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Environmental Testing Procedures

Course No. 425

(Course Outline shown below.)

For Whom Intended This course is for test laboratory managers, engineers and technicians. It also helps quality and reliability specialists and acquisition personnel in government and military activities and their contractors. It is designed to serve the needs of personnel in a wide range of industries.

Brief Course Description The course begins with an introduction and review of the many factors that must be addressed in order to undertake a meaningful environmental test. The instructor next discusses various environmental test applications such as product development, reliability, acceptance, qualification, life cycle, fatigue, accelerated, functional, endurance etc. Specific types of environmental tests such as vibration, shock, climatic, ESS/EST are discussed in detail.

For each testing environment, the course covers discussion of physical test facilities and an overview of the test equipment, including instrumentation and fixtures. Students will gain familiarity with specific test procedures, including test levels and durations. The process starts with a review of all applicable documents, such as specifications and standards, and defining what is expected from the test. Options such as test tailoring and deviation from written requirements of test documentation will be explored.

The course is presented as a series of highly-interactive lecture/discussion sessions. Special-interest discussions are encouraged outside of the regular course sessions.

Certificate Programs This course is required for TTi’s Environmental Engineering Specialist (EES) and Climatic Test Specialist (CTS) Certificate programs. It is an elective for any other TTi specialist certificate program.

Prerequisites There are no definite prerequisites. However, this course is aimed toward individuals involved in related technical fields. Supervisors are invited to contact TTi on prospective attendees’ backgrounds and needs.

Text Each student will receive a course workbook, including most of the viewgraphs used in the course presentation.

Course Hours, Certificate and CEUs Open courses meet seven hours per day. Upcoming presentation dates can be found on our current open course schedule. Class hours/days for on-site courses can vary from 14-35 hours over 2-5 days as requested by our clients. Upon successful course completion, each participant receives a certificate of completion and one Continuing Education Unit (CEU) for every ten class hours.

Course Outline No. 425

Introduction to Environmental Test Procedures
- Environment Simulation
- Simulation Complexity
- Test Tailoring
- Test Facilities
  - Adaptability
  - Control Capability
  - Consistency
Environmental Testing
- Objective
- Testing a Hypothesis
- Development Testing
- Design Verification Test
- Conservatism and Margins
- Qualification Testing
- Development Tests: Accelerated Testing
- “Life” Testing
- Types of “Life” Tests
  - Short-Term: Step-Stress
  - Long-Term: Fatigue & Durability
- Fatigue Life vs. Service Life
- Acceptance Testing
- Contractual Compliance Testing
- Production Test
- Monitoring Production Quality
Review of Vibration Theory
- Degrees of Freedom
- Single-Degree-of-Freedom (SDoF)
- SDoF--Sinusoidal Relationships
- Calculating Natural Frequency
- Forced Vibration
- Transmissibility
- Effect of Damping
- Isolation
- Damping Ratio
- Random Vibration
  - Special Definitions
  - Spectral Density
  - Calculating the RMS
Vibration Test Procedures
- Sine Vibration Testing
- Closed Loop Control
- Sweep Rates
- Resonant Search
- Fixture Evaluation
- Random Vibration Testing
- Choice of Test Procedures
- Types of Vibration tests
  - Swept Sine
  - Fixed Sine
  - Wide Band Random
  - Fixed Center Frequency Narrow Random
  - Swept Narrow Random
  - Combinations
- Vibration Test Method: Equipment Operation, Severities
- Information Required
- Tolerances: Sinusoidal and Random Vibration
- Excitation Control Options
- Test Set-up and Preparation
- Test Procedures
Review of Shock Theory
- What is Shock?
- Measuring and Analyzing Mechanical Shock
- Shock Response Spectrum
- Shock Synthesis
- Pulse Characterization
- Classical Shock
- Pulse Characterization
- Pulse Compensation
Shock Test Procedures
- Shock Tests
  - Purpose, Application
- Effect of Environment
- Pneumatic Drop Test Machine
- Free-Fall Machine
- Navy Impact Machines
  - “Light-Weight” Shock Tester
  - Pendulum Type
- Transients
  - Moderate-Level and/or Mid-Frequency Transients
  - Low Frequency Transients
  - Oscillatory Transients
- Decaying Oscillatory Acceleration
- Shock from Vibration Shaker
- Equipment Operation, Severities
- Tolerances
- Control Strategy
- Gravity and the Load Factor
- Test Setup
- Calibration
- Sample Shock Test Procedures
  - Functional
  - Transit Drop
  - Bench Handling
  - Crash Hazard
  - Rail Impact
  - Pyrotechnic Shock
- Failure Criteria
- Protective Packaging
- Product Fragility
- Damage Boundary Theory
- Step Velocity and Step Acceleration
- Damage Boundary Graph
Climatic Testing Procedures
- Low Temperature
- High Temperature
- Temperature Shock
- Temperature Cycling
- Humidity
- Humidity Cycling
- Solar Radiation
- Rain Test
- Salt Fog
- Sand and Dust
- Industrial Atmosphere (Gaseous)
- Fungus
Accelerated Testing
- Reducing Test Time
- Test Assumptions
- Which Environmental Forcing Functions Are Best?
- Rates of Test Acceleration
- Accelerated Test Models
- Miner’s “Rule”
- Principles of Test Time Compression
- Two Types of Test Acceleration
  - Higher Frequency of Occurrence
  - Exaggerate Load Levels
- Accelerated Test Cautions
Environmental Stress Screening
- Production Process Screening
- What is ESS?
  - ESS vs. Hardware Test
  - Background
  - NAVMAT P-9492
  - Environments
  - Screen Characteristics
  - Designing an ESS Process
  - Rules of Successful ESS
Application of Vibration in Environmental Stress Testing
- What does Vibration do?
- Excitation options: Electrodynamic
- Repetitive Impact
- ESS random vibration spectrum
- Selecting a vibration screen
- Linear vs. non-linear product response
- Level of assembly
- Hidden vibration test assumptions
- Vibration surveys
- Measurement philosophy
- Accelerometers
- Data acquisition
Appendix
- ISO/IEC Guide 25
- ESS Experiment
- MIL-STD-810E, F
Summary, Discussion
Award of Certificates for Successful Completion

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