Application of HyperMesh Certification to Inter-Rivet Buckling

This project aims to simplify the calculation of the margin of safety against inter-rivet buckling using the Altair HyperMesh Certification framework.

The provided code and documentation have been tested in version 2023.1 but should work in later versions too.

❗ Everything that follows is work in progress. ❗

Workflow for Metallic Structures 🛠️

Note that the implemented HSB formula is only applicable to load cases without transverse loads with respect to the direction of the fastener row. If there is a tensile transverse load, the actual reserve factor will be higher. If there is a compressive transverse load, the actual reserve factor will be lower.

1. Import the provided library irb_library.xml.
2. Create a structural property of type Panel_metallic and add the following metadata:
   • Fastener pitch s
   • Fastener row direction as x, y, z components
   • Clamping factor C
3. Create a design point set.
4. Create structural elements (design points) of type Panel_metallic.
5. Run the method provided method on the previously created design point set.

Testing

All files have been tested on the following models and results:

• Altair_Wingddp_start.hm and Altair_Wing_LC101_Take_Off_p27deg_Hot_Step1.op2 (part of a workshop by Altair, not available here)

Open Questions

• Are there more precise formulas for inter-rivet buckling than the ones presented in the HSB? These formulas neglect transverse forces (i.e. assume there are none).
• Is there a simpler way to get the fastener pitch than entering it manually as metadata?
• Not important but confusing: Why is Design Point abbreviated as DDP instead of DP?

Abbreviations 🗒️

• irb = inter-rivet buckling
• cr = critical
• sigma = stress in N/mm²
• n = force flow in N/mm