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Adrian Catangiu, Dan Nicolae Ungureanu and Veronica Despa

Abstract

The strength of materials is a complex function which involve two main components, material nature and the presence of defects. Usually glasses exhibit a fragile behavior due to a numerous flaws and the effect is a large range of data scattering in tensile strength measurement. The Weibull probability density function was applied to describe the scatter of experimental data in tensile test, which emphasize a difference between variance in case of tensile strength of three stainless steel grades and glass epoxy composite. The main goal is mathematical modeling of those distributions and finding of equations which predict the probability of failure for a sample subjected to a specific stress.

Open access

Dan Nicolae Ungureanu, Daniela Avram, Nicolae Angelescu, Adrian Catangiu, Florina Violeta Anghelina and Veronica Despa

Abstract

In this paper is presented a comparative study regarding the synthesis of hydroxyapatite powders. The chosen method of synthesis of this biomaterial was chemical co-precipitation. The structure, size and morphology of the obtained powders were analyzed by X-ray diffraction, infrared spectroscopy - FTIR, dynamic light diffusion DLS tehnique and scanning electron microscopy-SEM. The results obtained were compared with those obtained on a commercial hydroxyapatite powder. Investigation methods have confirmed the synthesis of a high purity hydroxyapatite with a optimal degree of crystallization and crystallinity for the reconstruction and regeneration of hard tissue.

Open access

Gheorghe Ion Gheorghe, Vasile Bratu, Adriana Cîrstoiu and Veronica Despa

Abstract

The scientific paper presents in summary the new concepts regarding the realization of cyber-mix-mechatronic systems with different industrial and societal applications.