Abaqus Load Skill
Apply mechanical and thermal loads to FEA models - forces, pressures, gravity, and heat flux.
When to Use This Skill
Route here when user mentions:
- "Apply a force", "add pressure", "put a load on"
- "Gravity", "self-weight", "body force"
- "Point load", "distributed load", "traction"
- "Heat flux", "thermal load"
- "Force in the X/Y/Z direction"
Route elsewhere:
- Fixed supports, displacements, symmetry →
/abaqus-bc
- Contact forces between parts →
/abaqus-interaction
- Initial temperature fields, pre-stress →
/abaqus-field
- Time-varying load profiles →
/abaqus-amplitude
Key Decisions
1. Which Load Type?
| User Describes |
Load Type |
Units |
| Force at a point/vertex |
ConcentratedForce |
N |
| Force spread over surface |
SurfaceTraction |
MPa |
| Normal pressure on surface |
Pressure |
MPa |
| Force along edge |
LineLoad |
N/mm |
| Self-weight, acceleration |
Gravity |
mm/s² |
| Heat input to surface |
SurfaceHeatFlux |
mW/mm² |
| Convective cooling/heating |
FilmCondition |
mW/(mm²·K) |
2. When to Convert Force to Traction
If user gives total force but it must be distributed:
Traction (MPa) = Total Force (N) / Surface Area (mm²)
Example: 1000 N on a 50×20mm face = 1000 / 1000 = 1.0 MPa
Sign Conventions
| Load Type |
Positive (+) |
Negative (-) |
| Pressure |
Compression (into surface) |
Tension (away from surface) |
| Force components (cf1, cf2, cf3) |
Positive axis direction |
Negative axis direction |
| Gravity |
Positive axis acceleration |
Negative axis (comp2=-9810 for -Y) |
What to Ask User
If not specified, clarify:
| Question |
Why It Matters |
| Force magnitude? |
Required for all loads |
| Direction (X, Y, Z)? |
Needed for directional loads |
| Point or distributed? |
Determines ConcentratedForce vs SurfaceTraction |
| Which surface/vertex? |
Defines load application region |
| Constant or time-varying? |
May need amplitude definition |
Direction Specification
| Load Type |
How Direction Works |
| ConcentratedForce |
cf1, cf2, cf3 = X, Y, Z components |
| SurfaceTraction |
directionVector=((origin), (endpoint)) |
| Pressure |
Always normal to surface (no direction needed) |
| Gravity |
comp1, comp2, comp3 = acceleration components |
| LineLoad |
comp1, comp2, comp3 = force/length components |
Common Scenarios
Standard Gravity Setup
- Acceleration: comp2 = -9810 mm/s² (for -Y direction)
- Requires material density defined - without it, gravity has no effect
Pressure vs Traction
- Pressure: Always normal to surface, simpler to define
- Traction: Arbitrary direction, use when force isn't perpendicular
Thermal Loads
- Heat flux: Direct heat input (mW/mm²)
- Film condition: Convection with ambient temperature
Time-Varying Loads
For loads that change over time:
- First define amplitude using
/abaqus-amplitude
- Reference amplitude name when creating load
Modifying Loads Across Steps
| Action |
Method |
| Change magnitude |
setValuesInStep() |
| Turn off load |
deactivate() |
| Different load in each step |
Create load with step name |
Troubleshooting
| Problem |
Likely Cause |
Solution |
| Zero reaction forces |
Wrong direction or tiny magnitude |
Check direction vector and units |
| Gravity has no effect |
Missing density |
Add density to material definition |
| Load region not found |
Typo in set/surface name |
Verify name matches exactly |
| Equilibrium not achieved |
Load too large |
Reduce magnitude or improve convergence |
| Negative eigenvalue |
Structure unstable |
Check BCs provide adequate support |
Validation Checklist
Before running analysis:
Code Patterns
For API syntax and implementation examples, see:
- API Quick Reference
- Common Patterns
- Troubleshooting Guide
1---2name: abaqus-load3description: Apply forces and pressures to structures. Use when user asks to apply a force, add pressure, put a load on, or mentions gravity, point loads, or distributed forces.4---56# Abaqus Load Skill78Apply mechanical and thermal loads to FEA models - forces, pressures, gravity, and heat flux.910## When to Use This Skill1112**Route here when user mentions:**13- "Apply a force", "add pressure", "put a load on"14- "Gravity", "self-weight", "body force"15- "Point load", "distributed load", "traction"16- "Heat flux", "thermal load"17- "Force in the X/Y/Z direction"1819**Route elsewhere:**20- Fixed supports, displacements, symmetry → `/abaqus-bc`21- Contact forces between parts → `/abaqus-interaction`22- Initial temperature fields, pre-stress → `/abaqus-field`23- Time-varying load profiles → `/abaqus-amplitude`2425## Key Decisions2627### 1. Which Load Type?2829| User Describes | Load Type | Units |30|----------------|-----------|-------|31| Force at a point/vertex | ConcentratedForce | N |32| Force spread over surface | SurfaceTraction | MPa |33| Normal pressure on surface | Pressure | MPa |34| Force along edge | LineLoad | N/mm |35| Self-weight, acceleration | Gravity | mm/s² |36| Heat input to surface | SurfaceHeatFlux | mW/mm² |37| Convective cooling/heating | FilmCondition | mW/(mm²·K) |3839### 2. When to Convert Force to Traction4041If user gives **total force** but it must be **distributed**:4243```44Traction (MPa) = Total Force (N) / Surface Area (mm²)45```4647**Example:** 1000 N on a 50×20mm face = 1000 / 1000 = 1.0 MPa4849## Sign Conventions5051| Load Type | Positive (+) | Negative (-) |52|-----------|--------------|--------------|53| Pressure | Compression (into surface) | Tension (away from surface) |54| Force components (cf1, cf2, cf3) | Positive axis direction | Negative axis direction |55| Gravity | Positive axis acceleration | Negative axis (comp2=-9810 for -Y) |5657## What to Ask User5859If not specified, clarify:6061| Question | Why It Matters |62|----------|----------------|63| Force magnitude? | Required for all loads |64| Direction (X, Y, Z)? | Needed for directional loads |65| Point or distributed? | Determines ConcentratedForce vs SurfaceTraction |66| Which surface/vertex? | Defines load application region |67| Constant or time-varying? | May need amplitude definition |6869## Direction Specification7071| Load Type | How Direction Works |72|-----------|---------------------|73| ConcentratedForce | cf1, cf2, cf3 = X, Y, Z components |74| SurfaceTraction | directionVector=((origin), (endpoint)) |75| Pressure | Always normal to surface (no direction needed) |76| Gravity | comp1, comp2, comp3 = acceleration components |77| LineLoad | comp1, comp2, comp3 = force/length components |7879## Common Scenarios8081### Standard Gravity Setup82- Acceleration: comp2 = -9810 mm/s² (for -Y direction)83- **Requires material density defined** - without it, gravity has no effect8485### Pressure vs Traction86- **Pressure**: Always normal to surface, simpler to define87- **Traction**: Arbitrary direction, use when force isn't perpendicular8889### Thermal Loads90- Heat flux: Direct heat input (mW/mm²)91- Film condition: Convection with ambient temperature9293## Time-Varying Loads9495For loads that change over time:961. First define amplitude using `/abaqus-amplitude`972. Reference amplitude name when creating load9899## Modifying Loads Across Steps100101| Action | Method |102|--------|--------|103| Change magnitude | setValuesInStep() |104| Turn off load | deactivate() |105| Different load in each step | Create load with step name |106107## Troubleshooting108109| Problem | Likely Cause | Solution |110|---------|--------------|----------|111| Zero reaction forces | Wrong direction or tiny magnitude | Check direction vector and units |112| Gravity has no effect | Missing density | Add density to material definition |113| Load region not found | Typo in set/surface name | Verify name matches exactly |114| Equilibrium not achieved | Load too large | Reduce magnitude or improve convergence |115| Negative eigenvalue | Structure unstable | Check BCs provide adequate support |116117## Validation Checklist118119Before running analysis:120- [ ] Load applied to correct region (surface, vertex, edge)121- [ ] Direction matches physical scenario122- [ ] Magnitude in correct units (N, MPa, mW/mm²)123- [ ] Load assigned to correct step (not Initial)124- [ ] Density defined if using gravity125- [ ] Reactions should balance applied loads126127## Code Patterns128129For API syntax and implementation examples, see:130- [API Quick Reference](references/api-quick-ref.md)131- [Common Patterns](references/common-patterns.md)132- [Troubleshooting Guide](references/troubleshooting.md)