Search Results

Abstract Dynamic stresses exist in parts of a catalyst muffler caused by the vibration of a moving vehicle, and it is important to clarify and predict the vibration response properties for preventing fatigue failures. Assuming a vibration isolating installation in the vehicle frame, the vibration transmissibility and local dynamic stress of the catalyst muffler were examined through a vibration machine. Based on the measured data and by systematically taking vibration theories into consideration, a new prediction method of the vibration modes and parameters was proposed that takes account of vibration isolating and damping. A lumped vibration model with the six-element and one mass point was set up, and the vibration response parameters were analyzed accurately from equations of motion. In the vibration test, resonance peaks from the hanging bracket, rubber bush, and muffler parts were confirmed in three excitation drives, and local stress peaks were coordinate with them as well.

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Abstract The civil aircraft nosewheel is clamped, lifted, and retained through the pick-up and holding system of the towbarless towing vehicle (TLTV), and the aircraft may be moved from the parking position to an adjacent one, the taxiway, a maintenance hangar, a location near the active runway, or conversely only with the power of the TLTV. The TLTV interfacing with the nose-landing gear of civil transport aircraft for the long-distance towing operations at a high speed could be defined as a towbarless aircraft taxiing system (TLATS). The dynamic loads induced by the system vibration may cause damage or reduce the certified safe-life limit of the nose-landing gear or the TLTV when the towing speed increases up to 40 km/h during the towing operations due to the maximum ramp weight of a heavy aircraft.

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Abstract Since vehicle structural flexibility and suspension nonlinearity are usually not considered, many existing vehicle models have difficulty in accurately describing the dynamic characteristics of the actual vehicle, which limits their practical applications. This article presents a rigid-flexible coupled system to investigate the dynamic behavior of a heavy-duty truck. An improved Maxwell-slip (IMS) model is proposed to describe the hysteresis nonlinearity of a leaf spring. In the coupled system, the axles and powertrain are simplified to be rigid, and the cab and frame are modeled using finite element method (FEM) considering their flexibility. During the solution process, the application of the FEM leads to a significant increase in the computer burden. Therefore, the iterated improved reduction system (IIRS) method is adopted to reduce the size of the large-size finite-element (FE) models to achieve the purpose of improving the calculation efficiency.

Abstract Based on the thermodynamic theory and the model of the air suspension system (ASS), two different calculation methods including Method I, using ASS’s initial parameters to calculate the mass flow rate and the total stiffness of the ASS, and Method II, using ASS’s initial parameters to determine the static stiffness, elastic stiffness, and damping coefficient of the ASS, are researched. To assess the accuracy of each calculation method and the ASS’s performance, a quarter-vehicle dynamic model equipped with the ASS and the steel spring is simulated and analyzed under the different excitations of the harmonic and random road surfaces. Experimental investigations are also used to verify the accuracy of the models. The research shows that the computation results of the two calculation methods I and II are similar under the same simulation conditions.

Abstract The design of the shafts and bearings significantly influences the dynamics of spiral bevel gears like most high-speed precision gears employed in the powertrains of emerging and traditional automobiles, trucks, and off-highway vehicles. In this article, the influence of design changes of gear-shaft-bearing configurations on the dynamics of spiral bevel gears is investigated by applying the finite element-based dynamic model. Two kinds of representative gear-shaft-bearing configurations, i.e., straddle-mounted pinion configuration and overhung-mounted pinion configuration, are compared from the viewpoint of the vibrations and dynamics of the spiral bevel-geared rotor system. The results show that the changes of gear-shaft-bearing configurations can lead to a significant change in spiral bevel gear dynamic responses, including dynamic mesh force, dynamic bearing loads, and so on. The underlying physics controlling these effects are also discovered.

Abstract The present article analyzes the influence of the track and rail vehicle vibrations on the biodynamic human subject. A mathematical model of 47 degrees of freedom (DoF) human body-vehicle-track vibratory system is formulated for the analysis of ride behavior of the vehicle and human body system. The human body, vehicle, and track system are assigned 7 DoF, 37 DoF, and 3 DoF, respectively, and the system is formulated using Newton’s method. Stationary random irregularities of the track are accounted for in the analysis, represented by the power spectral density (PSD) function, and are used as an input to the system. The ride comfort of the rail vehicle is examined based on the International Organization of Standardization (ISO) comfort specifications. The biodynamic human subject, vehicle, and track system are evaluated independently and integrated to examine the response of one system due to the excitation of another.

Abstract The article presents results of tests performed with the use of a ship engine of the type Sulzer 6AL20/24. The goal of the tests was to create and verify an identification procedure for the analyzed object’s reliability states to be used without interfering with the object operation processes. The proposed method is based on an analysis of vibrations and noise generated during the engine operation, which are considered to be the most significant diagnostic signals. The signals of the engine vibrations and noise recorded during the engine operation on a laboratory test stand have been analyzed in the time domain. A number of the recorded signal characteristics are calculated. The characteristics are statistically analyzed in order to choose those which can provide the basis for the identification of reliability states. Next, based on the spaces of ability and inability, states are formulated.

Abstract Vehicle vibration is the key consideration in the early stage of vehicle development. The most dynamic system in a vehicle is the powertrain system, which is a source of various frequency vibration inputs to the vehicle. Mostly for powertrain mounting system design, only the uncoupled powertrain system is considered. However, in real situations, other subsystems are also attached to the powertrain unit. Thereby, assuming only the powertrain unit ignores the dynamic interactions among the powertrain and other systems. To address this shortcoming, a coupled powertrain and driveline mounting system problem is formulated and examined. This 16 DOF problem is constructed around a case of a front engine-based powertrain unit attached to the driveline system, which as an assembly resting on other systems such as chassis, suspensions, axles, and tires.

Abstract This research examined tractor operators’ daily vibration exposure A(8) with different input riding parameters, i.e., average speed (m/s) (2.78, 3.89, 5.0), body mass (BM) (kg/m2) (35.3, 32.6, 25.4), and different terrain types (brick, farm, and tar roads). To arrange the systematic sequence of experiments, Taguchi’s L9 orthogonal array has been selected for this study. The signal-to-noise ratio (SNR) is calculated to analyze the overall influence of input parameters over the output parameters. In this study, it is found that A(8) responses exceeded the recommended action value among all the tractor operators according to ISO 2631-1 (1997). The average speeds and various terrain conditions were shown to be the most influential significant variables (p ≤ 0.05), with percentage contributions of 53.71% and 11.53%, respectively.

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Abstract The drone logistics distribution method, with its small size, quick delivery, and zero-touch, has progressively entered the mainstream of development due to the global epidemic and the rapidly developing global emerging logistics business. In our investigation, a drone and a delivery man worked together to complete the delivery order to a customer’s home as quickly as possible. We realize the combined delivery network between drones and delivery men and focus on the connection and scheduling between drones and delivery men using existing facilities such as ground airports, unmanned stations, delivery men, and drones. Based on the dynamic-vehicle routing problem model, the establishment of a delivery man and drone with a hybrid model, in order to solve the tarmac unmanned aerial vehicle for take-out delivery scheduling difficulties, linking to the delivery man and an adaptive large neighborhood search algorithm solves the model.

Abstract The riding-comfort of high-speed trains affects the travel experience of passengers, and the lightweight design technology of the carbody increases the flexible vibration and reduces passenger comfort. To this end, a vertical dynamics model of railway vehicles is established to demonstrate the potential of using passive inerter-based suspensions to reduce the flexible vibration of the carbody and improve riding-comfort. According to the characteristics of the inerter component, an appropriate inerter-based suspension is applied to the railway vehicle to reduce low-frequency resonance. The sum of the comfort indexes of the three reference points of the carbody is optimized as the objective function to improve the passenger comfort of the whole vehicle. The results reveal that the inerter-based suspension applied to the primary or secondary suspension has different effects on vehicle vibration.

Abstract The vibration transmissibility and ride comfort for the human body elements are the important evaluation parameters while traveling in a passenger’s vehicle because both directly influence the occupant’s health and effectiveness of working. These parameters also examine the sensitivity of the human body to vehicle vibrations, which is an important area of research and investigations these days. The present work analyzes the effects of road disturbances on the vehicle and human biodynamic subject vibrations. A nine degrees of freedom (9 DoF) three-wheeled coupled vertical-lateral vehicle dynamic model and eleven degrees of freedom (11 DoF) biodynamic model are formulated and integrated. The vibration transmissibility and ride comfort based on the International Organization for Standardization (ISO) and ISO 2631 standards are investigated for the different segments of a human subject in a seated posture.

Abstract Based on the dynamics theory and the negative stiffness structure (NSS), the optimal design of the driver’s seat suspension system of the cab or vehicle equipped with the NSS is proposed to enhance the driver’s ride comfort and health. To design the seat suspension system using the NSS, the dynamic models of the seat suspension system and the NSS are established to calculate the vibration equations. The influence of the geometrical and dynamic parameters of the NSS and the different operating conditions of the vehicle on the driver’s ride comfort are analyzed, respectively. Three indexes of the reduction of the root-mean-square displacement (xRMSs ), the weighted root-mean-square acceleration (aRMSs ) of the driver’s seat, and the seat effective amplitude transmissibility (SEAT) of the seat suspension system are selected to evaluate the NSS efficiency.

Abstract NVH refinement of commercial vehicles is the key attribute for customer acceptance. Engine and road irregularities are the two major factors responsible for the same. During powertrain isolators’ design alone, the mass and inertia of the powertrain are usually considered, but in practical scenarios, a directly coupled subsystem also disturbs the boundary conditions for design. Due to the upgradation in emission norms, the exhaust aftertreatment system of modern automotive vehicles becomes heavier and more complex. This system is further coupled to the powertrain through a flexible joint or fixed joint, which results in the disturbance of the performance of the isolators. Therefore, to address this, the isolators design study is done by considering a multi-body dynamics model of vehicles with 16 DOF and 22 DOF problems, which is capable to simulate static and dynamic real-life events of vehicles.