Multi-body System Dynamics Theory Research Articles

Effect of Some Structural Parameters on Firing Stability of Shooter-Weapon System

This article presents a method to establish the dynamic model of the Shooter-weapon system when firing based on Lagrange’s theorem and the theory of multibody system dynamics, in which the influence of the human body was taken into account. In the dynamic model, the influence of the gunner is solved by using elastic-damping links in the x, y and z axes. The dynamic model is created for a portable gas-operated submachine gun and contains three solids with seven degrees of freedom. The 7.62 mm AKM submachine gun has been used for the model simulation and experimental verification. The dynamic simulation was conducted and then the results were compared with the corresponding experimental data. The model simulation results are very close to the experimental results. This study aims to survey the influence of various parameters on gun stability in the shooting. It is possible to apply these results to portable automatic guns.

Effect of Some Structural Parameters on Firing Stability of Shooter-Weapon System

This article presents a method to establish the dynamic model of the Shooter-weapon system when firing based on Lagrange’s theorem and the theory of multibody system dynamics, in which the influence of the human body was taken into account. In the dynamic model, the influence of the gunner is solved by using elastic-damping links in the x, y and z axes. The dynamic model is created for a portable gas-operated submachine gun and contains three solids with seven degrees of freedom. The 7.62 mm AKM submachine gun has been used for the model simulation and experimental verification. The dynamic simulation was conducted and then the results were compared with the corresponding experimental data. The model simulation results are very close to the experimental results. This study aims to survey the influence of various parameters on gun stability in the shooting. It is possible to apply these results to portable automatic guns.

Effect of wheel flat on dynamic wheel-rail impact in railway turnouts

Wheel flat is a form of wheel tread defect that reduces the service life and running safety of trains and tracks. Based on the multi-body system dynamics theory, a rigid-flexible vehicle-turnout dynamic coupling modelwas established, and the wheel diameter-varying flat simulation method used to create wheel flat models of different sizes. The most unfavourable phase of flats on the wheels of a vehicle crossing a turnout was studied by scanning and calculating the phase of the flats. The influence of flat size and vehicle speed on a vehicle with flats crossing a turnout was also analyzed. The results show that, compared with a normal wheel crossing a turnout and a wheel flat acting on the interval rail, a wheel flat acting on the wheel load transition of the frog area will excite greater vertical wheel-rail forces and vertical axle box vibration acceleration; in the turnout area, the main frequency band of the vertical vibration acceleration of the axle box is 550–800 Hz, which is rarely affected by the size of flats or the speed of the vehicle. The third-order bending mode of the wheel is excited when the wheel transits from the wing rail to the point rail.

Dynamic analysis of main transmission mechanism of high-speed cold heading machine based on rigid-flexible coupling model

In the research of high speed cold heading machine, only single part is studied. The interaction between the components of the main drive mechanism is rarely studied. The motion of the main transmission mechanism of the cold heading machine was analysed. The interaction between the components of the main transmission mechanism was studied. This article adopts the theory of multi-body system dynamics. The rigid-flexible coupling model of the main transmission mechanism was established. The dynamics and kinematics simulation of the main transmission mechanism was carried out. The motion curve and stress of the rigid-flexible coupling model are obtained. Compared with the rigid model, the rationality of the rigid flexible coupling model was demonstrated. It provided a reference for further fatigue analysis and optimization of the main transmission mechanism.

Test technology research and fatigue damage prediction of a car body based on dynamic simulation load spectrum

The dynamic model of a high-speed electric multiple unit (EMU) is established based on the theory of rigid-flexible coupling multi-body system dynamics. Depending on the actual operating conditions of the vehicle, there are a variety of conditions of car body load-time history. We assess ineffective amplitude omission, load spectrum extrapolation, and extreme determination through the car body load-time history, and then obtain the car body fatigue load block spectrum. Finally, we perform a fatigue strength test on the whole car body on a car body fatigue test bench. It is shown that the accelerations of the three directions of the vehicle car body increase with increasing speed. When the train passes a curve, the lateral acceleration average becomes greater. There is also an increase in the car body accelerations in three directions when the train goes through a turnout or twisted line. Under the condition of a failed spring, the vertical acceleration of the car body is obviously increased. Anti-yaw damper failure will cause a significant increase in vehicle lateral acceleration. The failure of lateral and vertical dampers on the second suspension causes an insignificant acceleration increase in three directions. The car body acceleration increases the wear-type profile relative to the original profile in various working and speed level conditions a little. The influence on the damage of vehicle car body under various working conditions is predicted according to the obtained load spectrum.

Geometric Error Modeling and Sensitivity Analysis of CNC Internal Circular Compound Grinding Machine

In order to improve the machining accuracy and efficiency of the hole and sleeve parts, it is necessary to improve the overall grinding accuracy of the CNC (Computer Numerical Control) internal cylindrical compound grinding machine more accurately and efficiently. First of all, it is necessary to clarify the degree of influence of each error parameter on the grinding accuracy, and compensate each error according to the different degree of influence. In this paper, modeling calculation analysis is carried out for a certain type of CNC internal cylindrical compound grinding machine. Firstly, based on the theory of multi-body system dynamics, the topological structure of the CNC internal cylindrical compound grinder is established. According to the topological structure, the position, motion matrix and error matrix of the moving parts of the grinder are written. After data processing, the numerical control internal cylindrical compound grinder is calculated. Use this model to derivate each error parameter to obtain the sensitivity expression of each error parameter. After the actual structure parameters of the grinder are brought into the expression, the sensitivity coefficient of each error parameter can be determined by normalization treatment. The key error parameter with larger sensitivity coefficient is the key error parameter. Finally, several error parameters which have the greatest impact on the overall grinding accuracy of the grinder are obtained. This method provides the basis for the improvement of the grinding accuracy of the subsequent grinder, and creates conditions for the improvement of the machining accuracy of sleeve parts.

Dynamic behavior of a polyurethane foam solidified ballasted track in a heavy haul railway tunnel

Dynamic behavior of a new type of track using the polyurethane foam solidified ballast in heavy haul railway tunnels is comprehensively investigated in this study. First, a dynamic model of the vehicle–track–tunnel interaction system was developed based on the multi-body system dynamics theory and finite element method. Then, the dynamic effects of the polyurethane foam solidified ballast track on the train and the surrounding infrastructures were calculated and compared to those of the traditional ballasted track. Moreover, the effects of the elastic modulus and the solidified area size of polyurethane foam solidified ballast on the dynamic behavior were analyzed. Results show that, compared to the traditional ballast bed, polyurethane foam solidified ballast decreases the track stiffness and the vibration acceleration of the tunnel, while does not affect the vehicle safety (derailment coefficient and the rate of wheel load reduction). A larger elastic modulus of polyurethane foam solidified ballast has little effects on the wheel–rail interaction and the vibration acceleration of the tunnel, while a smaller modulus results in amplification of the displacements of rails and sleepers. Considering the vehicle–track interaction and tunnel vibration, the optimal elastic modulus of polyurethane foam solidified ballast is suggested to be 60–80 MPa. In addition, smaller solidified area of polyurethane foam solidified ballast presents lower effects on the vibration reduction and rate of wheel load reduction, while larger area leads to a higher derailment coefficient and cost. Therefore, an optimal solidified area size of polyurethane foam solidified ballast with the top width of 0.85 m is recommended.

Simulation of the Tracked Vehicle Climbing Over Vertical Wall

Based on theory of multi-body system dynamics, in the ADAMS virtual environment, a type of tank vehicle is presented as the research object, the simulation tests of the tracked vehicle on part of working condition of typical driving dynamics characteristics on cross-country mobility were obtained. The simulation of climbing over vertical wall of the tracked vehicles was obtained. Through the dynamics analysis and simulation of the tracked vehicle, the theoretical guidance of the tracked vehicle on maneuverability evaluation and optimization of the driving device are provided.

Numerical simulation on the aerodynamic performance of the high-speed train under crosswinds

With the continuously increased speed of the high-speed train, the lateral aerodynamic performance of high-speed trains has attracted more and more attention. Under strong crosswinds, the aerodynamic performance of trains deteriorate and air drag, lift and lateral forces borne by trains quickly increase, which has an impact on the lateral stability of trains and even leads to train derailment. This paper adopted computational fluid dynamics theory to establish an aerodynamic model for a high-speed train, computed aerodynamic forces and moments acting on the high-speed train and obtained the unsteady flow field of the high-speed train. In the meanwhile, this paper combined with multi-body system dynamics theory to establish a system dynamics model for the train and analyzed the safe aerodynamic performance of the high-speed train under cross winds. Computational results showed: Under cross winds, the aerodynamic performance of the high-speed train had a random fluctuation. When wind direction angle was 90°, aerodynamic forces (drag, lift and lateral forces) and moments (overturning moment, shaking moment and nodding moment) borne by the high-speed train were the largest; train speed was a main factor affecting the size of positive pressures of train and cross wind velocity had no obvious impacts on the positive and negative pressures of train body; the aerodynamic forces and moments of the high-speed train had a random fluctuation within a certain range with time; the frequency for the peak value of power spectral density of lateral forces of head train was within 25 Hz and the peak value of power spectral density was the largest when the main frequency was 1.6 Hz; the frequency for the peak value of power spectral density of overturning moment of head train was within 20 Hz and main frequency was 0.57 Hz. When the cross wind speed was 15 m/s, all safety indexes of the high-speed train running at the speed of 250 km/h were within the range of limited values and satisfied design requirements. Aerodynamic performance of the high-speed train with the suction chamber under the cross wind was computed and compared with original results. Aerodynamic force and force moments of the high-speed train under cross wind will be reduced obviously and running safety of the high-speed train can be improved through application of the suction chamber.

Launch Dynamics Modeling and Simulation of Vehicular Missile System

To study the dynamics of a vehicular missile system and determine initial disturbances of a missile, the multi-rigid-flexible launch dynamics model of a vehicular missile system is developed by using transfer matrix method for multibody system and launch dynamics theory. The overall transfer equation, overall transfer matrix, and characteristics equation of the system are deduced based on the automatic deduction theorem of overall transfer equation of multibody system. The equation governing the motion of the vehicular missile system is obtained by using the orthogonality of augmented eigenvector and body dynamics equations of the system. The launch dynamics equations of a missile are deduced, in which the mass misalignment and dynamic imbalance of the missile are considered. By combining the equation governing the motion of the system and launch dynamics equations of the missile, the launch dynamics equations of the vehicular missile system are developed. The vibration characteristics, dynamics response of the system, and initial disturbances of the missile are simulated. The simulation results show that the eigenfrequencies obtained by the proposed method and ordinary dynamics method have good agreement. Some factors that influence missile’s motion and initial disturbances are analyzed. The paper provides an effective approach to study the launch dynamics of a vehicular missile system.

Aerodynamic Characteristics and Safety of High-Speed Trains Embankment under Crosswinds

This paper studies aerodynamic performance and safety of the high-speed train on the embankment under the action of horizontal wind. Based on the aerodynamics and multi-body system dynamics theory, the high-speed train aerodynamics and dynamics model is established to simulate field characteristics, aerodynamic performance and dynamic performance of high-speed train running on 10-meter embankment. From the simulation we get safety indexes such as derailment coefficient, wheel weight reducing load rate, lateral wheelset force and the wheel/rail vertical force. And the running security region of the train on the embankment can be determined based on high-speed train vehicle test specification. The calculation results of this paper can provide reference for the safe operation of high-speed trains in horizontal wind.

Application of Multibody System Dynamics in Marine Machinery

The multibody system dynamics is to establish mathematical model suitable for computer program to solve the kinematics and dynamics analysis, and seek the efficient and stable numerical method, its fundamental purpose is computer application technology for dynamic analysis and simulation of complex mechanical system. Through the computer to solve the multibody system dynamics problems, engineers the main work only need to according to the reality of the situation build suitable dynamics model, and submit to the computer solution. Moreover, the computer can also provide the results analysis, the extremely difficult complex mechanical problems which cannot even solve can now use computer calculation function to facilitate the solution. In the early days, the multi-body system dynamics is only applicable to the aviation machinery and robot, and now, with the continuous deepening of its theory, multibody system dynamics has a wide range of applications in the ship mechanical design. Below, we first briefly introduce the basic theory of multi-body system dynamics, and then focus on the application of multi-body system dynamics in the ship mechanical design.

Co-Simulation Study for Fuzzy ESP Control Strategy on Vehicle

ESP can help the road vehicle to improve driving dynamics and prevent accidents which result from loss of control. Based on the theory and account method of Multi-body System Dynamics, the Multi-body System Dynamics model of an A-class car is built by the ADAMS/Car software, which includes steering system, front and rear suspension, braking system, body, and so on. In order to study the handling stability of vehicle with ESP control system, the vehicle yaw rate is set as the controlling aim, to build the fuzzy controller of ESP. The performance evaluation methods of vehicle with ESP are proposed to evaluate the handling stability of vehicle with ESP. The results show that the vehicle with ESP can keep the right path, the yaw rate and the vehicle slip angle is all controlled better. The handling stability of vehicle can be improved.

Wind Turbine Seismic Load Analysis Based on Numerical Calculation

Large-scale wind turbines have come into common use in Europe. Because violent earthquakes are relatively rare there, insufficient consideration has been given to the seismic impact on the wind turbine specifications; however, at present, there are many wind farms being constructed in earthquake-prone regions, and the seismic impact cannot be ignored in wind turbine designs. Based on the multi-body system dynamic theory and taking into consideration the soil-structure interaction, this paper proposes a blade-cabin-tower-foundation coupled model in order to study the load-bearing conditions of wind turbines under seismic impact. According to the basic theory of multi-body system dynamics, the wind turbine blade and tower system comprises a series of continuous discrete units, while soil-structure interaction in the tower system is realized through the spring and damping set on the interface between the foundation and the soil body; the cabin is simplified as a rigid model. Based on the Eurocode 8 earthquake load spectrum, the dynamic response of a wind turbine working under seismic impact is analysed, and the seismic load is compared. Results of the study can serve as references for designing key parts and control strategies of wind turbines for earthquake-prone regions.

Simulation and Study on Ride Comfort of Articulated Dump Truck Based on Rigid-Flex Coupling

For the poor ride comfort performance of the articulated dump truck, the dynamic model of ADT was built and its dynamic characteristics were also studied through finite element and multi-body system dynamic theory. According to the modal neutral file generated by finite element software with the flexible processing, the flexible coupling virtual prototyping model was set up for the multi-body dynamics simulation in ADAMS to obtain and analyze the data about the ADT ride comfort. This paper provided references for the design, redesign and optimization of the ADT.

Simulation Analysis of an Ambulance Carriage Interior Noise

Based on the theory of multi-body system dynamics, the analytical method of finite element and boundary element, the finite element model of vehicle body, the rigid-flexible coupled model of vehicle and the acoustic boundary element model of carriage were established by applying a variety of simulation software. Road roughness was simulated and the SPL of field point in carriage under the excitation was computed at the frequency range of 20-150Hz. Considering the size and the positive /negative nature of panels acoustic contribution at SPL peak of field point, damping treatments were taken on different combinations of panels to decrease multiple field points SPL peak and the optimal treatment was finally confirmed. The results showed that noise reduction measures can generally decrease the SPL peak around the crew.

Modeling and dynamics analysis of helical spring under compression using a curved beam element with consideration on contact between its coils

Helical springs are indispensable elements in mechanical engineering. This paper investigates helical springs subjected to axial loads under different dynamic conditions. The mechanical system, composed of a helical spring and two blocks, is considered and analyzed. Multibody system dynamics theory is applied to model the system, where the spring is modeled by Euler–Bernoulli curved beam elements based on an absolute nodal coordinate formulation. Compared with previous studies, contact between the coils of spring is considered here. A three-dimensional beam-to-beam contact model is presented to describe the interaction between the spring coils. Numerical analysis provides details such as spring stiffness, static and dynamic stress for helical spring under compression. All these results are available in design of helical springs.

Vibration Transfer Analysis of High Speed Train Considering Car body Flexibility

In order to research the influence of the flexible car body on the vehicle system dynamic performance and to achieve the reasonable match between high speed and lightweight，it is necessary to build vehicle system dynamic model with the rigid car body replaced by the flexible car body. Due to the lower structure natural vibration frequency of car body, the influence of carbody flexibility on vehicle system dynamic performance is more influential. The influences of structural vibration of car body on vehicle system dynamics performance were studied by finite element analysis (FEA) method and multi-body system (MBS) dynamics theory. Rigid-flexible coupled vehicle system dynamic models were built up and the car body key location’s vibration was analyzed through vibration transmission chain. The results show that the influences of high speed carbody structure vibration on vehicle system dynamics performance are distinguished especially in the domain of car body natural vibration frequency.

Optimization of Vehicle Handing and Stability Based on RSM

Based on the theory of multi-body system dynamics and simulation software ADAMS/Car, the whole vehicle model was established. Afterwards by means of pylon course slalom, the accuracy of modeling was tested. The analysis and evaluation were later made to draw a conclusion that the handling stability of model needed improved. So as to improve the handling stability, the index lateral acceleration, yaw rate, side slip angle were taken as target function while suspension stiffness parameters were designed variables. Optimization of vehicle handing stability was practiced by applying second-order Response Surface Methodology (RSM) model. The relationship could be obtained by least square method obviously. Moreover applying with linear interpolation the final objective function was decided. The minimum of final objective function was the optimal result. Simulation analysis was performed again for the whole vehicle model by parameters modification. Subsequently, the results showed that this method greatly improved handling stability.

With the Backlash Dynamics Simulation of a Crank-Slider Mechanism of the Internal Combustion Engine

On the basis of flexible multi-body system dynamics theory, we built flexible multi-body system dynamics models which include a backlash, and to a slider-crank mechanism as the research object, we made a preliminary study on the effect on the flexible components and the backlash of the kinematic pair on mechanical system dynamics characteristics. To consider the backlash of the kinematic pair and component of flexible space can show a preliminary research on the dynamic simulation, and focus on the backlash, friction and gravity field to influence in the dynamic characteristics of the system. The simulation results show that, due to the existence of backlash made the two components frequent collision in the process of the stretching, clearance, flexible and friction are closed, make the system nonlinear characteristics increased.