MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY SZAB CAMPUS ,KHAIRPUR MIR’S

PRESENTATION

ROLL NO K13ME45 NAME HASSAN RAZA SUBJECT SOM-II TOPIC CONCENTRATED STRESS, STRESS TENSOR

CONCENTRATED STRESS

• A stress concentration (often called stress raisers or stress risers) is a location in an object where stress is concentrated.

• An object is strongest when force is evenly distributed over its area, so a reduction in area, e.g., caused by a crack, results in a localized increase in stress.

EXPLANATION

• A material can fail, via a propagating crack, when a concentrated stress exceeds the material's theoretical cohesive strength.

• Cohesive strength:Theoretical stress that causes fracture in tensile test if material exhibits no plastic deformation.

• The real fracture strength of a material is always lower than the theoretical value because most materials contain small cracks that concentrate stress.

• Fatigue cracks always start at stress raisers, so removing such defects increases the fatigue strength.

The sharp corner at the brick has acted as a stress concentrator within the concrete causing it to crack

PREVENTION

• One method used to decrease the stress concentration is by creating the fillet at the sharp edges. It gives smooth flow of stress streamlines.

STRESS TENSOR

DEFINITIONStress Tensor is simply a convenient concise way of expressing the stress state inside of a material.ORTensor can be defined as the quantity which has magnitude with multiple direction.

EXPLANATION

• Tensor completely defines( determines the components of stress) in a body. i-e it gives information about magnitude direction and plane of action.

• Stresses acting on an plane, are typicallydecomposed into three mutually orthogonalcomponents. One component is normal tothe surface and represents direct stress. Theother two components are tangential to thesurface and represent shear stresses.