Chapter-2-Factor of safety (FOF)

Factor of safety (FOF)

Factor of safety:-

Factor of safety is used to determine.
     

1. Permissible Stress 
2. Allowable Stress
3. Safe Stress
4. Working Stress 

                                          

Failure Strength:-

For Static Load ;

Yield Strength is the failure criteria for the Ductile Material
Ultimate Strength is the failure criteria for Brittle Material also Ductile Material

For Static Load;

Endurance Limit is the failure criteria.

Brittle:- 

Material will not permits any deformation and goes to fractures ultimate strength will be the failure strength.

Ductile:- 

• Case-1: When a material does not undergo permanent deformation or is under the elastic limit, yield strength will be the failure strength.

• Case-1I: When Material undergo permanent deformation, ultimate strength will be the failure strength.

Chapter-1-Introductionn to Strength of Material (SOM)

Introduction to Strength of Material (SOM)-Mechanics of Deformable body

Strength of Material :-

It is study of internal resisting force developed due to elastic deformation of a body under the action of load.
Assumption made in Strength of Material Equation:-

1. Material is assumed to be homogeneous and isotropic.
2. Component is assumed to be prismatic.
3. Load is assumed as static load
4. Effect of self weight is neglected. 

Static Load:- 

When magnitude and direction is constant with respect to time.

Prismatic:-

All dimension are constant or same throughout the structure.

Homogeneous:-

Material is said it be isotropic, when it exhibit same elastic property at a point in a given direction.

Isotropic:-

Material is said it be isotropic, when it exhibit same elastic properties in any direction at a given point.