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Example 72 Bending Analysis with Shell Elements


General

  • Using shell elements, a model with a large aspect ratio can be analyzed with fewer meshes.
     

  • 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 Conditions

 

Item

Settings

Solver

Stress Analysis [Galileo]

Analysis Space

3D

Analysis Type

Static Analysis

Unit

mm

Analysis Options

Select [Constrain the freedom of shells]

 

 

Model

To model a thin beam with sheet elements, create a sheet body, of which body attribute name is Beam, with a size of 10x1 mm, and specify 0.1 mm as the thickness of sheet body.

 

 

Body Attributes and Materials Setting

Body Number/Type

Body Attribute Name

Material Name

0/Sheet

Beam

Material Property_001 *

* To compare the results with theoretical calculations, a special case is considered in which Young's modulus and Poisson's ratio of the material properties are set to 200 GPa and 0, respectively.

Boundary Condition

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Settings

Fix/Edge

Mechanical

Displacement

Select all UX/UY/UZ components.

UX=0, UY=0, UZ=0

 

Unselect all RX/RY/RZ components.

Fix_z/Edge

Mechanical

Displacement

Select the UZ component

UZ=0

 

Unselect other boundaries

Tributary_Moment/Edge

Mechanical

Distributed Face Load

Select [Set the total load].

MX=0.001

Results

Below is the displacement diagram with contours of Z displacement.

 

 

 

Comparison with Theoretical Calculation

Compare the results with the theoretical calculation of the bending moment load problem below.

 

Below is shown the theoretical model replicating the analysis model.

 

 

The following table lists the values of the model variables for the theoretical solution.

The values are given to match the model dimensions, boundary conditions, body attributes, and material properties of the project file.

Item Symbol Value Unit
Moment Load M 0.001 N·m
Young's Modulus E 2e+11 Pa
Poisson's Ratio ν 0 -
Length of beam L 0.01 m
Width of beam b 0.001 m
Thickness of beam h 0.0001 m

 

 

Below are formulas that give the second moment of a section in the bending load applied direction

and the bending displacement, z, at the position, y.

Noted that gravity is not taken into account.

 

 

 

 

The result of the comparison between the calculated result from the equations above and the analysis result of Example 72 is shown below.