Structural Dynamics

ATK has extensive capabilities in the structural dynamics/analysis arena, routinely performing Coupled Loads Analyses (CLA) for Shuttle (STS) and Expendable Launch Vehicle (ELV) payloads. Beyond typical liftoff and landing runs (for STS), and liftoff, engine cutoff events, and various flight profile events (for ELV), CLA capabilities also include on-orbit and jitter loads. The flowchart shows a pictorial of the CLA process.

ATK also provides thorough vibration test support. This includes developing vibration test specifications, pretest analyses, posttest analyses, and test support. Using Modal Survey as an example, ATK would predict relevant modes, develop an appropriate instrumentation set to capture those modes, and then correlate the Finite Element Model (FEM) to the measured modes.

ATK routinely creates FEMs utilizing various meshing packages, validating the FEMs through rigorous model check routines. Additional capabilities include reducing the FEM to Craig-Bampton format with associated Loads Transformation Matrices (LTMs) for further basedrive analyses or simply for delivery to a launch vehicle contractor.

ATK has supported numerous NASA, Principal Investigator, and Department of Defense programs. CLA experience includes STS and ELVs (Delta, Titan, Atlas, and HII). On-orbit loads work included loads imparted from the STS Reaction Control System (RCS), extra-vehicular activities (EVA), and rendezvous, berthing, and release activities. We have performed extensive on-orbit analyses for the Hubble Space Telescope (HST) servicing missions in order to protect the delicate HST solar arrays. Our analyses resulted in several HST mission flight rules and EVA restrictions. Jitter analyses included jitter sources such as stick-slip, thermally induced jitter, and jitter induced by onboard components like reaction wheels or stepper motors. Extensive statistical energy analyses (SEA) and basedrive analyses are also performed in order to specify component-level random levels based on system-level random analyses.

Structural Analysis has experience in support of vibration tests including acoustic, sine sweep, sine burst, random, force-limited random, shock, and modal survey. Support involves developing instrumentation sets, pretesting basedrive test simulations, posttest correlation, and on-site test support.

ATK has experience in dynamic simulation of mechanical systems using ADAMS. The deployment dynamics of developmental solar sail concepts for JPL were investigated.

CLA (liftoff⁄landing)	•				•	•	•		•
On-orbit loads⁄jitter	•	•	•		•				•
FEM	•	•	•		•	•	•
FEM validation	•	•	•	•	•	•	•	•
Pretest⁄Posttest		•	•	•	•			•	•
Vibration spec		•	•	•	•			•	•

Coupled Loads Process

In-house specialized tools

• FLAME — Matrix manipulator
• TRONS — Transient Response of Non-Linear Systems
• Various DMAPs
• NASGLU — LTM generation program

Commercially available tools

• MSC⁄NASTRAN
• MATLAB
• FEMAP
• Pro⁄E⁄MECHANICA
• AUTOSEA

Contact

space@atk.com