Page 67 - Fundamental of Engineering Design
P. 67
Factor of safety
◦ Guideline for selection of quantities values for factor of safety
are as follow:
Table 2.1 : Types of material and the value of factor of safety
Material fs
1 Cast iron component, failure due to maximum stress 3-5
2 Ductile material (steel, Al) subjected to external 1.5-2
static force. Has proper heat treatment and small
plastic deformation
3 Ductile material subjected to external fluctuating 1.3-1.5
force, fatigue failure
4 Component cam and follower, gears, bearing. 1.8-2.5
Failure cause by small pit.
5 Component piston rod, power rod, power screw or 3-6
stud. Sudden large lateral deflection. Critical
buckling load.
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