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Hi, I've a problem with my 3PB model of a sandwich structure (honeycomb core). Contact between sandwich structure and supports isn't realistic. I set contact in "SLIDE" but the result is wrong. So I obtained a displacement of 177 mm with a force of about 15000N, not real. I can't also view the results of CFAILURE, but I've set it in output requests. Can you take a look to my model? Thanks in advance. Hearing from you. Regards. 3PB_1.hm
Hey there, I am comparing different ways to simulate a sandwich structure going through a 3 point bending test. In order to check if I am defining well the structure, I have calculated theoretically the maximum stress and compared it to the different simulations I have done. Below are the results of a 3 point bending test applying a total force of 110N on a test-tube of 100x15x10 mm : Theoretically: Maximum stress- 7.33 MPa 1 solid (3D elements): Plies (2D elements) Core (3D) +Plies (2D): The total dimensions of the three test-tubes are the same, as well as the boundary conditions. Therefore, I don't understand why I am obtaining such different stress results nor which would be the best option to simulate this test. I hope you can help me with my problem. Thanks in advance!
Attached is a Hypermesh deck of a structure whose mass I’m trying to minimize. The structure has a square shaped core covered on the top and bottom by composite facesheets. Shell elements have been used for modeling. The size of the square and the thickness of its wall determine the buckling characteristics of the facesheets. I’ve modeled using a square of side 6mm and its wall thickness is 1.5 mm (shown in the snapshot below). By varying the size of this square and changing the wall thickness, I’m looking to minimse the mass, the constraint being that the buckling factor must always be greater than 1. Could you please help me achieve my objective? Thanks, Kushal Agarwal. square_foam_opti.hm
Hello guys, I'm currently trying to simulate a 3 point bending test to get the best material arrangement for high bending stiffness in a composite monocoque, while keeping the weight low. The laminate i strive for is a sandwich structure with an aramide honeycomb core in the centre and three plies of different material on top and on the bottom. These are the steps I did so far: 1) I created a CAD model, imported it to HyperMesh, organized the componets (specimen, impactor, support) and meshed them with 2D elements. 2) I created the materials. MAT1 for the impactor and the support of the 3 point bending test, MAT8 for the different plies and MAT9ORT for the honeycomb core. 3) After that I created the properties. PSHELL with an elementthickness of 2 for the impactor and support, PCOMPP for the plies and PSOLID with the honeycomb material for the core. 4) Then I created the different plies. 6 with the MAT8 material for the top and bottom layers and 5 with the MAT9ORT material for the core to get a total of 5 elements over the thickness of the core. The material type for all plies is ORTHOTROPIC. 5.1) I created a laminate with the 5 core plies and then did a "shell to solid conversion" with this laminate. After that I got a new component with 5 elements over the thickness. [5.2) In a second try I did the "shell to solid conversion" with the plies of the core which led to the same result as 5.1] 6) I assigned the PCOMPP property to the specimen elements, otherwise the laminate and layers weren't visible over 2D detailed element representation. 7) I updated the laminate with the other 6 plies. 8) Finally I created the load collectors and the load step, an output request for CSTRAIN and CSTRESS 9) I started OptiStruct to run the analysis. But after a few seconds i got these errors: *** ERROR 14: Missing MAT # 5 referenced by PLY # 7, (existing MAT with this ID is of incorrect type). *** ERROR 14: Missing MAT # 5 referenced by PLY # 8, (existing MAT with this ID is of incorrect type). *** ERROR 14: Missing MAT # 5 referenced by PLY # 9, (existing MAT with this ID is of incorrect type). *** ERROR 14: Missing MAT # 5 referenced by PLY # 10, (existing MAT with this ID is of incorrect type). *** ERROR 14: Missing MAT # 5 referenced by PLY # 11, (existing MAT with this ID is of incorrect type). *** Errors with missing, incorrect or duplicate IDs found 5 times. So when I got back to the model to check the properties, I wasn't sure if the PSOLID property and the MAT9ORT material are assigned to the plies in the laminate or to the new created component for the solids of the conversion. I want to get a laminate with from top to bottom: 3 layers of PCOMPP MAT8, the PSOLID MAT9ORT core and then 3 layers of PCOMPP MAT8 again. Is it even possible to creat such a laminate and if yes, in wich order should I assign the properties and creat the laminate?Or are there other ways to simulate this kind of sandwich structure in HyperMesh and OptiStruct? Here I uploaded the HM file so you can have a detailed look at my model: http://www.file-upload.net/download-10836303/3-point-bendingtest-setup-2.hm.html These are some screenshots of the different views on the model:By property, 2D detailed http://www.pic-upload.de/view-27981011/Forum-by_prop.png.htmlBy component, 2D detailed http://www.pic-upload.de/view-27981021/Forum-by_comp_2D.png.htmlBy component 2D traditional http://www.pic-upload.de/view-27981023/Forum-by_comp_1D.png.html I hope you get my problem and can help me fix it. Thanks in advance!