All categories

3 years ago

Define factor of safety and its significance

Engineering

1 answer:

grigory [225]3 years ago

8 0

Answer:

Factor of safety is defines as the ratio between the strength of a material and the maximum stress that is developed in the material as a result of any given loading.

Mathematically we can write

$F.O.S=\frac{Strength}{Stress_{working}}$

Consider any member of a machine that is under state of stress due to a general external loading, now we know that the material has a definite value of strength meaning that there is a definite value of force/stress at which the material will fail by fracture or by yielding as an example say a rod of steel will fail if we apply a load of 1000 Newton's on it.

Since as a basic principle of design we do not want any chance of failure in the machine at any cost we limit the maximum value of the stress that is developed in the machine part by designing the part in such a way that during the application of maximum load in the machine part the maximum stresses that are developed in the machine are well below the strength of the material for safety considerations. The factor by which the working stresses are less than the strength is termed as factor of safety.

Another significance of factor of safety is that if we need to estimate the loads on the machine that may act on it and we are not absolutely sure about the magnitude of the loads then we tend to increase the loads by a factor so that we design the structure to withstand greater loads hence if in case in the lifetime of the structure the loads exceed the normal value our structure will still remain structurally safe.

You might be interested in

At a festival, spherical balloons with a radius of 140.cm are to be inflated with hot air and released. The air at the festival

Tpy6a [65]

Answer:

find attached

Explanation:

5 0

3 years ago

If the old radiator is replaced with a new one that has longer tubes made of the same material and same thickness as those in th

Nookie1986 [14]

Answer: hello some parts of your question is missing attached below is the missing information

The radiator of a car is a type of heat exchanger. Hot fluid coming from the car engine, called the coolant, flows through aluminum radiator tubes of thickness d that release heat to the outside air by conduction. The average temperature gradient between the coolant and the outside air is about 130 K/mm . The term ΔT/d is called the temperature gradient which is the temperature difference ΔT between coolant inside and the air outside per unit thickness of tube

answer : Total surface area = 3/2 * area of old radiator

Explanation:

we will use this relation

K = $\frac{Qd }{A* change in T }$

change in T = ΔT

therefore New Area ( A ) = 3/2 * area of old radiator

Given that the thermal conductivity is the same in the new and old radiators

3 0

3 years ago

Proper ventilation is required when welding, so that you don't ____________.

galben [10]

I say the answers is A but if you mean ventilation in the area of the room then answer B

4 0

3 years ago

Read 2 more answers

For a fluid with a Prandtl Number of 1000.0, the hydrodynamic layer is thinner than the thermal boundary layers. a) True b) Fals

kvv77 [185]

Answer:

(b)False

Explanation:

Given:

Prandtl number(Pr) =1000.

We know that $Pr=\dfrac{\nu }{\alpha }$

Where $\nu$ is the molecular diffusivity of momentum

$\alpha$ is the molecular diffusivity of heat.

Prandtl number(Pr) can also be defined as

$Pr=\left (\dfrac{\delta }{\delta _t}\right )^3$

Where $\delta$ is the hydrodynamic boundary layer thickness and $\delta_t$ is the thermal boundary layer thickness.

So if Pr>1 then hydrodynamic boundary layer thickness will be greater than thermal boundary layer thickness.

In given question Pr>1 so hydrodynamic boundary layer thickness will be greater than thermal boundary layer thickness.

So hydrodynamic layer will be thicker than the thermal boundary layer.

8 0

3 years ago

A pipe is insulated such that the outer radius of the insulation is less than the critical radius. Now the insulation is taken o

irina [24]

Answer:

the heat transfer from the pipe will decrease when the insulation is taken off for r₂< $r_{cr}$

where;

r₂ = outer radius

$r_{cr}$ = critical radius

Explanation:

Note that the critical radius of insulation depends on the thermal conductivity of the insulation k and the external convection heat transfer coefficient h .

$r_{cr} =\frac{k}{h}$

The rate of heat transfer from the cylinder increases with the addition of insulation for outer radius less than critical radius (r₂< $r_{cr}$ ) 0, and reaches a maximum when r₂ = $r_{cr}$ , and starts to decrease for r₂< $r_{cr}$ . Thus, insulating the pipe may actually increase the rate of heat transfer from the pipe instead of decreasing it when r₂< $r_{cr}$ .

7 0

3 years ago