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Schiehlen, Werner

doi:10.1023/a:1009745432698

Cited by 415 publications

(55 citation statements)

References 109 publications

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“…The handling of flexible objects in multibody dynamics simulations has been a long term field of research until today [5,6,7,39,42,43,44]. The standard approach, which is supported by today's commercial software packages such as SIMPACK, ADAMS or VIRTUALLAB, represents flexible structures by vibrational modes, e. g. of Craig and Bampton type [12], that are obtained from numerical modal analysis within the range of linear elasticity.…”

Section: Introductionmentioning

confidence: 99%

Multi-body dynamics simulation of geometrically exact Cosserat rods

2010

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In this paper, we present a viscoelastic rod model that is suitable for fast and accurate dynamic simulations. It is based on Cosserats geometrically exact theory of rods and is able to represent extension, shearing (stiff dof), bending and torsion (soft dof). For inner dissipation, a consistent damping potential proposed by Antman is chosen. We parametrise the rotational dof by unit quaternions and directly use the quaternionic evolution differential equation for the discretisation of the Cosserat rod curvature. The discrete version of our rod model is obtained via a finite difference discretisation on a staggered grid. After an index reduction from three to zero, the right-hand side function f and the Jacobian f/(q,v,t) of the dynamical system q=v,v=f(q,v,t) is free of higher algebraic (e.g. root) or transcendental (e.g. trigonometric or exponential) functions and, therefore, cheap to evaluate. A comparison with Abaqus finite element results demonstrates the correct m echanical behaviour of our discrete rod model. For the time integration of the system, we use well established stiff solvers like Radau5 or Daspk. As our model yields computational times within milliseconds, it is suitable for interactive applications in virtual reality as well as for multi-body dynamics simulation

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Section: Introductionmentioning

confidence: 99%

Multi-body dynamics simulation of geometrically exact Cosserat rods

2010

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“…1 were derived using the Newton-Euler Formalism [18] incorporating the hand-rim contact forces into de equations of motion as…”

Section: Modelmentioning

confidence: 99%

A Modeling Framework to Investigate the Radial Component of the Pushrim Force in Manual Wheelchair Propulsion

Ackermann

Costa

Leonardi

2015

MATEC Web of Conferences

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Abstract.The ratio of tangential to total pushrim force, the so-called Fraction Effective Force (FEF), has been used to evaluate wheelchair propulsion efficiency based on the fact that only the tangential component of the force on the pushrim contributes to actual wheelchair propulsion. Experimental studies, however, consistently show low FEF values and recent experimental as well as modelling investigations have conclusively shown that a more tangential pushrim force direction can lead to a decrease and not increase in propulsion efficiency. This study aims at quantifying the contributions of active, inertial and gravitational forces to the normal pushrim component. In order to achieve this goal, an inverse dynamics-based framework is proposed to estimate individual contributions to the pushrim forces using a model of the wheelchair-user system. The results show that the radial pushrim force component arise to a great extent due to purely mechanical effects, including inertial and gravitational forces. These results corroborate previous findings according to which radial pushrim force components are not necessarily a result of inefficient propulsion strategies or hand-rim friction requirements. This study proposes a novel framework to quantify the individual contributions of active, inertial and gravitational forces to pushrim forces during wheelchair propulsion.

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“…The matrix representation of the frameF(s) w.r.t. a fixed global coordinate system {e (1) , e (2) , e (3) } of R 3 may be written as a triple of column vectors, i.e.…”

Section: Kinematics Of Cosserat and Kirchhoff Rodsmentioning

confidence: 99%

“…For simplicity we assume the undeformed rod to be straight and prismatic such that its intial geometry relative to {e (1) , e (2) , e (3) } is given by the direct product A × I with a constant cross section area A parallel to the plane spanned by {e (1) , e (2) }. Introducing coordinates (ξ 1 , ξ 2 ) in the plane of the cross section A relative to its geometrical center we may parametrise the material points X ∈ A × I of the undeformed rod geometry by X(ξ 1 , ξ 2 , s) = k=1,2 ξ k e (k) + s e (3) , and the deformation mapping X → x = Φ(X) is given by the formula…”

Section: Kinematics Of Cosserat and Kirchhoff Rodsmentioning

confidence: 99%