Ozden O. Ochoa
Hybrid Composites: Similitude and Performance
Cherif Saadane Chouchaoui (PostDoc), Paul Parks (UG student)
The design of hybrid composite structures is complicated by the number of design variables and the interaction of the constituents of the composite system. Since it is desirable to experimentally test the design and it is not practical to test a full scale riser model, the structural/material similitude concept will be applied to create a small scale model with a similar (close to identical) structural response. The structural/material similitude concepts for composite shells will be developed to assess the dynamic response of hybrid tubes as prototypes and models for potential wave basin testing.
The results enable the design community to select models and prototypes so that realistic structural performance of composite tubulars at multiple scales can be addressed.
The coefficients of the governing differential equation for a system and a model of the system are compared to develop scaling laws. The current analytical efforts will be extended to include axial tension, internal and external pressure in addition to bending loading conditions in the governing equations with appropriate constitutive equations. Further parametric evaluation of hybrid (glass-carbon) versus all carbon reinforced tubes will be undertaken to assure that identical failure initiation mode occurs in the prototype as well as the wave basin models. The analytical computational programs (in FORTRAN) developed for similitude , optimization and laminated shell stress-strain analysis will be integrated into a single preliminary design tool which will reside in the virtual basic format enabling interactive sessions with the user.
NIST sponsored ATP programs(leading companies Nortrop Grumman, Shell, Hydril) are addressing similar issues in long term response of composites in marine environment.
Hybrid composites offer both optimization and scaling options to tailor the design of tubulars effectively and efficiently.
October 1992 to September 1997
Mechanical and material properties of saturated hybrid composites
Software/programs for optimization and similitude algorithms:
1. " Material and Structural Characterization of Composite Tubulars," Keynote Address, Asia-Pacific Conference on Offshore Systems: Mobile and Floating Structures, Kuala Lumpur, Malaysia, December 1996.
2. " Design of Hybrid Composite Tubulars," OMAE, Florence, Italy, June 1996.
1. " Hybrid Composite Design: Optimization and Scaling Aspects," ISOPE, May 1996.
2;. " Micromechanical Analysis of Hybrid Composites," Reinforced Plastics and Composites, 16, pp.828- 836, 1996.