Engineering topics

Andrew J Lee

Publications and source records attributed to Andrew J Lee.

3 records

NASA NTRS2019

Inducing Bistability in Collapsible Tubular Masts Booms with Thin-Ply Composite Shells

Bistable rollable booms are favorable when a low strain energy requirement for the coiled state is imposed and have more controllable deployment when compared to monostable booms. An inextensional analytical model describing the bending deformation mechanics of Collapsible Tubular Mast (CTM) booms was used to determine how design variables induce bistability, or the existence of two strain energy wells in the rolled-up and unrolled states. The effects of varying lamina material, laminate layup, and shell arc geometries between different inner and outer shell segments on the second strain energy well and stiffness properties were determined for boom cross-sections formed by circular segments. The full design space for two-walled composite CTM booms was explored to evaluate the validity of the developed analytical model. Optimized CTM boom designs were experimentally characterized for comparisons against model results. The model under-predicted the stable coiled diameter of the co-cured two-walled booms by up to 8.9% and 23.4% for the individual thin shells wrapped alone.

Andrew J Lee↗

NASA NTRSDate not supplied

Structural Architectures for Self-Erecting Lunar Towers

The load carrying performance for deployable lunar tower architectures utilizing thin-ply composite booms are parametrically evaluated in this paper. These self-erecting towers support a communications and sensor platform on the lunar surface. The primary design consists of the Corrugated Rollable Tubular Boom (COROTUB) acting as the primary mast of the tower which supports the payload tip mass. Guy wires connecting the boom tip to spreader bars attached at the base deployer serve to correct any lateral eccentricities and provide dimensional stability. The analysis compares the maximum tip mass that this primary design can carry relative to a reference design that does not contain any guy wires or spreader bars. The results provide insights into whether the additional system mass and complexity associated with the cable-stayed design is worth the increased payload mass that can be supported. By setting the design limiting condition to a nominal maximum allowable deflection, the analysis reveals that primary design outperforms reference design for the majority of the design space. This outcome is found to be the case when the spreader bar length relative to the tower height exceeds7 a critical value. The analysis is extended to lunar towers with Collapsible Tubular Mast (CTM) booms, and similar trends are observed.

Jacob G Daye↗

NASA NTRSDate not supplied

Structural Architectures for Self-Erecting Lunar Towers

The load carrying performance for deployable lunar tower architectures utilizing thin-ply composite booms are parametrically evaluated in this paper. These self-erecting towers support a communications and sensor platform on the lunar surface. The primary design consists of the Corrugated Rollable Tubular Boom (COROTUB) acting as the primary mast of the tower which supports the payload tip mass. Guy wires connecting the boom tip to spreader bars attached at the base deployer serve to correct any lateral eccentricities and provide dimensional stability. The analysis compares the maximum tip mass that this primary design can carry relative to a reference design that does not contain any guy wires or spreader bars. The results provide insights into whether the additional system mass and complexity associated with the cable-stayed design is worth the increased payload mass that can be supported. By setting the design limiting condition to a nominal maximum allowable deflection, the analysis reveals that primary design outperforms reference design for the majority of the design space. This outcome is found to be the case when the spreader bar length relative to the tower height exceeds a critical value. The analysis is extended to lunar towers with Collapsible Tubular Mast (CTM) booms, and similar trends are observed.

Jacob G Daye↗