1 / 11

TCU Structural Analysis

TCU Structural Analysis. Brent R. Lee Southwest Research Institute (210) 522-6093 brent.lee@swri.org. Agenda. Requirements Compliance Table Analysis Approach and Assumptions Natural Frequencies Results Summary. Requirements Compliance Table. Structural Analysis Approach and Assumptions.

leola
Télécharger la présentation

TCU Structural Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TCU Structural Analysis Brent R. Lee Southwest Research Institute (210) 522-6093 brent.lee@swri.org

  2. Agenda • Requirements Compliance Table • Analysis Approach and Assumptions • Natural Frequencies • Results • Summary

  3. Requirements Compliance Table

  4. Structural AnalysisApproach and Assumptions • Analysis addresses three areas • Fatigue lifetime of component leads and solder joints • Shock sensitivity of components • Safety critical structures • Chassis structurally similar to previously qualified hardware (DI PIA, SWIFT XEP, OE SCA) • Fasteners are preloaded to 65% of material yield strength • Factors of safety: 1.25 on yield and 1.4 on ultimate • ANSYS (finite element analysis) used to determine natural frequencies of circuit board assemblies • Use board natural frequencies in component fatigue lifetime calculations based on Steinberg approach

  5. Chassis Qualification DI PIA OE SCA WIPER TCU

  6. Chassis Qualification (cont.) • No qualification problems anticipated • WIPER environment more severe, but lower enclosure height gives improved ruggedness • Chassis to be modeled mathematically and vibration tested OE SCA Finite Element Model

  7. Circuit Board Models • Typical WIPER VME module details • First natural frequency: 187 Hz • Ecircuit board = 3 x 106 psi, Estiffener = 10 x 106 psi • Simple and fixed supports at connectors and card retainers • Mass evenly distributed across entire module

  8. Circuit Board Natural Frequencies • Summary of WIPER module 1st mode frequencies • Desired frequency indicates minimum natural frequency needed for worst case component to meet mission fatigue requirements

  9. Circuit Board Natural Frequencies (cont) • CPU circuit board fails to meet WIPER random vibration requirements • Planned to reuse previously qualified board design with minimal changes (low-risk, low-cost) • Current configuration does not meet WIPER load environment • High peak PSD levels in random vibration spectrum (1.4 g2/Hz compared to 0.2 g2/Hz on previous program where board was used) • TCU currently located on spacecraft panel with most severe shock and random vibration environment

  10. Possible Solutions • Three suggested options to overcome this problem • Add cross-shaped stiffener to CPU circuit board • Requires modifying layout of CPU and other modules • Increases natural frequency of CPU board to 283 Hz (249 Hz required) • Modify the current chassis design in order to reorient modules (to stand on their ends) • Relocate the entire TCU to a different spacecraft panel

  11. Summary • TCU chassis meets all design requirements • Further analysis and testing will be used for verification • TCU circuit boards not able to meet current random vibration loads • Not confident that components on CPU board will meet fatigue lifetime requirements due to high peak PSD levels • Several alternatives are available to mitigate this problem

More Related