Finite element dynamic

Keywords orthogonal collocation, finite elements, dynamic optimisation, global optimisation, CNMPC... 

Farhat, C. and Hemez, E. M. Updating finite element dynamics models using element-by-element sensitivity methodology. AIAA Journal 31(9) (1993), 1702-1711. 

A representative full state finite element dynamic model of OWL is outlined in Fig. 5.4. It comprises the main and secondary mirror and their support structure including the interface to the ground. A typical result for transfer functions from reduced models with 1000 states and 25 states or considered modes are given in the Fig. 5.5. The transfer function describes the movement of the secondary mirror when subjected to wind loads in the -direction. As can be seen, the drastically reduced model still covers the... 

Pao YC, Ritman EL (1977a) Viscoelastic, fibrous, finite-element, dynamic analysis of beating heart. Proc Symp on Application of Computer Methods in Engineering, Los Angeles Univ South Cal Press, pp 477-486... 

Pao YC, Ritman EL (1977) Visceelastic fibrous finite element, dynamic analysis of the beating heart. 

B. A. Dendrou and E. N. Houstis, "Uncertainty Finite Element Dynamic Analysis," Report CSD-TR 271, Department of Civil Engineering, Purdue University, West Lafayette, Indiana, July 1978. 

Scott MH, Fenves GL (2006) Plastic hinge integration methods for force-based beam-column elements. J Struct Eng 132(2) 244-252 Spacone E, Filippou FC, Taucer FF (1996) Fibre beam-column model for non linear analysis of R/C hames part I formulation. Earthq Eng Struct Dyn 25(7) 711-725 Spiliopoulos KV, Lykidis GC (2006) An efficioit three-dimensional solid finite element dynamic analysis of reinforced concrete structures. Earthq Eng Struct Dyn 35(2) 137-157... 

If FS-post >1 is calculated, ground deformations from the design earthquake are often computed for dam performance evaluation, preferably using a nonlinear finite element dynamic analysis. The Newmark sliding block deformation analysis should be avoided for computing deformations of dams involving soil hquefaction. 

Seismic Deformations by Finite Element Dynamic Analysis... 

A more rigorous and direct method for computing earthquake-induced ground deformations, with and without soil liquefaction, is a nonlinear finite element dynamic analysis (Finn et al. 1994) that overcomes the uncertainties associated with the approximation embedded in the pseudo-static stability calculation and in the Newmark deformation analysis. With PWP calculations built into effective stress soil models, the finite element method has the capability to simulate the coupled effects from dynamic site response, generation of excess pore water pressures, soil liquefaction, and post-liquefaction behavior, and this is a trend method for quantitative evaluation of earthquake-induced ground deformations. 

Seismic analyses discussed in this entry include pseudo-static stability analysis, Newmark sliding block deformation analysis, post-earthquake static stability analysis, and finite element dynamic analysis for computing permanent ground deformations. 

Hughes, T. J. R., Franca, L. P. and Balestra, M., 1986. A new finite-element formulation for computational fluid dynamics. 5. Circumventing the Babuska-Brezzi condition - a stable Petrov-Galerkin formulation of the Stokes problem accommodating equal order interpolations. Cornput. Methods Appl. Meek Eng. 59, 85-99. 

The simplest case of fluid modeling is the technique known as computational fluid dynamics. These calculations model the fluid as a continuum that has various properties of viscosity, Reynolds number, and so on. The flow of that fluid is then modeled by using numerical techniques, such as a finite element calculation, to determine the properties of the system as predicted by the Navier-Stokes equation. These techniques are generally the realm of the engineering community and will not be discussed further here. 

S. E. Kistier and L. E. Scriven, "Finite Element Analysis of Dynamic Wetting for Curtain Coating at High Capillary Numbers," presented at... 

Reddy, J. N., and D. K. Gartling. The Finite Element Method in Heat Transfer and Fluid Dynamics. CRC Press (1994). 

For complex offshore structures or where foundations may be critical, finite-element analysis computer programs with dynamic simulation capability erm be used to evaluate foundation natural frequency and the forced vibration response. 

These apparent restrictions in size and length of simulation time of the fully quantum-mechanical methods or molecular-dynamics methods with continuous degrees of freedom in real space are the basic reason why the direct simulation of lattice models of the Ising type or of solid-on-solid type is still the most popular technique to simulate crystal growth processes. Consequently, a substantial part of this article will deal with scientific problems on those time and length scales which are simultaneously accessible by the experimental STM methods on one hand and by Monte Carlo lattice simulations on the other hand. Even these methods, however, are too microscopic to incorporate the boundary conditions from the laboratory set-up into the models in a reahstic way. Therefore one uses phenomenological models of the phase-field or sharp-interface type, and finally even finite-element methods, to treat the diffusion transport and hydrodynamic convections which control a reahstic crystal growth process from the melt on an industrial scale. 

When required, combined with the use of computers, the finite element analysis (FEA) method can greatly enhanced the capability of the structural analyst to calculate displacement and stress-strain values in complicated structures subjected to arbitrary loading conditions. In its fundamental form, the FEA technique is limited to static, linear elastic analysis. However, there are advanced FEA computer programs that can treat highly nonlinear dynamic problems efficiently. 

In particular it can be shown that the dynamic flocculation model of stress softening and hysteresis fulfils a plausibility criterion, important, e.g., for finite element (FE) apphcations. Accordingly, any deformation mode can be predicted based solely on uniaxial stress-strain measurements, which can be carried out relatively easily. From the simulations of stress-strain cycles at medium and large strain it can be concluded that the model of cluster breakdown and reaggregation for prestrained samples represents a fundamental micromechanical basis for the description of nonlinear viscoelasticity of filler-reinforced rubbers. Thereby, the mechanisms of energy storage and dissipation are traced back to the elastic response of tender but fragile filler clusters [24]. 

Correspondingly all calculations are finite element method (FEM)-based. Furthermore, the flow channel calculations are based on computer fluid dynamics (CFD) research test for the optimization of the mbber flow. 

Based on the shapes of the responses to step changes in controller output, and reasoning from the physical configuration of the extruder barrel, a reduced order dynamic model of the process was postulated. One can think of the Topaz program as order 80 (the number of nodes in the finite element subdivision), and the reduced model of order 4 (the number of dynamic variables). The figure below illustrates the model. 

Another well-established area of mechanical finite-element analysis is in the motion of the structures of the human middle ear (Figure 9.3). Of particular interest are comparisons between the vibration pattern of the eardrum, and the mode of vibration of the middle-ear bones under normal and diseased conditions. Serious middle-ear infections and blows to the head can cause partial or complete detachment of the bones, and can restrict their motion. Draining of the middle ear, to remove these products, is usually achieved by cutting a hole in the eardrum. This invariably results in the formation of scar tissue. Finite-element models of the dynamic motion of the eardrum can help in the determination of the best ways of achieving drainage without affecting significantly the motion of the eardrum. Finite-element models can also be used to optimise prostheses when replacement of the middle-ear bones is necessary. 

The advantages of this type of system are obvious the pore space is of sufficient complexity to represent any natural or technical pore network. As the model objects are based on computer generated clusters, the pore spaces are well defined so that point-by-point data sets describing the pore space are available. Because these data sets are known, they can be fed directly into finite element or finite volume computational fluid dynamics (CFD) programs in order to simulate transport properties [7]. The percolation model objects are taken as a transport paradigm for any pore network of major complexity. 

Advances in computational capability have raised our ability to model and simulate materials structure and properties to the level at which computer experiments can sometimes offer significant guidance to experimentation, or at least provide significant insights into experimental design and interpretation. For self-assembled macromolecular structures, these simulations can be approached from the atomic-molecular scale through the use of molecular dynamics or finite element analysis. Chapter 6 discusses opportunities in computational chemical science and computational materials science. 

Molecular calculations provide approaches to supramolecular structure and to the dynamics of self-assembly by extending atomic-molecular physics. Alternatively, the tools of finite element analysis can be used to approach the simulation of self-assembled film properties. The voxel4 size in finite element analysis needs be small compared to significant variation in structure-property relationships for self-assembled structures, this implies use of voxels of nanometer dimensions. However, the continuum constitutive relationships utilized for macroscopic-system calculations will be difficult to extend at this scale because nanostructure properties are expected to differ from microstructural properties. In addition, in structures with a high density of boundaries (such as thin multilayer films), poorly understood boundary conditions may contribute to inaccuracies. 

---