Multibody Dynamics Approach Research Articles

On the historical development of human walking dynamics

AbstractHuman walking is an interdisciplinary research topic. It started in the Ancient World with early observations and questions in philosophy, it was treated in the Middle Ages with experiments and data collection by physiologists, and in the 20th century models were designed, equations of motion were generated and simulations by multibody dynamics approaches were performed. More recently parameter optimization was used to overcome the problem of muscle overactuation and inverse dynamics methods were introduced. In the first part of the paper the early developments and mechanism models are described while in the second part parameter optimization is applied to gait disorder simulations as an example of recent research results. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Modelling and simulation of rigid bodies transportation by means of rotating flexible rollers

The paper deals with a modelling and simulation approach intended to the solution of a problem of rigid bodies transportation using rotating rollers. It is motivated by problematic phenomenon of ceramic tiles transportation inside long kilns during firing. The row of tiles, which is initially straight at the kiln beginning, is coming out curved at the kiln end or after the passage through a certain part of the kiln. The main aim of the work is the development of the modelling and simulation method for the verification of the problems arising from the tile movement through very long kilns and for the understanding of the problem causation. The multibody dynamics approach is chosen for the development of a comprehensive methodology for the numerical simulation of the tiles and rollers movement. Two approaches to the modelling of the system of tiles and rollers using the SIMPACK simulation tool are shown in the paper. The more suitable one is based on the Polygonal Contact Model developed for the fast and efficient contact analysis between complexly shaped rigid bodies. It can be concluded that the problems of the curved row of tiles are influenced by the flexibility of bent rollers and also occur for ideally cylindrical rollers. The presented simulation methodology can be generally used for the investigation of similar transportation systems.

Multibody Dynamic Approach of Flight Dynamics and Nonlinear Aeroelasticity of Flexible Aircraft

The flight and structural dynamics of a very flexible aircraft, especially while maneuvering, aremore tied together than those of conventional aircraft. Hence, it is necessary to study the coupled effects of flight dynamics, aeroelasticity, and control. This paper presents a multibody dynamic approach in which the flexible aircraft is modeled as a feedback-controlled multibody system under aerodynamic forces. The governing equations of the system are established by combining the equations of amultibody system, the ONERAaerodynamicmodel, and that of controls. The trim state of the flexible aircraft is solved using a dynamic relaxation method around which the perturbation equation is derived and solved for system stability. To demonstrate the advantage of multibody dynamics inmodeling the constrained system undergoing large displacements and rotations, the proposed approach is applied to the flexible aircraft in level flight and in the circling and dive–loop–climbmaneuvers. Beyond the flutter boundary, the limit cycle oscillations response is solved, in which several interesting aspects of flexible aircraft flutter are revealed. In the end, the jointflutter andattitude control is used to suppressflutter response and stabilize attitude.

Study on Thrust Force Reduction of Tripod Constant Velocity Joint

Tripod constant velocity joints are used in the driveshafts of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. This paper surveys some methods for reducing the thrust force based on the mechanisms inducing the thrust force, focusing on a method that creates dual contact between a roller and groove. This method has the advantage of requiring only a few design modifications, but its thrust force reduction mechanism has yet to be clarified. Therefore, a theory was constructed to describe the induction of thrust force by this method through the application of sliding velocities generated between the roller and dual contact groove. Subsequently, the effect of the thrust force reduction was investigated. This paper also describes the appropriateness of this theory. It was validated by comparing theoretical results with computational results based on a multibody dynamics approach and with experimental results of a prototype joint equipped with the dual contact grooves.

Study on Thrust Force Reduction of Tripod Constant Velocity Joint

A tripod constant velocity joint is used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. In this paper, in order to reduce the thrust force, some reduction methods are surveyed based on mechanisms inducing the thrust force. In these methods, the dual-contact method between a roller and a groove is focused. This method has the advantage of only a few design modifications, but reduction mechanisms have not been clarified. Therefore, a theory inducing the thrust force in this method is constructed by applying sliding velocities caused between the roller and this dual-contact groove, and the effectiveness of the thrust force reduction is studied. This paper also describes the appropriateness of this theory. It is verified by comparing these theoretical results with computational results by utilizing multibody dynamics approach and experimental results by using a prototype joint equipped with the dual-contact grooves.

Evaluation of the contact forces developed in the lower limb/orthosis interface for comfort design

Ankle-Foot Orthoses (AFOs) are technical aids that promote locomotion and rehabilitation of individuals with gait pathologies. Every pathology has its own requirements and this has led to classical solutions that are far from optimal in terms of comfort and overall performance for restoring the human gait. Formal scientific approaches are therefore necessary to take full advantage of the available technological potential and produce more efficient modern devices that can significantly improve the quality of life of people with locomotion impairment. In this work, a computational multibody dynamics approach is adopted. A multibody model of an active AFO is developed and integrated in a whole-body multibody human model developed in the MATLAB environment. In the adopted procedure, normal gait motion data is used as input to the biomechanical model. The experimental data was obtained in the gait lab by acquiring the kinematic and kinetic data of a stride of a healthy female subject. The aim of this integrated model is to estimate the loads transmitted at the foot-leg-orthosis interface. To achieve this, it is essential to decide where the contact between the lower limb and the orthosis should occur, and what are the forces generated in such interface. A contact model between a sphere and a plane is applied together with a friction model to determine the contact forces, and the properties used for the surfaces in contact were based on the available data in the literature and on experimental tests. The results revealed that the contact pressures obtained are below the PPTs (Pain Pressure Thresholds), which represent the patient’s comfort. However, the pressure is dependent on the contact properties between surfaces, meaning that these must be experimentally determined for each material. It was also uncovered that the weight of the orthosis is an important issue in the design of an active AFO as it greatly influences the moments at the ankle, knee, and hip and, therefore, the patient effort when wearing the orthosis.

Multibody Dynamic Model of Web Guiding System With Moving Web

In this paper, a multibody dynamic model is established to simulate the dynamics and control of moving web with its guiding system, where the term moving web is used to describe thin materials, which are manufactured and processed in a continuous, flexible strip form. In contrast with available researches based on Eulerian description and beam assumption, webs are described by Lagrangian formulation with the absolute nodal coordinate formulation (ANCF) plate element, which is based on Kirchhoff’s assumptions that material normals to the original reference surface remain straight and normal to the deformed reference surface, and the nonlinear elasticity theory that accounts for large displacement, large rotation, and large deformation. The rollers and guiding mechanism are modeled as rigid bodies. The distributed frictional contact forces between rollers and web are considered by Hertz contact model and are evaluated by Gauss quadrature. The proportional integral (PI) control law for web guiding is also embedded in the multibody model. A series of simulations on a typical web-guide system is carried out using the multibody dynamics approach for web guiding system presented in this study. System dynamical information, for example, lateral displacement, stress distribution, and driving moment for web guiding, are obtained from simulations. Parameter sensitivity analysis illustrates the effect of influence variables and effectiveness of the PI control law for lateral movement control of web that are verified under different gains. The present Lagrangian formulation of web element, i.e., ANCF element, is not only capable of describing the large movement and deformation but also easily adapted to capture the distributed contact forces between web and rollers. The dynamical behavior of the moving web can be accurately described by a small number of ANCF thin plate elements. Simulations carried out in this paper show that the present approach is an effective method to assess the design of web guiding system with easily available desktop computers.

Multibody Dynamics Approach to the Modeling of Friction Wedge Elements for Freight Train Suspensions. I: Theory

This paper presents a theoretical application of multibody dynamics with unilateral contact to model the friction wedge interaction with the bolster and the side frame. The objective of the proposed approach is to produce a stand-alone model that can better characterize the interaction between the bolster, the wedge, and the side frame. The new model allows the wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and the side frame), pitch (rotation about the lateral axis), and yaw (rotation about the vertical axis). The new model also allows for toe variation. The stand-alone model shows the capability of capturing the dynamics of the wedge which was unnoticed in previous models. The inclusion of unilateral contact conditions is integral in quantifying the behavior during lift-off and the stick-slip phenomena. The resulting friction wedge model is a three-dimensional, dynamic, stand-alone model of a bolster–friction wedge–side frame assembly.

Multibody Dynamics Approach to the Modeling of Friction Wedge Elements for Freight Train Suspensions. II: Applications

This paper presents an application of multibody dynamics with unilateral contact to model the friction wedge interaction with the bolster and the side frame. The new friction wedge model is a three-dimensional, dynamic, stand-alone model of a bolster–friction wedge–side frame assembly. It allows the wedge four degrees of freedom: vertical displacement; longitudinal (between the bolster and the side frame) displacement; toe in and toe out; and yaw (rotation about the vertical axis). The dedicated train modeling software NUCARS (Transportation Technology Center, Inc., Pueblo, Colo.) has been used to run simulations with similar inputs and to compare—when possible—the results with those obtained from the new stand-alone MATLAB (MathWorks, Natick, Mass.) friction wedge model. The stand-alone model shows improvement in capturing the transient dynamics of the wedge better. Also, it can predict not only normal forces going into the side frame and bolster, but also the associated moments. Significant simulation results are presented and the main differences between the current NUCARS model and the new stand-alone MATLAB models are highlighted.

A three-dimensional model of the boat—oars—rower system using ADAMS and LifeMOD commercial software

This paper presents a numerical model of the boat—oars—rower system in a three-dimensional multibody dynamics approach using the ADAMS commercial software. The system is composed of four main parts: a skiff, two oars and a rower. The boat and oar mechanical model takes into account all boat settings and kinematic constraints, thus permitting a sophisticated model personalization. The rower skeletal model is built in LifeMOD (an ADAMS plug-in) software. In the example, a skilled rower is modelled with 19 human segments and 18 human joints which are personalized to the rower using the 32 external anthropometric data of the GEBOD program. In order to focus the tests on the rower on boat model, simulations are performed with basic hydrodynamic models for a single degree of freedom for the boat at first and then three degrees of freedom are used to show the potential of the model. The model is driven with five command signals, three oar rotations, seat movement, and lower torso rotation. The computed boat velocity is in good agreement with on-water measurements and a sensitivity test consisting of small variations of rowing technique allows the authors to be confident of the ability of the model regarding future optimization studies.

507 トリポード形等速ジョイントのスラスト力低減に関する研究(ジョイントのモデリングとその応用,OS-19 マルチボディダイナミクス,総合テーマ「伝統を,未来へ!」)

To achieve reduction of thrust force of a tripod constant velocity joint, some reduction methods are determined based on mechanisms inducing the thrust force. In these methods, a dual-contact method is selected because of very few design change. A theory inducing the thrust force between a roller and this dual-contact groove is constructed. By comparing theoretical results with computational ones using multibody dynamics approach, the appropriateness of this theory is verified. This paper also describes the effectiveness of the thrust force reduction by testing a prototype joint equiped with the dual-contact groove.

トリポード形等速ジョイントのローラ挙動とスラスト力に関する研究(<特集>D&D2009)

A tripod constant velocity joint is used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To determine mechanisms inducing the thrust force, a detailed model is constructed based on a multibody dynamics approach. Though the joint is equipped with three rollers and grooves, this model consists of principal parts concerned with one roller and groove in order to precisely analyze frictional phenomena occurring between the roller and the groove. These principal parts are defined as rigid bodies and are connected by force elements of contact and friction. The appropriateness of this model is verified by comparing computational and experimental results and it is clarified that the principal factors inducing the thrust force are three kinds of sliding friction force at a contact point between the roller and the groove. This paper also describes the reason that the third rotating order component of the thrust force is induced by one roller and groove.

Study on Roller Behavior and Thrust Force of Tripod Constant Velocity Joint

Tripod constant velocity joints are used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To determine the mechanisms inducing the thrust force, a detailed model is constructed based on a multibody dynamics approach. Although the joint is equipped with three rollers and grooves, this model consists of the principal parts for one roller and groove in order to precisely analyze frictional phenomena occurring between the roller and the groove. These principal parts are defined as rigid bodies and are connected by force elements of contact and friction. The appropriateness of this model is verified by comparing computational and experimental results and it is clarified that the principal factors inducing the thrust force are three kinds of sliding friction force at the point of contact between the roller and the groove. This paper also describes the reason why the third rotating order component of the thrust force is induced by one roller and groove.

Contact and Impact in the Multibody Dynamics of Motor Protein Locomotion

This paper presents the development of a rigid multibody dynamics approach to modeling, simulation, and analysis of motor proteins. A key element of this new model is that it retains the mass properties, in contrast to many commonly used models that do not. The mass properties are usually omitted because their inclusion yields a model with multiple time scales whose simulation requires a significant amount of time. However, the proposed model can be numerically integrated in a reasonable amount of time. Thus this approach represents a new method for treating multiple scale models. In addition, retaining the mass properties allows a detailed study of contact and impact between the protein and substrate, which is critical for protein processivity. The new model also provides insights into the characteristics of the protein and its environment, specifically, the effective damping experienced by the protein moving through its fluid environment may be quite small yielding under or critically damped motion. This conclusion runs contrary to the widely accepted notion that the protein's motion is strictly over damped. Herein, the differences between the motion predicted by the old and new modeling approaches are compared using a simplified model of Myosin V.

The small mass assumption applied to the multibody dynamics of motor proteins

This paper presents a multibody dynamics approach to the modeling, simulation and analysis of motor protein dynamic behavior. Usually proteins are modeled as a collection of a small number of particles, oftentimes only two particles, with spring-like connections between them. However, these simple particle models potentially omit interactions and dynamics between the unmodeled particles and the environment that may be important. Multibody dynamics models can be used to address this issue. However, widely used techniques for analyzing particle models may not be applicable to multibody models. Herein the validity of the small mass assumption, which is central to the analysis of particle models, is examined in detail using a simplified multibody model of the molecular motor protein Myosin V.

Modeling, control, and simulation of dual rotor wind turbine generator system

A new wind turbine generator system (WTGS) is introduced, and its mathematical model, blade pitch control scheme, and nonlinear simulation software for the performance prediction are presented. The notable feature of WTGS is that it consists of two rotor systems positioned horizontally at upwind and downwind locations, and a generator installed vertically inside the tower. In this paper, this new WTGS is treated as a constrained multi-body system, and the equations of motion are obtained by using the multi-body dynamics approach. Aerodynamic forces and torques generated from each of rotor blades are calculated using the blade element theory. Various pitch control schemes depending on the wind speed and the main rotor's rotational speed are implemented. A relatively simple model for the load torque is obtained by using the test data of the doubly fed induction generator adopted in the new WTGS. Finally, FORTRAN and Matlab/Simulink-based hybrid simulation software is developed and used to predict and analyze the performance of the WTGS.

Thrust Force Analysis of Tripod Constant Velocity Joint Using Multibody Model

A tripod constant velocity joint is used in the driveshaft of front wheel drive vehicles. Thrust force generated by this joint causes lateral vibration in these vehicles. To analyze the thrust force, a detailed model is constructed based on a multibody dynamics approach. This model includes all principal parts of the joint defined as rigid bodies and all force elements of contact and friction acting among these parts. This model utilizes a new contact modeling method of needle roller bearings for more precise and faster computation. By comparing computational and experimental results, the appropriateness of this model is verified and the principal factors inducing the second and third rotating order components of the thrust force are clarified. This paper also describes the influence of skewed needle rollers on the thrust force and evaluates the contribution of friction forces at each contact region to the thrust force.

Virtual dummy with spine model for automotive vibrational comfort analysis

In this paper, the author presents a methodology for implementing a three-dimensional virtual dummy for human vibration investigations. The model is based on a multibody dynamics approach and includes a detailed spine submodel for accurate assessment of seated body vibration. The model has been used to compute vibrational modes and transmissibility functions. The response to vibrational inputs has been compared with previous experimental and numerical studies. The discussed model can be applied for the assessment of vibration dose value (VDV) and design optimisation of human-vehicle interface according to international standards.

Numerical and experimental analysis of the dynamic effects in compact cluster mills for cold rolling

Prevention of dynamic instability caused by chatter phenomenon may be difficult in case of the so-called “cluster mill” because of the number of back-up rolls used to avoid bending of the work roll. A numerical simulation of the dynamics of the cluster mill may help to prevent the strip defects and to predict the life of bearings and rolls. Analytical models proposed in the literature for the two- and four-high mills are unfortunately inapplicable. This paper investigates whether the multi-body dynamics approach can be effective in analysing the so-called “Z-Mill”. Service monitoring detected in a real case some clear and dark bands on the strip surface, which disappeared after a calibration of rolls position. A numerical model was built by assuming that the mill stand and the strip could be analysed separately. Validation allowed concluding that modelling is effective, if relevant parameters are tuned on the experimental evidences. In particular damping and friction coefficients look the most critical to predict the actual value of rolling force. Mechanical nonlinearities introduced by the contact among rolls and by bearings increase the computational effort, but their role is somewhere overestimated in the literature. In practice, the multi-body dynamics approach still shows some limits, but they should be overcome, if a deeper experimental validation will be performed on a dedicated test rig, suitably designed to be largely instrumented.

Noise and Vibration Reduction - the Cranktrain as a Main Powertrain Module

This paper discusses how the multi-body dynamics approach combined with flexible body effects is being applied to predict the vibrations of crankshaft, bearing loads or cranktrain noise level due to structural flexibility. The oil film effects in the journal bearing are implemented with the use of a finite difference method. An application example of a Diesel inline four-cylinder engine is given in this paper to show this sophisticated simulation model and to predict the dynamic response of the flexible system and loads in the journal bearings.