RD-T: 3597 Cell Phone Drop Test

This tutorial demonstrates how to simulate a free fall of a cell phone due to gravity from a height of 1001mm using 2nd order tetra elements.

Model Description

UNITS: Length (mm), Time (s), Mass (ton), Force (N) and Stress (MPa)
Simulation time: in Engine [0 - 3.3e^-3]
This is a very simple cell phone model used to demonstrate how to set up a drop test. The model is an assembly of two solid parts meshed with Tetra 10 elements, connected with spring elements, and contact defined between them.
To reduce the simulation time, the cell phone is dropped 1 mm from the ground with an initial velocity of -4429.4469 mm/s representing the velocity that it would have attained from a free fall of 1000 mm.
Boundary Conditions: Gravity load + initial velocity of -4429.4469 mm/s on the cell phone.
Elasto-plastic Material /MAT/LAW36 (Plastic)

[Rho_I] Initial density = 1.16E^-9 ton/mm³

[nu] Poisson's ratio = 0.3

[E] Young's modulus = 1000 MPa

STRAIN	0	16
STRESS	1	17

Load the Radioss User Profile

Launch HyperWorks Desktop.
From the Preferences menu, select User Profiles or click the icon in toolbar.
Select Radioss (Block140) and click OK.

Open the Model File

Click the Open Model icon to open the cellphone.hm file you saved to your working directory from the radioss.zip file.
Click Open.
The model loads into the modeling window.

Create the Curve Material

Click XYPlots > Curve Editor.
In the Curve editor window, click New.
For the curve name, enter stress_strain_curve.
Click proceed.
From the Curve editor window, select stress_strain_curve from the Curve List.
Enter the X and Y coordinates, as shown below.

Figure 2.
Click Update and then click Close.

Create and Assign the Material and Properties for Cell Phone Parts

In the Model Browser, right-click and select Create > Material to create a new material.
For Name, enter cell_phone.
For Card Image, select M36_PLAS_TAB and click Yes in the confirmation window.
Input the values, as shown below.

Figure 3.
Select N_func and set to 1.
Click fct_ID1 and select stress_strain_curve (the function curve previously created).
In the Model Browser, right-click and select Create > Property to create a property.
For Name, enter cell_phone.
For Card Image, select P14_SOLID and click Yes to confirm.
Set the variable I_tetra to a value of 1.

Figure 4.
In the Model Browser, expand the Components folder, highlight the components Cellphone_bottom and Cellphone_top and right-click to Assign (or use the Entity Editor) the newly created property and material.

Create the Property for Spring Links

In the Model Browser, right-click and select Create > Property to create a new property.
For Name, enter spring.
Set Card Image to P13_SPR_BEAM and click Yes to confirm.
Enter the following values:

Mass (MASS)

2e-6

Inertia (Inertia)

2e-4 mm⁴

Translation stiffness (K_Tensn, K_ShrY, and K_ShrZ)

50

Rotation stiffness (K_Tor, K_FlxY, and K_FlxZ)

100 N
Click return to return to Component panel.
In the Model Browser, select the component Connection_springs and right-click Assign to assign the newly created property to the spring component.

Define the Interface between Cell Phone Parts

In the Model Browser, right-click and select Create > Contact Surface.
For Name, enter self.
Click on Elements.
Switch from add shell elements to add solid faces.
Select elements by collector, select Cellphone_bottom and click select.
For face nodes, select nodes by collector, select cellphone bottom and click select > add > return.
In the Model Browser, right-click and select Create > Contact.
For Name, enter Self.
Set Card Image to TYPE7 and click Yes to confirm.
For Grnod_id (S), select nodes > by collector, select Cellphone_top, click select > add and click return.
For Surf_id (M), switch to Contactsurf, click on Contactsurf and select self.
Click OK.
Set Fric to 0.1.
Set Gapmin to 0.3.

Figure 5.

Figure 6.

Create a Rigid Wall

In the Model Browser, right-click and select Create > Rigid Wall.
For Name, enter GROUND.
Set the Geometry type to Infinite plane.
Click in the modeling window and press the F8 key on the keyboard.
Enter the node coordinates: X=0, Y=0, and Z=19.
Click create.
Click return to exit the panel.
In the Entity Editor, select the created node as Base node.
Make sure the normal vector is set to z-axis, as shown below.

Figure 7.
For d, enter 50.
To review, go to the Solver Browser and select the RWALL folder.
Right-click on GROUND and click Review.

Figure 8.
Click return to exit from the panel.

Create a Gravity Load

In the Model Browser, right-click and select Create > Set.
For Name, enter Gravity, set Card Image as GRNOD and click Yes to confirm.
Select Nodes of all three parts.
In the Model Browser, right-click and select Create > Load Collector.
For Name, enter loadcol1, set Card Image as GRAV_Collector and click Yes to confirm.
Set Direction to Z.
For Grnod_id, select Gravity from the Select Set dialog and click OK.
Set scale_y to -9810.0 indicating gravity in opposite Z direction.

Figure 9.
From the XYPlots pull-down, click Curve Editor.
In the Curve editor window, click New.
For Name, enter gravity.
Click proceed.
In the Curve editor window, select gravity from the Curve List.
Enter X and Y, as shown in the following image:

Figure 10.
Click Update and then click Close to exit the Curve editor window.
Back in Gravity load collector, update Ifunc to the curve just created.

Create an Initial Velocity

In the Model Browser, right-click and select Create > Load Collector.
For Name, enter Initial_velocity and set Card Image to INIVEL_Collector.
For Grnod_id, select the same set (Gravity) previously used.
For Vz =, enter the value -4429.4469.

Figure 11.

Create Output Request and Control Cards

Launch the HyperMesh Solver Browser from View > Browsers > HyperMesh > Solver.

Right-click in the Solver Browser general area to create the cards, shown below with the given values for each parameter:

Keyword Type	Keyword	Parameter	Parameter Value
CONTROL CARDS	TITLE	`Status`	[Checked]
CONTROL CARDS	TITLE	`TITLE`	Cellphone_drop
CONTROL CARDS	MEMORY	`Status`	[Checked
CONTROL CARDS	MEMORY	`NMOTS`	40000 Not needed
CONTROL CARDS	SPMD	`Status`	[Checked]
CONTROL CARDS	IOFLAG	`Status`	[Checked]
CONTROL CARDS	ANALY	`Status`	[Checked]
ALE-CFD-SPH	ALE_CFD_SPH_CARD	`Status`	[Checked]
ALE-CFD-SPH	ALE_CFD_SPH_CARD	`ALE_Grid_Velocity`	[Checked]
ALE-CFD-SPH	ALE_CFD_SPH_CARD	`GridVel_Gamma`	100.00
ENGINE KEYWORDS	RUN	`Status`	[Checked]
ENGINE KEYWORDS	RUN	`Tstop`	3e-3
ENGINE KEYWORDS	PARITH	`Status`	[Checked]
ENGINE KEYWORDS	PARITH	`Keyword2`	ON
ENGINE KEYWORDS	PRINT	`Status`	[Checked]
ENGINE KEYWORDS	PRINT	`N_Print`	-1000
ENGINE KEYWORDS	ANIM/ELEM	`Status`	[Checked]
ENGINE KEYWORDS	ANIM/ELEM	`VONM`	[Checked]
ENGINE KEYWORDS	ANIM/ELEM	`DENS`	[Checked]
ENGINE KEYWORDS	ANIM/ELEM	`PRES`	[Checked]
ENGINE KEYWORDS	ANIM/ELEM	`EPSP`	[Checked]
ENGINE KEYWORDS	ANIM/VECT	`Status`	[Checked]
ENGINE KEYWORDS	ANIM/VECT	`CONT`	[Checked]
ENGINE KEYWORDS	ANIM/DT	`Status`	[Checked]
ENGINE KEYWORDS	ANIM/DT	`Tstart`	0.0
ENGINE KEYWORDS	ANIM/DT	`Tfreq`	2e-4
ENGINE KEYWORDS	DT	`Status`	[Checked]
ENGINE KEYWORDS	DT	`Tscale`	0.0
ENGINE KEYWORDS	DT	`Tmin`	0.0

Export the Model

Click File > Export or click the Export icon .
Click the folder icon and navigate to the destination directory where you want to export to.
For Name, enter Cellphone and click Save.
Click the downward-pointing arrows next to Export options to expand the panel.
Select Merge starter and engine file to export both the Starter and Engine file in one file.
Click Export to export the file.

Run the Model in the Solver

Go to Start > Programs > HyperWorks 2019 > Radioss.
For Input file, browse to the exercise folder and select the file cellphone_0000.rad.
Click Run.

Expected Results

Review the listing files for this run and verify on the results. See if there are any warnings or errors in the .out files. Using HyperView, plot the strain and stress contour.