Weld Modeling and Analysis with FEMAP and NX Nastran

March 13, 2017

In this technical seminar, we look at how to extract weld line stresses and forces. Our assumption is that a post-weld heat treatment has been performed and that the residual stress state in the weld zone is quite low.

To illustrate this importance, we provide an FEA simulation of how residual stresses develop in a welded T-joint as it cools down to room temperature. Please don’t get your hopes up that this seminar will be the definitive work on weld modeling and analysis, the topic is just too broad to cover in an hour or even in a week of lectures. What we will show is our best practices at Predictive Engineering from ASME to Blodgett’s.

This webinar was held on Thursday, May 4, 2017.

Outline:

Warping and Residual Stresses in Fillet Welded T-Joint
- Transient nonlinear stress analysis with temperature dependent mechanical properties
Modeling – Where to begin? What should the geometry look like?
- Partial penetration welds (i.e., internal free face)
- Sharp corner vs. chamfer vs. fillet
- Glued connections vs. merged nodes
- Weld zones (i.e., ASME SEP)
- Heat affected zone (i.e., a different material model?)
Meshing – Ok, we’ve decided how we want to idealize it. How do we mesh it?
- The mesh convergence trap
- Connecting dissimilar mesh types
- Fillet welding (i.e., 3DOF)
Post Processing – Taking stresses or forces from the FE model and calculating useful results.
- Nominal stress methods (ASME VIII, special S-N curves, fatigue knockdown factors)
- Structural stress methods (Hotspot, extrapolated stress)
- Extracting forces with FBDs
- Blodgett’s Hand Calculations

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