COPV Course Syllabus

Course Syllabus

Day 1 – Afternoon

General introduction to geometry and structure of high-pressure COPV

  1. Definitions and Examples
  2. Spherical and Cylindrical COPV architecture and wind pat­terns
    – Overwrap wind patterns and implications
  3. Overwrap materials: Kevlar®, carbon, S2-Glass, Zylon®
    – Associated fiber properties
  4. Liner materials: aluminum, titanium, Inconel, stainless steel, HD polyethylene
    -Corresponding mechanical properties
  5. Manufacturing processes: wet winding, prepregs and pre­preg winding, elevated temperature curing,
  6. Manufacturing: autofrettage

COPV safety considerations

  1. Consequences of Failure
  2. Calculating potential blast energy
  3. Blast Fragmentation Analysis
  4. Effects of contained gases, loss of life support atmo­sphere
  5. Effects of combustion and fire

Failure modes:

  1. Liner fatigue (parent material and welds)
  2. Composite Stress Rupture
  3. Collateral damage/impact damage
  4. Liner failure during autofrettage or first pressurization
  5. Liner buckling

Certification standards

  1. NASA Requirements
    – Commercial Crew Requirements (ESMD-CCTSCR-12.10) and flow down to CCT-REQ-1130 and others
    – ISS Visiting Vehicle Requirements (SSP 50808 and 30558/30559)
    – Unmanned Programs
  2. AIAA USA Standard (S-081, S-081a and future versions)

Day 2


COPV Safety test and analyses

  1. Analyses
    – Leak Before Burst and Safe Life
    – Establishing material allowables
  2. Test requirements
    – Autofrettage and proof testing
    – Burst Tests
    – Cycle Tests
    – Vibration and Thermal/vacuum Tests
  3. Qualification and Acceptance Test Programs
    – Establishing fiber variability within a lot and between lots
    – COPV unit and lot acceptance testing
    – Acceptance criteria

Day 2


Damage Control Plans

  1. Visual Inspection Considerations
  2. Handling and Transporting Considerations
  3. Protective Devices

Ground Safety Considerations

  1. Ground Processing Requirements
  2. Range Safety Considerations
  3. Considerations for Risk to Ground Personnel and Exposure to the Public

Design Considerations

  1. Basic Concepts and Definitions
    – Elastic vs. Plastic Response of composite
  2. Introduction to orthotropic elasticity of a lamina
    – Unidirectional composite forms (tow, band, lamina)
    – Definition of various moduli and Poisson’s ratios
    – Layered composite stiffness properties
    – Through thickness compression (important to thick over­wraps)
  3. Thermal effects in overwrap mechanical response
    – Thermal expansion coefficients (fibers, liners and COPV)
    – Effects of temperature excursions on overwrap and liner response

Day 3


Winding pattern design

  1. Implications on overwrap shear stress profiles within layers and between layers
  2. Isotensoid and other dome designs in cylindrical pressure vessels
  3. Theoretical models for liner and overwrap response
  4. Shear stress behavior and influence on the liner
  5. Potential for delamination and debonding
  6. Effects of winding pattern on impact damage sensitivity

Autofrettage, purpose and risks in implementation

  1. Effect on stress state
  2. Role of Bauschinger effect
  3. Connection to buckling risk and fatigue risk

Day 3


Approaches to liner fatigue modeling under pressure cycling

  1. Advanced fracture mechanics approaches, modeling fa­tigue crack growth (connection to Safe Life and Leak Before Burst concepts)
  2. Description of NASA-developed NASGRO, fracture me­chanics and fatigue crack growth analysis software
  3. NDE methods for detecting small cracks and flaws (prob­abilities of detection)
  4. Strain-life models (Morrow, Fatemi-Socie)
  5. Cyclic stress-strain laws (Ramberg-Osgood)
  6. MLE-based statistical analysis approaches, reliabil­ity modeling, test data generation, including size effects, uncertainty

Day 4


Liner buckling

  1. Mechanical models (including effects of autofrettage)
  2. Bonded vs. unbonded liners
  3. Triggers and methods of prevention
  4. Rippling effects from wrap pattern imprint

Overwrap stress-rupture phenomena and reliability modeling

  1. Fiber Strand and Vessel (including sub-scale) Testing Phenomenological power-law/Weibull models and relating strength and life in one parameter set
  2. Mechanism of stress rupture based on fiber Weibull flaw statistics and micromechanical matrix creep
  3. Material data bases, data generation and, uncertainty quan­tification in reliability prediction
  4. Temperature and size effects in stress-rupture modeling and accelerated testing
  5. Relevance of Safety Factors as provided in standards

Day 4


Nondestructive evaluation (NDE) of liner, and crack and flaw detection techniques

  1. Visual (dents, scuff marks)
  2. Dye penetrant methods
  3. X-ray and ultrasonic
  4. Eddy current
  5. Borescope based profilometry

Overwrap NDE to detect broken tows, wraps and de­lamination

  1. Acoustic emission during proof testing or autofrettage
  2. Flash/infrared thermography
  3. Laser shearography
  4. Digital image correlation of overwrap strains during proof (or burst testing) and high resolution video byproduct
  5. Visual and ultrasonic techniques

Day 5


  1. Special Considerations: Operating COPVs in the Space Environment: Protecting against Micro Meteoroid and Orbital Debris (MMOD); End of Life and Disposal of Pressure Vessels which Have Stored Hypergolic Fluids
  2. Special Topic – USC Rocket Propulsion Laboratory: Experi­ences Modeling a Composite Combustion Chamber
  3. New concepts in pressure vessel standards: proposed changes to AIAA S-081b and ISO 1119-x including the newly introduced ISO 11119-4
  4. Standards for the Automotive Industry. Comparison of standards applicable for transport on public roads for stored hydrogen and compressed natural gas with standards in the aerospace sector.
  5. Summary – revisit failure methods, and traceability to certifi­cation standards and importance of design considerations

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