Composite Overwrapped Vessels Research Articles

Simulation Analysis of Delamination Damage for the Thick-Walled Composite-Overwrapped Pressure Vessels.

In order to verify the delamination damage occurring in thick-walled composite-overwrapped pressure vessels, firstly, for composite delamination damage, a composite laminate model was established. Model I and model II delamination failure processes of composite structures were simulated and verified based on a tiebreak contact algorithm for different mesh sizes, respectively, and the approximate equivalent results were achieved by correcting the inter-ply strength. Then, for in-plane damage to composite materials, the elastic–plastic process was verified by selecting a progressive damage model, with quasistatic nonlinear tensile shear of sample specimens as an example. Further, under the purpose of generality and simplicity, the location of the first occurrence of delamination failure was simulated and analyzed with the tiebreak contact algorithm and a reasonable mesh size, using quasistatic loading of a thick composite-overwrapped pressure vessel cylindrical section as an example. The results showed that delamination occurred at approximately the center, which is in general agreement with the experimentally observed phenomenon. On this basis, the locations of the first significant delamination phenomena in composite-overwrapped vessels under three different ratios of plus or minus 45-degree layup angles were predicted. Finally, the differences in structural strength between the single laying methods and the combined laying method were compared. The results showed that the ratio of 50% had a higher modulus value than a pure 0° ply, but too large a ratio was detrimental to the improvement of structural properties.

Potential Composite Structures for NASA Future Launch Vehicles and Crew Spacecraft

Because of their well known specific strength, stiffness and excellent durability properties, advanced composites are being considered for primary structures in launch vehicles, crew modules and various components for increased performance and cost reduction. Therefore, it is prudent and beneficial to review the engineering practices and lessons learned in connection with their use in related aeronautic and energy applications, where they are already replacing formerly used metallic materials. Examples of composite components will be shown for the reusable space shuttle orbiter where a number of different composite systems performed very satisfactorily. In addition, very large potential polymer composite designs for future launch vehicles will be discussed. Among them are payload shrouds, interstage structures and the typical intertank shell, wherein thrust booster rockets are often attached between the core stage propellant and oxidizer tanks. In addition, cryogenic propellant composite vessels of different sizes and shapes were fabricated with mostly excellent results, although some spectacular failures were also observed. High pressure composite overwrapped vessels, with and without metallic liners, will be described. Compared to widely used metallic materials, some special features of composites are listed. Relevant design allowables, depending on mission requirements, will be summarized and currently used design practice for aircraft and spacecraft in the US will be reviewed. The well-known “building - block” approach, which is often used to design military as well as civilian aircraft, will be summarized. Some of the most popular micromechanics and macromechanics computer programs used to analyze composite structures, especially with finite elements, will be listed. Although very high temperature composites like carbon/carbon, carbon/ceramic and ceramic/ceramic fiber/matrix systems are also selectively used, the focus in our discussion will be on advanced polymer matrix, carbon/glass fiber systems.