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  • Users: jball1
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  1. jball1

    Accumulation of error in Abaqus Explicit?

    I am performing an analysis of an event that takes between 0.1 seconds and 1 second. My stable time increment is usually between 2E-7 and 5E-6. In the past, I have used Abaqus Implicit to solve this type of problem. I believe I was told at one point that Implicit methods are generally better...
  2. jball1

    Assessing Plug Welds with Blodgett Line Method

    I am evaluating a plug weld joint using loads from FEA. I would like to apply the Blodgett line method, if possible. Tables 6 and 7 in Blodgett (pg 7.4-8) seem to indicate that this is permissible? I am struggling with calculating the section properties though, since the welds are...
  3. jball1

    Extracting nodal forces

    I have multiple perpendicular plates throughout my model that are modeled with shells that are tied together (like the web and flange of a T-beam). The tie constraint represents welds. I would like to extract forces and moments at the nodes on the interface at the location of each weld, and...
  4. jball1

    Connector Damage/Failure

    I have a model that includes several bolted joints. In this model, I have modeled the fasteners with connector elements which have the three translational stiffnesses defined (two shear, one axial). This is a transient analysis. I am predicting failure in a minority of the bolts in two of...
  5. jball1

    Static vs dynamic application of load

    I typically evaluate large steel structures subjected to severe, dynamic loads. The loading is severe enough that it is not uncommon for our analyses to predict significant plasticity. Because the structures are large and complex, we typically use a global/local approach for evaluation of...
  6. jball1

    Modeling strut with connectors

    Apologize for the really basic question. I am modeling a strut acting between two points that has different releases on each end (fixed on one end, one moment released on the other). Do I need three connectors to represent the strut? One each to represent the releases on each end, and then a...
  7. jball1

    Can't edit a contact interaction

    I created a contact interaction in CAE. Now I can't seem to edit it. Specifically, I can't edit the initial clearance, which I have set to "Uniform value across slave surface: 0". I want to remove this initial clearance. However, it is not an editable field now, for some reason. I am trying...
  8. jball1

    Point based fasteners

    I am trying to use Abaqus’s “point based fasteners” to model a bolted connection which connects two large structures with 200 bolts. This is a dynamic analysis of a large structure. I can't significantly refine my mesh in way of the connection or the problem will become prohibitively...
  9. jball1

    Double-precision causing Exception Access Violation error

    I am attempting to run a dynamic analysis of a large composite structure. I am getting an “Exception_Access_Violation” error when I try to datacheck the model. The error seems like it is related to a specific composite section definition that I am trying to use. The structure is...
  10. jball1

    Does number of integration points or number of DOF drive Abaqus Explicit solution time?

    When I run a dynamic model with implicit time integration, I typically assume that solution time and number of DOF are correlated. The number of DOF is correlated to the size of the stiffness matrix, and factoring the stiffness matrix drives the solution time (NLGEOM=ON). I am less familiar...
  11. jball1

    Best Abaqus strain metric for comparison with strain gage data

    I using Abaqus/Explicit to correlate with strain gage test data for a dynamic test of a composite component. Peak strains measured in the test are ~0.005 in/in, so definitely elastic. I am trying to understand the difference between my two options for strain output, "Nominal Strain" and...
  12. jball1

    Start implicit analysis at non-zero time

    I am trying to solve a fluid structure interaction problem using a coupled eulerian lagrangian approach. Abaqus is the Lagrangian code that simulates the behavior of the structure. For a period of time (we'll say 0.05 sec) where the structure is not loaded, I solve only the fluid, using the...
  13. jball1

    SImple model with Abaqus connector element

    I am trying to build a really simple model to help me understand connectors in Abaqus. Here is my model: https://files.engineering.com/getfile.aspx?folder=e0be12ce-13b7-4f05-9ff3-0a9f13e3cdcd&file=connector.model.png I feel dumb, but I can't figure out how to connect one end of the wire that...
  14. jball1

    Warped Elements

    Can anyone point me to a resource which explains specifically how warped quad elements affect FEM results? I have been doing some searching online, but haven't had much success finding specifics. One powerpoint I have found seems to suggest that warped elements underestimate bending strains...
  15. jball1

    I am a mechanical an engineer with

    I am a mechanical an engineer with a few years of experience. Most of the work I do is transient, structural finite element analysis. I have gotten reasonably competent at building models and pumping out results, but I regularly come across gaps in my fundamental knowledge. I have been doing...
  16. jball1

    Abaqus environment file - auto update working directory

    Hi, Can I modify my Abaqus environment file such that whenever I open a CAE or an ODB, the working directory is changed to the location of the opened CAE or ODB? Thanks, Andrew
  17. jball1

    Velocity change in pipe due to abrupt diameter change

    I would appreciate help with what seems like it is probably a pretty easy fluid mechanics problem. I need to calculate the velocity change in a pipe due to an abrupt diameter change (see attached figure). I have the velocity in the larger pipe, and need to calculate the velocity in the smaller...
  18. jball1

    *Dynamic time stepping algorithm

    I am trying to validate a dynamic implicit analysis performed in a different software package by running the same analysis in Abaqus. The other software package uses a HHT time stepping algorithm with alpha = 0 (no numerical damping). In order to perform an apples to apples comparison, I ran a...
  19. jball1

    Abaqus animation

    I am running a dynamic analysis in Abaqus (implicit) that solves over ~10,000 time increments. I would like to animate the results, but would like to only include every 10 results or so to speed up the animation and reduce the file size. How do I do this? Thank you.
  20. jball1

    At a crossroads and would appreciate advice

    I am an engineer with 9 years’ experience all at a large defense contractor. My career moved in the direction of increasing technical depth until about a year and a half ago. At that point, I took on a role where I was part-time technical and part-time in an interfacing with the customer role...

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