- #1
Kivenkantaja
- 5
- 0
Hello,
I'm having an issue trying to solve an equation- the problem is worded as such:
"A tie bar is made of a material having an ultimate tensile strength of 231 mPa, and must carry a load of 255 kN. What is the diameter of the bar if a factor of safety of 7 is required?I know that the formula to find factor of safety is ultimate stress/allowable stress. So I'm thinking I need to find the allowable stress in order to find the final answer.
So here is what I have attempted, but I feel that I'm way off:
A = 3.1416(d^2)/4 = .25*pi*d^2
255 kN*1000 = 255*10^3 N
231 mPa*100 000 = 231*10^6 n/m^2
231*10^6 N/m2= 255*10^3 N/.25*pi*d^2
.25*pi*d^2 = 255*10^3 N/231*10*6 N/m^2
d^2 = 255*10^3 N/.25*3.1416*231*10^6 N/m^2
d^2 = 255 000 N/1.8143*10^8 N/m^2
d^2 = 1.4055*10^-3m^2
= 1.39m
I'm having an issue trying to solve an equation- the problem is worded as such:
"A tie bar is made of a material having an ultimate tensile strength of 231 mPa, and must carry a load of 255 kN. What is the diameter of the bar if a factor of safety of 7 is required?I know that the formula to find factor of safety is ultimate stress/allowable stress. So I'm thinking I need to find the allowable stress in order to find the final answer.
So here is what I have attempted, but I feel that I'm way off:
A = 3.1416(d^2)/4 = .25*pi*d^2
255 kN*1000 = 255*10^3 N
231 mPa*100 000 = 231*10^6 n/m^2
231*10^6 N/m2= 255*10^3 N/.25*pi*d^2
.25*pi*d^2 = 255*10^3 N/231*10*6 N/m^2
d^2 = 255*10^3 N/.25*3.1416*231*10^6 N/m^2
d^2 = 255 000 N/1.8143*10^8 N/m^2
d^2 = 1.4055*10^-3m^2
= 1.39m