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Damping through friction tends to be one of the most efficient methods to suppress damage to structures from earthquakes. Realizing robust structures is therefore highly dependent on designing for the dynamic forces of friction-damped structures and exploring their reliability against natural disasters. This paper presents a simplified matrix analysis algorithm for multi-story friction-damped buildings. The behavior of friction-damped systems has analyzed more accurately by modeling the master-slave degree of freedom of the joints. First, the formulation of the problem is discussed, and a condensed general equation is derived. Then, an end-to-end solution is proposed to find the responses of structures. The displacement response of each story has been carried out in both condensed and non-condensed general equations, and the results clearly show the accuracy of the proposed method. The numerical analysis and the results of the simulation of various friction-damped structures depicts the proposed approach consists with the commercial finite element method and is applicable for the analysis various types of structures. It is noted that the acceleration and displacement responses of the structures investigated under the proposed method and the traditional finite element method are so consistent that only a 1.5% difference is observed. Moreover, as a result of the proper allocation of degrees of freedom during the analysis, this method yields a reduction in computational costs especially in large buildings. [ABSTRACT FROM AUTHOR]

The paper presents the results obtained from a numerical and analytical analysis carried out on a set of concrete beams reinforced with steel bars, Fiber Reinforced Polymer (FRP) bars and hybrid combinations of FRP-steel bars. To this purpose a database of experimental results, available in literature, was collected. A simple and reliable two-dimensional Finite Element (FE) model was defined. In the numerical simulations, the linear and nonlinear behavior of all materials was adequately modeled by appropriate constitutive laws. To simulate the concrete post-cracking tensile behavior a specific tension stiffening model was used. In order to overcome convergence difficulties, to simulate the quasi-static response of RC beams, a dynamic approach was adopted. Furthermore, to assess the effectiveness of the current Italian guideline, on same set of RC beams, an analytical analysis was performed. The comparisons between numerical/analytical results and experimental data highlighted the reliability of both the proposed FE model and the analytical model. The results show that the tension stiffening model used in the FE analysis provides good results with low and normal reinforcement ratios, whereas the numerical predictions are not acceptable with high reinforcement ratios. The analytical results provided by the Italian guideline are satisfactory, compared to experimental data. [ABSTRACT FROM AUTHOR]

Chiral systems are a class of structures, which may exhibit the anomalous property of a negative Poisson's ratio. Proposed by Wojciechowski and implemented later by Lakes, these structures have aroused interest due to their remarkable mechanical properties and numerous potential applications. In view of this, this paper investigates the on-axis mechanical properties of the general forms of the flexing anti-tetrachiral system through analytical and finite element models. The results suggest that these are highly dependent on the geometry (the ratio of ligament lengths, thicknesses, and radius of nodes) and material properties of the constituent materials. We also show that the rigidity of an anti-tetrachiral system can be changed without altering the Poisson's ratio. The anti-tetrachiral system, with the unit cell shown in red. [ABSTRACT FROM AUTHOR]

Many of the aerospace components are characterized by having pocket-shaped thin-walled structures. During milling, the varying dynamics of the workpiece due to the change of thickness affects the final part quality. Available dynamic models rely on computationally prohibitive techniques that limit their use in the aerospace industry. In this paper, a new dynamic model was developed to predict the vibrations of thin-walled pocket structures during milling while taking into account the continuous change of thickness. The model is based on representing the change of thickness of a pocket-structure with a two-directional multispan plate. For the model formulation, the Rayleigh-Ritz method is used together with multispan beam models for the trial functions in both the x-and y-directions. An extensive finite element (FE) validation of the developed model was performed for different aspect ratios of rectangular and nonrectangular pockets and various change of thickness schemes. It was shown that the proposed model can accurately capture the dynamic effect of the change of thickness with prediction errors of less than 5% and at least 20 times reduction in the computation time. Experimental validation of the models was performed through the machining of thin-walled components. The predictions of the developed models were found to be in excellent agreement with the measured dynamic responses. [ABSTRACT FROM AUTHOR]

In modeling axial field machines, three-dimensional (3-D) finite-element method (FEM) models are required in accurate computations. However, 3-D FEM analysis is generally too time consuming in industrial use. In order to evaluate the performance of the axial flux machine rapidly, an analytical design pro- gram that uses quasi-3-D computation is developed. In this paper the main features of the developed program are illustrated. Results given by the program are verified with two-dimensional and 3-D finite element computations and measurements. According to the results, it is possible to evaluate the performance of the surface-mounts axial flux PM machine with reasonable accuracy via an analytical model using quasi-3-D computation. [ABSTRACT FROM AUTHOR]