An Overview on Continuous Contact Force Models for Multibody Dynamics

2012 ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Hertz Contact ◽  
Dynamic Simulations ◽  
Ball Impact ◽  
Continuous Contact ◽  
Multibody Dynamic ◽  
Contact Impact ◽  
Impact Events

The nature of the constitutive contact force law utilized to describe contact-impact events plays a crucial role in predicting the dynamic response of multibody systems. The main goal of this work is present a survey of the literature on the most relevant penalty-force based approaches for multibody dynamic simulations. In this process, the fundamental characteristics of the purely elastic and the dissipative contact force models are analyzed, namely the models which have been developed based on the Hertz contact law. In particular, the different models are compared in this study for a simple impact problem for the sole purpose of comparison of the models and examining their validity compared to those from experiments. Results obtained for a classical ball impact on a massive surface are presented and used to discuss the main assumptions and procedures associated with the different penalty-force approaches. The force models are found to be quite well representative of the contact forces in an impact, and that they can be applied for the analysis of impact in more complex systems a such as the ones in planar and spatial multibody mechanical systems.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

scholarly journals Dynamic Response of Multibody Systems With Multiple Clearance Joints

2011 ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Physical And Mechanical Properties ◽  
Contact Forces ◽  
Force Model ◽  
Modeling And Analysis ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Dissipative Term

A general methodology for the dynamic modeling and analysis of planar multibody systems with multiple clearance joints is presented. The inter-connecting body components that constitute a real joint are modeled as colliding bodies, which dynamic behaviors are influenced by geometric, physical and mechanical properties of the contacting surfaces. A continuous contact force model, based on the elastic Hertz theory, together with a dissipative term, is used to evaluate the intra-joint contact forces. The incorporation of the friction, based on the classical Coulomb’s friction law, is also included. The suitable contact force models are embedded into the dynamic equations of motion for the multibody system. A simple mechanical system with multiple clearance joints is used to demonstrate the accuracy and efficiency of the presented approach and to discuss the main assumptions and procedures adopted. The effects of single versus multiple clearance joints are discussed.

scholarly journals Dynamic Response of Multibody Systems with Multiple Clearance Joints

2012 ◽  
Vol 7 (3) ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Physical And Mechanical Properties ◽  
Contact Forces ◽  
Force Model ◽  
Normal Contact ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Dissipative Term

A general methodology for the dynamic modeling and analysis of planar multibody systems with multiple clearance joints is presented. The inter-connecting bodies that constitute a real physical mechanical joint are modeled as colliding components, whose dynamic behavior is influenced by the geometric, physical and mechanical properties of the contacting surfaces. A continuous contact force model, based on the elastic Hertz theory, together with a dissipative term associated with the internal damping, is utilized to evaluate the intra-joint normal contact forces. The incorporation of the friction phenomenon, based on the classical Coulomb’s friction law, is also included in this study. The suitable contact force models are embedded into the dynamic equations of motion for the multibody systems. In the sequel of this process, the fundamental methods to deal with contact-impact events in mechanical systems are presented. Finally, two planar mechanisms with multiple revolute clearance joints are used to demonstrate the accuracy and efficiency of the presented approach and to discuss the main assumptions and procedures adopted. The effects of single versus multiple clearance revolute joints are discussed.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2006 ◽  
Vol 1 (3) ◽  
pp. 240-247 ◽  
Author(s):  
P. Flores ◽  
J. Ambrósio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, with the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four-bar mechanism is used as an illustrative example and some numerical results are presented, with the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Modeling Expected Wear in Revolute Joints With Clearance in Multibody Mechanical Systems

2007 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Research Work ◽  
Contact Forces ◽  
Joint Surface ◽  
Force Model ◽  
Wear Model ◽  
Continuous Contact ◽  
Revolute Joints ◽  
Sliding Motion ◽  
Impact Forces ◽  
Contact Impact

The main goal of this work is to develop a methodology for studying and quantifying the wear phenomenon in revolute clearance joints. In the process, a simple model for a revolute joint in the framework of multibody systems formulation is presented. The evaluation of the contact forces developed is based on a continuous contact force model that accounts for the geometrical and materials properties of the colliding bodies. The friction effects due to the contact in the joints are also represented. Then, these contact-impact forces are used to compute the pressure field at the contact zone, which ultimately is employed to quantify the wear developed and caused by the relative sliding motion. In this work, the Archard’s wear model is used. A simple planar multibody mechanical system is used to perform numerical simulations, in order to discuss the assumptions and procedures adopted throughout this work. Different results are presented and discussed throughout this research work. From the main results obtained, it can be drawn that the wear phenomenon is not uniformly distributed around the joint surface, owing to the fact that the contact between the joint elements is wider and more frequent is some specific regions.

scholarly journals Small nanoparticles, surface geometry and contact forces

2018 ◽  
Vol 474 (2211) ◽  
pp. 20170723 ◽  
Author(s):  
Yoichi Takato ◽  
Michael E. Benson ◽  
Surajit Sen
Keyword(s):  
Contact Force ◽  
Contact Forces ◽  
Spherical Nanoparticles ◽  
Hertz Contact ◽  
Surface Geometry ◽  
Impact Forces ◽  
Nonlinear Contact ◽  
Amorphous Surface ◽  
The Impact ◽  
Small Nanoparticles

In this molecular dynamics study, we examine the local surface geometric effects of the normal impact force between two approximately spherical nanoparticles that collide in a vacuum. Three types of surface geometries—(i) crystal facets, (ii) sharp edges, and (iii) amorphous surfaces of small nanoparticles with radii R <10 nm—are considered. The impact forces are compared with their macroscopic counterparts described by nonlinear contact forces based on Hertz contact mechanics. In our simulations, edge and amorphous surface contacts with weak surface energy reveal that the average impact forces are in excellent agreement with the Hertz contact force. On the other hand, facet collisions show a linearly increasing force with increasing compression. Our results suggest that the nearly spherical nanoparticles are likely to enable some nonlinear dynamic phenomena, such as breathers and solitary waves observed in granular materials, both originating from the nonlinear contact force.

scholarly journals ANALYSIS OF RIGID AND FLEXIBLE DYNAMICS OF A SPACE-SLIDER-CRANK MECHANISM BASED ON FINITE ELEMENT METHOD

2021 ◽  
Vol 50 (02) ◽  
Author(s):  
NGOC THAI HUYNH ◽  
CONG RO HOANG ◽  
TRUNG KIEN TRAN ◽  
VAN HOAI LE
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Force ◽  
Maximum Principal Stress ◽  
Contact Forces ◽  
Element Analysis ◽  
Ball Impact ◽  
Contact And Impact ◽  
Crank Mechanism ◽  
Element Method

The investigation analyzes effects of clearance size in revolute and spherical joints with clearance on rigid-flexible dynamic of a space slider crank mechanism by finite element method. The model of the mechanism was designed by Solidworks and then velocity, acceleration, displacement, stress and contact force were determined by finite element analysis of rigid-transient dynamic in ANSYS. The results simulation indicated that the clearance size in revolute and spherical with clearance has sightly effected on the velocity of the slider, but has significantly effected on acceleration, contact force as journal and ball impact into bearing and socket with high peaks of acceleration and contact force as presented in the graph of acceleration and contact forces. The graph outlined that journal and ball motion with three types: free light, contact and impact motion. Clearance size created deviation for the displacement of the slider from 4.29 mm to 9.87 mm and maximum principal stress increases from 8.4 MPa to 10 MPa when clearance size increases from 0 mm to 0.3 mm.

scholarly journals Translational Joints With Clearance in Rigid Multibody Systems

2007 ◽  
Vol 3 (1) ◽  
Author(s):  
P. Flores ◽  
J. Ambrósio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Mechanical System ◽  
Multibody Systems ◽  
Force Model ◽  
Planar System ◽  
Continuous Contact ◽  
Impact Forces ◽  
Clearance Joint ◽  
Contact Impact ◽  
Rigid Multibody Systems ◽  
Rigid Multibody

A computational methodology for dynamic description of rigid multibody systems with translational clearance joints is presented and discussed in this work. Over the past years, extensive work has been done to study the dynamic effect of the revolute joints with clearance in multibody systems, in contrast with the little work devoted to model translational joints with clearance. In a joint with translation clearance, there are many possible ways to set the physical configuration between the slider and guide, namely: (i) no contact between the two elements, (ii) one corner of the slider in contact with the guide surface, (iii) two adjacent slider corners in contact with the guide surface, and (iv) two opposite slider corners in contact with the guide surfaces. The proposed methodology takes into account these four different situations. The conditions for switching from one case to another depend on the system dynamics configuration. The existence of a clearance in a translational joint removes two kinematic constraints from a planar system and introduces two extra degrees of freedom in the system. Thus, a translational clearance joint does not constrain any degree of freedom of the mechanical system but it imposes some restrictions on the slider motion inside the guide limits. When the slider reaches the guide surfaces, an impact occurs and the dynamic response of the joint is modeled by contact-impact forces. These forces are evaluated here with continuous contact force law together with a dissipative friction force model. The contact-impact forces are introduced into the system’s equations of motion as external generalized forces. The proposed methodology is applied to a planar multibody mechanical system with a translational clearance joint in order to demonstrate its features.

Onset of Mechanical Separation in Bellows-Supported Rotary Face Seals

1965 ◽  
Author(s):  
Franklin D. Hart ◽  
Carl F. Zorowski
Keyword(s):  
Contact Force ◽  
Operating Conditions ◽  
Contact Forces ◽  
Force Distribution ◽  
Continuous Contact ◽  
Dynamic Mechanical ◽  
Face Seals ◽  
Contact Force Distribution ◽  
System Resilience ◽  
Mechanical Separation

The problem of incipient dynamic mechanical separation in bellows-supported rotary face seals is analyzed assuming the bellows to be represented by a series of distributed springs and dampers supporting a rigid seal carrier. An expression is developed for the distribution of contact forces between the seal and mating rings generated by the coupled effects of shaft pulsation and mating-ring wobble. This expression is used to determine the operating conditions which will produce the onset of separation by applying the criterion that the contact force distribution will go to zero at some point on the seal when separation is imminent. Results are presented in the form of equations and graphs which define the minimum initial compression necessary to maintain continuous contact in terms of system resilience and damping, amplitude of mating-ring wobble and shaft pulsation, and operating frequency.

Sign in / Sign up

Export Citation Format

Share Document