Dropped Test Simulation of a falling object including gravity
Dropped Test Simulation of a falling object including gravity
(OP)
Dear all,
I would like to ask if anyone can help me with an issue that I came in contact with.
I am trying to model an impact event of a dropped test and I would like to model the gravity as well. The simulation consists of an analytical rigid surface for the projectile including a reference point to apply the weight, velocity and gravity. The second part is a concrete beam (100x100x600) meshed using C3D8R elements .
The weight is 10.6 kg dropped in a free fall with an impact velocity of 4.43 m/s. I also have restrained the degrees of freedom on the bullet, except from the translation movement in the vertical direction.
I have defined three steps for the impact.
1st step: application of boundary conditions
2nd step: application of velocity
3rd step: application of weight x gravity using a load (also an amplitude was used).
The results do not seem to be realistic as I think something goes wrong with the definition of the steps. I am wondering if anyone can provide me with any help on this issue.
Many thanks to all,
StathiPol12
I would like to ask if anyone can help me with an issue that I came in contact with.
I am trying to model an impact event of a dropped test and I would like to model the gravity as well. The simulation consists of an analytical rigid surface for the projectile including a reference point to apply the weight, velocity and gravity. The second part is a concrete beam (100x100x600) meshed using C3D8R elements .
The weight is 10.6 kg dropped in a free fall with an impact velocity of 4.43 m/s. I also have restrained the degrees of freedom on the bullet, except from the translation movement in the vertical direction.
I have defined three steps for the impact.
1st step: application of boundary conditions
2nd step: application of velocity
3rd step: application of weight x gravity using a load (also an amplitude was used).
The results do not seem to be realistic as I think something goes wrong with the definition of the steps. I am wondering if anyone can provide me with any help on this issue.
Many thanks to all,
StathiPol12





RE: Dropped Test Simulation of a falling object including gravity
Why not using a initial velocity and starting the simulation right before the impact?
RE: Dropped Test Simulation of a falling object including gravity
I have attached an image for your convenience. I would like to simulate the gravity on the projectile so I guess this needs to be in a different step. The steps I followed are as follows:
I have applied an isotropic point mass thought the interaction step on the reference point on the projectile of 0.0106 tonne.
I have applied an initial velocity on the reference point, and then I would like to deactivate the initial velocity and leave the projectile to interact with the concrete surface. Is there any other way to model gravitational force?
Regards,
StathPol
RE: Dropped Test Simulation of a falling object including gravity
The initial velocity is a initial condition - not a BC. So it does no constraint anything during the simulation and just defines the starting situation.
RE: Dropped Test Simulation of a falling object including gravity
Thank you for your quick reply. As aforementioned, the calculated velocity is 4.43 m/s and was defined on the reference point as load x gravity during the second step. I also have defined a point mass to account for the inertial. In the step module, I defined the following:
Incrementation tab - Stable increment estimation - element by element
Time scaling factor - 0.9
It does not converge now as it aborts the analysis. The analysis is elastic analysis before I apply the plasticity values in the model.
Regards,
RE: Dropped Test Simulation of a falling object including gravity
Why does the analysis abort? What is written in the .msg or .sta?
Is your unit system consistent?
RE: Dropped Test Simulation of a falling object including gravity
Well, I had a small issue which I sorted out with the steps..Is there any way that we can create a separate short step to give the velocity and then the next step to suppress it? I will finish what I am doing and then attach the file.
http://www.eng-tips.com/viewthread.cfm?qid=269563
RE: Dropped Test Simulation of a falling object including gravity