108,310 research outputs found
Kinematic quantities of finite elastic and plastic deformation
Kinematic quantities for finite elastic and plastic deformations are defined
via an approach that does not rely on auxiliary elements like reference frame
and reference configuration, and that gives account of the inertial-noninertial
aspects explicitly. These features are achieved by working on Galilean
spacetime directly. The quantity expressing elastic deformations is introduced
according to its expected role: to measure how different the current metric is
from the relaxed/stressless metric. Further, the plastic kinematic quantity is
the change rate of the stressless metric. The properties of both are analyzed,
and their relationship to frequently used elastic and plastic kinematic
quantities is discussed. One important result is that no objective elastic or
plastic quantities can be defined from deformation gradient.Comment: v5: minor changes, one section moved to an Appendix, 26 pages, 2
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Creating gameplay mechanics with deformable characters
This paper presents how soft body simulation can create deformable characters and physics-based game mechanics that result in a more varied gameplay experience. A framework was implemented that allows the creation of a fully deformable soft body character within a games application where the simulation model properties could be altered at runtime to create gameplay mechanics based on varying the deformation of the character. The simulation model was augmented to allow appropriate methods of player control that complemented the character design and its ability to deform. It was found that while the implementation of deformation-based mechanics created a more varied gameplay experience, the underlying simulation model allowed for a limited amount of deformation before becoming unstable. The ffectiveness of the framework is demonstrated by the resulting mechanics that are not possible through the use of previous methods
Simplified modelling of the behaviour of 3D-periodic structures such as aircraft heat exchangers
In this paper, experimental, analytical and numerical analysis are used to study and model the mechanical behaviour of a heat exchanger core consisting of a 3D-periodic structure. The purpose of the present investigation is not only to acquire knowledge on the mechanical behaviour of a given heat exchanger core but also to propose a simplified approach to model this behaviour. An experimental study is carried out in order to get an insight on the mechanical behaviour of this structure. Global static characteristics are obtained via analytical and finite element analysis of a unit cell of the core. Dynamic behaviour is studied by means of finite element calculations based on the results of the static modelling. The proposed approach is validated by comparison with experimental tests results
A 3D discrete model of the diaphragm and human trunk
In this paper, a 3D discrete model is presented to model the movements of the
trunk during breathing. In this model, objects are represented by physical
particles on their contours. A simple notion of force generated by a linear
actuator allows the model to create forces on each particle by way of a
geometrical attractor. Tissue elasticity and contractility are modeled by local
shape memory and muscular fibers attractors. A specific dynamic MRI study was
used to build a simple trunk model comprised of by three compartments: lungs,
diaphragm and abdomen. This model was registered on the real geometry.
Simulation results were compared qualitatively as well as quantitatively to the
experimental data, in terms of volume and geometry. A good correlation was
obtained between the model and the real data. Thanks to this model, pathology
such as hemidiaphragm paralysis can also be simulated.Comment: published in: "Lung Modelling", France (2006
An elasto-visco-plastic model for immortal foams or emulsions
A variety of complex fluids consist in soft, round objects (foams, emulsions,
assemblies of copolymer micelles or of multilamellar vesicles -- also known as
onions). Their dense packing induces a slight deviation from their prefered
circular or spherical shape. As a frustrated assembly of interacting bodies,
such a material evolves from one conformation to another through a succession
of discrete, topological events driven by finite external forces. As a result,
the material exhibits a finite yield threshold. The individual objects usually
evolve spontaneously (colloidal diffusion, object coalescence, molecular
diffusion), and the material properties under low or vanishing stress may alter
with time, a phenomenon known as aging. We neglect such effects to address the
simpler behaviour of (uncommon) immortal fluids: we construct a minimal, fully
tensorial, rheological model, equivalent to the (scalar) Bingham model.
Importantly, the model consistently describes the ability of such soft
materials to deform substantially in the elastic regime (be it compressible or
not) before they undergo (incompressible) plastic creep -- or viscous flow
under even higher stresses.Comment: 69 pages, 29 figure
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