An Efficient General Purpose Contact Search Algorithm Using the Relative Coordinate System for Multibody System Dynamics

2007 ◽  
Vol 120 ◽  
pp. 129-134 ◽  
Author(s):  
Hui Je Cho ◽  
Dae Sung Bae ◽  
Jin Hwan Choi ◽  
Ja Choon Koo
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Contact Force ◽  
Search Algorithm ◽  
General Purpose ◽  
Contact Pair ◽  
Force Model ◽  
Relative Coordinate ◽  
Contact Search ◽  
Bounding Boxes

Dynamic analysis of many mechanical systems is often involved with contacts among bodies. This paper presents an efficient and general-purpose contact search algorithm for multibody dynamics in the context of the compliance contact force model. While many conventional collision detection algorithms are based on the absolute coordinate system, this paper proposes to use the relative coordinate system in detecting a contact. A boundary box of a defense surface geometry is divided into many blocks. A contact reference frame is defined on the defense body of a contact pair. Since all geometric variables necessary to detect a contact are measured relative to the contact reference frame attached to the defense body, the variables belonging to the defense body are constant, which significantly reduces computation time associated with the contact search. Therefore, the contact reference frame plays a key role in developing an efficient contact search algorithm. Contour of the defense body is approximated by many piecewise triangular patches, while contour of the hitting body is represented by hitting nodes along its boundary. Bounding boxes inside which contain each body of a contact pair are defined at a preprocessing stage to eliminate an exhaustive contact inspection when two bodies are in a distance. If two bounding boxes are turned out to be in a contact during the pre-search, each node on the hitting boundary is inspected to find out to which block the node belongs in the post-search. Since each block dividing the boundary of the defense body has a list of patches, each node on the hitting boundary is tested for a contact only with the patches in the block that the node belongs. Actual contact calculation is then carried out to find the contact penetration used in calculating the compliant contact force. Numerical example is performed to demonstrate the validity of the proposed method.

Numerical and experimental analysis for the skew phenomena on the flexible belt and roller contact systems

2011 ◽  
Vol 226 (5) ◽  
pp. 1365-1381 ◽  
Author(s):  
J S Yoon ◽  
J H Choi ◽  
T Suzuki ◽  
J H Choi
Keyword(s):  
Contact Force ◽  
High Speed ◽  
Search Algorithm ◽  
Simple Algorithm ◽  
Cylindrical Body ◽  
Force Model ◽  
Stick Slip ◽  
Contact Search ◽  
Detailed Search ◽  
Ansys Workbench

The thin, flexible, flat belt system is frequently employed for power transmission, conveyor systems, and various manufacturing process equipments, such as printers, elevators, and automated teller machines. In general, some critical problems can happen during operation, since a thin flexible belt on rollers can easily skew. This is especially serious for high-speed belt operations. In this skewed situation, due to possible relative roller misalignment, roller deflection, and/or belt non-uniformity itself, a thin flexible belt can move along the perpendicular direction to the travelling direction. In this investigation, an efficient analysis method for simulating skewing phenomena of thin flexible belt systems is presented using the complete integration of large deformable finite element methods and multibody dynamics. A 4-node shell element is used to describe a thin flexible belt and two rigid cylindrical bodies describe the roller. Each cylindrical body is fixed with a pin joint and the positions of the rollers are adjusted to impose a tension to thebelt. For the interactions between the belt and the rollers, an efficient contact search algorithm based on a compliant contact force model is presented in this study. The contact search algorithm is composed of a pre-search and a detailed search to identify points of contact between the belt and the rollers. In the pre-search, a simple algorithm is used to identify lines on the belt that are close enough to the rollers that there might potentially be contact between them. The detailed search is performed by making efficient two-dimensional (2D) comparisons of the cross-section of the roller with a 2D projection of the belt lines identified in the pre-search. Afterwards, the contact force is generated by a compliant force model that uses a stick–slip frictional algorithm. The simulation model is validated against experimental measurement systems for thin flexible belt and rollers. It shows a good agreement with the numerical results. Furthermore CPU time with commercial software ANSYS Workbench is compared to check the performance of the algorithm. The proposed method is more than 10 times faster compared with ANSYS Workbench.

scholarly journals A study of contact methods in the application of large deformation dynamics in self-contact beam

2020 ◽  
Author(s):  
Babak Bozorgmehri ◽  
Xinxin Yu ◽  
Marko K. Matikainen ◽  
Ajay B. Harish ◽  
Aki Mikkola
Keyword(s):  
Finite Element ◽  
Complementarity Problem ◽  
Penalty Method ◽  
Search Algorithm ◽  
Contact Point ◽  
Iteration Scheme ◽  
Contact Dynamics ◽  
Force Model ◽  
Contact Constraint ◽  
Contact Search

AbstractThis paper introduces a procedure in the field of computational contact mechanics to analyze contact dynamics of beams undergoing large overall motion with large deformations and in self-contact situations. The presented contact procedure consists of a contact search algorithm which is employed with two approaches to impose contact constraint. The contact search task aims to detect the contact events and to identify the contact point candidates that is accomplished using an algorithm based on intersection of the oriented bounding boxes (OBBs). To impose the contact constraint, an approach based on the complementarity problem (CP) is introduced in the context of beam-to-beam contact. The other approach to enforce the contact constraint in this work is the penalty method, which is often used in the finite element and multibody literature. The latter contact force model is compared against the frictionless variant of the complementarity problem approach, linear complementarity problem approach (LCP). In the considered approaches, the absolute nodal coordinate formulation (ANCF) is used as an underlying finite element method for modeling beam-like structures in multibody applications, in particular. The employed penalty method makes use of an internal iteration scheme based on the Newton solver to fulfill the criteria for minimal penetration. Numerical examples in the case of flexible beams demonstrate the applicability of the introduced approach in a situation where a variety of contact types occur. It was found that the employed contact detection method is sufficiently accurate when paired with the studied contact constraint imposition models in simulation of the contact dynamics problems. It is further shown that the optimization-based complementarity problem approach is computationally more economical than the classical penalty method in the case of studied 2D-problems.

scholarly journals The Celestial Reference System in Relativistic Framework

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference System ◽  
Light Deflection ◽  
Coordinate Systems ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference System ◽  
Relativistic Framework

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.

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.

Effect of payloads contact upon the coupled dynamic response of two cooperating robots

Robotica ◽  
1996 ◽  
Vol 14 (6) ◽  
pp. 659-665
Author(s):  
G. Shagal ◽  
S.A. Meguid
Keyword(s):  
Dynamic Response ◽  
Function Method ◽  
Search Algorithm ◽  
Contact Region ◽  
Dynamic Equations ◽  
Penalty Function Method ◽  
The Finite Element Method ◽  
Contact Search ◽  
Cooperating Robots ◽  
Lagrange’S Method

The coupled dynamic response of two cooperating robots handling two flexible payloads is treated using a new algorithm. In this algorithm, the dynamic equations describing the system are obtained using Lagrange's method for the rigid robot links and the finite element method for the flexible payloads. The contact between the flexible payloads is modelled using the penalty function method and a contact search algorithm is employed to identify the contact region.

Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids

1992 ◽  
Author(s):  
Hamid M. Lankarani ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Impact Analysis ◽  
Equations Of Motion ◽  
Solid Particles ◽  
Hertzian Contact ◽  
Contact Period ◽  
Force Model ◽  
Unknown Parameters ◽  
Contact Force Model ◽  
Energy And Momentum

Abstract A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.

Experimental Validation of a Volumetric Planetary Rover Wheel/Soil Interaction Model

2013 ◽  
Author(s):  
Willem Petersen ◽  
John McPhee
Keyword(s):  
Contact Force ◽  
Interaction Model ◽  
Contact Model ◽  
Soil Parameters ◽  
Model Parameters ◽  
Force Model ◽  
Normal Contact ◽  
Planetary Rover ◽  
Normal Contact Force ◽  
Contact Force Model

For the multibody simulation of planetary rover operations, a wheel-soil contact model is necessary to represent the forces and moments between the tire and the soft soil. A novel nonlinear contact modelling approach based on the properties of the hypervolume of interpenetration is validated in this paper. This normal contact force model is based on the Winkler foundation model with nonlinear spring properties. To fully define the proposed normal contact force model for this application, seven parameters are required. Besides the geometry parameters that can be easily measured, three soil parameters representing the hyperelastic and plastic properties of the soil have to be identified. Since it is very difficult to directly measure the latter set of soil parameters, they are identified by comparing computer simulations with experimental results of drawbar pull tests performed under different slip conditions on the Juno rover of the Canadian Space Agency (CSA). A multibody dynamics model of the Juno rover including the new wheel/soil interaction model was developed and simulated in MapleSim. To identify the wheel/soil contact model parameters, the cost function of the model residuals of the kinematic data is minimized. The volumetric contact model is then tested by using the identified contact model parameters in a forward dynamics simulation of the rover on an irregular 3-dimensional terrain and compared against experiments.

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