Week - 3 Drop test Challenge

Student: Ryan Hoover

Coursework: LS-Dyna week 3 challenge – Cell Phone Drop Test

The objective of this challenge is to develop a complete LS-Dyna input deck, starting with only geometry of a simplified cell phone and an impact plate. The student must create all the needed cards for LS-Dyna to run a complete simulation that has reasonable qualitative value. The quantitative results of the simulation are not critical. The qualitative results and the visualization of the simulation are critical.

The provided Drop_Test_onlymesh.k LS-Dyna keyword input file was loaded into LS Pre-Post. Measurements confirmed the length dimension is in millimeters. A unit system of Newtons, millimeters, and seconds was chosen. An input deck was created to simulate the phone dropping onto the plate with an initial velocity of 1000 mm/sec downward. The plate is a 15 mm thick plate with arbitrary material properties. The plate was anchored at the 4 corners with XYZ translational constraints.

*SECTION_SHELL card was created with a thickness of 15 mm, section ID 1 was assigned.

*MAT_024 card was created with material ID 1. Parameters of density 8.05e-12, elasticity 2500, Poisson 0.3, Yield 300, and ETAN 1908.7 were assigned.

*PART card was created, ID 1 with name “Plate”. The plate nodes and elements were assigned to part 1. Material ID 1 and Section ID 1 were assigned to Part 1.

*SECTION_SOLID card was created with section ID 2.

*MAT_024 card was created with material ID 2. Parameters of density 1.5e-12, elasticity 2500, Poisson 0.3, Yield 300, and ETAN 1908.7 were assigned.

*PART card was created, ID 3 with name “Phone”. The phone nodes and elements were assigned to part 3. Material ID 2 and Section ID 2 were assigned to Part 3. I should have used 2 for the part ID, but I already had completed the input deck so I just left it as part 3.

*BOUNDARY_SPC_NODE card was created. Single point constraints were added to the four corner nodes of the plate, part ID 1. The constraints were applied in the 3 translation XYZ directions. No rotational constraints were applied.

*SET_NODE_LIST card was created. All nodes of the phone part were added to this set. Set ID 1.

*INITIAL_VELOCITY card was created. Node Set 1, the phone nodes, were assigned as to NSID parameter. -1000 was assigned to the VZ parameter. Al other parameters were left at 0.

*SET_SEGMENT card was created with ID 1 and name set_segment_phone. All nodes of the phone part were assigned to the set.

*SET_SEGMENT card was created with ID 2 and name set_segment_plate. All nodes of the plate part were assigned to the set.

*CONTACT_AUTOMATIC_SURFACE_TO_SURFACE card was created with ID1 and name phone_to_plate. The segment set ID1 (phone) was set as the slave and segment set ID2 (plate) was set as the master. All other parameters were left as default.

*CONTROL_TERMINATION card was created. The ENDTIM parameters was assigned 0.012 to have a total simulation time of 12 milliseconds. All other parameters were left as default.

The following ASCII Database cards were added. All cards were assigned with a value of 0.0001 to the DT parameter. 1 was assigned to the BINARY parameter for all cards.

*DATABASE_ELOUT, *DATABASE_GLSTAT, *DATABASE_MATSUM, *DATABASE_RCFORC

*DATABASE_BINARY_D3PLOT card was created. 5.0e-04 was assigned to the DT parameter. All other parameters were left as default.

The input deck was saved as PhoneDrop.k

The input deck was run in LS-Run

After running in LS-Run, the d3plot binary file was opened in LS-PrePost to visualize the simulation.

Figure 1 below shows the Von-Mises stress at the time of contact when the dropping phone impacts the plate. The stress contour shows a fringe scale of RED = 0.1766 MPa and BLUE approximately 0. The upper RED scale value is equivalent to 17.66 Newtons per square centimeter.

Figure 1 – Von-Mises stress contour at impact

Please see attached PDF that contains the plots in this answer.

Figure 2 below shows the vertical force at the interface of the phone and plate. The impulse is approximately 3 milliseconds long in duration, starting just after 7 milliseconds and stopping at 10 milliseconds. The peak force is near 150 Newtons.

Figure 2 – Impact Force

Please see attached PDF that contains the plots in this answer.

Figure 3 below shows the velocity of the phone. The initial velocity is 1000 mm/sec downward. The phone contacts the plate just after 7 milliseconds and bounces upward with very little loss in energy. After the impact, the phone is travelling upward at a velocity just under 1000 mm/sec.

Figure 3 – Phone Velocity in the Vertical Direction.

Please see attached PDF that contains the plots in this answer.

Figure 4 below shows the phone displacement. The phone travels just over 8 millimeters before bottoming out from the plate’s force reaction and then travels upward until the termination time of the simulation at 12 milliseconds.

Figure 4 – Phone Displacement in the Vertical Direction

Please see attached PDF that contains the plots in this answer.

The conclusion of the simulation is that the input deck was correctly developed and run in LS-Dyna with no errors. All required cards were created to run the simple phone drop simulation. The material parameters of density and elasticity were adjusted to create a simulation with good qualitative results.

END OF WEEK 3 CHALLENGE

Please see attached input deck PhoneDrop.k

Please see attached simulations results Week3.zip

THANK YOU!