Theanalyst
Automotive
Hello guys, I have a question about analyzing the diaphragm stresses induced in a peice of sheet metal. Here is the model problem:
If you can imagine the lid of a tupper ware box, and imagine that the outer circumference is like a surface, flat, with a small radial thickness to it, take another similar lid, put it against this one, and weld the outer surfaces together. This would form an enclosed volume in the middle, which is compressible. Now, let us assume there is pressure acting all around the outside of this trapped volume, for convenience sake, lets name it an empty biscuit.
Since this was made out of standard steel sheet metal, and when the centers of this buscuit are compressed together due to pressure outside, we have stresses induced on the weld joints, and also in the sheet metal portion. Since the compression in the center is exceeding half the thickness of the sheet metal, this is a non linear, large strain problem. The stresses induced in the sheet metal, after a point, would jump over to diaphragm stresses, i.e., stresses along the sheet metal surface stretching the marterial, and that is something I dont know if my linear static solver can capture, because it seems like the stress state is considerably different. But, this is all I have, and my question is how do I get close to those stress states with shell elements, linear static stress solver, and standard generic isotropic steel material properties, like E and poisson's ratio.
I dont have any non linear capabilities. I was wondering what kind of assumptions are needed, and how do I interpolate the results from the linear solve, to capture those stresses in the sheet metal? How would adaptive meshing play into this situation? Please let me know if I need to describe anything else. I'd be happy to elaborate it more. Thanks a lot. Sunny.
If you can imagine the lid of a tupper ware box, and imagine that the outer circumference is like a surface, flat, with a small radial thickness to it, take another similar lid, put it against this one, and weld the outer surfaces together. This would form an enclosed volume in the middle, which is compressible. Now, let us assume there is pressure acting all around the outside of this trapped volume, for convenience sake, lets name it an empty biscuit.
Since this was made out of standard steel sheet metal, and when the centers of this buscuit are compressed together due to pressure outside, we have stresses induced on the weld joints, and also in the sheet metal portion. Since the compression in the center is exceeding half the thickness of the sheet metal, this is a non linear, large strain problem. The stresses induced in the sheet metal, after a point, would jump over to diaphragm stresses, i.e., stresses along the sheet metal surface stretching the marterial, and that is something I dont know if my linear static solver can capture, because it seems like the stress state is considerably different. But, this is all I have, and my question is how do I get close to those stress states with shell elements, linear static stress solver, and standard generic isotropic steel material properties, like E and poisson's ratio.
I dont have any non linear capabilities. I was wondering what kind of assumptions are needed, and how do I interpolate the results from the linear solve, to capture those stresses in the sheet metal? How would adaptive meshing play into this situation? Please let me know if I need to describe anything else. I'd be happy to elaborate it more. Thanks a lot. Sunny.
