CLI 512 – Thermal and Random Vibration Stressing for HALT, ESS, HASS and COTS Testing

Brief overview for management and participants

Classical approach to thermal environmental testing – simulation

Purpose of environmental testing during development

  • Purpose of HALT – highly accelerated life testing
  • Purpose of environmental stress screening (ESS) as production step
    • Initially 100%; later sampling
    • Commonly-used tools: thermal ramping and random vibration
    • Importance of rapid thermal ramping
    • Opportunity to determine and extend limits during product development

Classical sinusoidal vibration never observed in service; useful concept

  • Introduction: terminology, importance of understanding resonant behavior
  • Electrohydraulic and electrodynamic shaker systems
  • Resonance searches and dwells

Introduction to random vibration

  • Sources of random vibration in service and transportation
  • Spectral density measurement and analysis – the frequency domain
  • Probability density – the time domain

Random vibration test practice – simulation

  • Interpreting, implementing, ignoring military standards, e.g. MIL-STD-810
  • Recommended test practices, e.g. IEST
  • Equalization before testing; methods and limits

Determining and extending limits – stimulation

  • HALT – highly accelerated life testing during product development
  • HASS – highly accelerated stress screening (post production)
  • ESS – Environmental stress screening of electronics hardware production
  • Philosophical differences from testing – stimulation vs. simulation Multiple- vs. conventional single-axis-at-a-time vibration
  • Conventional single-axis
  • Mechanical and pneumatic repetitive shock (RS) stimulators

Attachment fixtures; vacuum hold-downs

Additional climatic verification test methods: temperature, altitude, humidity, salt spray, etc. as time permits

Summary of course for management and participants

 

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