TY - GEN
T1 - Optimization of imperfection-insensitive continuous tow sheared rocket launch structures
AU - Lincoln, Reece L.
AU - Weaver, Paul M.
AU - Pirrera, Alberto
AU - Groh, Rainer M.J.
N1 - Publisher Copyright:
© 2021, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved.
PY - 2021
Y1 - 2021
N2 - Geometric imperfection sensitivity is the largest influencing factor that limits the design of thin-walled monocoque cylinders. Current generation cylindrical architectures, such as those found in rocket launch vehicles, rely on the use of sandwich or blade-stiffened structures to reduce the imperfection sensitivity of the cylinder. Whilst much research has focused on the creation of new knockdown factors that relate to the modern architectures used, this paper focuses on reducing the imperfection sensitivity of a monocoque cylinder from a design perspective. Variable-angle composites that steer the fibers in curvilinear paths offer an opportunity to design structural load paths. By steering the fibers, the effective area over which geometric imperfections influence the buckling behavior of the cylinder is reduced. This diminishes the imperfection sensitivity of thin-walled cylinders undergoing axial compression. Continuous Tow Shearing (CTS) is one such variable-angle manufacturing technique. It does not cause common in-process manufacturing defects associated with Automated Fiber Placement, such as fiber wrinkling or fiber buckling. In addition, there is a shearing anglethickness coupling that results in local thickness build-ups, which, whilst potentially increasing the mass of the structure, enable embedded stiffeners to be created by shearing the tows. Three genetic algorithm (GA) optimizations are carried out to maximize the imperfect massspecific buckling load to investigate the efficacy of CTS and tow-steered designs in reducing imperfection sensitivity. The first optimization considers idealistic manufacturing capabilities with a random geometric imperfection. The second and third optimizations consider current manufacturing capabilities and are compared against one another to analyze the use of a evolutionary hybrid GA and a probabilistic, reliability-based GA. In all three optimizations, the optimum laminate from the GA demonstrates imperfection insensitivity.
AB - Geometric imperfection sensitivity is the largest influencing factor that limits the design of thin-walled monocoque cylinders. Current generation cylindrical architectures, such as those found in rocket launch vehicles, rely on the use of sandwich or blade-stiffened structures to reduce the imperfection sensitivity of the cylinder. Whilst much research has focused on the creation of new knockdown factors that relate to the modern architectures used, this paper focuses on reducing the imperfection sensitivity of a monocoque cylinder from a design perspective. Variable-angle composites that steer the fibers in curvilinear paths offer an opportunity to design structural load paths. By steering the fibers, the effective area over which geometric imperfections influence the buckling behavior of the cylinder is reduced. This diminishes the imperfection sensitivity of thin-walled cylinders undergoing axial compression. Continuous Tow Shearing (CTS) is one such variable-angle manufacturing technique. It does not cause common in-process manufacturing defects associated with Automated Fiber Placement, such as fiber wrinkling or fiber buckling. In addition, there is a shearing anglethickness coupling that results in local thickness build-ups, which, whilst potentially increasing the mass of the structure, enable embedded stiffeners to be created by shearing the tows. Three genetic algorithm (GA) optimizations are carried out to maximize the imperfect massspecific buckling load to investigate the efficacy of CTS and tow-steered designs in reducing imperfection sensitivity. The first optimization considers idealistic manufacturing capabilities with a random geometric imperfection. The second and third optimizations consider current manufacturing capabilities and are compared against one another to analyze the use of a evolutionary hybrid GA and a probabilistic, reliability-based GA. In all three optimizations, the optimum laminate from the GA demonstrates imperfection insensitivity.
UR - http://www.scopus.com/inward/record.url?scp=85100299749&partnerID=8YFLogxK
U2 - 10.2514/6.2021-0202
DO - 10.2514/6.2021-0202
M3 - Conference contribution
AN - SCOPUS:85100299749
SN - 9781624106095
T3 - AIAA Scitech 2021 Forum
SP - 1
EP - 19
BT - AIAA Scitech 2021 Forum
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2021
Y2 - 11 January 2021 through 15 January 2021
ER -