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Proof Stress

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  To know about proof stress, first understand the behavior of materials. Like ductile and brittle materials. We all know the ductile is elastic and show permanent deformation under external load. Meanwhile the brittle doesn't show much deformation.  But now the question is how much deformation will be considered as under ductile category or in brittle category. To distinguish between ductile and brittle materials. proof stress show significant role to find the category of materials. i.e. ductile or brittle. Stress-strain curve for x material is shown below. To find the material X is ductile or brittle  proof stress point should be located on stress strain curve of the material. For many ductile materials other than mild streel, eg. aluminum, copper, high tensile steel etc. no definite yield point is obtained. for such materials, the shape of the stress-strain diagram is given below. In such a case, the yield stress is obtained by measuring the stress corresponding to some residual
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Important Topics for exam point of view

 Short answer type questions 1. Definitions  like; Strength, stress, Poisson's ratio, stress-strain diagram, bulk modulus, relation between elastic constants, principal stress, shear force, bending moment, types of beam, types of loads, strain energy, hoop stress, proof stress, theories of failure. 2. Topics for long questions 1. shear force and bending moment diagram  2. bending stress  3. principal stress analytical as well as graphical method
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Mohr’s Circle (for a body subjected to direct stresses in two mutually perpendicular faces)

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  Mohr’s circle for stress on an oblique section of a body subjected to direct stresses in two mutually perpendicular faces. Detailed step by step procedure to draw the mohr's circle for a body subjected to direct stresses in two mutually perpendicular faces (When both stresses are of tensile nature) Things to remember before drawing mohr's circle  👉tensile stress is taken as positive and compressive stress is taken as negative. 👉 you can use appropriate scale  Step 1. Draw a straight line OB length equals to σx Step 2. Mark a point A on line OB and Length of OA is equal to σy . Step 3. Mark Mid point C of line joining A and B Step 4. Draw a circle With mid point C and passing through points A and B Step 5. Locate an inclined plane in this circle by marking a radial line CD at double the angle 2θ at which the required plane is inclined with a given plane. Step 6. Draw DE  perpendicular from D to x-axis. Now the mohr's circle is completed  Now we have to find the result va
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Mohr's circle (subjected to direct stresses in two mutually perpendicular faces and it is accompanied by a shear stress)

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Best and easy way to understand and draw the Mohr’s circle   Mohr’s circle for stress on an oblique section of a body subjected to direct stresses in two mutually perpendicular faces and it is accompanied by a shear stress Detailed step by step procedure to draw the mohr's circle for a   body subjected to direct stresses in two mutually perpendicular faces ( When both stresses are of tensile nature ) Things to remember before drawing mohr's circle  👉tensile stress is taken as positive and compressive stress is taken as negative. 👉a pair of shear stress on // planes forming a clockwise couple is positive and a pair of shear stress on // planes forming a counter-clockwise couple is negative. 👉 you can use appropriate scale  for eg.  σ x (Megapascal) = σ x (centimeter)   1 MPa=1cm Step 1 . Draw a straight line length OB length equals to  σ x. Step 2 .  Mark a point A on line OB and Length of OA is equal to  σ y   . Step 3.   Draw a Perpendicular line AE and BF, length of AE a
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Types of Stress

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 Types of Stress 1. Tensile stress ( σ ) When the component is subjected to two equal pulls, the component  tend to elongate due to the external force. The stress induced in the material is known as tensile stress. L is the original length of the component                δ L is the change in length of the component Strain  When the component is subjected to two equal pulls or push, the component  tend to elongate or shorten respectively, due to the external force. Then the ratio of change in length to the original length is known as stain stain ( ɛ)  =  δ L/ L Stain has no units (Unitless) 2.  Compressive stress ( σ ) When the component is subjected to two equal push, the component  tend to shorten due to the external force. The stress induced in the material is known as compressive stress. 3. Shear stress ( τ ) When forces are transmitted from one part of a body to other, the stresses developed in a plane parallel to the applied force are the shear stress. Shear stress acts parall
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Stress

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Strength of Materials  The strength of any material can be defined in terms of Stress. Stress is the only way by which strength can be defined.  And the Stress is defined as follows: Stress (σ) When a material is subjected to an external force, a resisting force induced within the component. The internal resistance force induced per unit area due to external force acting on a material or intensity of the forces distributed over a given section is called the stress at a point.  Stress is donated by  σ                               σ=P/A                Where P is External Force applied                                                                 A is Cross-Sectional Area When Force (P) is acting on the material is tends to split it into two  pieces P is in terms of Newton (N) and A as original area (Before applying external force (P)), in square meters ( m 2 ), the stress  σ  will be expresses in N/  m 2 . This unit is called Pascal (Pa). Units of stress 1 kPa = 10 3 Pa = 10 3 N/
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