on the wheel axles were investigated. In computer experiments of both types, the deviations of the elastic properties of elastic wheels found by calculation are within the limits of the accuracy of measurements of the experimental data. Based on the results of computer experiments of the first type, regression equations were obtained reflecting the dependence of the elasticity coefficients of the elastic wheels studied on the air pressure in the tire for various values of the vertical dynamic loads on the wheel axes. According to the results of computer experiments of the second type, equations of regression of the coefficients of elasticity and normal deflection of wheels with tires of different sizes from air pressure in tires at constant values of vertical dynamic loads on the wheel axle are obtained. The high correlation values for these regression equations indicate the high importance of the relationships in the found correlation dependencies. The application of the proposed calculation method makes it possible to simplify and shorten the work on the choice of tires of optimum sizes to different tractors, taking into account the specific conditions of their operation. It was calculated that wheels with tires 18.4R38 are optimal on the rear axle of the MTZ-82 tractor.

Experimental Design Electromechanical Machine to Produce Electricity by Vertical Dynamic Load

Experimental Design Electromechanical Machine to Produce Electricity by Vertical Dynamic Load

A probabilistic estimate of the vertical dynamic forces acting on the track, in the model of a three-layer beam under the influence of a four-axle freight car

The article contains a method for determining the ma-the permanent way as deflections, angles of section rotation, bending trix of mutual spectral densities of vertical dynamic forces acting on a moments, transverse forces, stresses of its three-layer structures. railway track, depending on its spectrum of irregularities. It will allow to Mathematical model of track oscillations is used for calculations make a more accurate calculation of the mean values and mean-square as a construction containing three infinitely long beams, the lower deviations of vertical dynamic forces, as well as such characteristics of of which lies on the modified Winkler base. Authors present formulas for finding amplitude-frequency characteristics connecting vertical deflections of structural layers and vertical dynamic load acting on a track. A method is described for finding a matrix of mutual spectral densities of vertical dynamic forces acting on a track having real deviations from its position in the profile, with the passage through it of a four-axle freight car. Considered example finds the amplitude-frequency characteristic that connects the vector of dynamic forces in the contacts of wheels and rails with the vector of vertical displacements of wheel centers for the model of a four-axle car. Concluding authors give the results of calculations of the amplitude-frequency characteristic of the elements of the matrix of mutual spectral densities of vertical dynamic forces acting on the track. The received statistical estimations can be used at calculations of service life of ballastless track constructions and loading on roadbed.

Response of circular footing on dry dense sand to impact load with different embedment depths

Machine foundations with impact loads are common powerful sources of industrial vibrations. These foundations are generally transferring vertical dynamic loads to the soil and generate ground vibrations which may harmfully affect the surrounding structures or buildings. Dynamic effects range from severe trouble of working conditions for some sensitive instruments or devices to visible structural damage. This work includes an experimental study on the behavior of dry dense sand under the action of a single impulsive load. The objective of this research is to predict the dry sand response under impact loads. Emphasis will be made on attenuation of waves induced by impact loads through the soil. The research also includes studying the effect of footing embedment, and footing area on the soil behavior and its dynamic response. Different falling masses from different heights were conducted using the falling weight deflectometer (FWD) to provide the single pulse energy. The responses of different soils were evaluated at different locations (vertically below the impact plate and horizontally away from it). These responses include; displacements, velocities, and accelerations that are developed due to the impact acting at top and different depths within the soil using the falling weight deflectometer (FWD) and accelerometers (ARH-500A Waterproof, and Low capacity Acceleration Transducer) that are embedded in the soil in addition to soil pressure gauges. It was concluded that increasing the footing embedment depth results in increase in the amplitude of the force-time history by about 10-30% due to increase in the degree of confinement. This is accompanied by a decrease in the displacement response of the soil by about 40- 50% due to increase in the overburden pressure when the embedment depth increased which leads to increasing the stiffness of sandy soil. There is also increase in the natural frequency of the soil-foundation system by about 20-45%. For surface foundation, the foundation is free to oscillate in vertical, horizontal and rocking modes. But, when embedding a footing, the surrounding soil restricts oscillation due to confinement which leads to increasing the natural frequency. Moreover, the soil density increases with depth because of compaction, which makes the soil behave as a solid medium. Increasing the footing embedment depth results in an increase in the damping ratio by about 50-150% due to the increase of soil density as D/B increases, hence the soil tends to behave as a solid medium which activates both viscous and strain damping.

The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

Capacity Design Criteria of 3D Steel Lattice Beams for Applications into Cultural Heritage Constructions and Archaeological Sites

Three-dimensional lattice beams are highly efficient technical solutions to cover large spans, especially when the single members do not have intermediate restraints able to prevent lateral-torsional buckling phenomena. Hence, lattice structures are widely applied in any field of civil and industrial engineering. In the present paper, in the framework of a research project funded by both the Campania Region and the European Community, a compound structure made of welded lattice beams and structural glass slabs is proposed as a structural system for valorisation and protection of monumental constructions and archaeological sites. Due to both the risk exposure of monumental heritage to be protected and the use of structural glass, the definition of an appropriate design criterion is mandatory in order to avoid development of brittle collapse mechanisms, mainly under static and dynamic vertical loads. The attention is herein paid to the design procedure, with a brief description of basic ideas behind the project itself and the main focus on the parametric capacity design of structural members. The proposed procedure, whose validity is quite general, has been subsequently verified by linear and non-linear numerical analyses calibrated on the basis of experimental investigations carried out on both the beam material and full-scale beam prototypes.

Numerical simulation on behavior of pile foundations under cyclic axial loads

On the basis of the two dimensional finite element analysis model, the pile foundations’ mechanical effect of the rigid pile composite foundation under the dynamic load was researched. Through the research, the development law and deformation property of axial force of pile body, shaft resistance of pile, and cumulative settlement of pile head under vertical cyclic dynamic loads were concluded. Through the comparison and analysis of the test results of dynamic models, the test results of Poulos (1989) and cumulative settlement model of the single pile under cyclic loads were confirmed. Based on the above research, Fortran language was adopted to introduce the soil attenuation factor, the secondary development of relevant modules of ABAQUS was carried out, and the effect of soil attenuation factor on dynamic property of pile-soil was discussed further.

Effect of compressible parameters on vertical vibration of an elastic pile in multilayered poroelastic media

This paper mainly investigates the influences of compressible parameters on the vertical vibration of a pile embedded in layered poroelastic soil media. The pile is treated as a 1D elastic bar by the finite element method, and fundamental solutions for the layered poroelastic soils due to a vertical dynamic load are obtained by the analytical layer element method. Based on the compatibility conditions, the pile-soil dynamic interaction problem is solved. The numerical scheme has been compiled into a Fortran program for numerical calculation. Influences of the pile-soil stiffness ratio, compressible parameters, vibration frequency and the soil stratification are discussed.

Performance Measurements of Gas Bearings With High Damping Structures of Polymer and Bump Foil Via Electric Motor Driving Tests and One Degree-of-Freedom Shaker Dynamic Loading Tests

This paper presents comprehensive test measurements for gas journal bearings with damping structures of a bump foil layer and/or a polymer layer. A one-pad top foil forms the bearing surface, under which the bearing structure and a bearing housing are located. Test bearings include gas foil bearings (GFBs), gas polymer bearings (GPBs), and gas foil-polymer bearings (GFPBs). In addition, three metal shims were employed to create wedge effects in the GFPBs. First, static load-deflection tests of test bearings estimate the radial assembly clearance. Second, shake dynamic loading tests identify frequency-dependent dynamic characteristics. An electromagnetic shaker provides flat bearing specimens with one degree-of-freedom (1DOF) vertical dynamic loading. GFPB was measured to exhibit a higher structural damping and lower stiffness than GFB. Lastly, the electric motor driving tests examine the rotordynamic stability performance. A permanent magnet (PM) synchronous motor drives a PM rotor supported on a pair of test journal bearings. As a result, the GFPBs with mechanical preloads enhanced the rotordynamic performance with no subsynchronous motions up to the maximum rotor speed of 88 krpm, and the bearing friction characteristics as well. Furthermore, they showed comparable rotordynamic performance to three-pad GFBs from a past literature, even with larger bearing clearances and small mechanical preloads.