Week - 3 Drop test Challenge

Objective - To perform a Drop Test of a phone and check how the impact effects the overall design and if stresses are within limits.

Changes made to the model -

• Unit system followed - tonne mm s
• Solid elements created for Ground deleted instead of shell elements to keep less node count.
• Shell and Solid sections with ELFORM=2 were created and assigned to respective bodies. Also a thickness of 2 mm was assigned to Ground shell elements.
• MAT20 (Rigid) is used for Ground with properties of Steel and was assigned to Part.
• MAT24(Piecewise Linear Plasticity) material is used for Phone with properties of steel and was assigned to Part.
• Contact Interface was created b/w Phone and Ground –Automatic Surface to Surface with friction coefficient as 0.2 and Slave nodes were selected for Phone and Master Nodes were selected for Ground.
• Initial Velocity is created and all nodes of phone is selected and value of gravity is given.
• SPC set is created to constrain boundary nodes of Ground in all DOFs.
• Control Termination card is created and an end time of 4 ms is given.
• Outputs requested – Binary_D3Plot, Under ASCII GLSTAT,MATSUM,NODOUT is requested at every 0.2 ms.
• Run results -

  Total No. of Cycles	Simulation Time (s)
  8311	10

Von-Mises Stress Plot (MPa) -

Max Von-Mises stress = 156.539 MPa observed at side edges of the Phone after impact.

Total, Internal & Kinetic Energy -

Max Total Energy (J)	Max Internal Energy (J)	Max Kinetic Energy (J)
41.8	41.5	30.5

• Change in Kinetic Energy is observed as soon as the phone touches the ground. After impact there is a change in velocity and hence the curve shows a steep decline.
• If the analysis continues for some more time whole of Kinetic energy would convert to Internal Energy.

Conclusion -

• Since Yield limit of material considered is 250 MPa and max Von-Mises stress observed is lesser than that it could be concluded that the phone could survive such a fall for the given material.