Multibody Analysis Research Articles

Pseudo-elastic wire application in robotized cutting systems

Abstract Analytical and simulation results with pseudo-elastic core wire in stone cutting applications are discussed. System specifications and requirements are defined for the operation of the wire at tensions, speed and general conditions similar to the ones optimized for cutting with standard rope wires with beads of the same diameter. Multi-body dynamic simulation parameters are derived from scale homogenization approach. They are used to run multi-body simulation analysis according to the cutting force requirements. Different simulation schemes and approaches are invented to model the effective cutting forces and system dynamic behavior. Constitutive non-linear pseudo-elastic material model is exploited to be utilized in finite element analysis. The results obtained are further used in finite element analysis in order to study the variation of forces among different sections of pseudo-elastic wire. Finally finite element transient analysis is performed to have an insight into the behavior of the wire under time variant loads.

Multibody Analysis of Terminal Phase for a Reentry Vehicle: A Comparative Study

The multibody analysis of the system formed by an entry vehicle and a parachute is the subject of the present paper. In particular, two different models of the system made of bridles (connecting the vehicle to the suspension point) and riser (connecting the suspension point to the suspension lines of the parachute) are considered. This allows one to highlight if and how the simplifying assumptions at the basis of many techniques adopted for sizing the suspension system are reasonable and if they affect the most important factors that characterize the final phase of an entry trajectory, such as peak load and maximum deceleration at parachute inflation and landing site dispersion footprint. A Monte Carlo analysis is performed to account for uncertainties on initial conditions and system parameters

Multibody Dynamics Simulation and Experimental Investigation of a Model-Scale Tiltrotor

Abstract : The objective of this investigation is to develop a multibody analytical simulation model to predict the dynamic response, aeroelastic stability, and blade loading of a soft-inplane tiltrotor wind-tunnel model and correlate that with experimental data. A Joint Vertical Aircraft Task Force is currently developing requirements to meet Army and Navy needs for a heavy lift transport rotorcraft that is expected to include, at a minimum, a 20-ton payload lift capability. Development of soft-inplane tiltrotor technology is beneficial for providing viable lightweight hub design options for this future application. Experimental testing, either in flight testing or with a wind tunnel test article, is becoming prohibitively expensive. Advanced simulation and modeling of these complex tiltrotor hub configurations using multibody dynamics codes may prove to be an alternative to such expensive experimental verifications in the future. The use of multibody dynamics codes to predict and reduce the risk of encountering aeromechanical instabilities and adverse loading situations for a soft-inplane tiltrotor hub design is detailed in this investigation. Comprehensive rotorcraft-based multibody analyses enable simulation and modeling of the rotor system to a high level of detail such that complex mechanics and nonlinear e ects associated with control system geometry and joint free-play may be considered. The influence of these and other nonlinear e ects on the aeromechanical behavior of the tiltrotor model is examined. A parametric study of the design parameters which influence the aeromechanics of the soft-inplane rotor system is also included in this investigation.

Modeling of Geometric Structure for Numerically Controlled Grinder Based on Multi-Body System Theory

According to the multi-body system theory and geometric topology analysis method, combining the geometric structure and working principle of thread NC grinder, made the kinematics analysis for each parts of NC grinder. And the mathematical model for geometric topology structure of grinding machine system was established; the precision machining equations of NC grinder was deduced. Furthermore, the paper used the coordinate transformation principle of homogeneous to deduce the precision processing equation of NC grinder, all of that was based on the moving relationship of the machine tool, the workpiece and the grinding wheel, and got a kind of method that it can use multiple line grinding wheel to grind small radius, small screw pitch and multiple thread. This method laid a theoretical foundation for NC grinder machine processing which used multi-line grinding wheel to grind threads, and improve the grinding efficiency and precision of multi-line grinding wheel; in addition, this method has obtained good effect in grinding thread production.

Effects of Eccentricity on Transmission Errors of Trochoidal Gears

This article deals with the effects of eccentricity on transmission errors of trochoidal gears (consisting of a roller gear and cam gear). For the tests, three types of roller gears and three types of cam gears (which had different eccentricity) were used. The experimental results showed that the peak to peak values of transmission errors had a tendency to be greater under a larger eccentricity. The measured transmission error waveforms fluctuated with periods 1/fr, 1/fc and 1/zrfr (in which fr and fc are the rotational frequencies of the roller gears and cam gears, while zr is the number of rollers). The peaks with nfr (n = 1, 2, 3, …), nfc, nzrfr, nzrfr ± mfr (m = 1, 2, 3, …) and nzrfr ± mfc appeared in the measured transmission error spectra. The amplitudes of peaks with fr and nzrfr ± mfr increased as er increased, while the amplitudes of peaks with fc and nzrfr ± mfc increased as ec increased. The transmission errors of test gears with eccentricity were estimated by the multibody analysis (MBA). A reasonable correlation exits between the calculated results obtained by the MBA and the measured experimental results.

Vibrating Simulation of Diesel Engine Based on Multi-Body Dynamics

Taking example of a four-cylinder inline diesel engine that used in vehicle, this paper makes an assembly engine of three-dimensional that based on virtual prototype technology. While using the flexible-body dynamics simulation, the main bearing load that effect engine’s vibration will be gained. And the key point vibration response will be gained when the support part constrained. The experimental results coincide with the simulation results shows the correction of the simulation analysis. The initial stage of the vibration can be predicted by using the method of multi-body system analysis, and this guide the designer to identify the engine vibration.

Multibody Dynamic Analysis of Automobile Wiper Based on Virtual Prototype

Virtual prototype plays an important role in agile designing and manufacturing. Finite Element Analysis and multibody analysis software can also assist engineers with developing and analyzing sophisticated machines. In this paper, a virtual model of an automobile wiper is modeled and used to be simulated under virtual environment of ADAMS, which is a famous tool in mechanical engineering. After simulation, the vibration and noise that the wiper works with have been found and some suggestions are given in discussion and conclusion.

Modeling 3D revolute joint with clearance and contact stiffness

The clearances in the kinematic joints are due to deformations, wear, and manufacturing errors; the accurate modeling of these effects in multibody analysis is a complex issue but in many practical applications, it is mandatory to take into them into account in order to understand the actual behavior of mechanical systems. In this paper, the authors present a general computer-aided model of a 3D revolute joint with clearance suitable for implementation in multibody dynamic solvers. While a perfect revolute joint imposes kinematic constraints, the proposed revolute joint with clearance leads to a force constraint. The revolute joint has been modeled by introducing a nonlinear equivalent force system, which takes into account the contact elastic deformations. The model depends on the structural and geometrical properties of materials in contact that have been investigated using finite element models. The purpose is to give a general approach to study the influence of actual joints on kinematic, dynamic, and structural behavior of mechanisms. The proposed model has been applied in dynamic simulations of a spatial slider-crank mechanism.

Reduced Order Models Using Generalized Eigenanalysis

This article discusses the use of generalized eigenanalysis to extract reduced order models from the linearization of structural and aeroelastic problems written in differential-algebraic form. These problems may arise from multi-body analysis and in general from mixed approaches, where a high degree of generality and modelling flexibility are sought. A method based on a shift technique is proposed, that allows to exploit the regularity of the matrix pencil resulting from the linearization of differential-algebraic problems. Alternatively, the generalized Schur decomposition, or QZ decomposition, is directly used to select a cluster of eigenvalues related to the dynamic states. The two approaches are used to reduce the model to ordinary differential in state-space form. The two methods are applied to simple numerical problems, highlighting their robustness and versatility compared to other techniques. They are also applied to numerical models of a high-altitude long endurance aircraft obtained using a free general-purpose multi-body solver and a dedicated mixed variational solver.

340 路面凹凸を考慮した操舵反力シミュレータの開発

The steering reactive torque of an automobile is one of the important information for a driver to estimate the road conditions. The characteristics of the reactive force depend on the stiffness property of mechanical components, layout of suspension links, and so on. In developing the automobile, it is desirable to realize an intuitive evaluation of operability before prototyping. For this purpose, we developed a steering torque simulator based on real-time multibody analysis in previous study. This paper describes method of enhancement of the reality of developed simulator by considering the influence of road roughness. To consider the influence of road roughness, we implemented OpenCRG, which is a open file formats and open source tools for the detailed description, creation and evaluation of road surface. Several kinds of road profiles were implemented in the steering torque simulator, and the generated torque was evaluated. In addition, the deformation of the contact patch was also considered by modifying the tire model.

326 行列演算ライブラリを用いたリアルタイムマルチボディ解析の効率評価

326 行列演算ライブラリを用いたリアルタイムマルチボディ解析の効率評価

Modeling and Kinematics Characteristic Analysis of Twist Beam Rear Suspension Using ADAMS/Car

The multi-body system analysis has become one of the main simulation techniques to calculate the kinematics characteristics of a car suspension under wheel travel or to build a virtual prototype model of a vehicle in order to predict the vehicle dynamics performance. The modeling of twist beam rear suspensions is always difficult for the unique structural behavior of this component. A non-linear method based on multi-body dynamics software (ADAMS/Car) was used to represent the twist beam within the suspension system. The kinematics characteristic analysis of the rear suspension was realized by means of ADAMS/Car. The main suspension parameters (toe angle, camber angle and wheel track variation) were calculated by changing wheel travel. The result shows that the method of suspension kinematics analysis by using ADAMS/Car can be used in the design of suspensions conveniently.

A Review of Research on Brake Groan

AbstractBased on consulting a number of literatures, the classification of brake vibrations and noises, a review of mechanisms, research methods and influence factors on break groan which has not been researched in China was presented. The brake groan results from the stick-slip moving between the brake disk and pads. The research methods include test research and theoretical research, and the latter can be divided into the methods of linear and nonlinear system dynamics, multi-body system dynamics and finite element analysis. System friction, mechanical system parameters and power transmission system parameters are the factors that influence brake groan. Finally, it is pointed out that the future research should focus on the mechanism of brake groan as well as the influence parameters in vibration source and transmission path systematically to instruct the matching and optimization of system parameters.

Virtual Prototyping Process Supported by New Diagnostic Method -Method of Metal Magnetic Memory

The aim of this work is to implement a new nondestructive testing (NDT) method based on the metal magnetic memory (MMM) effect into comprehensive diagnostic approach for power-line connectors, which is of great practical importance. Essence of this method lies in detection of stress concentration zones (SCZs) in material of the considered element during its operation (before micro-cracks and fracture occurs). If to compare with the traditional NDT methods, which indicate SCZs after the failure (post factum), this method provides major progress in the field of NDT. In this paper an approach of connection of numerical structural simulation (static and dynamic) with MMM-based testing method is also proposed. SCZs in power-line mechanical connector were evaluated and dynamic analysis of a complete power line, which included the analyzed connector, was carried out by means of MSC.ADAMS. Uniqueness of this analysis consist in integration of FEM analysis, MSC.ADAMS multibody system analysis (for testing of working conditions in advance - during virtual prototyping) and verification using MMM method. This hybrid approach enables to accomplish diagnostic analysis of selected construction elements and provides the possibility to take into consideration actual working conditions (e.g. vibrations) of the element. Proposed diagnostics method can substantially increase operational safety of electrical connectors and lines.

Design optimization framework for tiltrotor composite wings considering whirl flutter stability

This paper constructs the design optimization framework for the composite wing of a tiltrotor aircraft based on the Korea Aerospace Research Institute (KARI) Smart Unmanned Aerial Vehicle (SUAV) TRS4 model. The present optimal design attempts to find the cross-section layout that minimizes the structural weight of a composite wing, while satisfying a series of design constraints. The framework consists of various analysis and design tools that include a 2-D beam cross-section analysis, a whirl flutter analysis, and a 3-D strain/stress analysis under the worst wing-loading case. The variation of wing sectional properties of tiltrotor aircrafts in the course of design optimization greatly affects the whirl flutter stability and shows considerable influence on the structural integrity of the wing. In the design framework, the whirl flutter stability is analysed by the nonlinear flexible multibody analysis code DYMORE and the structural integrity is investigated using a MATLAB-based 3-D strain analysis module along with the previous load analysis result. The MATLAB is used to conduct the optimization with a gradient-based optimizer and integrate all of the design and analysis tools. The nonlinear constraints associated with the aeroelastic stability and the structural integrity are also considered. For optimal design examples using the developed framework, a simplified cross-section model based on the KARI SUAV TRS4 composite wing is considered as an initial model. Design optimization examples are investigated to show the validity of the proposed framework and to illustrate the reduction of the structural weight of the composite wing. It is observed that weight reductions of wing structures by 26% and 40% are achieved, while maintaining the whirl flutter stability margins.

Recursive Dynamics Algorithm for Multi-body System Modeling and Analysis Considering Small Amplitude Liquid Sloshing

Any complex mechanical multibody system can be transformed into an equivalent tree system.Based on the spatial operator algebra theory,the recursive dynamics process for liquid-filled system is introduced considering small amplitude liquid sloshing,and the sloshing force between tank and liquid can be obtained by momentum theorem and the momentum moment theorem as the tank and liquid are regarded as individual bodies.The wave height function and velocity potential function expressed by modal variables are derived from the modal analysis theory of finite element method.The tank and its adjacent objects are connected with the equivalent spring and damping and by using an inboard 6-DOF virtual hinge attached on the reference frame of tank the kinematics and dynamic variables can be transferred and the maximum amount of information of liquid sloshing can be saved.The multibody system inboard joint of the tank is treated as an under-actuated joint in unknown tank movement circumstance,so as to derive the recursive dynamic algorithm for liquid-filled system under small amplitude liquid sloshing based on the spatial operator algebra theory which still holds on the rigid-liquid coupling mechani.

58291 Efficiency Evaluation of the Real-time Multibody Analysis with Matrix Libraries(High Performance Formalisms and Computation)

58291 Efficiency Evaluation of the Real-time Multibody Analysis with Matrix Libraries(High Performance Formalisms and Computation)

1110 マルチボディ車両モデルを利用した路面凹凸形状の推定(OS2-3 路面とタイヤ,OS2 交通・物流システムのダイナミクス,オーガナイズド・セッション(OS))

Road roughness is a significant factor to the ride comfort and the maneuverability of an automobile. In this paper, we propose an estimation method of a road profile from measurement data during running test with an experimental vehicle. The estimation method is based on iterating multibody analysis, and uses multibody vehicle model based on an electric vehicle developed in our laboratory. In order to confirm of the validity of the estimation method, running test was conducted with this electric vehicle. Estimated road profile was compared to an actual road profile, and the accuracy of an estimated road profile was evaluated.

Prediction of UH-60A Structural Loads Using Multibody Analysis and Swashplate Dynamics

The first part of this paper compares three rotor blade structural dynamic formulations: a finite element formulation with modal reduction, a full finite element formulation without modal reduction, and a multibody-based full finite element formulation for arbitrary large deformations. The second part of this paper studies the effect of swashplate dynamics on blade loads and servo-actuator loads. In all cases, measured airloads, damper force, and control pitch angles from the UH-60A flight tests are used to predict and analyze the structural loads. In the first part, the emphasis is on the validation of a multibody formulation, which is first verified with analytical solutions for beams undergoing hypothetical large deformations (elastica), then validated with the Princeton beam large deformation tests, and then finally used to predict the UH-60A structural loads. Two flight conditions are considered: a high-speed, high-vibration flight and a highly loaded dynamic stall flight. Predictions from the multibody analysis are compared with the full finite element and finite element based modal methods. It is observed that the predicted blade loads do not show any significant difference between the three formulations. In the second part, the four-bladed multibody rotor model is coupled to a swashplate-servo model to predict servo loads and to study the effect of swashplate dynamics on blade loads. It is observed that the higher frequencies of servo loads, 8/rev and 12/rev for this rotor, require modeling the swashplate dynamics. The low-frequency component, which is a dominant 4/rev load for this rotor, is less affected by swashplate dynamics and is determined primarily by the accuracy of the 3, 4, and 5/rev pitch-link loads. The 3-5/rev pitch-link loads, and in general the structural loads on the rotor blade, are not affected by swashplate dynamics.

Computational investigation of blast survivability and off-road performance of an up-armoured high-mobility multi-purpose wheeled vehicle

Since ballistic and blast survivability and off-road handling and stability of military vehicles, such as the high-mobility multi-purpose wheeled vehicle (HMMWV), are two critical vehicle performance aspects, they both (including the delicate balance between them) have to be considered when a new vehicle is being designed or an existing vehicle retrofitted (e.g. up-armoured). Finite-element-based transient non-linear dynamics and multi-body longitudinal dynamics computational analyses were employed, relatively, in the present work to address the following two specific aspects of the performance of an HMMWV: first, the ability of the vehicle to survive detonation of a landmine shallow buried into sand underneath the right wheel of the vehicle and, second, the ability of the vehicle to withstand a simple straight-line brake manoeuvre during off-road travel without compromising its stability and safety of its occupants. Within the first analysis, the kinematic and structural responses (including large-scale rotation and deformation, buckling, plastic yielding, failure initiation, fracture, and fragmentation) of the HMMWV to the detonation of a landmine were analysed computationally using the general-purpose transient non-linear dynamics analysis software ABAQUS/Explicit. The second analysis was carried out using Simpack, a general-purpose multi-body dynamics program, and the main purpose of this analysis was to address the vehicle stability during the off-road travel. The same sand model was used in both types of analysis. Finally, the computational results obtained are compared with general field-test observations and data in order to judge the physical soundness and fidelity of the present approach.