Home / Examples / Coupled Analysis / Thermal-Stress Analysis [Watt/Galileo] / Example 3: Deformation due to the Temperature Gradient #3 - Multiple Materials

Example 3: Deformation due to the Temperature Gradient #3 - Multiple Materials

General

• A heating chip is placed on a substrate. Under the condition of heating by chip and cooling by natural convection,
  the temperature distribution is calculated the same as in Example 10, resulting in thermal expansion. Using the results, the stress is calculated in the stress analysis.
   

• The temperature distribution is calculated using the thermal analysis [Watt].
  The result is forwarded to the stress analysis [Galileo] as a thermal load corresponding to the reached temperature.
   

• The deformation, the displacement and the stress are solved.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')




• Results will vary depending on Femtet version and the PC environment.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

Analysis Conditions

Select Thermal analysis and Stress analysis.

Item	Settings
Solver	Thermal Analysis [Watt] Stress Analysis [Galileo]
Thermal-Analysis Type	Steady-State Analysis
Options	N/A *

* [Thermal Load] is selected by default for the thermal-stress coupled analysis.

 

The Step/Thermal Load tab is set as follows.

Tab	Setting Item	Settings
Step/Thermal Load *	Reference Temperature	25 [deg]

* The reached temperatures come from the thermal analysis.

Model

The same as Example 10 of thermal analysis.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Solid	SUB	006_Glass_epoxy *
1/Solid	GND	008_Cu *
2/Solid	MAINCHIP	001_Alumina *
3/Solid	SUBCHIP	001_Alumina *
4/Solid	HOLE	008_Cu *
5/Solid	HOLE	008_Cu *
6/Solid	HOLE	008_Cu *
7/Solid	HOLE	008_Cu *
8/Solid	HOLE	008_Cu *
9/Solid	HOLE	008_Cu *
10/Solid	HOLE	008_Cu *
11/Solid	HOLE	008_Cu *

* Available from the material DB

 

The heat quantities of MAINCHIP and SUBCHIP are set up as follows.

Body Attribute Name	Tab	Settings
MAINCHIP	Heat Quantity	0.2 [W]
SUBCHIP	Heat Quantity	0.1 [W]

Boundary Conditions

The coefficient of heat transfer for the natural convection is set on the bottom face of GND as follows:

The radiation from the top and the sides is omitted.

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Bottom/Face	Thermal	Heat Transfer/Convection	Natural convection *: 1.39 [W/m2/deg5/4] Room temperature: 25[deg]

 

* The coefficient for the natural convection is calculated as follows.

 

2.51×C×（1/L)＾（1/4） = 1.39 [W/m2/deg5/4]

where

C = 0.26

Size of the substrate : 0.06x0.04

L (Typical Length) = (0.06 x 0.04 x 2) / (0.06 + 0.04) = 0.048

Results

The temperature distribution as a result of Watt is shown below.

 

The next figure shows the vectors of displacement as a result of Galileo following Watt.

The substrate corners which shows the low temperature are bent downward.