Mechanics

• Stress is the unit strength of a material.
• Normal stress is either tensile stress or compressive stress.
• Compressive force will tend to shorten the member while Tension force on the other hand will tend to lengthen the member.
• Shearing Stress is produced when there is sliding between separate bodies or whenever the applied loads cause one section of the body to tend to slide its adjacent section.
• Forces parallel to the area resisting force cause shearing stress
• Tensile and Compressive stresses are caused by forces perpendicular to the area on which they act.
• Shearing stress is also known as tangential stress
• Bearing stress is the contact pressure between separate bodies. P bearing force and A bearing are are perpendicular to each other.
• Thin walled Pressure vessels ares closed structures containing liquids or gases under pressure.These include tanks,pipes and pressurized cabins in aircraft and space vehicles. It is a general rule,the pressure vessels are considered to be thin walled when the ratio of inner radius to wall thickness is greater than 10
• Tangential stress is also called circumferential and hoop stress
• Axial stress is also known Longitudinal stress or meridional stress
• It can be observed that the tangential stress is twice that of the longitudinal stress
• Strain in mechanics measures the deformation in a material when mechanical stress is applied. Mathematically mechanical strain is equal to the ratio of change in length to the original length.
• Proportional limit from the origin to this point, the stress strain curve is a straight line
• Elastic Limit point beyond which permanent deformation occurs
• Yield point point beyond which increase in strain without increase in applied load
• Ultimate strength is the highest ordinate on the stress strain curve
• Rupture strength stress at failure ,considering necking gives true rupture strength. True rupture strength and Nominal
• Hookes law in 19th century while studying springs and elasticity,English scientist Robert Hooke noticed that many materials exhibited a similar property when stress strain relationship was studied
• There was a linear region where the force required to stretch the material was proportional to the extension of the material known as Hookes Law
• Hooke's Law states that the strain of the material is proportional to the applied stress within the elastic limit of that material
• If you plot stress versus strain, for small strain this graph will be linear, and the slope of the line will be a property of a material known as Young's Elastic Modulus
• Strain energy is defined as the energy stored in a body due to deformation
• U is the symbol for Area of the force-deformation diagram
• Poisson's ration (v) is the deformation of a material perpendivular to the loading direction. It is negative ratio of traverse strain to axial strain
• Axial strain is also known Longitudinal strain
• Transverse strain is also known as lateral strain
• Dilatation(e) the change in volume per unit volume. It is also equal to volumetric strain.
• K - bulk modulus of the material and modulus of compression of the material SHEAR