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Adapt/combine known methods to demonstrate an expert judgment elicitation process that: 1.Models expert's inputs as a triangular distribution, 2.Incorporates techniques to account for expert bias and 3.Is structured in a way to help justify expert's inputs. This paper will show one way of "extracting" expert opinion for estimating purposes. Nevertheless, as with most subjective methods, there are many ways to do this.
Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L(sub 4) and L(sub 5) and the collinear point L(sub 3) of the Circular Restricted Three-Body Problem (CRTBP) in the Sun-Earth system.
Metallic triangular rollable and collapsible (TRAC) booms have deployed two Cubesat-based solar sails in low Earth orbit, making TRAC booms the most popular solar sail deployment method in practice. This paper presents some concerns and solutions surrounding the behavior of these booms in the space thermal environment. A 3.5-cm-tall, 4-meter-long TRAC boom of Elgiloy cobalt alloy, when exposed to direct sunlight in a 1 AU deep space environment, has a predicted tip motion of as much as 0.5 meters. Such large thermal deflections could generate unacceptable distortions in the shape of a supported solar sail, making attitude control of the solar sail spacecraft difficult or impossible. As a possible means of mitigating this issue, the thermal distortion behaviors of three alternative material TRAC booms are investigated and compared with the uncoated Elgiloy baseline boom. A tenfold decrease in induced curvature is shown to be possible relative to the baseline boom. Potential thermal distortions of the LightSail-A solar sail TRAC booms are also examined and compared, although inconclusively, with available on-orbit camera imagery.
Finite element analysis is used to investigate Triangular Rollable and Collapsible (TRAC) composite booms. The TRAC booms are subjected to a suite of loading conditions, including in-plane bending, out-of-plane bending, and axial compression. Simulations containing as-designed boom geometry are performed, as are simulations with geometric deviations associated with the as-built conditions of a sample TRAC boom. Namely, a cross-sectional twist along the length of the boom is incorporated into the analysis to study the effect of the twist on the deformation characteristics of the boom. Twisting in the sample boom was observed after short-term storage in a rolled configuration and may be attributed to differential creep deformation between the inner and outer flanges of the TRAC boom. Simulations are conducted with and without the effects of gravity to understand the significance of gravity on testing conditions. Booms of three lengths are evaluated: 3 meters, 7.5 meters and 30 meters. The mechanical responses of the TRAC booms are discussed with reference to the effects of gravity, boom length and cross-sectional twisting. Gravity is found to have a more significant effect on boom mechanical response as boom length is increased. Cross-sectional twisting is found to have a more significant effect on boom mechanical response in the shorter booms.
High-strain composite deployable space structures are used for space infrastructure and science applications such as solar array supports, antennae, camera masts, and lightweight structures supporting solar sailing propulsion ele-ments. Triangular, Rollable, and Collapsible (TRAC) deployable composite booms are one example of a high-strain composite deployable structure and were studied using novel experimental test and characterization methods developed under the Gravity Offloading and Analysis of Long Imperfection-sensitive Ele-ments (GOALIE) project. In the present work, a subscale 7-m-long TRAC boom was suspended vertically to orient gravity along the length of the boom. By ori-enting vertically, highly nonlinear and unstable behavior often encountered dur-ing horizontally oriented gravity offload testing of similar structures was reduced. Pretest analytical predictions of TRAC booms indicated three unique failure modes, loads, and locations for three unique loading cases of in-plane bending, out-of-plane bending, and axial compression. To investigate the predicted behav-ior, an experimental test was set up to impart mechanical loads to a subscale TRAC boom. The experimental setup, loading cases, and instrumentation used to characterize the mechanical response of a subscale TRAC boom are described in this paper.
Finite element analysis is used to investigate Triangular Rollable and Collapsible (TRAC) composite booms. The TRAC booms are subjected to a suite of loading conditions, including in-plane bending, out-of-plane bending, and axial compression. Simulations containing as-designed boom geometry are performed, as are simulations with geometric deviations associated with the as-built conditions of a sample TRAC boom. Namely, a cross-sectional twist along the length of the boom is incorporated into the analysis to study the effect of the twist on the deformation characteristics of the boom. Twisting in the sample boom was observed after short-term storage in a rolled configuration and may be attributed to differential creep deformation between the inner and outer flanges of the TRAC boom. Simulations are conducted with and without the effects of gravity to understand the significance of gravity on testing conditions. Booms of three lengths are evaluated: 3 meters, 7.5 meters and 30 meters. The mechanical responses of the TRAC booms are discussed with reference to the effects of gravity, boom length and cross-sectional twisting. Gravity is found to have a more significant effect on boom mechanical response as boom length is increased. Cross-sectional twisting is found to have a more significant effect on boom mechanical response in the shorter booms.
High-strain composite deployable space structures are used for space infrastructure and science applications such as solar array supports, antennae, camera masts, and lightweight structures supporting solar sailing propulsion elements. Triangular, Rollable, and Collapsible (TRAC) deployable composite booms are one example of a high-strain composite deployable structure and were studied using novel experimental test and characterization methods developed under the Gravity Offloading and Analysis of Long Imperfection-sensitive Elements (GOALIE) project. In the present work, a subscale 7-m-long TRAC boom was suspended vertically to orient gravity along the length of the boom. By orienting vertically, highly nonlinear and unstable behavior often encountered during horizontally oriented gravity offload testing of similar structures was reduced. Pretest analytical predictions of TRAC booms indicated three unique failure modes, loads, and locations for three unique loading cases of in-plane bending, out-of-plane bending, and axial compression. To investigate the predicted behavior, an experimental test was set up to impart mechanical loads to a subscale TRAC boom. The experimental setup, loading cases, and instrumentation used to characterize the mechanical response of a subscale TRAC boom are described in this paper.
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This seminar focuses on its applications to geoprocessing, leaving aside its applications to cartography.
Aileron effectiveness & dihedral effect of wing- body combination with variable-incidence wing & half-delta controls at wing tips
Free flight tests of lifting surface reentry vehicles at mach 0.6 to 1.5
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Pressure distribution at supersonic speeds on conically cambered wing with and without pylon mounted engine nacelles
Stress calculations in linear thin shells of aeolotropic material using deflections obtained by finite element method
Linear heat transfer problems inside equitriangular region solved by integral transform series
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