Draft Agenda
Day 1: Morning
1. General introduction to geometry and structure of high-pressure COPV
a. Definitions and Examples
b. Spherical and Cylindrical COPV architecture and wind patterns
• Overwrap wind patterns and implications
c. Overwrap materials: Kevlar®, carbon, S2-Glass, Zylon®
• Associated fiber properties
d. Liner materials: aluminum, titanium, Inconel, stainless steel, HD polyehtylene
• Corresponding mechanical properties
e. Manufacturing processes: wet winding, prepregs and prepreg winding, elevated temperature curing,
f. Manufacturing: autofrettage
2. COPV safety considerations
a. Consequences of Failure
• Calculating potential blast energy
• Blast Fragmentation Analysis
• Effects of contained gases, loss of life support atmosphere
• Effects of combustion and fire
b. Failure modes:
• Liner fatigue (parent material and welds)
• Composite Stress Rupture
• Collateral damage/impact damage
• Liner failure during autofrettage or first pressurization
• Liner buckling
3. Certification standards
• 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
• AIAA USA Standard (S-081, S-081a and future versions)
• MIL-STD-1522
• Other requirements and standards (ISO, EU, UN)
Day 1: Afternoon
Computational Workshop A
In this workshop the user step through the entire process of generating an axisymmetric model of a COPV and post processing the results using the Wound Composite Modeler.
The model will consist of helical layers with and without friction and hoop layers.
4. COPV Safety test and analyses
a. Analyses
• Leak Before Burst and Safe Life
• Establishing material allowables
b. Test requirements
• Autofrettage and proof testing
• Burst Tests
• Cycle Tests
• Vibration and Thermal/vacuum Tests
c. Qualification and Acceptance Test Programs
• Establishing fiber variability within a lot and between lots
• COPV unit and lot acceptance testing
• Acceptance criteria
Day 2: Morning
5. Damage Control Plans
a. Visual Inspection Considerations
b. Handling and Transporting Considerations
c. Protective Devices
6. Ground Safety Considerations
a. Ground Processing Requirements
b. Range Safety Considerations
c. Considerations for Risk to Ground Personnel and Exposure to the Public
7. Design Considerations
a. Basic Concepts and Definitions
• Elastic vs. Plastic Response of composite
b. 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
c. Thermal effects in overwrap mechanical response
• Thermal expansion coefficients (fibers, liners and COPV)
• Effects of temperature excursions on overwrap and liner response
Day 2: Afternoon
Computational Workshop B
This workshop extends to concepts learned in the
first workshop to the creation of a three-dimension COPV.
8. Winding pattern design
a. Implications on overwrap shear stress profiles within layers and between layers
b. Isotensoid and other dome designs in cylindrical pressure vessels
c. Theoretical models for liner and overwrap response
d. Shear stress behavior and influence on the liner
e. Potential for delamination and debonding
f. Effects of winding pattern on impact damage sensitivity
9. Autofrettage, purpose and risks in implementation
a. Effect on stress state
b. Role of Bauschinger effect
c. Connection to buckling risk and fatigue risk
Day 3: Morning
10. Approaches to liner fatigue modeling under pressure cycling
a. Advanced fracture mechanics approaches
modeling fatigue crack growth (connection to Safe Life and Leak Before Burst concepts)
b. Description of NASA-developed NASGRO, fracture mechanics and fatigue crack growth analysis software
c. NDE methods for detecting small cracks and flaws (probabilities of detection)
d. Strain-life models (Morrow, Fatemi-Socie)
e. Cyclic stress-strain laws (Ramberg-Osgood)
f. MLE-based statistical analysis approaches
Reliability modeling, test data generation, including size effects, uncertainty
Day 3: Afternoon
Computational Workshop C
This workshop demonstrates the use of the Wound Composite Modeler (WCM) as a COPV design tool. The WCM will be used to gauge the effect of parameters such as wind angle, number of layers, and liner materials on the maximum stresses which occur in a COPV due to a standard operating pressure.
11. Liner buckling
a. Mechanical models (including effects of autofrettage)
b. Bonded vs. unbonded liners
c. Triggers and methods of prevention
d. Rippling effects from wrap pattern imprint
12. Overwrap stress-rupture phenomena and reliability modeling
a. Fiber Strand and Vessel (including sub-scale) Testing
b. Phenomenological power-law/Weibull models and relating strength and life in one parameter set
c. Mechanism of stress rupture based on fiber Weibull flaw statistics and micromechanical matrix creep
d. Material data bases, data generation and, uncertainty quantification in reliability prediction
e. Temperature and size effects in stress-rupture modeling and accelerated testing
f. Relevance of Safety Factors as provided in standards
Day 4: Morning
13. Nondestructive evaluation (NDE) of liner, and crack and flaw detection techniques
a. Visual (dents, scuff marks)
b. Dye penetrant methods
c. X-ray and ultrasonic
d. Eddy current
e. Borescope based profilometry
14. Overwrap NDE to detect broken tows, wraps and delamination
a. Acoustic emission during proof testing or autofrettage
b. Flash/infrared thermography
c. Laser shearography
d. Digital image correlation of overwrap strains during proof (or burst testing) and high resolution video byproduct
e. Visual and ultrasonic techniques
15. Nondestructive evaluation (NDE) of liner, and crack and flaw detection techniques
a. Visual (dents, scuff marks)
b. Dye penetrant methods
c. X-ray and ultrasonic
d. Eddy current
e. Borescope based profilometry
16. Overwrap NDE to detect broken tows, wraps and delamination
a. Acoustic emission during proof testing or autofrettage
b. Flash/infrared thermography
c. Laser shearography
d. Digital image correlation of overwrap strains during proof (or burst testing) and high resolution video byproduct
e. Visual and ultrasonic techniques
Day 4: Afternoon
Computational Workshop D
This workshops demonstrates the concept of autofrettage. An autofrettage analysis will be performed to demonstrate how tensile stresses in the liner may be reduced in order to extend the fatigue life of a COPV.
17. Special Topic- USC Rocket Propulsion Laboratory: Experiences Modeling a Composite Combustion Chamber
18. Summary-Revisit Failure Methods, and traceability to certification standards and importance of design considerations