Learn how to run a dynamic analysis online by performing a drop-test to investigate the impact stresses and deformations induced on a pair of headphones that have been dropped from a height of 1.7 m using cloud-based FEA. Learn more about FEA with SimScale: https://www.simscale.com/ Watch the full webinar here: https://www.youtube.com/watch?v=KjWOzrnOiG8

1. DYNAMIC IMPACT ANALYSIS OF
STRUCTURES – ONLINE
DAVID SHORT

2. DAVID SHORT
Application Engineer
2+ years experience in CFD & FEA application
engineering. Coming from a marine
engineering background, he has knowledge of
both solid mechanics and fluid dynamics.

3. 1. Benefits of Using Simulation
2. Introduction to SimScale
3. Today’s Topic: Dynamic Impact
Analysis of Headphones
4. Live Demonstration
5. Results Summary
6. Q & A

7. ACCELERATE YOUR
DESIGN PROCESS
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9. STRUCTURAL ANALYSIS CAPABILITIES

10. Static load in a double girder
gantry crane.
FINITE ELEMENT ANALYSIS – STRUCTURAL SIMULATION TYPES
Cell phone crashing
onto the floor.
Airfoil’s warped displacement
field of the 8th eigenmode.
Static Dynamic Frequency

11. FINITE ELEMENT ANALYSIS – NONLINEARITIES
Geometric
Materials
Physical
Contacts
Large
Deformations
Plastic
Hyperelastic
Creep
Separating
Contacting

13. HEADPHONE DROP TEST
● Simulation of a pair of headphones dropped
from a 1.7 m height onto the ground
Question: Will the PVC component break or
deform?

14. HOW TO GET STARTED
1. CAD IMPORT
Upload your CAD model
or import it from other cloud
services into SimScale.
2. SIMULATION SETUP
All steps to define and run
a simulation are done
within SimScale.
3. DESIGN DECISION
Use simulation insights
to make better and faster
design decisions.

15. (https://giphy.com/gifs/simulation-impact-dvHG2fx4yHAe4)
DYNAMIC IMPACT ANALYSIS
Time-dependent simulation of colliding bodies
Workflow
1. Model device and impact object at a small
distance apart
2. Apply a physical contact between the device
and impact object
3. Calculate impact velocity to be applied as a
simulation initial condition
4. Run the dynamic FEA

16. SETUP

17. SETUP – TEST CONDITIONS
Test Scenario:
● Headphones dropped from 1.7 m height
● Impact velocity, Vi
Where:
■ A, acceleration= 9.81 m/s^2
■ X, distance= 1.7 m

18. SETUP – MODELLING APPROACH
1. Model only a small portion of the drop
2. Use time steps small enough to capture full
detail of the impact
a. Initial time steps can be calculated using the impact
velocity and the modelled gap distance. Time before
impact equals dist/Vi (0.018/5.775= 0.00312 [s]),
therefore 0.001 [s] is a sensible initial time step.
b. Use smaller time steps during impact. After 0.003
seconds has elapsed reduce time step size to 0.0001
[s].
3. Ensure simulation interval captures full
timespan of the impact and resulting force
peaks

20. RESULTS – ORIGINAL GEOMETRY
Two distinct pain
points in the PVC
component where
stresses are greater
than yield (55 Mpa)
Von Mises Stress [Pa]
Risk of large amounts of plastic deformation and possible breakage!

21. GEOMETRY MODIFICATION
Addition of mass at fragile elbow

22. RESULTS –MODIFIED GEOMETRY
● Lower stresses experienced at elbow where
geometry has been modified.
● Risk of failure at other points on the device,
meaning further design iterations should be
carried out to maximise the headphone’s
longevity.
Von Mises Stress [Pa]