Week - 3 Drop test Challenge

OBJECTIVE:

To create an input file for the drop test assigning required keywords and run the simulation to study the output data obtained.

INPUT MODEL:

Simplified FE model of a cellphone and floor

PROCEDURE:

• MEASURE the approximate distance between the FE parts.
• The obtained distance is 19.8mm.

• Remove the ELEMENT_SHELL from the Keyword Manager as it is not required for the simulation.

• The ELEMENT_SOLID part of the model is kept with ELFORM=1.

• Assign separate PART for the phone elements along with SECID and MID.

• Create new Section keyword for the phone elements.
• Create new Material keyword (MAT_024) for the phone elements by inputting properties of Aluminium alloy as phone material.

• Assign separate PART for the floor elements along with SECID and MID.

• Create new Section keyword for the phone elements.
• Create new Material keyword (MAT_020) for the floor elements by inputting properties of Concrete as floor material.

• Create new Entity_Boundary_Spc to constraint the floor part in all directions.

• Create new Entity_Set_Node as phone and foor.

• Create new INITIAL_VELOCITY keyword for the phone elements by inputting the velocity value as -10mm/ms along Z-axis (appropriate sign to move the phone perpendicular to the floor).

• Create new Entity_Set_SEGM as phone and foor.

• Create new CONTACT_AUTOMATIC_SURFACE_TO_SURFACE keyword and assign the slave and master nodes as phone and floor elements respectively and MSTYP-SSTYP as 3(PART).

• Create new CONTROL_TERMINATION keyword to assign simulation runtime as 5ms.

• Create new DATABASE_ASCII keyword and DATABASE_BINARY_D3PLOT keyword to get output data from the simulation run at every 0.1ms interval.

RESULT:

• The maximum stress (Von Mises) obtained during the simulation is 144.9MPa.

• The Global kinetic energy which is based on the initial velocity of the phone is 7.42 Joules.
• K.E. drastically reduces at the instant of impact around 1.9 ms and the impact energy is transferred back as rebound energy with slightly reduced value.

• Therefore the Total energy of the system which is K.E. has been reduced after the impact as shown below.

• The resultant force experienced during the impact is almost 25 kN at 2.2 ms.

• The simulation was done to roughly mimics a cellphone drop on the floor.
• The values obtained for stress is within 270 MPa of yield strength for Aluminium based alloys.