CTETRA Error - in Lattice Component
Altair EmployeeHi,
I am getting ''CTETRA element 4821 is distorted (zero or negative Jacobian).'' this error in my analysis. In my lattice component i used tetra with 0.5 element size and each unit cell of my component is 1mm x 1mm x 1mm so the whole component size is 10mm x 1mm x 1mm . How the error can be rectified and I tried the same approach for single solid beam there I didnt get any error. I dont know if its because of lattice or I have to change any mesh size ?, I turned off PARAM , CHECKELM to NO but that doesnt help me and for combining the each unit cell into single one i used Geo-> Solid Edit-> Boolean ( A+B) will this be a problem ? since I tried without combining there was no error but the analysis showed only on one unit cell, So where the problem is any help from experts would be nice . Thanks
PS : I have attached my model with BCs for your reference .
Kind Regards,
Muthu
Answers
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Hi Muthu,
Few solid elements have almost zero volume which is not allowed. Suggest to remesh those elements and try again.0 -
Hallo @Prakash Pagadala How can I eliminate the zero volume for elements problem, If I decrease the mesh size that is no of elements will be more that will make the problem clear or any other method to clear up . Can you suggest . Thank you .
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Kind Regards,
Muthu.
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Zero volume means the element is flat (tria) but with four nodes which is not a valid solid element. You can identify the element and move the nodes to give it some volume.
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@Prakash Pagadala Hi Prakash that issue is solved and also the simulation is working but in Hyperview for my loadcase it consider only on that unitcell in which i applied. It is not considering like whole model. Should I have to combine all the induvidual unitcells ? How can I resolve this problem i attached hm file of lattice model and both of the picture. First one has the error and like 2nd picture I have to simulate which is solid beam where both ends are constrained . My question is why the lattice beam model doesnt resemble like my solid beam in result . Thanks in advance .
Regards,
Muthu.
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Hi,
Yes, else load will not transfer to the rest of the structure.
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Hi @Prakash Pagadala ,
Thanks for your reply , Yes this sounds good that I have to combine all the unit cell into a single structure ( like the way we applied loads for solid structure) But I have tried Geometry-> Solid Edit -> Boolean ( Union A+B) to combine each unit cell to single component , this didnt work (this leads to get me the zero volume element error ). Could you help me how I can able to combine those single unit cells into a complete structure so that I can apply the loads to transfer to the rest of the structure. Thank you so much for your effort to help with
Kind Regards,
Muthu.
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You need to choose element size based on the geometry as I can see the side length of the structure is 1 and you are using a element length more than that.
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@Prakash Pagadala Sorry, In this model I chose element size as 0.5 in this model(I am sure), not exceeding 1 since I know the length of the side is 1. But how I can able to combine each unit cells into single combined structure to apply loads.
Kind Regards,
Muthu
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Try advanced boolean option and mesh with proximity ON in volume tetra and check if this helps.
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@Prakash Pagadala Hi Mr.Prakash, As you said I have tried advance boolean operations to combine ( I selected A^B - Del common parts in between) with that I have combine each single unit cells in to one another. But when i simulate it says I am getting ''CTETRA element 4821 is distorted (zero or negative Jacobian)'' , But only when I use boolean operations this error comes, if I dont use then for result it takes only the unit cell which we applied the force like the way I told before with pictures. Is there any other way to solve this issue. Because I have to do linear analysis with whole component as 10mm x 10mm x 10mm the lattice beam which i showed is just 1 row in the whole component. So this problem has to be gone in order to proceed further. Anticipating you response .Thanks
Kind Regards,
Muthu.
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@Prakash Pagadala Hi Mr.Prakash , thank you for the effort you took to reply my questions. that was helpful and i resolved the issue that i am gone through. Hope you having a good day today
Kind Regards,
Muthu.
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