energy release in dent growth in a sandwich panel

[jongustav]

Hi !

I'm modelling a sandwich structure using one part which I have partioned into a core block and a face sheet. The core is elastic-perfect plastic and the face sheet with engineering constants. Initially I have a quarter circle without core support so to simulate a dent (using symmetry). So the subject is to compress the structure using displacement, now this is working properly , but ! I would like to get the energy realese rate at the advancing ''crack'' tip of the dent..
note: there is no bifurcation in this problem instead the dent is growing perpendicular as it starts to buckle due to compression, then the core is continuasly damaged due to the facesheet's out of plane buckling .. but how to get the energy realese rate without using advancing crack tip elements??

Any help on the subject is appreciated // Jon

 

[SWComposites]

Unless you use the new Abaqus VCCT elements, you have to set up duplicate nodes along the crack line and incementally open up the crack, and use the resulting forces and displacements at each step to get the strain energy release rate. There are many papers in the literature on VCCT methods for calculating strain energy release rate. Search for papers by T. K. O'Brien , also those by P. J. Minguet. Some referneces are given in this paper:

http://www.swcomposites.com/Papers/JCTR_Bonded_Joints_Paper.pdf

 

[jongustav]

Hi
Well the thing is that there is'n really a crack, so the vcct elements are not what I need,, see . since the core elements get crushed by the advancing facesheet buckle ´. But maybe the second alt. with duplicate nodes between the face and core sections would do it?
..To clearify : I don't have a crack , but an advancing dent front causing the core elements to get crushed... sort of a wave motion of an elastic beam..
ANy other suggestions?

 

[SWComposites]

So why do you want to calculate a SERR?

 

[jongustav]

cause, my supervisior has made a closed form criterion for dentgrowth in sandwichpanels and I want to numerically confirm the accuracy for a circular damage on o sandwichpanel. And the energy realese rate (Gc) is a very convenient way to describe the growth rate due to it's clos relation to just crack growth and delamination problems.
So there is a need to find the energy relesed at the advancing tip call it crushfront.. since the criterion Minguet has written does exclude the fact that te core that is crushed actually still supports the face so the energy needed to advance is actually larger than just supposing a hole without any support at all. So to say it is a design criteria which reestimates the compressive load .
//