DETERMINATION OF EPOXY RESIN ’ S MECHANICAL PROPERTIES BY EXPERIMENTAL-COMPUTATIONAL PROCEDURES IN TENSION Assist . Prof . VLDILV
The use of epoxy resins in metal structures for adhesive reasons is getting wider. Epoxy resins possess enhanced mechanical, chemical and physical properties, i.e. increased shear and compression strength, resistance in solvents, as well as at high temperatures. Tensile tests were carried out with standard aluminium tension specimens glued with epoxy resins. The thickness of the glue and the acting crosssection area were variable. The specimens were cemented under constant temperature and humidity conditions. The experimental results were simulated with the aid of FEM-based procedures, while the stress–strain curves of the epoxy resins, as obtained by nanoindentations and corresponding FEM-supported algorithm, were taken into account. The obtained results allow the determination of the epoxy resins’ strength versus its thickness and the occupying cross-section area.
Thin hard coatings stress–strain curve determination through a FEM supported evaluation of nanoindentation test results
Abstract The widespread use of thin hard physical vapor deposited (PVD) coatings in various technical applications necessitates the precise knowledge of their mechanical properties. Up to now the coating elasticity and plasticity properties were approached with the aid of simplified considerations of the nanoindentation procedure and a consequent evaluation of the obtained nanohardness measurement results, depending, however, on the indentation load. In the present paper a continuous finite elements method (FEM) simulation of the nanoindentation hardness test is introduced in order to describe the coating elastic and plastic deformation during this test and herewith to extract precisely and independent of the indentation load the coating stress–strain curve. Characteristic applications of the developed procedure demonstrate the adequacy of this method to determine the coatings constitutive laws of various coating materials deposited under different conditions.
The Determination of Physicochemical Characteristics of Biodiesel and Its Blending Oils
The viscosity,combustion heat,sulfur content,carbon residue,ash,flash point,moisture and cetane value of biodiesel and its blending oils with diesel were determined.The influence of temperature on the viscosity was studied,and the physicochemical characteristics of biodiesel and its blending oils were compared with diesel.The results indicated that biodiesel and its blending oils had some superior performances and good application prospect.