scholarly journals Human Joint Simulation Using LifeMOD Co-Simulation

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Eric Fahlgren ◽  
Mark Carlson ◽  
Andrew S. Elliott
Keyword(s):  
Chromium Steel ◽  
Large Displacement ◽  
Small Displacement ◽  
Cobalt Chromium ◽  
Artificial Joints ◽  
Walking Gait ◽  
Body Dynamics ◽  
Elastic Responses ◽  
Multi Body ◽  
Ultra High Molecular Weight

Advanced design of human artificial joints requires an in-depth understanding of the dynamic interaction between the very stiff bone replacement material and the softer viscoelastic cartilage replacement material. It must take into account both the large displacement gross motions as well as the small displacement elastic responses. A co-simulation methodology has been developed in BRG LifeMOD, connecting Adams∕Solver, a large displacement multi-body dynamics code, to Marc, a nonlinear finite element code. This efficient co-simulation approach allows for each code to handle that portion of the system for which it is most capable, while adding the potential to work across multiple CPUs and operating systems as desired. The method was applied using LifeMOD∕KneeSIM to simulate an artificial knee joint, containing cobalt chromium steel and ultra-high molecular weight polyethylene contact elements, undergoing a normal walking gait to predict kinematics, forces and the resulting wear patterns.

Dynamics of Hypoid Gears With Emphasis on Effect of Shaft Rotation on Vibratory Response

2007 ◽  
Author(s):  
Tao Peng ◽  
Teik C. Lim
Keyword(s):  
Rotational Motion ◽  
Degrees Of Freedom ◽  
Transmission Error ◽  
Rotor System ◽  
Large Displacement ◽  
Small Displacement ◽  
Hypoid Gears ◽  
Gear Mesh ◽  
Vibratory Motion ◽  
Multi Body

The effect of large displacement rotational motion of the shafting system on the higher frequency, small displacement vibratory motion primarily excited by gear transmission error and variation of gear mesh stiffness is examined in this paper. Traditional hypoid gear dynamic analysis based on a pure vibration model assumes that the system perturbs about its mean position without coupling to the large displacement rotational motion. To improve on this approach and understanding of the influences of the dynamic interaction, a coupled multi-body dynamic and vibration simulation of the hypoid geared rotor system is performed. In the proposed formulation, a multi-degrees-of-freedom, multi-body hypoid geared rotor system dynamic model is developed to calculate the combined motion of the large displacement rotation of the shaft and small vibratory motion of the gear pair. The formulation may be generalized to other forms of gearing because hypoid gears have more complicated geometry and time-varying mesh characteristics when compared to parallel axis gears. Numerical simulation results are compared to those derived from the classical analytical method that only considers pure vibration effect. The proposed theory also provides new approaches to investigate both steady-state and transient geared rotor system dynamics.

A Numerical and Experimental Analysis of a Chain of Flexible Bodies

1994 ◽  
Vol 116 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Marco Giovagnoni
Keyword(s):  
Virtual Work ◽  
Equations Of Motion ◽  
Numerical Data ◽  
Small Displacement ◽  
Flexible Bodies ◽  
Rigid Link ◽  
Body Dynamics ◽  
A Chain ◽  
Multi Body ◽  
Kinematic Solution

A flexible multi-body dynamics approach is described. It uses an equivalent rigid link system from which are measured small displacements. The equations of motion are obtained by direct application of the principle of virtual work. Some terms in the virtual and real components have been neglected by virtue of the small displacement assumption. The use of sensitivity coefficients allows one to obtain a formulation which can be easily interfaced with any kinematic solution algorithm. It also enables one to check the correctness of the chosen equivalent rigid link system. The theory is then employed to reproduce numerically the experimental recordings obtained from a flexible linkage. Agreement between experimental and numerical data is good.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

Tanker Truck Sloshing Simulation Using Bi-Directionally Coupled CFD and Multi-Body Dynamics Solvers

2014 ◽  
Author(s):  
Michael S. Barton ◽  
David Corson ◽  
John Quigley ◽  
Babak Emami ◽  
Tanuj Kush
Keyword(s):  
Body Dynamics ◽  
Tanker Truck ◽  
Multi Body

Study of Self-Propelled Pufferfish Driven by Multiple Fins: A Comparison Between Rigid and Deformable Fins

2017 ◽  
Author(s):  
Ruoxin Li ◽  
Qing Xiao ◽  
Lijun Li ◽  
Hao Liu
Keyword(s):  
Underlying Mechanism ◽  
Operating Conditions ◽  
The Self ◽  
Fish Swimming ◽  
Propulsion Efficiency ◽  
Live Fish ◽  
Body Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Multi Body ◽  
Better Than

In this work, we numerically studied the steady swimming of a pufferfish driven by the undulating motion of its dorsal, anal and caudal fins. The simulations are based on experimentally measured kinematics. To model the self-propelled fish swimming, a Computational Fluid Dynamics (CFD) tool was coupled with a Multi-Body-Dynamics (MBD) technique. It is widely accepted that deformable/flexible or undulating fins are better than rigid fins in terms of propulsion efficiency. To elucidate the underlying mechanism, we established an undulating fins model based on the kinematics of live fish, and conducted a simulation under the same operating conditions as rigid fins. The results presented here agree with this view by showing that the contribution of undulating fins to propulsion efficiency is significantly larger than that of rigid fins.

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