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The elaborated paper presents a series of methodologies with which the dynamic characteristics (damping coefficient, damping factor) can be determined, depending on the working conditions, of a hyperelastic material using vibration theory. These methodologies can be extended to characterize any type of hyperelastic material. The main aim of this work is to develop experimental technology and methodology to characterize this type of materials like rubber to establish a series of dynamic factors like damping factor, transmissibility at resonance, pulsation at resonance, dynamic elastic constant. These characteristics are variable, depending on composition, request, etc. In conclusion, they are not available in specialized literature as are the characteristics of linear-elastic materials. The application of numerical calculation programs in carrying out resistance calculations, in the case of structures made of such materials, is also impossible to achieve, having as an impediment the lack of knowledge of the values of the material characteristics. [ABSTRACT FROM AUTHOR]

The main aim of this article is to present a fatigue cycle counting program for a given application. The application is an example from a given case presented in the literature, with the analytical solution discussed herein. Cycle counting for irregular fatigue spectra is important to evaluate for various given load cases, in different industries. Such evaluations are difficult to make without dedicated computer programs. Several specific methods are available in the technical literature to evaluate irregular fatigue spectrums. For this study, one of the most well-known and used methods was chosen, the rainflow-counting algorithm. This method extracts the number of cycles from an irregular fatigue recording which, in turn, is used in the Palmgren-Miner rule to evaluate the fatigue damage for the examined application, considering that the Wohler curve is given. The developed program is written in the Python programming language. The theoretical background is presented for the application and the use of it with the program algorithm. [ABSTRACT FROM AUTHOR]

Metal-composite joints, or hybrid joints are prevalent in aerospace structures due to their high strength and low weight. Such structures are usually found in areas where because of the load configuration, the use of composite materials is possible. Thereby, the analysis of such areas needs to consider both components, the metallic and the composite part. In this paper a hybrid joint is analyzed, consisting of a metallic stiffener, a multilayered honeycomb composite material, and joining fasteners, which constitute the joint between the isotropic and orthotropic materials. The present article has two main purposes: the first is to illustrate a pre-design procedure aimed to evaluate the load-carrying capability of a hybrid joint structure, thereby giving an estimate if the structure can withstand the given loading conditions; the second purpose is to present two types of finite element modeling techniques, one that captures the real geometric structure of the composite material and another which uses a simplified equivalent model, based on the desired level of evaluation of the composite material part. A comparison between the two models is made, highlighting the advantages and disadvantages of the two forms of evaluations. For the metallic parts - stiffener and fasteners, both static and fatigue analyses were performed, as fatigue failure represents the common service failure mode for this type of structural components. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to describe the creation and use of a fatigue analysis program written in VBA, designed for the preliminary sizing of metallic structural components used in aerospace applications, subjected to one or multiple fatigue loading cases. The VBA programing language was chosen because of its direct control over the most common spreadsheet computational program, Microsoft Excel. Metal fatigue analysis is an important type of analyses for modern structures. Fatigue failure accounts for around 80-90 percent of common structural failures, and therefore, a quick and reliable analysis is necessary so as to evaluate the structure’s bearing capacity to fatigue load. Due to the nature of the fatigue load and the importance of the structural component, such an analysis can be very time consuming, starting from the finite element model preparation and going through the actual analysis; thus, there is a need for a tool that can evaluate the stress data from the numerical simulation and give reliable information about the behavior of the structural component. [ABSTRACT FROM AUTHOR]