Model Preparation

---
name: orcaflex-modal-analysis-model-preparation
description: 'Sub-skill of orcaflex-modal-analysis: Model Preparation (+2).'
version: 1.0.0
category: engineering
type: reference
scripts_exempt: true
---

# Model Preparation (+2)

## Model Preparation


1. **Ensure static convergence** before modal analysis
2. **Use appropriate segment lengths** for accurate mode shapes
3. **Include all relevant objects** in the analysis
4. **Consider boundary conditions** (fixed vs. free ends)


## Analysis Configuration


1. **Number of modes** - Start with 20-30 modes, increase if needed
2. **DOF thresholds** - Use 10-15% for initial screening
3. **Object selection** - Focus on critical structural members
4. **Batch processing** - Compare across configurations


## Results Interpretation


1. **Low-frequency modes** - Often global bending/heave
2. **High-frequency modes** - Local vibrations, may indicate VIV risk
3. **Mixed DOF modes** - Coupled motions, require careful assessment
4. **Clustering** - Multiple modes at similar frequencies indicate sensitivity