The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.
This paper presents some of our results regarding calculus of the functionally graded plates (FGPs). Such plates are made of Functionally Graded Materials (FGMs), which represent a new material class belonging to the composite materials. Our paper presents some material laws in a comparative way. But the main purpose of this paper is to provide calculus concepts and calculus methodologies, based on the means available in scientific research of mechanical engineering field, for the calculation of plates made of FGMs. Thus, the authors use the concepts of multilayer plate and equivalent plate, using both analytical and numerical calculus. The numerical method used are the Finite Element Method (FEM).The calculation aims both to determine the displacements and the stresses of the plates under statical loads, as well as to determine the free vibration frequencies. The research methodology is based on combining analytical calculation, where and when possible, with numerical simulation. The validation of our results is done by comparison with the analytical solution and the comparative analysis of the methods.
The underwater robot is part of a project with “terrestrial–maritime” collaborative robots, whose mission is recognition and rescue. From a structural point of view, some small changes were made in this study to the original robot. These changes consisted of making supports to hold the two plexiglass tubes, since the tube containing the battery system is larger. A larger tube was chosen because the aim was to increase the travel autonomy of the mini remotely operated vehicle (ROV). The mini submarine will move in an unstructured environment and will be able to reach a depth of 100 m. The purpose of the article is to present a point of view regarding the effect of the behavior of the mini ROV on tensions produced by the forced assembly of the sealing cover of the cylinder containing its command-and-control system. Both the gripping elements and the sealing lids are made using 3D printing technology, and the material used is polylactic acid (PLA). For the numerical analysis, the finite element method is used in both static and dynamic conditions. The results of this work refer to the field of tensions and displacements. The main conclusions emphasize the fact that the gripping performed for sealing is influenced by the usage of oiled mechanisms.
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