A comparative study of velocity increment generation between the rigid body and flexible models of MMET

Abstract The problem of joint reactions indeterminacy, in engineering simulations of rigid body mechanisms is most often caused by redundant constraints which are defined as constraints that can be removed without changing the kinematics of the system. In order to find a unique set of all joint reactions in an overconstrained system, it is necessary to reject the assumption that all bodies are rigid. Flexible bodies introduce additional degrees of freedom to the mechanism, which usually makes the constraint equations independent. Quite often only selected bodies are modelled as the flexible ones, whereas the other remain rigid. In this contribution it is shown that taking into account flexibility of selected mechanism bodies does not guarantee that unique joint reactions can be found. Problems typical for redundant constraints existence are encountered in partially flexible models, which are not overconstrained. A case study of a redundantly constrained spatial mechanism is presented. Different approaches to the mechanism modelling, ranging from a purely rigid body model to a fully flexible one, are investigated and the obtained results are compared and discussed.

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Evaluation of rigid body force in liquid sloshing problems of a partially filled tank: Traditional CFD/SPH/ALE comparative study

Ocean Engineering ◽

10.1016/j.oceaneng.2021.109556 ◽

2021 ◽

Vol 236 ◽

pp. 109556

Author(s):

Zhemin Cai ◽

Ameen Topa ◽

Luke P. Djukic ◽

Manudha T. Herath ◽

Garth M.K. Pearce

Keyword(s):

Comparative Study ◽

Rigid Body ◽

Body Force ◽

Liquid Sloshing

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Compliant Interface in Component Mode Synthesis

Volume 2: 16th International Conference on Multibody Systems, Nonlinear Dynamics, and Control (MSNDC) ◽

10.1115/detc2020-22255 ◽

2020 ◽

Author(s):

Pierangelo Masarati ◽

Fanny Darbas ◽

Israël Wander

Keyword(s):

Rigid Body ◽

Structural Component ◽

Strain Energy ◽

Rigid Body Motion ◽

Component Mode Synthesis ◽

Body Motion ◽

Structural Components ◽

Definition Of ◽

Flexible Models

Abstract Substructuring, or component mode synthesis, requires components to share interface regions. When components modeled with rather different, often incompatible levels of refinement need to be connected, correctly defining the interfaces may be important. This work proposes the definition of the reduction of interface regions to the equivalent rigid-body motion which minimizes the strain energy in the structural component. The proposed formulation provides a natural and physically sound solution for the connection of detailed structural components within coarse, multi-rigid-body and 1D flexible models.

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