Week - 3 Drop test Challenge

Drop Test of Smartphone in LD-DYNA

AIM: - To Create the Solver Input Deck for the Drop Test of a Smartphone.

Objective: - The main objective of this challenge is to create the solver input deck for the drop test of a smartphone.

Procedure: -

• Here first need to import the given meshed model into the LS Prepost.
• For that, Open LD-Dyna - File - Open - Browse for the drop test mesh.k model - Open. This will open the mesh model for the drop test in the LS Prepost.
• Image 1: Imported given model
• Here, we can see that the model of smartphone which is solid meshed model and a two meshes for mimicking the ground, one is solid mesh and the other one is shell meshed.
• But, for the simulation we will be taking only the solid mesh.
• Image 2: Imported already meshed model
• Title of this project is given by using title card.
• Image 3: Keyword manager to insert title
• NODESET id created on the mobile phone part to assign the velocity at the point of impact.
• Image 4: Set Node List card
• Here, we need to create a section for Section Solid. we need to define section for phone as well as rigid floor.
• Model - Keyword - Section - Solid - Accept - Done.
• Image 5: Section - Solid card
• To define part id's Model - Keyword Manager - Assign Part - Assign PID and SECID - Accept - Done.
• This way we can create the part set for both the Floor and Phone.
• Image 6: Part id card
• Nodes has been selected by using model - Keyword Manager - Node card - Select particular part - Accept - Done.
• Image 7: Node id card
• We need to create the material like phone will be the elastic material and floor will be the rigid material.
• Aluminium material has been chosen for phone material.
• Material card is created by using Model - Select Keyword - Choose MAT Keyword - Open MAT (001) card - select the phone - Input the values of Density (Rho), E, Etan and Poison's Ratio (PR) in that card - Accept - Done.
• Image 8: Elastic (001) material card for phone
• Here, in this challenge we have consider cement material for the floor to make it rigid floor.
• Material card is created by using Model - Select Keyword - Choose MAT Keyword - Open MAT (020) card - select the phone - Input the values of Density (Rho), E, Etan and Poison's Ratio (PR) in that card - Accept - Done.
• Image 9: Rigid (020) material card for floor
• In LS-DYNA there is no unit system, so in this project we have used unit system of kg, mm, ms ....... etc.
• Initial velocity has been assigned by using Initial - Velocity - Assign the Node Set Id - Give the Velocity as - the velocity is in negative z axis - Accept - Done.
• Image 10: Initial velocity card
• Then open the Initial - Velocity - Assign the NSID - Give Velocity in Z axis - Apply - Done.
• Image 11: Element - Solid card
• Similarly, we can request for contact force (RCFORC), MATSUM, ELOUT etc in the database ASCII option card.
• Image 12: Database - ASCII option card
• Since, we need to generate the plot of the energies of the simulation we need to request for it using the GLSTAT in Database ASCII keyword and set the DT which is the time interval in which the points on the plots are plotted.
• Image 13: Database - Binary_D3PLOT card
• Then we need to set control termination card, for that Model - Keyword Manager - Control - Termination - Set the total time of run as 20 ms.
• Image 14: Control - Termination card
• Then we need to give the contact and also, we need to apply the velocity to the whole phone model.
• In the contact creation we need to make the Contact - Automatic - Surface - to - Surface.
• For making this contact we need to have a PART SET we can use Model - Create Entity - Set Date - Set Part - Apply.
• Image 15: Contact - Automatic_Surface_To_Surface card
• In this challenge Phone is chosen as slave id and Floor has been chosen as a master id. Because floor has a higher stiffness value than the phone material.
• We need to create a single point constraint SPC on the ground.
• for that Create entity - Boundary - SPC - Pick the nodes at the opposite edge of the ground mesh elements - Apply.
• This will create a NODE SET with those selected nodes.
• Image 16: Boundary_SPC_SET card
• Similarly, to obtain the animation of the simulation we can request for Database - Binary - d3plot - set the time interval which means in every 1 ms the simulation is recorded.
• Then, we need to save the file with the .k extension which is the keyword file extension for the LS-DYNA.
• Then we need to open the LS-DYNA program manager and open the keyword file in that and then select run.
• This will run the problems and the results can be post processed in LS-Prepost.

Results =

• Open new LS Prepost - File - Open Binary Plot - Select the d3plot file of drop test - open. This will show up the simulation in the LS Prepost.
• Select Fringe component tool on side tool bar - Select stress - Choose Von Mises Stress - Apply.
• This will show the Von Mises Stresses stress contour of the simulation.
• Image 17: Effective Stress Distribution
• We need to choose the ASCII plot tool on side tool bar - Choose GLSTST or MATSUM - Load the respective file - Choose the Energies we need to plot - choose the part - select plot.
• Image 18: Von Mises Stress Distribution in the Phone at the time of impact.
• Image 19: Total energy plot for the phone
• The above graph plotted total energy vs the time.
• Image 20: Internal energy plot for the phone
• The above graph plotted Internal energy vs the time.
• Image 21: Kinetic energy plot for phone
• The above graph plotted kinetic energy vs the time of the simulation.

Conclusion: -

• Thus the drop test of the Cell phone failing on a rigid floor has been simulated and results have been discussed. From the challenge I learned about the process of setting up the solver deck for the drop test of the mobile phone.