V&S 522 – HALT, ESS and HASS with emphasis on Random Vibration

Overview for management and participants

  • Purpose of environmental testing, particularly vibration and shock aboard space vehicles
  • Purpose of environmental stress screening (ESS)
  • Extensions to HALT (highly accelerated life testing) and to HASS
  • Types of vibration tests: resonance search/dwell, fatigue, specification
  • Approximate scheduling so managers can audit special topics

Quiz for evaluation of attendee prior knowledge

Classical sinusoidal vibration never observed in service; useful concept

  • Introduction: terminology, structural resonant behavior, passive and active isolation
  • Sinusoidal vibration measurements: units, sensors, readouts, errors
  • Calibration of sensors and systems; traceability to NIST

Most machinery vibration is complex; introduction to spectrum analysis

Sinusoidal vibration testing

  • Electrohydraulic and electrodynamic shakers; theory, tradeoffs, limits
  • Power amplifier theory, operation, limitations, distortion effects
  • Controls for sinusoidal vibration testing
  • Sinusoidal vibration test practice
  • Vibration and shock test fixtures; fixtures for stress screening
  • Practical limits: transverse motion; specimen size and weight

Introduction to random vibration

  • Sources of random vibration during launch, orbit, reentry
  • No possible equivalence to sinusoidal vibration; terminology and definitions
  • Spectral density measurement and analysis – the frequency domain
  • Probability density – the time domain

Random vibration test practice

  • Interpreting and implementing standards, e.g. MIL-STD-810
  • Equalization before testing; methods and limits; controls

Combined environment (CERT) testing; reliability tests, e.g. MIL-STD-781

Environmental stress screening (ESS) of electronics hardware production

  • Single vs. multi-axis vibration
  • Pneumatic repetitive-shock machines

Extensions to HALT and HASS

Optional extensions to acoustical environment (intense noise) testing

Optional extension to mechanical shock

  • Instrumentation for measuring shock in service and during tests
    • Sensors, readouts, errors
    • Calibration
    • Shock spectrum analysis; shock response spectrum
  • Shock testing standards and methods
    • Shock testing machines; limitations
    • Use of shaker
    • Explosives

Witnessing of tests

Course summary; optional final examination; award of certificates

back to top back to Top