Application of Substructure Techniques to Syntactic Metal Foams in a Finite Element Environment

The presented work focuses on the development of a novel method that can numerically describe the properties of metal matrix syntactic foam (MMSF) with low memory requirements and short computational times without losing the properties of the interior structure. In this paper, we propose a novel method that avoids using the homogenization technique and instead rearranges stiffness matrices and constructs specific substructures to perform the overall construction. The two-dimensional cases are discussed in order to focus on the methodology itself. First, the reductions and structural design with solid mesh structures were performed, and then the model was applied on structures filled with iron hollow spheres. So far, the method has been used to evaluate small deformations to see how suitable the subspace technique is for describing metal foams. Aluminum was used as the matrix material, as it is one of the most common materials for MMSFs. The optimal parameters were searched that resulted in the shortest running time for the given construction. Since in the proposed substructure technique only the displacement values at the boundary points are computed, a back-calculation step for each selected substructure was performed to see the interior deformations in the vicinity of an iron hollow sphere

A Method for Measuring Normal and Shear Stiffness of Laminate Stacks of Electric Motors

Structural simulations of electric motors require precise material models. Laminate stacks that are made of several identical steel sheets are particularly challenging to simulate using FEA. The structural stiffness of laminate stacks usually follows transversal isotropic behavior. Measuring a complete laminate stack used in passenger cars is challenging due to its size and the high testing load needed to reach real loads experienced while in operation. A new method capable of performing such measurements is presented in this article, with the help of equipment normally used for testing structures used in civil engineering. Two sets of exemplary results are presented utilizing this measurement procedure, that were performed on a real automotive rotor laminate stack: axial compression stiffness from a cyclic test, and shear stiffness at various axial preload levels. In the axial compression load case, the loading and unloading curves form a hysteresis, that changes in every test cycle. Shear stiffness shows high dependance on the axial compression preload. After loading and unloading the stack with shear loads, significant plastic deformations remain

Textilkompozitok mezőgazdasági alkalmazásának mechanikai megalapozása = Substantiation of adaptation of composites in agriculture

A kutatás a textilkompozit rétegek anyagjellemzőinek megállapítási módjára dolgozott ki eljárást a mátrix és a szálanyag tulajdonságaiból meghatározva azt. Megállapította azokat a dimenzió nélküli tényezőket, amelyek hatással vannak az anyagtulajdonságra. Ezek függvényében végeselem eljárással térbeli cellamodellt alakított ki, amely alkalmas az anyagtulajdonságok számítására. A számítási módszert konkrét kísérleti eredményekkel ellenőrizve igazolta a számítási modell helyességét. A kutatás foglalkozott a textilkompozit lemez csillapításával is. Megállapította, hogy a belső csillapítás Coulomb csillapítással közelíthető. | The research developed method for the evaluation of the material properties of composites using the properties of the matrix and the reinforcement. Determined those dimensionless factors which affecting the composite's material properties. Developed the finite element spatial cell model of the composite which is capable to evaluate the composite's material properties. The evaluation method was checked and verified using experimental results. The research dealt with the damping properties of the composite plate. Ascertained, that the inner damping can be approximated using Coulomb damping