Week - 3 Drop test Challenge

Mobile Drop Test on Rigid Surface

OBJECTIVE:  To run a drop test simulation of a mobile phone dropped on to a floor under initial velocity condition using LS-Dyna

PROCEDURE :

1. Start LS-PrePost and import the keyword file.

2.The imported keyword file contains 3 parts but for this particular simulation 2 parts can be used, i.e., skin or the sheet on top of rigid body is not required.

3. We need only one type of floor. Hence, we can delete the floor made of block elements and retain the floor plate made of shell elements. Delete it by going to parts option under the keyword manager.

4. Now go to the Parts option under the keyword manager button. The already present parts are not named properly. We will rename them as Phone and Floor respectively.

5. Now we need to assign proper materials and sections to the parts. The floor has to be modeled as a rigid part and the phone is to be modeled during an elastic material.

6. In this case, I chose Aluminum as the material for the phone. The material properties of aluminum were used to define the Aluminum material card and it was assigned to the phone part. While defining the material for the floor plate, the CMO (Centre of mass constraint option) was set as 1 to apply global constraints on the floor. Con1 and Con2 both were set as 7 in order to completely constrain the floor plate in space.

7. The next step is to define the section for the panel and phone. Since both are solids , SECTION_SOLID is used to define both materials.

8. Now that section and material is defined, the parts should be assigned with their respective section and material ID.

9. Now that we have completely defined the parts, we will move on to defining the boundary conditions. We have to assign an initial velocity to the phone in the negative Z direction. In order to do that we first need to create a node-set containing all the nodes of the phone. We can do it by either using the Create entity option or by going into the sets option under the keyword’s manager. After creating the node-set, assign an initial velocity to this node-set by using the velocity option under the Initial keyword in the Keywords manager.

10. Now we need to define contact between the Phone and the floor in order for the impact to occur. An automatic surface to surface contact is defined using the contact keyword under the keyword’s manager, keeping the floor as the master part and the phone as the slave.

11. Now apply boundary SPC condition for the base plate. This SPC (single point constraint) should be added using new entity and all the sides should be constrained.

12. The distance between the bottom edge of the phone and the floor plate is roughly 11 mm. With an initial velocity of 15.64 mm/ms, the impact will most likely happen after ~0.7ms. So, the termination time has to be greater than 0.7ms to capture the impact properly. Thus, we will define the termination time as 2ms.

13. Result requests

1. The result requests are made using the Database keyword.
2. Under the ASCII option, we will select the GLSTAT(global statistics), Matsum(Material energies), and RCFORC(Resultant Interface Forces). The Time interval between outputs(DT) is kept as 0.01 for all the results.

After all this are defined, save the keyword file. Now open LS-Dyna Manager and click on start LS_Dyna Analysis. Now import the saved keyword file and run the analysis. Now open LS-PrePost and open the binary D3plot file of the saved keyword file.

CONCLUSION:

1. The solver deck for the drop test was created from scratch.
2. The analysis ran successfully, giving the requested results