Learning Forum

[alicemariapiccirillo]

Hello to every one,

I am trying to set up a simulation in autodyn in which I should represent a hypervelocity impact of a particle over an aluminum layer.

The particle is about 0,1 mm with a speed of 1km/s and the layer is thin 0,5 mm.

I am would use SPH discretization because it is what best fit with HVI phenomena simulation, but I am encountering a lot of problems. 

The simulations stop every time, after some microseconds, with the error "time step too small" or "degenerate cells".

Can someone give me some advice on the appropriate parameter setting for this type of simulation?

[jamiestenhouse]

Hi Alice,

I realise I am a bit late posting, but I am currently undertaking a similar HVI project in AUTODYN so thought I'd share what I've learned in case it helped.

Have you calculated a suitable end time for your model? (distance/velocity=time) I took distance as the plate thickness + 2 or 3 times the particle diameter (my particle geometry 'touches' the plate at time = 0 to save unnecessary simulation time through empty space.

Have you checked that global erosion has been unchecked? (I don't think erosion settings are necessary for SPH)

Are you completing your model in 2D or 3D? What material, strength and failure models have you used?

Thanks

Jamie

[alicemariapiccirillo]

Hi Jamie,

 

Thank you for your reply.

 

Yes, I have considered almost 1ms as the final time for the computation, and I have unchecked the global erosion.

 

My model is in 3D, the plate is in aluminum 6061 and the projectile in aluminum 2023 T. The material models used for the two different Aluminum are a Mie-Gruneisen ("Shock") equation of state and Steinberg-Guinan strength model.

 

I did a trade-off in these two months and I have found a number of sph particles that allows me to get some results in a considerable amount of time (2/3 days).

 

If you have other tips for my problem, I would be happy to listen to it.

 

Thanks 

Alice

[Conorryan98]

Hello,nnI am currently about to start a project using ANSYS Autodyn to simulate a HVI into a brittle material. Unfortunately I have never used Ansys before.nnDo you know of any good resources/tips/advise so that I can start to learn how to use the software?.Many thanks,nnConor n

[ramgopisetti]

Well Multiple Responses make it Difficult to work out, ok I am followign the order of posting. n1) SPH is the best way to simulate Material failure, but it need better formulation to capture the deformation at such speeds, generally use MLS or default type.In general, use LSDYNA SPH section to impliment your model as it is more stable in my expereince. Usign the body Interactions ( nodes to surface) -> frictional is recommended. nGenerally, HVI problems needs control on the time step and its factor, try using 0.85 and keep the stef size to be small to capture the interaction. Always use some kind of erosion criteria like EPS or (D1,D2,D3,D4) to simulate the damage. Use JH1,JH2 or JC(4D) models for brittle-> Papers are best source for these model. Smaller the prticel size better the results as with the Mesh convergence. Try these and comment down for futher support. nCheers, nRamnn