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  1. Ld3Ake

    Reading results file from global model into local model

    Hi, I have a quick global to local submodelling question. I have an Abaqus model and that all works fine on my computer. I've followed the instructions of Referring to the global model results from the submodel analysis so that it correctly locates the global results file. The problems arises...
  2. Ld3Ake

    Another Bolt Preload Question...

    Ah, I see. Thanks for that, I didn't know you had to modify the step and tell it to "fix at current length". That has got rid of the weird excessive deformation at the mid-plane elements. Naturally of course, my results still don't match that of the paper, but at least I can move on to...
  3. Ld3Ake

    Another Bolt Preload Question...

    Hi guys, I am sure there are many of you who have done a 3D bolted joint model. At the moment I am trying to validate my FE model, and so I am currently using this paper to benchmark my results: http://www.sciencedirect.com/science/article/pii/S026382230400340X Three-dimensional finite element...
  4. Ld3Ake

    Finding joint loads for a structure

    Ok, so the plot thickens. We are using a composite materials, and specifically a composite sandwich structure, so we are particularly interested in knowing if our panel is suitable for rivet fastening. We have done experimental coupon tests on our material for shear and pull out, so what we know...
  5. Ld3Ake

    Finding joint loads for a structure

    Sure no problem The first shows the general assembly (the lines down the middles are where I applied BCs for this scenario) Link The second is an example of the job after it has been run, focussing specifically on the joint loads. Link The third is an exaggerated deflection showing what is...
  6. Ld3Ake

    Copy coordinate system

    I have the same question. Yes, I can create another coordinate system in the Visualisation module but that gets a bit tedious each time you tweak the model and run the job again. Thus far all the coordinate systems I have created in the assembly module to appear in the final results.
  7. Ld3Ake

    Finding joint loads for a structure

    Hi, Does anyone have any experience about how to find the forces acting on a joint that is subjected to an out of plane load? For example I have a square panel that I want to attach to a frame around the perimeter, so I would like to work out the corresponding joint loads in shear and tension...
  8. Ld3Ake

    Fasteners and Free Body Visualisation

    Hi, I have created an Abaqus model which uses the Fasteners connection type to join two surfaces. The fasteners have been defined as attachment points. Is there a way I can get a free body cut specifically for the nodes that the attachment point is connected to? I know how to generate a...
  9. Ld3Ake

    Simple Tension test û why is my model too stiff?

    Hi guys, I got a reply from my Nastran reseller. Basically the problem was related to how Nastran how output results. Apparently it can't get stress and strain to output in the same analysis (well it can, but it generates "effective strain", i.e. von mises strain, which is not correct for a...
  10. Ld3Ake

    Simple Tension test û why is my model too stiff?

    Hi, I’m trying to validate my FEA models by using experimental stress-strain data from a composite tension test. I’m using NEI Nastran but for some reason the FEA results are way too stiff. I thought initially it was a material model issue so then I changed to an isotropic material – aluminium...
  11. Ld3Ake

    Reverse Classical Laminate Theory

    I am actually testing woven fabrics but I am trying to back out an equivalent unidirectional laminate so I can use the properties for FEA. In the end I managed to get my program to work but I had to make some tweaks to it after working out what was the problem. Basically for a balanced laminate...
  12. Ld3Ake

    Reverse Classical Laminate Theory

    Hi, has anyone tried performing classical laminate theory in reverse, i.e. getting lamina stiffness and strength values from experimental laminate data? I have been attempting to do so but I can’t seem to get my formulation to work correctly. I’m 99% sure it is correct because I can go from Q...
  13. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    Ha bringing the 787 into the discussion is worthy of a whole new thread entirely! Sure, in perfect operation the maintenance costs will be lower as there are fewer parts. The obvious flaw is what do you do if your one-piece fuselage gets hit? As far as I'm aware there is no way to accurately...
  14. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    Ok, thank you very much for replying RPstress. Obviously the specific stiffness of the composite is greater than aluminium, and when I ran the buckling analysis again using a thickness for the composite that is equivalent in mass to aluminium the buckling load was far superior. So, as a very...
  15. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    I am just using an arbitary Carbon/Epoxy Composite: E11 = 128Gpa, E22 = 8.5Gpa G12 = 3.4GPa, The laminate is 2.2mm thick, with an 11ply layup [45/-45/0/-45/45/90]s (the 90 ply is the middle). So far I have used this layup uniformly across the whole structure. The aluminium is 7050 with...
  16. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    Oh and another question. This is the buckling mode that my model produces. Is this physically possible? Ideally I would have some physical data to validate my model but in this case I have to design the structure for the test specimen. I just want to get something that is a reasonable first...
  17. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    Thanks for any info you may have.
  18. Ld3Ake

    Carbon Composite vs Aluminium Frame FEA

    Hi I want to determine the optimal layup for a carbon composite frame structure but I am new to composite finite element modelling. So far I have just been setting up simple geometries analysing static and buckling load cases that I have been comparing against an aluminium model. The...
  19. Ld3Ake

    How to add rigid mass to impact model

    Hi, I am using the automated impact analysis module of NEI Nastran with Femap to model a drop test for a container. To reduce the complexity I have decided to model the corner of the container in isolation. Now this container is going to contain cargo that I want to simulate as a rigid mass. I...

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