FACTOR OF SAFETY It is defined as the ratio of the material strength ultimate strength or yield strength or endurance strength to the working or allowable stress. Factor of safety= Material strength/Design stress Factor of safety for static loading of ductile material: In case of the static loading of ductile materials where the yield point is clearly defined, the factor of safety is based on yield strength and is defined as Factor of safety= Yield strength/Design stress Factor of safety for static loading of brittle material: In case of the static loading of material, the factor of safety is based on the ultimate strength. Factor of safety= Ultimate strength/Design stress Factor of safety for fatigue loading: In case of fatigue loading, the factor of safety is based on endurance limit. Factor of safety= Endurance limit/Design stress CONTACT STRESS When two bodies having curved surfaces like two spheres or two cylinders or cylinder or flat surface or sphere and flat surface are pressed against each other, the point or line contact between the two bodies changes to area contact. The stress developed in the two bodies in the contact zone is known as contact stress or Hertz contact stress. Eg: The contact stress is induced in a contact zone of wheel and rail, cam, and follower, mating gear teeth, rolling contact bearing, etc CRUSHING STRESS OR BEARING STRESS A localized compressive stress at the area of contact between two components having no relative motion between them is known as crushing stress or bearing stress. Crushing stress= Force/projected area of contact

1. MATERIAL DESIGN AND Industrial drafting

2. Presented By: Stanley Christy 16ME009
Guided By: Prof. Dharini Shah

3. • Factor of safety
• Contact stress
• Crushing and Bearing stress

4. FACTOR OF SAFETY
• It is defined as the ratio of the material strength
ultimate strength or yield strength or endurance
strength to the working or allowable stress.
Factor of safety= Material strength/Design stress
• Factor of safety for static loading of ductile
material: In case of the static loading of ductile
materials where the yield point is clearly defined, the
factor of safety is based on yield strength and is defined
as
Factor of safety= Yield strength/Design stress

5. • Factor of safety for static loading of brittle material: In case
of the static loading of material, the factor of safety is based
on the ultimate strength.
Factor of safety= Ultimate strength/Design stress
• Factor of safety for fatigue loading: In case of fatigue
loading, the factor of safety is based on endurance limit.
Factor of safety= Endurance limit/Design stress

6. When two bodies having curved surfaces like two spheres or
two cylinders or cylinder or flat surface or sphere and flat
surface are pressed against each other, the point or line
contact between the two bodies changes to area contact. The
stress developed in the two bodies in the contact zone is
known as contact stress or Hertz contact stress.
Eg: The contact stress is induced in a contact zone of wheel
and rail, cam, and follower, mating gear teeth, rolling contact
bearing, etc

7. CRUSHING STRESS OR BEARING
STRESS
A localized compressive stress at the area of contact
between two components having no relative motion
between them is known as crushing stress or bearing
stress.
Crushing stress= Force/projected area of contact