Thermal analysis - Thermal stress

Tutorial resources

These downloadable resources will be used to complete this tutorial:

Datasets_Thermal_Analysis.zip - (5 mb)

Transcript

00:04

Thermal analyses provide you with insights into energy transfer

00:07

heat can be applied in different ways and transported from

00:11

one place to another by radiation conduction and convection.

00:15

Using a thermal breaker assembly design,

00:18

we apply heat generating loads and heat transfer loads to

00:21

see if the design works effectively as a breaker.

00:26

This design is a strip of metal made up of two separate bodies

00:30

that is attached to a box at 85

00:33

°F.

00:34

The breaker loses heat to the environment but heats up when a current is applied

00:40

to analyze whether the design works effectively as a thermal

00:43

breaker switch to the simulation workspace and select thermal stress study

00:49

to set up the study first will review

00:51

the materials using the study materials command.

00:56

The design is modeled as two bodies both made of steel.

00:59

We can create a bimetal strip from this design by

01:02

changing the material of one of the bodies to brass,

01:05

brass and steel expand with temperature at different rates.

01:08

And the idea is that when the brass reaches a critical temperature,

01:12

it will lift the contact.

01:14

First,

01:14

we need to physically constrain the model with fixed

01:17

structural constraints in the holes for the rivets.

01:22

Now, we can begin to apply thermal loads,

01:25

set an applied temperature to account for the temperature being applied

01:28

to the breaker from the box to which it is secured,

01:32

select the same surfaces for the rivet holes and then

01:34

select the bottom face that is resting on the box.

01:38

The box has a surface temperature of 85

01:41

°F.

01:42

So we'll set the temperature to 85

01:44

°F.

01:47

Next,

01:47

apply convection heat load to the external faces of

01:50

the design that are losing heat to the environment.

01:54

Don't include any of the faces between the two bodies or

01:57

the bottom face that is resting on the 85 degree box

02:03

set, the convection value to 1000

02:06

and then set the ambient temperature to 85

02:09

°F

02:10

by simply adding the F for Fahrenheit to the value.

02:14

Now set the internal heat generated when current is applied

02:18

for this load, select both bodies set the value to 500 watts, then click OK.

02:25

Finally apply automatic contacts.

02:28

So the study knows that heat can be passed between the two bodies by conduction

02:32

to improve the solve accuracy. Set the absolute mesh size to 0.1 inches

02:39

precheck shows there are no issues with the set up. So now we can solve the analysis.

02:46

When the analysis is complete, we can check the results.

02:49

We can see the high degree of stress primarily between the two bodies

02:53

switching to displacement.

02:55

We can see the maximum displacement,

02:57

this displacement is enough to break contact and open the circuit.

03:02

Create a point probe,

03:03

move around the assembly and see what the displacement values are

03:08

or stress values. If you're presently displaying stress,

03:12

this is an effective way to interrogate your design.

Video transcript

00:04

Thermal analyses provide you with insights into energy transfer

00:07

heat can be applied in different ways and transported from

00:11

one place to another by radiation conduction and convection.

00:15

Using a thermal breaker assembly design,

00:18

we apply heat generating loads and heat transfer loads to

00:21

see if the design works effectively as a breaker.

00:26

This design is a strip of metal made up of two separate bodies

00:30

that is attached to a box at 85

00:33

°F.

00:34

The breaker loses heat to the environment but heats up when a current is applied

00:40

to analyze whether the design works effectively as a thermal

00:43

breaker switch to the simulation workspace and select thermal stress study

00:49

to set up the study first will review

00:51

the materials using the study materials command.

00:56

The design is modeled as two bodies both made of steel.

00:59

We can create a bimetal strip from this design by

01:02

changing the material of one of the bodies to brass,

01:05

brass and steel expand with temperature at different rates.

01:08

And the idea is that when the brass reaches a critical temperature,

01:12

it will lift the contact.

01:14

First,

01:14

we need to physically constrain the model with fixed

01:17

structural constraints in the holes for the rivets.

01:22

Now, we can begin to apply thermal loads,

01:25

set an applied temperature to account for the temperature being applied

01:28

to the breaker from the box to which it is secured,

01:32

select the same surfaces for the rivet holes and then

01:34

select the bottom face that is resting on the box.

01:38

The box has a surface temperature of 85

01:41

°F.

01:42

So we'll set the temperature to 85

01:44

°F.

01:47

Next,

01:47

apply convection heat load to the external faces of

01:50

the design that are losing heat to the environment.

01:54

Don't include any of the faces between the two bodies or

01:57

the bottom face that is resting on the 85 degree box

02:03

set, the convection value to 1000

02:06

and then set the ambient temperature to 85

02:09

°F

02:10

by simply adding the F for Fahrenheit to the value.

02:14

Now set the internal heat generated when current is applied

02:18

for this load, select both bodies set the value to 500 watts, then click OK.

02:25

Finally apply automatic contacts.

02:28

So the study knows that heat can be passed between the two bodies by conduction

02:32

to improve the solve accuracy. Set the absolute mesh size to 0.1 inches

02:39

precheck shows there are no issues with the set up. So now we can solve the analysis.

02:46

When the analysis is complete, we can check the results.

02:49

We can see the high degree of stress primarily between the two bodies

02:53

switching to displacement.

02:55

We can see the maximum displacement,

02:57

this displacement is enough to break contact and open the circuit.

03:02

Create a point probe,

03:03

move around the assembly and see what the displacement values are

03:08

or stress values. If you're presently displaying stress,

03:12

this is an effective way to interrogate your design.

For more, see Thermal Loads.

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Thermal stress

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Improve your experience – allows us to show you what is relevant to you

Customize your advertising – permits us to offer targeted advertising to you

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Your experience. Your choice.