BASICS OF Mechanics mechanica engg 009.pptx

basic of mechanics

1. Automation & Robotics Department of Mechanical Engineering Maulana Azad National Institute of Technology, Bhopal (MANIT) Bhopal Basic Terms In Mechanics Presented By:  Sayak Subhra Scholar No.: 2321606109 Date : 11/09/2023

2. Sl. No.  Title 1. Axial Stress & Strain 2. Shear Stress & Strain 3. Poission’s Ratio 4. Yield and Tensile Strength in Ductile and Brittle Material 5. Thermal Expansion 6. Hardness 7. Creep 8. Fatigue Contents

3. Stress : Force per unit area , the viscous capability of object that resist to change the size . Types :Nominal & Shear Nominal Stress : Axial/Nominal stress : it is a normal stress perpendicular to area .Types : Tensile and Compressive Tensile : it helps in increase the size Compressive : it helps in decrese the size Axial Strain : Change in size parallel to the axis of the applied force . Shear Stress : it is a normal stress parallel to the axis of the applied force Tensile & Compressive

4. Shear Stress : It ’s in plane stress of cross section Shear strain : It occurs when the deformation of an object is response to a shear stress (i.e. parallel to a surface) Elongation : Angular , implies to diagonal elongtaion or compression Shear and Nominal Stress and perpendicular to each other . Strain : Change in size , tough in very eleatic material like rubber shape also changes

5. Poission’s Ratio : The ratio of lateral strain to the longitudinal strain is called Poisson's ratio. The lateral strain is always negative since the diameter decreases with the applied force. Therefore, we can state Poisson's ratio as the negative ratio of lateral strain to the longitudinal strain. Range -1< gamma <0.5 Yield strength is a measurement to determine the maximum stress that can be applied before permanent shape change is achieved in ductile materials. Whereas, tensile strength is the point of fracture. Deformation of materials occurs after yield strength has been reached then tensile strength is tested. Stree & Stain curve in Ductile Material

6. Thermal expansion : is the tendency of matter to change in volume in response to temperature alterations . Hardness : is defined as the resistance of a material to permanent deformation during application of load. Creep (sometimes called cold flow) is the property of materials that results in progressive deformation when a constant load/factor is applied over time. Factors Affecting Creep in Materials Temperature: One of the most significant factors influencing creep is temperature. Load/Stress. Alloying Elements. Environmental Factors. Microstructure.

7. Fatigue : is the initiation and propagation of cracks in a material due to cyclic loading.