Aircraft Landing Gear Static Load & Deformation Test
Project: Aircraft Landing Gear Static Load & Deformation Test
August 2023 · Aviation Component Test Center
Performed full-scale structural deformation testing on a commercial aircraft landing gear assembly to:
Quantify stress distribution under simulated landing impacts
Validate FEA models for fatigue life prediction
Identify potential overload risk zones
Test Setup
1. Instrumentation
16 × SE-86H High-Speed Static Strain Systems (256 total channels)
Sampling rate: 1kHz (24-bit resolution)
Bridge configuration: 3-wire quarter-bridge (350Ω strain gauges)
Sensor Layout:
| Component | Measurement Points | Key Parameters |
|---|---|---|
| Main fitting | 32 | Bending moment (My, Mz) |
| Shock strut | 28 | Axial compression (P) |
| Torque links | 18 | Shear stress (τxy) |
| Wheel axle | 22 | Torsion (Mx) |
2. Loading Protocol
Vertical load steps: 50%, 75%, 100%, 125% of MLW (Max Landing Weight)
Drag/lateral loads: Combined loading per FAR 25.473
Measurement phases:
Pre-load (5% MLW for zeroing)
Ramp loading (10s to target)
Dwell (60s stabilization)
Key Results
1. Stress Hotspots
| Location | Peak Strain (με) | Safety Margin |
|---|---|---|
| Lower trunnion | 1,850 | 1.8× |
| Drag brace pin hole | 2,120 | 1.5× |
| Shock strut piston | 980 | 2.2× |
2. Nonlinear Effects
Detected 15% stiffness reduction at 125% MLW due to:
Bushing deformation (accounted for 60% of compliance)
Local yielding in lugs (ε > 0.2%)
3. FEA Correlation
MAC (Modal Assurance Criterion): 0.89 for primary load paths
Critical discrepancy:
Predicted vs. actual stress at torque links differed by 12%
Root cause: Friction modeling in joints required adjustment
Engineering Outcomes
Design Improvements
Increased trunnion wall thickness by 2mm (reducing peak strain by 18%)
Modified bushing material from Cu-Al alloy to Cu-Be (improved wear resistance)
Maintenance Impact
Established in-service strain limits:
Alert level: 1,500με (requires inspection)
Rejection level: 2,000με (immediate removal)
Certification Data
Demonstrated compliance with:
FAR 25.723 (landing gear strength)
AC 25.733-1 (shock absorption tests)
Technical Terms
MLW: Maximum Landing Weight
Quarter-bridge: Strain gauge circuit with 1 active gauge
MAC: Quantitative comparison metric for FEM validation
This test provided definitive load-path characterization, enabling 15% weight reduction in next-gen landing gear designs while maintaining safety margins. The SE-86H systems demonstrated exceptional performance in capturing microstrain-level deformations under dynamic loading conditions.
