Question

Q3 (SO1: 100%) A safety valve operated by a helical tension spring through a lever mechanism as shown in the figure. Diameter of the valve is 50 mm. In normal operating conditions, the valve is closed and the pressure ""P"" inside the chamber is 0.5 N/mm². When the pressure inside the chamber increases to 0.6 N/mm², the valve opens and lifts 5 mm. An Engineer suggests to use 5 mm wire diameter spring with index 8. The spring material is Hard-Drawn A227. Design the spring and calculate: a) Minimum and maximum forces $F_{min}$ & $F_{max}$ on the spring (in N) b) Free length $L_0$ of the spring such that $L_0$ < 125 mm. c) Static factor of safety of the spring body with $F_{max}$ calculated in part (a). d) Fatigue factor of safety of the spring body using the Goodman failure criterion with Zimmerli data. The spring is unpeened. Note: Initial tension of the spring ""Fi"" is included in ""$F_{min}$"" and should not be considered in the calculations. The spring end hooks are full twisted.

          Q3 (SO1: 100%)
A safety valve operated by a helical tension spring through a lever mechanism as shown in
the figure. Diameter of the valve is 50 mm. In normal operating conditions, the valve is
closed and the pressure ""P"" inside the chamber is 0.5 N/mm². When the pressure inside
the chamber increases to 0.6 N/mm², the valve
opens and lifts 5 mm. An Engineer suggests to use
5 mm wire diameter spring with index 8. The spring
material is Hard-Drawn A227. Design the spring
and calculate:
a) Minimum and maximum forces $F_{min}$ & $F_{max}$ on
the spring (in N)
b) Free length $L_0$ of the spring such that
$L_0$ < 125 mm.
c) Static factor of safety of the spring body
with $F_{max}$ calculated in part (a).
d) Fatigue factor of safety of the spring body
using the Goodman failure criterion with
Zimmerli data. The spring is unpeened.
Note: Initial tension of the spring ""Fi"" is included in ""$F_{min}$"" and should not be considered
in the calculations. The spring end hooks are full twisted.

Q3 (SO1: 100%)
A safety valve operated by a helical tension spring through a lever mechanism as shown in
the figure. Diameter of the valve is 50 mm. In normal operating conditions, the valve is
closed and the pressure ""P"" inside the chamber is 0.5 N/mm². When the pressure inside
the chamber increases to 0.6 N/mm², the valve
opens and lifts 5 mm. An Engineer suggests to use
5 mm wire diameter spring with index 8. The spring
material is Hard-Drawn A227. Design the spring
and calculate:
a) Minimum and maximum forces Fmin Fmax on
the spring (in N)
b) Free length L0 of the spring such that
L0 < 125 mm.
c) Static factor of safety of the spring body
with Fmax calculated in part (a).
d) Fatigue factor of safety of the spring body
using the Goodman failure criterion with
Zimmerli data. The spring is unpeened.
Note: Initial tension of the spring ""Fi"" is included in ""Fmin"" and should not be considered
in the calculations. The spring end hooks are full twisted.

Added by Michael S.

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