Home / Examples / Stress Analysis [Galileo] / Example 33: Analysis of an Fallen Object

Example 33: Analysis of an Fallen Object

General

• An object consisting of a substrate and a frame falls onto the floor and bounces off. The transient analysis is performed.
   

• The deformation, the displacement distribution, and the stress distribution 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.

 

• The stress transient analysis is available in an optional package.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

Analysis Conditions

Item	Settings
Solver	Stress analysis [Galileo]
Analysis Type	Transient Analysis
Large deformation	Large Displacement
Options	Select [Acceleration].

 

The acceleration, the transient analysis, and the high-level setting tabs are set up as follows .

Tab	Setting Item	Settings
Acceleration	Acceleration	(X,Y,Z) = (0, 0, -9.8) [m/s2]
Transient analysis	Timestep	0.0005 [sec]
	Number of Calculation Steps	20
	Output Interval	1

Model

The object falls from the height of 1.5 [m].

The calculation begins when the object is positioned 0.001 [m] above the floor, with an initial velocity of -5.420369 [m/s].

The frame and the substrate are solid bodies. The floor is a rigid body.

 

 

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Mesh Size	Material Name
9/Solid	FRAME	10	001_Al *
10/Solid	SUB	5	008_Cu *
11/Solid	RIGID		Rigid

* Available from the Material DB

 

Material property of the rigid body is set up as follows.

Material Name	Tab	Settings
Rigid	Elasticity	Young's Modulus: 1.0e20 [Pa] Poisson's Ratio: 0.0
	Density	1000 [kg/m3]

 

Initial velocities are set in the body attributes.

Body Attribute Name	Tab	Settings
FRAME	Initial Velocity	(X,Y,Z) = (0, 0, -5.420369) [m/s]
SUB	Initial Velocity	(X,Y,Z) = (0, 0, -5.420369)[m/s]

Boundary Conditions

The bottom face of the frame makes a contact with the top face of the rigid floor.

The displacement of the rigid floor is set to zero, because it is fully fixed.

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Contactor/Face	Mechanical	Contact Surface	Contact Surface Classification: Contactor Surface
Target/Face	Mechanical	Contact surface	Contact Surface Classification: Contactee Surface
Fix/Face	Mechanical	Displacement	Select UX, UY, and UZ all. Set all components to zero.

 

* After setting the contact surface, go to the [Model] tab,
 

 

and click [Boundary Pair] . Pair "Contactor" and "Target" in the Boundary Pair dialog box.

Results

The general mesh size is set to 14.

The contour diagrams below show von Mises equivalent stress. Note that [Set Emphasizing Scale] is set to 10 on the Displacement Diagram tab of [Graphics Setup].

The rigid body is hidden.

 

The moment of the collision (t = 0.0002 [sec])

 

0.0001 sec after the collision (t = 0.0003 [sec])

 

0.0003 sec after the collision (t = 0.0005 [sec])

 

These diagrams show that the substrate deforms as time passes since the collision.