Case Study: SMSS Strut Verification Test
This project involved the linear static analysis and testing of the JWST Secondary Mirror Support Struts (SMSS) for a sub element structural verification test. Finite element analysis was performed on an ~5 foot long SMSS sub element test article exposed to two load cases:
Case 1) An axial compression load down the axis of the strut was applied.
Case 2) An axial normal load was applied to induce bending into the strut.
For both load cases stress/strain analysis was necessary to verify that the structure would be properly loaded to Design Limit Load (DLL) and maintain positive margins of safety. The strains were calculated for the highest loaded region, and the locations of the strain gauges and LVDTs were defined. A buckling analysis was conducted to verify that the test setup did not inducing any new failure modes. Strain and deflection predictions were made at increment steps up to 1.25xDLL. As the incremental loads steps were applied, recorded strain and displacement were compared to predictions. All verification test objectives were met and a final report was written.
Software used: MSC/NASTRAN
Case Study: King Air Winglet
This project involved the linear static analysis, dynamic analysis, and testing of the King Air Winglet. The program was a design, analyze, build, and test project of a prepreg composite/foam core winglet. A series of verification tests were conducted on the full scale winglet for these load environments: (1) Modal Frequency Response; (2) Structural Impact Damage (Bird Strike); (3) Winglet Aerodynamic Bending.
Finite element analysis was performed on the winglet based on the type of load environment. A modal analysis was conducted to predict the natural frequencies in a simulated wing test stand. A frequency response tap test was conducted, and the measured and predicted frequencies were within program requirements.
A shock or bird strike test was conducted by impacting the composite skin in the highest stressed region of the winglet due to aerodynamic loading. The standardized strike load resulted in complete failure of ~3 square inches of the composite skin. The damaged winglet was then tested in a simulated aerodynamic load environment by bending the winglet tip inboard and outboard. Analysis predictions for strain, displacement and natural frequency were verified, and the winglet was qualified to the stringent FAA/DER requirements and review.
Case Study: THADD Launch Canister
This project involved the linear static analysis and testing of the Terminal High-Altitude Area Defense (THAAD ) Launch Canister.
The program was a material technology demonstration of a filament wound composite launch tube. A verification test was conducted on the launch tube, under internal pressure loading. Finite element analysis was performed on the ~6 foot long sub element test article exposed to internal launch pressures.
Stress/strain analysis was conducted to verify the tube would be properly loaded to MEOP pressure and maintain positive margins of safety. The strains were calculate for the highest loaded region, and the locations to place the strain gauges were defined. Strain and deflection prediction were made at increment pressures up to MEOP. As the incremental pressures steps were applied, recorded stain and displacement were compared to predictions. All verification test objectives were met, and a final report was written.
Case Study: Telescoping Mast
This verification or demonstration test involved the analysis and testing of a Deployable Telescoping Mast. The project was a design, analyze, build, and test project of a filament wound composite mast consisting of ten concentric cylinders powered by a mechanical lifting system.
The analysis for the load verification test was based on closed form calculations for the mechanical advantage provided by the lifting mechanism. The calculated lifting load, drive motor torque, and required power were determined. A mast payload mass simulator was placed on top of the development mast, consisting of four concentric composite cylinders. The telescoping mast was activated and the measured lifting load, drive motor torque, and power consumption all compared favorable with predicted values.
A patent was issued in 2011 for the design of this device.
Software used: NEi/NASTRAN