Abaqus Amplitude Skill
This skill defines time-varying load and boundary condition profiles in Abaqus. Amplitudes act as multipliers that scale loads/BCs over time.
When to Use This Skill
Route here when user mentions:
- "Gradually increase the load", "ramp up the force"
- "Cyclic loading", "sinusoidal excitation"
- "Pulse load", "impulse", "impact loading"
- "Time-varying boundary condition", "loading history"
- "Smooth transition", "avoid sudden load application"
- "Earthquake input", "harmonic excitation"
Route elsewhere:
- Constant static loads (no amplitude needed) →
/abaqus-load
- Initial conditions, predefined fields →
/abaqus-field
- Dynamic analysis setup →
/abaqus-dynamic-analysis
Workflow: Defining Amplitudes
Step 1: Understand User's Load Profile
Ask if unclear:
- What shape? Ramp, sinusoidal, pulse, decay, custom?
- What timing? Duration, frequency, peak time?
- What magnitude? Amplitude is a multiplier (0.0-1.0 typical)
Step 2: Choose Amplitude Type
| User Describes |
Amplitude Type |
Key Parameters |
| Linear increase/decrease |
TabularAmplitude |
Time-value pairs |
| Smooth transition (no shock) |
SmoothStepAmplitude |
Time-value pairs |
| Sinusoidal/harmonic |
PeriodicAmplitude |
Frequency, coefficients |
| Exponential decay |
DecayAmplitude |
Initial, decayTime |
| Custom time history |
TabularAmplitude |
User-provided data |
| Sudden on/off |
TabularAmplitude |
Step-like data points |
Most common: TabularAmplitude with linear ramp (0,0) to (1,1)
Step 3: Determine Time Reference
| Setting |
When to Use |
timeSpan=STEP |
Time relative to current step start (most common) |
timeSpan=TOTAL |
Time from analysis beginning (multi-step analyses) |
Step 4: Define Data Points
For TabularAmplitude and SmoothStepAmplitude:
- Data is (time, amplitude_factor) pairs
- Time values must be strictly increasing
- Factor typically ranges 0.0 to 1.0 (can exceed if needed)
- Factor multiplies the load/BC magnitude
Step 5: Apply to Load or BC
Amplitudes are referenced by name when creating:
- Loads: ConcentratedForce, Pressure, Gravity, etc.
- BCs: DisplacementBC, VelocityBC, etc.
Key Decisions
Common Load Profiles
| Profile |
Data Pattern |
Use Case |
| Linear ramp |
(0,0), (1,1) |
Quasi-static loading |
| Ramp up/down |
(0,0), (0.5,1), (1,0) |
Load cycle |
| Hold at peak |
(0,0), (0.1,1), (1,1) |
Ramp then sustain |
| Triangular pulse |
(0,0), (0.001,1), (0.002,0) |
Impact/impulse |
| Step function |
(0,0), (0,1), (1,1) |
Sudden application |
Smooth vs. Tabular
| Use SmoothStepAmplitude when |
Use TabularAmplitude when |
| Dynamic analysis (avoid shocks) |
Static analysis |
| Convergence issues from sudden loads |
Exact load profile needed |
| Continuous derivatives required |
Step functions needed |
What to Ask User
| Input |
Required |
How to Get |
| Load profile shape |
YES |
Ask: "How should the load vary over time?" |
| Peak time |
YES |
Ask: "When should the load reach its maximum?" |
| Duration |
YES |
Typically matches step time |
| Frequency (if cyclic) |
If periodic |
Ask: "What frequency in Hz?" |
| Smooth or sudden |
Recommended |
Ask if dynamic analysis |
Validation Checklist
After defining amplitude:
Troubleshooting
| Problem |
Likely Cause |
Solution |
| "Amplitude not monotonic in time" |
Time values not increasing |
Fix time sequence |
| Convergence issues with sudden load |
Discontinuity in profile |
Use SmoothStepAmplitude |
| Load too high/low |
Misunderstanding multiplier |
Amplitude is factor; adjust load magnitude |
| Wrong timing in multi-step |
STEP vs TOTAL confusion |
Check timeSpan setting |
Code Patterns
For API syntax and code examples, see:
- API Quick Reference - Full parameter details
- Common Patterns - Ready-to-use snippets
- Troubleshooting Guide - Error solutions
1---2name: abaqus-amplitude3description: Define time-varying amplitudes. Use when user mentions ramp, time-varying, cyclic, pulse, or gradually increasing loads. Does NOT handle static constant loads.4---56# Abaqus Amplitude Skill78This skill defines time-varying load and boundary condition profiles in Abaqus. Amplitudes act as multipliers that scale loads/BCs over time.910## When to Use This Skill1112**Route here when user mentions:**13- "Gradually increase the load", "ramp up the force"14- "Cyclic loading", "sinusoidal excitation"15- "Pulse load", "impulse", "impact loading"16- "Time-varying boundary condition", "loading history"17- "Smooth transition", "avoid sudden load application"18- "Earthquake input", "harmonic excitation"1920**Route elsewhere:**21- Constant static loads (no amplitude needed) → `/abaqus-load`22- Initial conditions, predefined fields → `/abaqus-field`23- Dynamic analysis setup → `/abaqus-dynamic-analysis`2425## Workflow: Defining Amplitudes2627### Step 1: Understand User's Load Profile2829Ask if unclear:30- **What shape?** Ramp, sinusoidal, pulse, decay, custom?31- **What timing?** Duration, frequency, peak time?32- **What magnitude?** Amplitude is a multiplier (0.0-1.0 typical)3334### Step 2: Choose Amplitude Type3536| User Describes | Amplitude Type | Key Parameters |37|----------------|----------------|----------------|38| Linear increase/decrease | TabularAmplitude | Time-value pairs |39| Smooth transition (no shock) | SmoothStepAmplitude | Time-value pairs |40| Sinusoidal/harmonic | PeriodicAmplitude | Frequency, coefficients |41| Exponential decay | DecayAmplitude | Initial, decayTime |42| Custom time history | TabularAmplitude | User-provided data |43| Sudden on/off | TabularAmplitude | Step-like data points |4445**Most common:** TabularAmplitude with linear ramp (0,0) to (1,1)4647### Step 3: Determine Time Reference4849| Setting | When to Use |50|---------|-------------|51| `timeSpan=STEP` | Time relative to current step start (most common) |52| `timeSpan=TOTAL` | Time from analysis beginning (multi-step analyses) |5354### Step 4: Define Data Points5556For TabularAmplitude and SmoothStepAmplitude:57- Data is (time, amplitude_factor) pairs58- Time values must be strictly increasing59- Factor typically ranges 0.0 to 1.0 (can exceed if needed)60- Factor multiplies the load/BC magnitude6162### Step 5: Apply to Load or BC6364Amplitudes are referenced by name when creating:65- Loads: ConcentratedForce, Pressure, Gravity, etc.66- BCs: DisplacementBC, VelocityBC, etc.6768## Key Decisions6970### Common Load Profiles7172| Profile | Data Pattern | Use Case |73|---------|--------------|----------|74| Linear ramp | (0,0), (1,1) | Quasi-static loading |75| Ramp up/down | (0,0), (0.5,1), (1,0) | Load cycle |76| Hold at peak | (0,0), (0.1,1), (1,1) | Ramp then sustain |77| Triangular pulse | (0,0), (0.001,1), (0.002,0) | Impact/impulse |78| Step function | (0,0), (0,1), (1,1) | Sudden application |7980### Smooth vs. Tabular8182| Use SmoothStepAmplitude when | Use TabularAmplitude when |83|------------------------------|---------------------------|84| Dynamic analysis (avoid shocks) | Static analysis |85| Convergence issues from sudden loads | Exact load profile needed |86| Continuous derivatives required | Step functions needed |8788## What to Ask User8990| Input | Required | How to Get |91|-------|----------|------------|92| Load profile shape | YES | Ask: "How should the load vary over time?" |93| Peak time | YES | Ask: "When should the load reach its maximum?" |94| Duration | YES | Typically matches step time |95| Frequency (if cyclic) | If periodic | Ask: "What frequency in Hz?" |96| Smooth or sudden | Recommended | Ask if dynamic analysis |9798## Validation Checklist99100After defining amplitude:101- [ ] Time values are strictly increasing102- [ ] Factor range is appropriate (usually 0.0-1.0)103- [ ] timeSpan matches analysis intent (STEP vs TOTAL)104- [ ] Amplitude name matches what load/BC references105- [ ] For dynamic: smooth transitions to avoid numerical shocks106- [ ] For periodic: frequency and coefficients are correct107108## Troubleshooting109110| Problem | Likely Cause | Solution |111|---------|--------------|----------|112| "Amplitude not monotonic in time" | Time values not increasing | Fix time sequence |113| Convergence issues with sudden load | Discontinuity in profile | Use SmoothStepAmplitude |114| Load too high/low | Misunderstanding multiplier | Amplitude is factor; adjust load magnitude |115| Wrong timing in multi-step | STEP vs TOTAL confusion | Check timeSpan setting |116117## Code Patterns118119For API syntax and code examples, see:120- [API Quick Reference](references/api-quick-ref.md) - Full parameter details121- [Common Patterns](references/common-patterns.md) - Ready-to-use snippets122- [Troubleshooting Guide](references/troubleshooting.md) - Error solutions
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