Complex Loading

Purpose-

To perform mechanical testing under complex loading and local stress/strain states that occur in aerospace structures during service; obtain relevant information to characterize material performance under service-like loading, including failure loads, non-destructive evaluation (NDE) results, and strain field data (digital image correlation).

Equipment/Test Method
Tension - torsion test machine

Tension Torsion Machines (2)
-Tension loads up to 50 kips
-Torsion loads up to 3 kip-inch
Axial -Tension and Bending

Axial-Tension and Bending (ATB)
– Up to 10-kips axial loading
– Transverse loading up to 4 kips
Biaxial test stand

Biaxial Test Machine
– Loads up to 225 kips in one direction; 165 kips transverse
Uniaxial test machine

Uniaxial Test Machines (2)
– 100-kip machine with 4 posts allows attachment of complex load fixtures

Typical/Recent Experiments

  • ATB was developed by personnel from the U.S. Army Research Laboratory to test composite rotor blade materials which are subjected to complex states of cyclic loading
  • Use of ATB to reproduce cracking morphologies observed in Atlas V rocket fuel tanks
  • Tension torsion testing conducted to evaluate composite rotorcraft materials under service-like loading. Materials have been tested before and after low-velocity impact damage.
  • Biaxial testing done to qualify new aluminum-lithium alloy as Space Shuttle External Tank replacement alloy