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
