A team of NASA engineers is exploring an advanced composite solution that someday might be used to create boosters even more powerful than the massive solid rocket booster for the agency’s Space Launch System (SLS). To understand how well these new materials could withstand the immense strains of a launch, the engineers conducted a test that involved pressurizing a booster structure made of composite materials to its breaking point to see how it compares with the metallic booster cases currently used.
In the case burst test conducted by Orbital ATK of Promontory, Utah, a booster case 25 feet long and 92 inches in diameter was subjected to 3,000 pounds per square inch of pressure – well beyond what would be encountered in flight conditions – to verify exactly what loads the composite material could withstand.
“The test is very dramatic,” says Angie Jackman of the SLS Spacecraft/Payload Integration and Evolution office at NASA’s Marshall Space Flight Center in Huntsville, Ala., where the SLS Program is managed for the agency. “When composites fail, it’s the glue or the resin that fails first — not the fiber that fails. There’s a big boom, and it’s all spaghetti.”
Before the test, damage was purposefully caused at multiple points on the case to study what effect it would have on how the case fared. The damaged case performed as well as an intact case, demonstrating not only that the composite case could withstand the rigors of launch, but that it could do so even in a damaged condition.
During the test, the case failed within 1 percent of pretest estimates, validating the models for strength of the composites. The rocket motor case test is part of an effort to optimize a composite case design that may be stronger and lighter, yet more affordable than traditional steel cases. In turn, this would provide increased payload performance due to reduced weight inherent in composite materials.