HOW MATERIALS REACT TO EXTERNAL FORCE
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. Ail 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.
Compression 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.
ДОПОЛНИТЕЛЬНЫЙ СЛОВАРЬ:
bar- брусок, прут
completely – полностью, совершенно
compression - сжатие
creep - ползучесть
cross-sectional area – площадь поперечного сечения
cyclic stress – циклическое напряжение
elastic deformation – упругая деформация
Task 1. Answer the questions
1. What are the external forces that cause the elastic deformation of materials?
The external forces such as tension, compression, torsion, bending, and shear cause the elastic deformation of materials.
Describe those forces that change the form and size of materials.
The compression and tension the forces that change the form and size of materials.
Because compression is a pressure causing a decrease in volume of material. And tension is a pulling force, at which the material is pulling and change its size.
2. What are the results of external forces?
The results of external forces are creep and fatigue.
3. What kinds of deformation are the combinations of tension and compression?
When a metal bar is bent, one side of it is stretched and subjected to a tensional force, and the other side is compressed.
Task 2. Find the following word combinations in the text:
1. отвечать требованиям современной технологии – to meet the needs of modern technology
2. используя лабораторные методы – using the laboratory techniques
3. новые способы использования металлов – new ways of using metals
4. сжатие, растяжение, изгиб, кручение, срез – compression, tension, bending, torsion, shear
5. возвращать первоначальный размер и форму – to return original size and form
6. внешняя сила – external force
7. постоянная деформация – permanent deformation
