1.Solid Mechanics- simple stress & strain.ppt
- 1. Dr. Sujit Kumbhar Assistant Professor, Sharad Institute of Technology College of Engineering, Yadrav (An Autonomous Institute) SOLID MECHANICS Simple Stress and Strain Concept
- 2. Topic cover Stress and strain Introduction to stress and strain, stress strain diagram Elasticity and plasticity and Hooke’s law Shear Stress and Shear strain Load and stress limit Axial force and deflection of body
- 3. Stress and strain DIRECT STRESS When a force is applied to an elastic body, the body deforms. The way in which the body deforms depends upon the type of force applied to it. Compression force makes the body shorter. A tensile force makes the body longer
- 5. Stress and strain Source: Strength of Materials by R.K.Bansal
- 6. Stress and strain Source: Strength of Materials by R.K.Bansal
- 7. Stress and strain Source: Strength of Materials by R.K.Bansal
- 8. A F Area Force Stress 2 / m N Tensile and compressive forces are called DIRECT FORCES Stress is the force per unit area upon which it acts. ….. Unit is Pascal (Pa) or Note: Most of engineering fields used kPa, MPa, GPa. ( Simbol – Sigma)
- 9. L x Strain DIRECT STRAIN , In each case, a force F produces a deformation x. In engineering, we usually change this force into stress and the deformation into strain and we define these as follows: Strain is the deformation per unit of the original length. The symbol Strain has no unit’s since it is a ratio of length to length. Most engineering materials do not stretch very mush before they become damages, so strain values are very small figures. It is quite normal to change small numbers in to the exponent for 10-6 ( micro strain). called EPSILON
- 10. MODULUS OF ELASTICITY (E) •Elastic materials always spring back into shape when released. They also obey HOOKE’s LAW. •This is the law of spring which states that deformation is directly proportional to the force. F/x = stiffness = kN/m •The stiffness is different for the different material and different sizes of the material. We may eliminate the size by using stress and strain instead of force and deformation: •If F and x is refer to the direct stress and strain , then A F L x L A x F Ax FL hence and
- 11. E Ax FL •The stiffness is now in terms of stress and strain only and this constant is called the MODULUS of ELASTICITY (E) • A graph of stress against strain will be straight line with gradient of E. The units of E are the same as the unit of stress. ULTIMATE TENSILE STRESS •If a material is stretched until it breaks, the tensile stress has reached the absolute limit and this stress level is called the ultimate tensile stress.