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Crushable Foam Model - ERR: the ratio of deformation speed to wave speed exceeds 1

Crushable Foam Model - ERR: the ratio of deformation speed to wave speed exceeds 1

Crushable Foam Model - ERR: the ratio of deformation speed to wave speed exceeds 1

(OP)
Hi all,

I am in the process of modelling a helmet impact (EPS foam helmet) onto a rigid surface. The way I have gone about this is defining a discrete rigid surface, foam helmet (crushable foam material) and a discrete rigid (shell) headform. In the assembly I have assigned a predefined velocity field to the head and the headform (what I have done is VERY similar to this http://129.97.46.200:2080/v6.14/books/gsk/default....).

The problem is, when the job is submitted it works perfectly until the headform seemingly crushes the helmet completely flat. At this stage, the job aborts and gives the above ERR message. The material properties I have used for the foam is the same as that found in the link provided in the previous paragraph.

Thank you all for your help, if you need anything clarified please let me know!

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