Abaqus Dynamic Analysis Skill
This skill handles explicit and implicit dynamics for impact, crash, drop test, and transient response analysis.
When to Use This Skill
Route here when user mentions:
- Impact, crash, collision, drop test
- Transient response, time-varying response
- Shock loading, blast loading, explosive loading
- High-speed events, wave propagation
- "What happens when it hits..."
Route elsewhere:
- Natural frequency extraction →
/abaqus-modal-analysis - Static/constant loads →
/abaqus-static-analysis - Harmonic/sinusoidal response → modal + steady-state dynamics
- Very long transients (minutes+) → consider implicit or quasi-static
Prerequisites
Before dynamic analysis:
- Geometry and mesh ready
- Material MUST have density defined (required for mass matrix)
- Understand event duration and loading type
Workflow: Setting Up Dynamic Analysis
Step 1: Gather Information from User
Ask if unclear:
- What's the event duration? Milliseconds, seconds, or longer?
- Initial velocity? For drop tests or impact
- Is contact involved? Parts colliding or touching
- What output needed? Stress, velocity, acceleration, energy?
Step 2: Choose Explicit vs Implicit
| Factor | Explicit | Implicit |
|---|---|---|
| Time scale | Short (us to ms) | Longer (ms to s) |
| Step size | Automatic (very small) | User-controlled |
| Nonlinearity | Handles well | May need iterations |
| Memory | Lower | Higher |
| Contact | Natural handling | Needs care |
| Best for | Impact, crash | Vibration, long transient |
Decision rule:
- Event < 10ms with impact/contact → Explicit
- Event > 100ms without severe nonlinearity → Implicit
- In between → Either can work, explicit often easier
Step 3: Set Time Period
| Event Type | Typical Duration |
|---|---|
| High-speed impact | 0.1-10 ms |
| Drop test | 1-100 ms |
| Blast loading | 1-50 ms |
| Seismic/vibration | 1-100 s |
Step 4: Define Initial Conditions
For drop tests and impact:
- Set initial velocity on the impacting part/region
- Velocity is applied in the Initial step
Step 5: Configure Output
Field outputs: S (stress), U (displacement), V (velocity), A (acceleration), PEEQ (plastic strain)
History outputs for energy balance (explicit): ALLKE, ALLIE, ALLWK, ETOTAL
Step 6: Consider Mass Scaling (Explicit Only)
| Option | Effect | When |
|---|---|---|
| None | True inertia | Very short events, accuracy critical |
| At beginning | Scale once | Quasi-static explicit |
| Throughout | Continuous scaling | When inertia less important |
Warning: Mass scaling speeds up analysis but affects inertial response.
Step 7: Run and Validate
Use /abaqus-job to submit, then check:
- Energy balance (ETOTAL approximately constant)
- Stable time increment (explicit)
- Results physically reasonable
Key Parameters
| Parameter | Explicit | Implicit |
|---|---|---|
| Time period | Event duration | Event duration |
| Time increment | Automatic | Specify initial, min, max |
| Element library | EXPLICIT | STANDARD |
| Element type | C3D8R recommended | C3D8R or C3D8 |
| Hourglass control | ENHANCED | Default |
Validation Checklist
- Density defined in material
- Time period appropriate for event
- Initial conditions applied (velocity, position)
- Output frequency captures behavior (100+ frames typical)
- Energy balance acceptable (ETOTAL constant for explicit)
- Results physically reasonable
Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| "Time increment too small" | Small/distorted elements | Use mass scaling or coarsen mesh |
| Energy balance error | Hourglass or instability | Check hourglass energy, add control |
| Analysis takes forever (explicit) | Long time period | Consider implicit instead |
| Convergence failure (implicit) | Severe nonlinearity | Use explicit or smaller increments |
Related Skills
/abaqus-material- Define density (required)/abaqus-amplitude- Time-varying loads/abaqus-field- Initial velocity and predefined fields/abaqus-interaction- Contact for impact problems/abaqus-odb- Results extraction
Code Patterns
For API syntax and code examples, see:
