A STUDY OF MECHANICAL ROBUSTNESS OF PORTABLE ELECTRONIC DEVICE SUBJECTED TO MECHANICAL DROP

Mechanical drop is one of the main factors which cause damage to electronic
devices especially to mobile phone. The effect of mechanical drop has caused electronic
and material failure to mobile phones. The objectives of this project are to conduct
simulation and physical drop tests in order to analyze the mechanical drop effects on the
mobile phone. The constraints are the physical drop tests are high cost and the results can
only be analyzed by visual inspection. The cost constraint has caused a limitation to only
two drop test specimens which are two function-able mobile phones model Nokia 3310.
The methodology of this project is to set up a drop test plan based on the ASTM Standard
(D 5276-98), followed by conducting physical and simulation drop testing. One drop
specimen is used for each type of drop: Flat Drop and Edge Drop. Both drops are static
free fall from a height of l.Om onto a concrete impact surface. Additional multiple
dummy drops are conducted by using a dummy phone to obtain a more consistent drop
procedure. This is because the drop specimens are allowed to be dropped once to prevent
cumulative drop impact damage from affecting the results. The physical drop tests are
recorded using a video camera and the video is split into multiple images using software.
The physical drop tests show that edge drop sustains higher impact energy which causes
material failure. As for simulation drop test, a solid model of the mobile phone is done
using 3D Laser Digitizer and CATIA but the modeling file could not be open in ANSYS.
Instead, a PDA ANSYS model is used as a replacement for the mobile phone model. The
PDA model is then assigned elements and materials properties for the simulation drop
test using the ANSYS LS-DYNA Drop Test Module (DTM). There were several
problems occurred during the simulation which prevents it from completing. As a
conclusion, all the objectives set are met except for the simulation drop test which is still
under troubleshooting.