Part II. Church Slavonic with modern language

Church Slavonic with modern language. In 1760 he pub­lished the first history of Russia. He also revived the art of Russian mosaic and built a mosaic and coloured-glass factory. Most of his achievements, however, were un­known outside Russia. He died in St. Petersburg on April 15, 1765.

Unit3 Materials Science and Technology

I. Text Л: «Materials science and technology», Text B: «Mechanical Properties of Materials».

II. Famous people of science and technology: Igor Sikorskiy, Andrey Tupoiev.

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TextAi «MECHANICAL PROPERTIES OF MATERIALS»

Materials Science and Technology is the study of ma­terials and how they can be fabricated to meet the needs of modern technology. Using the laboratory techniques and knowledge of physics, chemistry, and metallurgy, scientists are finding new ways of using metals, plastics and other materials.

Engineers must know how materials respond to exter­nal forces, such as tension, compression, torsion, bend­ing, and shear. All materials respond to these forces by elastic deformation. That is, the materials return their original size and form when the external force disap­pears. The materials may also have permanent deforma­tion or they may fracture. The results of external forces are creep and fatigue.

Compressio n is a pressure causing a decrease in vol­ume. When a material is subjected to a bending, shear­ing, or torsion (twisting) force, both tensile and comp­ressive forces are simultaneously at work. When a metal bar is bent, one side of it is stretched and subjected to a tensional force, and the other side is compressed.