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.
Creep behaviour determination of monolayer plasma-sprayed coatings under dynamic or static loads
Knowledge of the mechanical and creep properties for various plasma-sprayed coatings on machine elements is of essential significance in order to ensure their safe operation. In previous investigations, plasma-sprayed coatings were examined by means of an impact test to determine their dynamic creep behaviour. In order to investigate the static creep behaviour of plasma-sprayed coatings and to allow correlation with the dynamic behaviour, a micro-indentation test device and a related FEM-supported test simulation procedure were developed and experiments using specimens with various coating material specifications were conducted. The stress strain rates vs. the applied loads were predicted and are discussed. The properties determined were used to define the safety against creep of plasma-sprayed coatings on machine elements exposed to dynamic or static operational loads.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.