Questions tagged [nastran]

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In Nastran, how to ignore fatal error due to failed convergence and move on to next subcase?

At the moment the whole analysis stops when 1 subcase fails to converge. How can I keep the analysis going such that all subcases are are run, even if they all might produce an error? I'm pretty sure ...
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0answers
27 views

In a nonlinear static two-step subcase, why does the load step decrease after the first step?

I am using MSC Nastran for nonlinear static analysis (sol 400). Step 1 contains a small perturbation load laterally on a thin-walled cylinder. Step 2 contains a very large compressive load. ...
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1answer
34 views

For arc-length method in nastran, how to analyse post-buckling behaviour with load decrease

I am currently trying to model the buckling behaviour of a cylinder using sol 400 nonlinear static analysis using Nastran. I am using the arc-length (modified Riks) method as apparently it can ...
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1answer
185 views

Free pre-processor for Nastran?

I want to do a non-linear analysis (possibly SOL 400) on Nastran. I used PyNastran (python module) to set-up the BDF file for a Linear buckling analysis (sol 105). However I feel like it might be too ...
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1answer
35 views

How would I do a buckling analysis with an additional fixed known lateral force?

I am using Nastran for buckling analysis, and I'm new to all of this so please bear with me. For a linear buckling analysis, I understand that you must first apply any compressive load in the static ...
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1answer
84 views

Nastran / Frequency Response / Free-Free

There are examples of using SOL 108 and SOL 111 to create a frequency response. In Siemens Simcenter (NX Nastran), the examples focus on a tower with a seismic mass. The model drives the mass with ...
0
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1answer
137 views

MSC Nastran - BAR3/4 elements - can't assign any properties

I'm modeling a pipe in Patran, and I'd like to try bar3 and bar4 elements. I assing the properties CBEAM to my geometry, but when I create the mesh, Patran tell me bar3 and bar4 don't support that ...
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0answers
23 views

MSC Nastran CQUAD8 on a pipe - excessive pivot ratio

I'm modelling a pipe in Patran with CQUAD8 elements, but I get this error, like the structure is not costrained. I do have costrains on both ends of the pipe. What can the problem be? If I use ...
2
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3answers
86 views

Do internal / external stresses affect modal frequency?

Imagine a cantilevered beam, fixed on one end and with a tension line connecting the other end to ground (e.g. perpendicular to the length of the beam). If I increase the tension, does the modal ...
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1answer
110 views

Boundary Conditions fro Static Structural Analysis of a Turbine Rotor Using FEM

I am trying to perform static structural analysis of a turbine rotor which is rotating at a given angular speed, say 1000 rad/s. I also know the pressure distribution from CFD analysis. What are the ...
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1answer
297 views

How to create a non uniform pressure load in MSC Patran

I need to simulate an external pressure load that varies sinusoidally along a circular arc. The sinusoidal variation is with arc length. I know how to create a uniform pressure load in Patran but do ...
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1answer
358 views

How to use failure criteria in isotropic material (NASTRAN)

I'm quite new in NASTRAN enviroment, and I am wondering how to use failure criteria which I can define when creating my isotropic MAT1 material for 1D elements (like CBEAM). From the Quick Reference ...
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3answers
2k views

Inertia Relief and Buckling SOL105 in Nastran

Has anyone ever tried running buckling simulations in Nastran where inertia relief is invoked? I am just using a simple plate and I am getting "funny" modes (unrealistically low eigenvalues which ...
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1answer
851 views

Where does weight mass conversion ratio '0.00259' come from in Nastran?

I think this is very fundamental question. I am wondering why 0.00259 is used as weight-mass conversion ratio, when inch/pound unit is used in Nastran. Could anyone explain the reasons?