Computational Mechanics New advances in the forced response computation of periodicstructures using the wave finite element ( WFE ) method
The wave finite element (WFE) method is investigated to describe the harmonic forced response of onedimensional periodic structures like those composed of com plex substructures and encountered in engineering applica tions. The dynamic behavior of these periodic structures is analyzed over wide frequency bands where complex spatial dynamics, inside the substructures, are likely to occu r. Within the WFE framework, the dynamic behavior of periodic structures is described in terms of numerical wave modes. Their computation follows from the consideration of the finite element model of a substructure that involves a large number of internal degrees of freedom. Some rules of thumb of the WFE method are highlighted and discussed to circumvent numerical issues like ill-conditioning and i stabilities. It is shown for instance that an exact analytic relation needs to be considered to enforce the coherence between positive-going and negative-going wave modes. Besides, a strategy is proposed to interpolate the frequency r esponse functions of periodic structures at a reduced number of discrete frequencies. This strategy is proposed to tackl e the problem of large CPU times involved when the wave modes are to be computed many times. An error indicator is formulated which provides a good estimation of the level of accuracy of the interpolated solutions at intermediate poi nts. Adaptive refinement is carried out to ensure that this error indicator remains below a certain tolerance threshold. Numerical experiments highlight the relevance of the propose d approaches.
The TRIC shell element: theoretical and numerical investigation
The TRIC facet triangular shell element, which is based on the natural mode method, is seen under the light of the non-consistent formulation proposed by Bergan and co-workers. Under this formulation, the convergence requirements are fulfilled even with relaxed conditions on the conformity demands of the displacement shape functions. The intrinsic connection between the non-consistent formulation and the natural mode method is demonstrated, establishing thus a rigorous theoretical foundation for the TRIC element. Under the perspective of the non-consistent formulation, TRIC's convergence characteristics are established by satisfying apriori the patch test due to its inherent properties and thus guaranteeing convergence to the exact solution. Furthermore, the element's accuracy, robustness and efficiency are tested in a number of judiciously selected numerical examples on benchmark plate and shell problems, while a CPU time comparison with a pure displacement-based isoparametric shell element demonstrates its computational merits.
Adsorption of immunoglobulin Y in supermacroporous continuous cryogel with immobilized Cu(2+) ions.
The influence of temperature, pH and ionic strength on the adsorption of Immunoglobulin Y (IgY) in IDA-Cu(2+) cryogel system was studied by batch equilibrium measurements. The adsorptive equilibrium data were obtained at 17 and 27°C, pH 5.0 and 6.5, and at ionic strength of 50 and 200mmolL(-1) NaCl. Langmuir, Freundlich and Langmuir-Freundlich models were fitted to equilibrium data, while the enthalpy of adsorption of IgY in IDA-Cu(2+) cryogel system was calculated through Van't Hoff analysis. The binding of IgY on cryogel was stronger at 27°C and lowest pH and ionic strength values, with apparent maximum adsorption capacity of 27mgg(-1). The adsorption of protein in the resin was spontaneous in all analyzed cases. The results provide valuable information to enable the improvement of IgY purification processes.