Dynamic thermo-mechanical responses of road-soft ground system under vehicle load and daily temperature variation

A complete road-soft ground model is established in this paper to study the dynamic responses caused by vehicle loads and/or daily temperature variation.A dynamic thermo-elastic model is applied to capturing the behavior of the rigid pavement,the base course,and the subgrade,while the soft ground is characterized using a dynamic thermo-poroelastic model.Solutions to the road-soft ground system are derived in the Laplace-Hankel transform domain.The time domain solutions are obtained using an integration approach.The temperature,thermal stress,pore water pressure,and displacement responses caused by the vehicle load and the daily temperature variation are presented.Results show that obvious temperature change mainly exists within 0.3 m of the road when subjected to the daily temperature variation,whereas the stress responses can still be found in deeper places because of the thermal swelling/shrinkage deformation within the upper road structures.Moreover,it is important to consider the coupling effects of the vehicle load and the daily temperature variation when calculating the dynamic responses inside the road-soft ground system.

Reflective cracking viscoelastic response of asphalt concrete under dynamic vehicle loading

In order to investigate the mechanical response of reflective cracking in asphalt concrete pavement under dynamic vehicle loading, a finite element model is established in ABAQUS. The viscoelastic behavior is described by a prony series which is calculated through nonlinear fitting to the creep test data obtained in the laboratory. Based on the viscoelastic theory, the time-temperature equivalence principle, fracture mechanics and the dynamic finite element method, both the Jintegral and the mix-mode stress intensity factor are utilized as fracture evaluation parameters, and a half-sine dynamic loading is used to simulate the vehicle loading. Finally, the mechanical response of the pavement reflective cracking is analyzed under different vehicle speeds, different environmental conditions and various damping factors. The results indicate that increasing either the vehicle speed or the structure damping factor decreases the maximum values of fracture parameters, while the structure temperature has little effect on the fracture parameters. Due to the fact that the vehicle speed can be enhanced by improving the road traffic conditions, and the pavement damping factor can become greater by modifying the components of materials, the development of reflective cracking can be delayed and the asphalt pavement service life can be effectively extended through both of these ways.

Investigation on nonlinear rolling dynamics of amphibious vehicle under wind and wave load

Nonlinear amphibious vehicle rolling under regular waves and wind load is analyzed by a single degree of freedom system.Considering nonlinear damping and restoring moments,a nonlinear rolling dynamical equation of amphibious vehicle is established.The Hamiltonian function of the nonlinear rolling dynamical equation of amphibious vehicle indicate when subjected to joint action of periodic wave excitation and crosswind,the nonlinear rolling system degenerates into being asymmetric.The threshold value of excited moment of wave and wind is analyzed by the Melnikov method.Finally,the nonlinear rolling motion response and phase portrait were simulated by four order Runge-Kutta method at different excited moment parameters.

Flight Loads and Dynamics of Flexible Air Vehicles

Based on the equations of motion of flexible air vehicles includingrigid-body modes and elastic structural modes, and applying influence coefficients of linearaerodynamics, a set of equations are derived and a method is presented for analysis of flight loadsand dynamic characteristics. The problems in the fields of flight mechanics and aeroelasticity suchas static aeroelastic divergence, trim and deformation, aerodynamic loads distribution, flutter andflight dynamics can be solved by the procedure. An airplane with high aspect ratio wings isanalyzed, and the results show that the coupling between rigid -body modes and elastic modes isdistinct and should not be overlooked.

Test and numerical investigations on static and dynamic characteristics of extra-wide concrete self-anchored suspension bridge under vehicle loads

The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite element simulations, the static deformations of different components, stress increments and distributions of the girder, as well as the vibration characteristics and damping ratio of the Hunan Road Bridge were analyzed, which is the widest self-anchored suspension bridge in China at present. The dynamic responses were calculated using the Newmark-β integration method assisted by the simulation models of bridge and vehicles, the influences on the dynamic impact coefficient(DIC) brought by the vehicle parameters, girder width, eccentricity travel and deck flatness were also researched. The spatial effect of the girder is obvious due to the extra width, which performs as the stress increments distribute unevenly along the transverse direction, and the girder deflections and stress increments of the upper plate change as a "V" and "M" shape respectively under the symmetrical vehicle loads affected by the shear lag effect, cross slope and local effect of the wheels, the maximum of stress increments are located in the junctions with the inner webs. The obvious girder torsional deformation and the apparent unevenness of the hanger forces between the two cable planes under the eccentric vehicle loads, together with the mode shapes such as the girder transverse bending and torsion which appear relatively earlier, all reflect the weakened torsional rigidity of the extra-wide girder. The transverse displacements of towers are more obvious than the longitudinal ones. As for the influences on the DIC, the static effect of the heavier vehicles plays a major role when pass through with a higher speed and the changes of vehicle suspension stiffness generate greater impacts than the suspension damp. The values of DIC in the vehicle-running side during the eccentric travel, affected by the restricts from the static effects of the eccentric moving trucks, are significantly smaller than the vehicle-free side, the increase in the road roughness is the most sensitive one among the above influential factors. The results could provide references for the design, static and dynamic response analysis of the similar extra-wide suspension bridges.

Dynamic reliability analysis of supercavity vehicle with stochastic parameters under impact loads

With dynamic reliability problems of stochastic parameters,supercavity vehicle is subject to impact loads.The supercavity vehicle is modeled by using eight-node super-parametric shell elements.The tail impact loads of supercavity vehicle structures are simplified into two stationary random processes with a certain phase difference,and the random excitations are transformed into sinusoidal ones in terms of the pseudo excitation method.The stress response of stochastic structure can be obtained through combining Newmark method with pseudo excitation perturbation method,and then all required digital features for dynamic reliability of supercavity vehicle have be calculated.The expressions of the mean value and the variance of dynamic reliability of supercavity vehicle with stochastic parameters are educed on the basis of the Poisson formula of calculating dynamic reliability.Finally,the influence of the randomness of structural parameters on the dynamic reliability is analyzed.And the feasibility and availability of this method were validated by comparing with the Monte Carlo method.

Finite Element Modeling and Parametric Analysis of Pavement Dynamic Responses under Moving Vehicle Load

This paper intends to develop finite element models that can simulate vehicle load moving on pavement system and reflect the pavement response of vehicle and pavement interaction.We conduct parametric analysis considering the influences of asphalt concrete layer modulus and thickness,base layer modulus and thickness,and subgrade modulus on pavement surface displacement,frequency,and strain response.The analysis findings are fruitful.Both the displacement basin width and maximum value of dynamic surface displacements are larger than those of static surface displacements.The frequency is positively correlated with the pavement structure moduli,and negatively correlated with the pavement structure thicknesses.The shape of dynamic and static tensile strain is similar along the depth of the pavement structure.The maximum value of dynamic tensile strain is larger than that of static tensile strain.The frequency of entire pavement structure holds more significant influence than the surface displacement and strain do.The subgrade modulus has a significant effect on surface displacement,frequency and strain.

Dynamic Response of Double-Sided Loess Slope under Vehicle Load

In order to verify and study the dynamic response law on the double-sided loess slope under the action of the waves generated by automobile traffic,we select a double-sided loess slope from the long section of Anzi Road as the research object.Both field investigations and on-site monitoring processes are conducted,for the purpose of providing robust basis for road protection in these conditions.In detail,vehicleinduced vibration signals are different according to different vehicle types,speeds,as well as positions,and thus are collected,respectively.Based on the statistical analysis of the signals,the vibration response law and frequency spectrum characteristics of the slope are summarized.The results show that:①The dynamic response of the doublesided loess slope increases as the vehicle load increases,and the strong vibration response area is located in the middle of the side slope;②When the vehicle load is small,the vibration wave amplification effect is obvious.On the contrary,when the vehicle load is large,the vibration wave amplification effect is weakened;③The spectrum distribution of the X-direction wave is single-peak shape,and the dominant frequency is concentrated in 30-50 Hz;the frequency spectrum distribution of the Zdirection wave shows a multi-peak shape,and the dominant frequency is concentrated in 20-180 Hz;④The vibration wave propagates in the slope.The frequency change shows little correlation with the type,speed and position of the vehicle,and instead,it is mainly determined by the slope itself.This study reveals the dynamic response on doubled-sided loess slopes and provides both theoretical and practical significance for the road protection in such situations.

Quantification of the Vertical Load Applied to the Pavement during Cornering Maneuver of a Battery Electric Commercial Vehicle

The wheel loads of heavy trucks are the major source of pavement damage,given the repeated loadings imposed by them due to transient events and surface irregularities.While related studies focus on steady-state context regarding simplified vehicle’s parameters and ideal pavement conditions,this paper aims to analyze the vertical load applied to the pavement by considering cornering maneuver as a transient event,on a battery electric vehicle truck.In this concern,measurements were performed on a rigid truck,with two steering front axles,in a closed course proving ground.The relationship has been presented between vehicle’s speed,lateral acceleration and transferred vertical load for a given curve radius of 85.6 m and 3.7°of transversal slope.The measurements results indicated that for every 10 km/h increasing on the vehicle’s speed,additional 110 kgf will be transferred to the pavement on the outer side of the cornering radius.This value itself could not be considered high,but it will be also added to the static load,or overload in some truck applications.

Numerical Simulation-Based Analysis of the Impact of Overloading on Segmentally Assembled Bridges

Segmentally assembled bridges are increasinglyfinding engineering applications in recent years due to their unique advantages,especially as urban viaducts.Vehicle loads are one of the most important variable loads acting on bridge structures.Accordingly,the influence of overloaded vehicles on existing assembled bridge structures is an urgent concern at present.This paper establishes thefinite element model of the segmentally assembled bridge based on ABAQUS software and analyzes the influence of vehicle overload on an assembled girder bridge struc-ture.First,afinite element model corresponding to the target bridge is established based on ABAQUS software,and the load is controlled to simulate vehicle movement in each area of the traveling zone at different times.Sec-ond,the key cross-sections of segmental girder bridges are monitored in real time based on the force character-istics of continuous girder bridges,and they are compared with the simulation results.Finally,a material damage ontology model is introduced,and the structural damage caused by different overloading rates is compared and analyzed.Results show that thefinite element modeling method is accurate by comparing with on-site measured data,and it is suitable for the numerical simulation of segmental girder bridges;Dynamic sensors installed at 1/4L,1/2L,and 3/4L of the segmental girder main beams could be used to identify the dynamic response of segmental girder bridges;The bottom plate of the segmental girder bridge is mostly damaged at the position where the length of the precast beam section changes and the midspan position.With the increase in load,damage in the direction of the bridge develops faster than that in the direction of the transverse bridge.Thefindings of this study can guide maintenance departments in the management and maintenance of bridges and vehicles.

Dynamic Characteristics of Metro Vehicle under Thermal Deformation of Long-Span Cable-Stayed Bridge

In order to study the influence of thermal deformation of long-span cable- stayed bridge (LSCSB) on the dynamic characteristics of metro vehicle on the bridge, based on the theory of vehicle-track coupled dynamics, the rigid-flexible coupled dynamic model of metro vehicle-track-LSCSB system is established by using finite element method and multi-rigid-body dynamics. Adopting this model, the deformation of LSCSB subject to temperature is analyzed, then the comprehensive effect of track random irregularity and rail deformation caused by temperature load is considered to study the dynamic characteristics of metro vehicle running through the bridge, and finally the influences of temperature increment and running speed on concerned dynamic indices of vehicle are studied. The results show that the LSCSB deforms obviously subject to temperature load, and the overall performance is that the cooling is arched, and the heating is bent, and the shape variable changes almost linearly with the temperature load. According to the parameters studied in this paper, the rail deformation caused by temperature load increases the wheel-rail vertical force, derailment coefficient and wheel load reduction rate by 1.5%, 3.1% and 5% respectively. The vertical acceleration of the vehicle body decreases by 2.4% under the cooling condition, while increases by 3.7% under the heating condition. The dynamic response of the bridge changes under temperature load. The maximum vertical and horizontal displacement in the middle of the main beam span are 6.24 mm and 2.19 mm respectively, and the maximum vertical and horizontal acceleration are 1.29 cm/s2 and 2.54cm/s2 respectively. The derailment coefficient and vertical acceleration of vehicle body are more affected by temperature load, and the wheel load reduction rate and wheel-rail vertical force are more affected by speed. The conclusion of this paper provides a reference for subsequent scholars to study the influence of thermal deformation on the dynamic response of vehicles on LSCSB.

Evaluation of High-Speed Track Quality Using Dynamic Simulation of Vehicle-Track Interaction

Track quality is a determinant factor for evaluating the overall performance of vehicle track interaction with respect to safety, ride quality and maintenance. Important parameters specifying the general quality of the track include track geometry (undamped) and track stiffness (damped), which can be evaluated by measurements taken along with track sections. A new co-simulation model based on Finite Element Method (FEM) and Multi Body Simulation (MBS) is built for the detailed description of track quality and its contribution to vehicle track interaction without simplifying the track structure as interconnected single elements. The simulation models and tools have been validated with the help of measured track geometry, track stiffness and dynamic wheel rail forces along the track sections of high speed lines. A comparative study between high speed lines using conventional ballasted track and ballastless track showed a significantly better quality in ballastless track sections. The dynamic forces which were determined by simulations and verified by measurements along the ballastless track section were comparatively less than the specified limits by German regulations for ballastless track design. Lower levels of dynamic forces can be utilized for optimization of track design and installation procedures with respect to lower initial costs.

Reduction of global effects on vehicles after IED detonations

Global effects caused by the detonation of an IED near a military vehicle induce subsequent severe acceleration effects on the vehicle occupants.Two concepts to minimize these global effects were developed,with the help of a combined method based on a scaled experimental technology and numerical simulations.The first concept consists in the optimization of the vehicle shape to reduce the momentum transfer and thus the occupant loading.Three scaled V-shaped vehicles with different ground clearances were built and compared to a reference vehicle equipped with a flat floor.The second concept,called dynamic impulse compensation(DIC),is based on a momentum compensation technique.The principal possibility of this concept was demonstrated on a scaled vehicle.In addition,the numerical simulations have been performed with generic full size vehicles including dummy models,proving the capability of the DIC technology to reduce the occupant loading.

Analysis of Slope Stability with Dynamic Overloading from Earthquake

The analysis of slope earthquake stability is one of the most important research subjects in geotechnical engineering and earthquake engineering.Two different concepts of slope earthquake stability are put forward：strength reserve stability and dynamic overloading stability.The first concept of slope earthquake stability has been widely accepted,and relative analysis methods are also well de-veloped;the second one,however,is seldom mentioned until now,and the failure criterion and the analysis method based on this concept are yet to be explored.What are researched are just the failure criterion and the analysis method of dynamic overloading earthquake stability.The criterion of critical earthquake peak acceleration for the dynamic overloading stability of a slope and its analysis method,the load increasing method（LIM）,are put forward.The dynamic overloading earthquake stability of a loess slope at Changshougou（长寿沟） in Baoji（宝鸡） City,Shaanxi（陕西） Province,China,is analyzed with LIM.The analysis result reveals that the dynamic overloading earthquake stability of the slope is quite high to the action of the earthquake ground motion,with exceeding probability of 10% in the next 50 years.

Optimized speed control for electric vehicles on dynamic wireless charging lanes: An eco-driving approach

As the adoption of Electric Vehicles(EVs)intensifies,two primary challenges emerge:limited range due to battery constraints and extended charging times.The traditional charging stations,particularly those near highways,exacerbate these issues with necessary detours,inconsistent service levels,and unpredictable waiting durations.The emerging technology of dynamic wireless charging lanes(DWCLs)may alleviate range anxiety and eliminate long charging stops;however,the driving speed on DWCL significantly affects charging efficiency and effective charging time.Meanwhile,the existing research has addressed load balancing optimization on Dynamic Wireless Charging(DWC)systems to a limited extent.To address this critical issue,this study introduces an innovative eco-driving speed control strategy,providing a novel solution to the multi-objective optimization problem of speed control on DWCL.We utilize mathematical programming methods and incorporate the longitudinal dynamics of vehicles to provide an accurate physical model of EVs.Three objective functions are formulated to tackle the challenges at hand:reducing travel time,increasing charging efficiency,and achieving load balancing on DWCL,which corresponds to four control strategies.The results of numerical tests indicate that a comprehensive control strategy,which considers all objectives,achieves a minor sacrifice in travel time reduction while significantly improving energy efficiency and load balancing.Furthermore,by defining the energy demand and speed range through an upper operation limit,a relatively superior speed control strategy can be selected.This work contributes to the discourse on DWCL integration into modern transportation systems,enhancing the EV driving experience on major roads.

Dynamic Rollover Prediction of Heavy Vehicles Considering Critical Frequency

Rollover of commercial heavy vehicles can cause enormous economic losses and fatalities.It is easier for such vehicles to rollover if the driver’s steering frequency is close to the critical frequency of the vehicle’s roll motion;however,the critical roll frequency has rarely been investigated.In this study,the second-order transfer function between the steering input and roll angle was developed to calculate the critical frequency of the vehicle’s roll motion.The simulated spectrum and transfer function were then used to dynamically predict the peak lateral load transfer ratio.Laboratory experiments were conducted using a scaled vehicle to verify the critical roll frequency.The results suggest that the peak value of the lateral load transfer ratio during steering can be accurately determined from the driver’s input,and the critical roll frequency has a dominant effect on the dynamic rollover of heavy vehicles.

Research on the Dynamic Response of Submerged Floating Tunnels to Wave Currents and Traffic Load

Submerged floating tunnel(SFTs)are typically subjected to complex external environmental and internal loads such as wave currents and traffic load.In this study,this problem is investigated through a finite element method able to account for fluid-structure interaction.The obtained results show that increasing the number of vehicles per unit length enhances the transverse vibrational displacements of the SFT cross sections.Under ultimate traffic load condition,one-way and two-way syntropic distributions can promote the dynamic responses of SFTs whereas two-way reverse distributions have the opposite effect.

Overloading and Pavement Service Life <br/>—A Case Study on Narayanghat-Mugling Road, Nepal

The ability of a pavement structure in carrying out its function reduces in line with the increase of traffic load, especially if there are overloaded heavy vehicle passing through the road. This study was done to know the effect of overloading vehicles on the road pavement and remaining service life of the pavement. In this study, the service life of pavement due to overloaded vehicles was analyzed using the AASHTO 1993. In Narayanghat-Mugling road the composition of traffic seems to be 83.76% heavy vehicles, 9.18% medium vehicle and 7.05% light vehicle. For the direction of Narayanghat-Mugling, the pavement service life might be reduced by 59.90% due to overloading condition, while for the opposite direction, the service life would not reduced caused by the same factor. The impact of overload conditions on the road pavement showed premature failure;that is, a condition which the damage reduced the life of roads before the design life of the road is reached. From the results, it can be concluded that overloaded vehicles on the road are very influential to the reduction in pavement service life. Therefore, it is expected that road users to comply with existing regulations in the conduct of transportation. As overloading is increasing, it has to be controlled by rules and regulations with penalty to control the overloading. So fines must be associated with intensified enforcement when considered in further strategy. Regular monitoring, inspection and enforcement are the effective ways to control overloading. Use of technology (Automatic overloading information system) may be the effective way to control the overloading.

EV Charging Station Load Prediction in Coupled Urban Transportation and Distribution Networks

The increasingly large number of electric vehicles(EVs)has resulted in a growing concern for EV charging station load prediction for the purpose of comprehensively evaluating the influence of the charging load on distribution networks.To address this issue,an EV charging station load predictionmethod is proposed in coupled urban transportation and distribution networks.Firstly,a finer dynamic urban transportation network model is formulated considering both nodal and path resistance.Then,a finer EV power consumption model is proposed by considering the influence of traffic congestion and ambient temperature.Thirdly,the Monte Carlo method is applied to predict the distribution of EVcharging station load based on the proposed dynamic urban transportation network model and finer EV power consumption model.Moreover,a dynamic charging pricing scheme for EVs is devised based on the EV charging station load requirements and the maximum thresholds to ensure the security operation of distribution networks.Finally,the validity of the proposed dynamic urban transportation model was verified by accurately estimating five sets of test data on travel time by contrast with the BPR model.The five groups of travel time prediction results showed that the average absolute percentage errors could be improved from 32.87%to 37.21%compared to the BPR model.Additionally,the effectiveness of the proposed EV charging station load prediction method was demonstrated by four case studies in which the prediction of EV charging load was improved from27.2 to 31.49MWh by considering the influence of ambient temperature and speed on power energy consumption.