Example51 Deformation of Viscoelastic Bar

General

  • The model is a bar made of viscoelastic plastic, polystyrene. It is forced to bend.
     

  • It is subjected to the temperature change below and over the glass transition temperature.
     

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

  •  

 

Analysis Space

Item

Settings

Analysis Space

3D

Model unit

mm

 

Analysis Conditions

It is subjected to the temperature change below and over the glass transition temperature.

Select “Thermal load” and “Step analysis”

 

Item

Settings

Solvers

Mechanical 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

Time Setting

Set up

Reference temperature

25[deg]

Step/Reached Temperature Setting

Step

Time [s]

Substeps

Reached temperature [deg]

1

60

5

25

2

3540

5

25

3

3600

5

25

4

3660

5

120

5

3720

5

120

6

7200

5

120

7

7260

5

120

 

Options for the Multi-Step Analysis

Save the results of substeps : Select

 

The reference temperature (non-stress temperature) is 25[deg]

Select [Multi-step thermal analysis] for the Step Setting, [Set up] for the Time Setting.
Also, set up in the [Step/Reached Temperature Setting].

 

Each step below consists of 5 substeps.

 

Step 1 : 60[s] : The load is increased gradually for 1 minute.

Step 2 : 3540[s] : The load is sustained for almost 1 hour.

Step 3 : 3600[s] : The load is decreased gradually for 1 minute.

Step 4 : 3660[s] : The temperature is increased to 120[deg] in 1 minute.

Step 5 : 3720[s] : The load is increased gradually for 1 minute.

Step 6 : 7200[s] : The load is sustained for almost 1 hour.

Step 7 : 7260[s] : The load is decreased gradually for 1 minute.

 

Save results of substeps is selected by default to output all the results at substeps.

Model

A rectangle polystyrene plate is 0.4[mm] thick.

 

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

0/Solid

Plate

PS

 

The material properties for PS are set up as follows:

Material Name

Tab

Properties

PS

Elasticity

Material Type: Elastic/Isotropic

Temperature Dependency: N/A

Material Property:

Young’s modulus: 1.39×10^9[Pa]

Poisson’s ratio: 0.35

Viscoelasticity

Defined by Prony series [coefficient input]

Relaxation Component: Shear only

Relaxation Table:

 

Temperature Dependency and Shift Function: WLF

Reference temperature: 113[deg]

C1: 8.86

C2: 101.6

 

Coefficient of Expansion

0x10^-6[1/deg]

Boundary Conditions

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Settings

Fix_all/Face

Mechanical

Displacement

Select all X/Y/Z components.

UX=0, UY=0, UZ=0

Pz/Edge

Mechanical

Distributed edge load

Select “Set the total load”.

X=0, Y=0, Z=-1.0×10^-2

 

Select “Time dependency” and set “Weight function” as follows.

This setting means the following.

60[s] : The load is increased gradually for 1 minute.

3540[s] : The load is sustained for almost 1 hour.

3600[s] : The load is decreased gradually for 1 minute.

3720[s] : The load is increased gradually for 1 minute.

7200[s] : The load is sustained for almost 1 hour.

7260[s] : The load is decreased gradually for 1 minute.

Results

The deformations at 3540[sec] and 7200[sec] are shown below.

The contour indicates the displacement.

The contour diagram shows the displacement.

 

Deformation at 3540[s]. Temperature is 25[deg].

 

Deformation at 7200[s]. Temperature is 120[deg].

 

The deformation is larger at 120[deg], even though the mechanical load is the same as that of 25[deg].

The graph below shows the displacement of the plate tip.

 

 

The displacement is constant at 20[deg].

If unloaded, it returns to the original state.

The displacement increases at 120[deg] even though the load is constant.

If unloaded, it doesn’t return to the original state.