9.5 Определи верны ли данные высказывания или нет:

1. The strength of materials is one of the fields of building science.

2. The strength of materials only studies bearing reactions of structural systems.

3. The strength of materials does not cover dimensions and choice of materials.

4. A deformation takes place when the material is in a state of stress.

5. Strain expresses the deformation change.

6. Compressive stress elongates the material in the axis of the applied load.

7. Tensile stress reduces the length of the material in the axis of the applied load.

8. Shear stress causes opposing forces to act along parallel lines of action.

9. Yield strength, compressive strength, tensile strength, fatigue strength, and impact strength are not the terms in the strength of materials.

6. Ответь на вопросы:

1. Its purpose is to determine the dimensions of the constructions in order to resist to strains which they have to withstand

What does the pronoun its refer to?

2. It enables to ensure the good performance of the beams under the permanent and service loads.

What does the pronoun it refer to?

3. this science studies the mechanical properties of materials used in the construction industry.

What does the demonstrative adjective this refer to?

4. it is to determine the quantities of matter necessary and sufficient to achieve these forms

What does the demonstrative adjective these refer to?

5. this is called the strain.

What does the pronoun this refer to?

6. it is expressed as the quotient of the displacement and the length of the specimen.

What does the pronoun it refer to?

7. Compressive strength for materials is generally higher than that of tensile stress.

What does the pronoun that refer to?

9.7 Прочитай, переведи текст stress-strain relations и расположи абзацы в правильной последовательности:

1. Specifying how stress and strain are to be measured, including directions, allows for many types of elastic moduli to be defined. The three primary ones are:

2. Elasticity is the ability of a material to return to its previous shape after stress is released. In many materials, the relation between applied stress and the resulting strain is directly proportional to a certain limit, and a graph representing those two quantities is a straight line. The slope of this line is known as Young’s modulus, or the modulus of elasticity. The modulus of elasticity is the mathematical description of an object or substance tendency to be deformed elastically (i.e. non-permanently) when a force is applied to it. The elastic modulus of an object is defined as the slope of its stress-strain curve in the elastic deformation region:

3. Young’s modulus describes tensile elasticity or the tendency of an object to deform along an axis when opposing forces are applied along that axis; it is defined as the ratio of tensile stress to tensile strain. It is often referred to simply as the elastic modulus.

4. The shear modulus or modulus of rigidity describes the tendency of an object to shear when acted upon by opposing forces; it is defined as shear stress over shear strain. The shear modulus is part of the derivation of viscosity.

5. Where lambda is the elastic modulus; stress is the force causing the deformation divided by the area to which the force is applied; and strain is the ratio of the change caused by the stress to the original state of the object. An alternative definition is that the elastic modulus is the stress required to cause a sample of the material to double in length. This is not realistic for most materials as the value is greater than the yield stress of the material or the point where elongation becomes nonlinear, but some may find this definition more intuitive.

6. Plasticity or plastic deformation is the opposite of elastic deformation and is accepted as unrecoverable strain. Plastic deformation is retained even after the relaxation of the applied stress. Most materials in the linear-elastic category are usually capable of plastic deformation. Brittle materials, like ceramics, do not experience any plastic deformation and will fracture under relatively low stress. Materials such as metals usually experience a small amount of plastic deformation before failure while soft or ductile polymers will plastically deform much more.

7. The bulk modulus describes volumetric elasticity, or the tendency of an object to deform in all directions when uniformly loaded in all directions; it is defined as volumetric stress over volumetric strain, and is the inverse of compressibility. The bulk modulus is an extension of Young’s modulus to three dimensions.