Home / Examples / Stress Analysis [Galileo] / Example 47: Peel Off

Example 47: Contact Analysis with Peeling Taken into Account

General

Simple contact analysis is performed with peeling taken into account.
Two cubes are sandwiched by two plates. Both cubes are attached to the upper plate. The right cube is sticky and adheres to the lower plate. The left cube does not adhere to the lower plate at all. Their simple boundary conditions reflect the difference.
Unless specified in the list below, the default conditions will be applied.

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

Analysis Space

Item	Settings
Analysis Space	2D
Model Unit	mm

Analysis Conditions

Item	Settings
Solver	Stress Analysis [Galileo]
Analysis Type	Static Analysis
Options	Select thermal load

The Step/Thermal Load tab is set as follows.

Tab

Setting Item

Settings

Step/Thermal Load

Step Setting

Multi-step Thermal Load Analysis

Reference Temperature

25 [deg]

Step/Reached Temperature Setting

Step	Number of Substeps	Reached Temperature [deg]
1	1	50
2	1	0
3	1	-25

Model

Two cubes are sandwiched by two plates. Both cubes are attached to the upper plate. The top face of the upper plate and the bottom face of the lower plate are fixed.

The right cube is sticky and adheres to the lower plate. The left cube does not adhere to the lower plate at all. Their simple boundary conditions reflect the difference.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Sheet Body	Fixed_Plate	Plate
1/SheetBody	Fixed_Plate	Plate
2/SheetBody	Bond_Cube	Cube
3/SheetBody	Bond_Cube	Cube

The material properties are set as follows. The coefficient of linear thermal expansion is set only to Cube.

Material Name	Tab	Properties
Plate	Elasticity	Material Type: Elastic/Isotropic Young's Modulus: 1x109 [Pa] Poisson's Ratio: 0.3
Plate	Coefficient of Linear Thermal Expansion	0.0 [1/deg]
Cube	Elasticity	Material Type: Elastic/Isotropic Young's modulus: 1x109 [Pa] Poisson's Ratio: 0.3
Cube	Coefficient of Linear Thermal Expansion	10.0 [1/deg]

Boundary Conditions

The boundary conditions set on the bottoms of the two cubes are different. See the table below for details.

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Fix/Edge	Mechanical	Displacement	Select the X and Z components. UX=0, UZ=0
Auto_Dry/Edge	Mechanical	Simple contact	Simple Contact Classification : Automatic Judgment
			Automatic Judgment Setting : Coefficient of Friction : 0.0 Take into account peeling: Deselected
Auto_Sticky/Edge	Mechanical	Simple contact	Simple Contact Classification : Automatic Judgment
			Automatic Judgment Setting : Take into account peeling: Selected Peel Strength : 5x103 [Pa]

Results

The principal stresses and the displacement are shown below for each step. The scale factor for the displacement is 200.

< Step 1 / Reached temperature = 50 deg. >

Slip Bond

The cubes expand due to the temperature rise. Compressive stresses are generated inside the cubes.

The left cube slips on the lower plate and the right cube adheres to the lower plate.

The directions of the compressive principal stress differ and the deformations differ between the right and left.

< Step 2 / Reached temperature = 0 deg. >

Off contact Bond

The cubes contract due to the descent of the temperature. Tensile stresses are generated inside the cubes.

The left cube is off the lower plate. The right cube still adheres to the plate because the tensile stress on the boundary is less than the peel strength (5 [kPa]).

< Step 3 / Reached temperature = -25 deg. >

Off contact Off contact

Finally, the right cube is off the lower plate because the tensile stress exceeds the peel strength.