Multibody Dynamic Analysis Research Articles

Dynamics modeling and error analysis for antenna pointing mechanisms with frictional spatial revolute joints on SE(3)

This paper presents a non-smooth multibody dynamic formulation and error analysis of an antenna pointing mechanism including frictional spatial revolute joints (FSRJs) with small clearance in the framework of the special Euclidian group SE(3). The formulation leads to an inertial frame-invariant, a compact and unified description for rigid bodies and spatial revolute joints (SRJs). The geometric constraint of the bearing is covered by four open semi-cylinders, which can be treated as bilateral constraints assuming that the impact effects are negligible. The frictional contact problem is formulated as a horizontal linear complementary problem (HLCP), which is embedded in the Lie-group integration scheme. Error of the antenna pointing mechanism is modeled by means of the adjoint transformation and POE-based formula. The evolution of errors is obtained through the solution of non-smooth dynamics. The obtained numerical results illustrate the influences of FSRJs in dynamics modeling and error analysis of the antenna pointing mechanism.

Damping Variation Effects in Vehicle Semi-active MR Suspensions: A Stress Concentration Analysis

Semi-active vehicle suspensions are used to improve the limited comfort performance of passive vehicle suspensions by varying the damping coefficient according to a control strategy. These benefits have been usually studied in a transient and frequency domain, but rarely in a multi-body dynamic analysis considering the mechanical components and their joints. In this study, the controllability effects of a magnetorheological (MR) damper on the mechanical components of a McPherson automotive suspension are investigated using a stress concentration analysis. Finite element analysis was used with a Quarter of Vehicle (QoV) suspension model configured with an MR damper, and then compared with the passive damper. The simulation results show that an SA damper in the suspension not only improves the dynamic behavior of a road vehicle, but it also has the positive effect of reducing the stress concentrations in a critical suspension element, the knuckle, that are generated by high amplitude road profiles such as rough roads or dangerous street bumps.

Curving Performance of Straddle-Type Monorail Vehicle with Single-Axle Bogies Based on Spatial Multi-Body Dynamic Analysis

Straddle-type monorail ,as a unique technology, energy saving and environmental protection, is different from the subway of urban rail transit system. In order to study the curving performance of a new type of the straddle-type monorail vehicle with single-axle bogies ,the three-dimensional spatial dynamics model which consists of the vehicle model and track model designis proposed by the multi-body dynamics soft ADAMS. The monorail vehicle dynamic model which consists of three types of tire -track contact model and the nonlinear model of the horizontal stop is established. Based on the dynamic model, the influences such as pre pressure and curve super-high rate parameters of the curve passing for the dynamic characteristics are discussed. The simulation results show that the suitable preload for the guide and stabilizer tires of straddle-type vehicle with single-axle bogies is 5KN and after selecting the appropriate pre-pressure, the super-high rate is recommended to be 8%-10%.

Numerical Evaluation of Structural Safety of Linear Actuator for Flap Control of Aircraft Based on Airworthiness Standard

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.

Fatigue Simulation of Railway Car Bogie Frame Based on Multi-body Dynamics and Finite Element Analysis

This paper proposes to combine multi-body dynamics and finite element method to study the fatigue strength and fatigue life of the bogie frame from the perspective of taking the vehicle as a whole. The analysis model established by the multi-body dynamics simulation software SIMPACK, the dangerous positions are determined from FEA software ANSYS, Based on the load-time history and Miner cumulative damage theory, the fatigue strength prediction is carried out using n-soft software, the study shows that the time-load history of each key position obtained by simulating working conditions can predict the life of components more accurately, this method can be applied to the initial stage of product design.

Experimental and Numerical Study on Ergonomic Evaluation of Automotive Seating Comfort

Automotive car seats play a vital role in providing optimum comfort to the occupants when it comes to vehicle comfort. The objective of this study was to perform an experimental and numerical investigation of the ergonomic evaluation of automotive seating comfort. A questionnaire survey was carried out on car drivers driving two different cars namely Tata Indica and Maruti Swift, to understand the perception of drivers on seating comfort. Posture monitoring techniques using Kinect camera and pressure mapping systems were used to analyze the sitting posture and sitting angle. A multibody dynamics analysis technique was used to evaluate the human body exposed to vehicle vibration. The vertical vibration transmissibility was measured from different body segments using this model. Also, with the help of a multibody dynamics simulation model, the results were compared and validated with existing literature. This study suggests suitable sitting posture and sitting angle derived with the help of multibody dynamics simulation along with the experimental investigation, which would reduce the fatigue of the driver when exposed to prolonged driving.

A Multidisciplinary Approach for Optimization Design of CNC Machine Tools

The main objective of this research is to propose a multidisciplinary approach for the development and design of Computer Numerical Control (CNC) machine tools using numerical optimization methods combined Multi-Body Dynamic (MBD) analysis and to control design co-simulation. Metamodels based Sequential Approximate Optimization (SAO) for the co-simulation optimization problems are developed. The metamodels are constructed as approximate models for exact dynamic analysis responses by using simultaneous Kriging metamodeling method. SAO problems for single objective and multi-objective optimization designs are carried out based on the augmented Lagrange multiplier (ALM) method. An application of the proposed method on optimizing Proportional-Integral-Derivative (P-I-D) coefficients of PID controllers of a CNC machine tool model is performed to demonstrate the usefulness of integrating different research methods in numerical simulation. Therefore, this work overcomes a difficult task in tuning the PID controller which requires extensive experience and understandings of research and development (R&D) engineers. Moreover, the optimal PID controllers obtained by the multidisciplinary approach can help to increase the contouring accuracy of the CNC machine tools.

Contact dynamics analysis of the single-pin meshing pair of a tracked vehicle

Single-pin meshing pairs are widely used in light-tracked vehicles. The purpose of this paper is to establish a nonlinear contact algorithm between the sprocket and track for multibody dynamics simulation. Based on the actual configuration, the tooth groove profile is discretized into three cambered surfaces, and the track pin is modeled as a cylinder with a protrusion. A body-fixed frame is introduced for each contact surface to facilitate the geometric contact criteria and contact force evaluation. Then the features of equal-pitch, sub-pitch and extra-pitch meshing are described with multibody dynamics analysis. It indicates that track pitch and sprocket pitch are the critical process parameters. A field test was performed to excavate the cause of chassis vibration. Compared with simulation results, the proposed contact model can effectively simulate the high-frequency excitation applied on a tracked vehicle. To improve its service life, a suggestion for the sprocket and track design is developed to fully use the sub-pitch meshing.

Multi-body dynamic analysis of offshore wind turbine considering soil-structure interaction for fatigue design of monopile

Fatigue design of monopile foundation for an offshore wind turbine using multi-body dynamic analysis is the theme of this paper. For this purpose, a benchmark turbine is modelled in Kane's approach considering soil-structure interaction for a site at the North Sea. Each soil layer is modelled using the p-y curve, and the dynamic response of the combined system is simulated using aero-hydro-servo-elastic analysis. The fatigue life is estimated following IEC 61400-3 guidelines. The numerical analysis presented in this study shows stress-based fatigue analysis using rainflow algorithm in the light of soil-structure interaction for short-term damage accumulation. Besides short-term effects, the study also investigates serviceability criteria over the lifespan of the structure, i.e. long-term effects. Finally, design curves are developed for a given power rating. Overall, the study highlights the importance of soil-structure interaction and its impact on the fatigue life of offshore wind turbines.

Continuous multi-body dynamic analysis of float-over deck installation with rapid load transfer technique in open waters

Targeting at the innovative float-over deck (FOD) installation with rapid load transfer technique, the continuous numerical simulations of the specific mating process are conducted based on the coupled multi-body model developed in the paper, where the detailed interaction effects of the Leg mating unit (LMU) and the Deck support unit (DSU), especially the time-varying hydrodynamic forces are considered simultaneously. The established model coincides with the experimental and SIMO results in terms of barge motion responses both at regular and random wave excitations. The motions of barge and topside as well as the corresponding loads of the LMU and DSU are analyzed. It shows that the quick load transferring operation leads to significant changes on barge motion responses and the trim angles of barge and topside have significantly influence on the loads of DSU and LMU. Moreover, the feasibility of the rapid FOD installation system at harsh open sea condition is carried out and arriving that it is functional well when suffering from long period swell. The results prove that the continuous simulation method representing the real-situation of the rapid load transfer technique can constantly investigate the consecutive responses and detect the potential risk of the FOD installation in advance.

Design of end coil angular position and centerline shape of C-type side load coil spring for reducing side load of MacPherson strut suspension

MacPherson strut suspension, which is widely used vehicle suspension type, decreases the riding comfort and durability of strut module due to the side load generated at the damper. In this study, a method for designing a C-type side load coil spring is proposed to reduce the side load, considering not only the centerline shape, but also the end coil angular position of the spring. The effect of end coil angular position as well as centerline shape on the force axis are analyzed through finite element analysis (FEA) and regression analysis. Formulas are established based on the analyses and the C-type coil spring was designed considering the effects of both design variables on the force axis. Then, the side load of the MacPherson strut suspension on which the designed C-type side load coil spring was mounted was calculated by using the flexible multibody dynamic analysis method. Finally, a side load reduction effect of C-type side load coil spring is analyzed by comparing with that of helical-type coil spring.

A Track Geometry Measuring System Based on Multibody Kinematics, Inertial Sensors and Computer Vision.

This paper describes the kinematics used for the calculation of track geometric irregularities of a new Track Geometry Measuring System (TGMS) to be installed in railway vehicles. The TGMS includes a computer for data acquisition and process, a set of sensors including an inertial measuring unit (IMU, 3D gyroscope and 3D accelerometer), two video cameras and an encoder. The kinematic description, that is borrowed from the multibody dynamics analysis of railway vehicles used in computer simulation codes, is used to calculate the relative motion between the vehicle and the track, and also for the computer vision system and its calibration. The multibody framework is thus used to find the formulas that are needed to calculate the track irregularities (gauge, cross-level, alignment and vertical profile) as a function of sensor data. The TGMS has been experimentally tested in a 1:10 scaled vehicle and track specifically designed for this investigation. The geometric irregularities of a 90 m-scale track have been measured with an alternative and accurate method and the results are compared with the results of the TGMS. Results show a good agreement between both methods of calculation of the geometric irregularities.

Multibody Dynamic Analysis of a Wind Turbine Drivetrain in Consideration of the Shaft Bending Effect and a Variable Gear Mesh Including Eccentricity and Nacelle Movement

Due to the energy crisis and global warming issues, the wind energy is becoming one of the most attractive renewable energy resources in the world. The drivetrains in the wind turbine tend to fail more prematurely than those in any other applications. Gearbox is the subsystem that causes the most downtime for the wind turbines. In the previous research, only the torsional flexibility of the shaft was considered in the drivetrain model. However, because the shaft is longer than other parts, and components connected by the shaft affect each other via shaft bending, the flexibility of the shaft cannot be ignored. In this study, a spherical joint that consists of three rotational springs was used to define the shaft bending. This shaft bending will affect the drivetrain rotation, the translational motion and the gear mesh contact force. Additionally, the eccentricity and the nacelle movement are analyzed due to the coupled motion. In this paper, a mathematical model of the drivetrain is proposed, which is a three-dimensional dynamic model that includes flexible bearings, a gear mesh model, shaft flexibility, eccentricity, and nacelle movement. The equation of motion of the drivetrain is derived using Lagrange's equation. The governing equation is solved numerically via direct numerical integration. The dynamic responses of the system and contact forces between the gear tooth in the time and frequency domains are calculated numerically. The study shows that this dynamic model of the drivetrain will be highly useful for subsequent studies on the wind turbine condition monitoring.

이산요소법과 다물체 동역학의 통합 해석 프로그램 Xdynamics 개발

이산요소법과 다물체 동역학의 통합 해석 프로그램 Xdynamics 개발

Experimental and Numerical Investigation of Solar Panels Deployment with Tape Spring Hinges Having Nonlinear Hysteresis with Friction Compensation

In this work, experimental and numerical investigation on the deployment of solar panels with tape spring (TS) hinges showing complex nonlinear hysteresis behavior caused by the snap-through buckling was conducted. Subsequently, it was verified by comparing simulation results by multi-body dynamics (MBD) analysis with test results on ground-based deployment testing considering gravity compensation, termed zero-gravity (Zero-G) device. It has been difficult to predict the folding and unfolding behavior of TS hinges because their moment–rotation relationship showed a nonlinear hysteresis behavior. To realize this attribute, an algorithm that checks the sign of angular velocity of the revolute joints was used to distinguish folding from unfolding. The nonlinear hysteresis was implemented in terms of two path-dependent nonlinear moment–rotation curves with the aid of the expression function (a kind of user subroutine) in MBD software RecurDyn. Finally, it was found that the results of the deployment analysis were in excellent agreement with those of the test when the friction torques of the revolute joints were properly identified by an inverse analysis with the test frames, thus validating the MBD model.

Investigation of Linear Higher Harmonic Control Algorithm for Rotorcraft Vibration Reduction

Abstract A linear quadratic Gaussian (LQG) controller for active vibratory loads reduction in helicopters is proposed based on a revisited higher harmonic control (HHC) input by active trailing-edge flaps (ATEFs). Conventional individual blade control (IBC) input is redefined using N − 1/rev interblade phase lead, N/rev collective, and N + 1/rev interblade phase lag signals where 1/rev frequency modulation originates from the multiblade coordinate (MBC) transform. A Mach-scaled flap blade is designed and analyzed by the multibody dynamics analysis DYMORE. A linear time-invariant representation is identified from N/rev envelopes of the input and output responses obtained by DYMORE analysis. A matlab/simulink closed-loop control simulation is designed using the identified state-space realization. The N/rev vibratory loads are reduced up to 52% with flap deflections and the linear control results match well with the nonlinear responses obtained from DYMORE. Furthermore, the multivariable closed-loop stability estimated by the loop transfer functions using disk margin analysis reveals sufficient gain and phase margins.

Stability Evaluation of the Transmission Line by using Galloping Simulation

Galloping phenomenon is one of the vibrations caused by icing. If galloping phenomenon continues, short-circuit or ground fault may occur, so analysis of galloping phenomenon through research on transmission line stability is necessary. The DenHartog method, which is frequently used for the galloping stability determination of the transmission line, considers only the vertical movement of the transmission line. In this study, we analyze the motion of multi-degree-of-freedom objects, using a computer aided engineering program. We modeled transmission lines as a multi mass-spring-damper systems using RecurDyn, which is a multibody commercial dynamics analysis program to analyze the galloping phenomenon dynamically. Damping inside transmission line derived from the Rayleigh damping theory through the free vibration experiment of transmission line. ANSYS Fluent, a flow analysis program, was used to derive the aerodynamic coefficients for transmission line with asymmetric cross-section. Using the derived aerodynamic coefficient, we confirmed the galloping occurrence condition of DenHartog method and modeled the wind load acting on the transmission line to conduct galloping simulation. Through the analysis of the motion of a multi-degree-of-freedom transmission line, the occurrence of galloping was classified into ovoid and vertical trajectories, and the case of no galloping was defined as regular trajectory, and the range of angle of attack that causes the instability of transmission lines was defined.

Multibody dynamics analysis (MDA) as a numerical modelling tool to reconstruct the function and palaeobiology of extinct organisms

AbstractRecent advances in computer technology have substantially changed the field of palaeontology in the last two decades. Palaeontologists now have a whole new arsenal of powerful digital techniques available to study fossil organisms in unprecedented detail and to test hypotheses regarding function and behaviour. Multibody dynamics analysis (MDA) is one of these techniques and although it originated as a tool used in the engineering and automotive industry, it holds great potential to address palaeontological questions as well. MDA allows the simulation of dynamic movements in complex objects consisting of multiple linked components. As such, this technique is ideally suited to model biological structures and to obtain quantifiable results that can be used to test the function of musculoskeletal systems rigorously. However, despite these advantages, MDA has seen a slow uptake by the palaeontological community. The most likely reason for this lies in the steep learning curve and complexity of the method. This paper provides an overview of the underlying principles of MDA and outlines the main steps involved in conducting analyses. A number of recent studies using MDA to reconstruct the palaeobiology of fossil organisms are presented and the potential for future studies is discussed. Similar to other computational techniques, including finite element analysis and computational fluid dynamics, the non‐invasive and exploratory power of MDA makes it ideally suited to study the form and function in vertebrates for which no modern analogues exist.

Structural design and optimization of a novel shimmy damper for nose landing gears

Passive vibration suppression devices known as shimmy dampers are vital in maintaining stability and safety of certain landing gears. Yet, systematic design, performance analysis, and optimization of such devices are rarely discussed in the literature. This paper presents structural design optimization of a novel shimmy damper for nose landing gears. This new design is a multifunctional mechanism integrating the shimmy damper into the torque link system of the nose landing gear. It features symmetric load distribution, and it can be tailored to existing nose landing gears. Here, the damper design concept is developed in the structural sense and optimized for the nose landing gear of a Piper Cheyenne aircraft. Dynamic loads from a representative shimmy scenario are employed in the analysis and design procedures. Utilizing equivalent static load method, topology optimization with transient loads is performed to obtain optimal material distribution satisfying the objective function and constraints. Flexible multibody dynamics analysis based on a high-fidelity finite element model is utilized in the analysis of design candidates and for validating the final design. To ensure adequate strength under the dynamic torque loads and to offer sufficient damping needed for stabilizing the nose landing gear, a three-piece torque link mechanism emerged through multiple design iterations guided by the topology optimization. Using numerical simulations, the final design is shown to satisfy the strength requirement while providing sufficient damper stroke. The results from the present study signal a vast potential in improving shimmy mitigation strategies by eliminating the need for costly redesigns of landing gears susceptible to shimmy.

Acceleration and higher-order analyses solved by extending the superposition principle: The incipient motion technique

The superposition principle, when applicable in the kinematic analysis of a mechanism, makes it possible to relate the studied mechanism with its component structures, and reduces the computation burden by exploiting the relationships among different data sets. Acceleration and higher-order analyses of holonomic or first-order non-holonomic mechanisms, and the velocity analysis of mechanisms with time-dependent (rheonomic) constraints need the solution of linear and non-homogeneous equation systems. The non-homogeneity of these problems forbids the use of the superposition principle to solve them. In this work, a novel kinematic-analysis technique (Incipient Motion Technique) that fully exploits the properties of linear and non–homogeneous equation systems is proposed. This solution technique has advantages similar to the ones of the superposition principle, holds for rheonomus systems, too, is efficient enough to use it in general purpose programs for multibody dynamics analysis, and is simple enough to present it in courses for graduate students.