نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Strength of materials

نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Strength of materials (also named mechanics of materials) is a branch of applied mechanics involving studying of stresses, strains and deflections of parts and structures under different loading conditions. The course is essential as a pre-request for studying: Mechanical design, Manufacturing processes (cutting and forming), structural design, soil mechanics and...etc

نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Objectives: After studying the course students are expected to be familiar of the concepts of stresses, strains and deflections and to apply their knowledge to calculating different types of stresses, strains and deflections using different techniques

نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Types of stress

نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Definitions: - Normal stress: the intensity of loading on a cross-section perpendicular to the direction of loading. i.e.: the load share of the unit area of cross-section. Normal stress can be tension (positive), when it tends to elongate the body or compression (negative) when it tends to shorten the body. Normal stress is normally given the symbol (б)

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 Normal Strain (): Strain is a measure of the deformation of the material and is a nondimensional Quantity i.e. it has no units. It is simply a ratio of two quantities with the same unit. Since in practice, the extensions of materials under load are very very small, it is often convenient to measure the strain in the form of strain x i.e. micro strain.

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Shear stress:Shear stress: A stress acting on an area parallel to the direction of load. Shear stress is normally given the symbol ( Ʈ ).

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Hooke's law* states that when a material is loaded within elastic limit, the stress is directly proportional to strain, i.e. Young's Modulus or Modulus of Elasticity

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Statically Indeterminate Structures When the equations of statics are not sufficient to find forces and/or reaction the structure is said to be indeterminate. The problem arises from the existence of redundant forces. Redundant forces are those which can be removed without affecting the stability of the structure.

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 THERMAL STRESS Change in temperature cause bodies to expand or contract. Amount of deformation (δ T ), experessed by the relation: δ T =αL(∆T) where α is the coefficient of linear expansion L is the length ∆T is the temperature change

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 Torsion Sometimes machine parts are subjected to pure torsion or bending or combination of both torsion and bending stresses.

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The maximum torsional shear stress at the outer surface of the shaft may be obtained from the following equation:

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