Coupled Radiative Thermal and Nonlinear Stress Analysis for Thermal Deformation in Large Space Structures

Large space structures are capable of large thermal deformations in the space environment. A case of large-scale thermal deformation was observed in the analysis of the Near Earth Asteroid Scout solar sail, with predicted tip displacements of more than one meter in seven-meter booms. Experimental data supports the broad conclusions of the analysis, but shows poor agreement on the details of the thermal deformation. Prediction that is precise enough to drive engineering decisions will require coupled thermal-stress analysis with features that are not found in current multiphysics codes. This paper describes a simple method for stepwise coupling between commercial nonlinear stress analysis software and radiative thermal analysis software. Results are presented for a round stainless steel tube, which is a common case in existing literature

Shape Accuracy of a Joint-Dominated Deployable Mast

This paper presents a study to capture and model friction related changes in the un-loaded configuration of deployable masts with articulated joints. A finite model of a rep-resentative mast structure is described. This model includes a detailed treatment of the latching mechanism. The parameters of the computational model are based on direct mea-surements on components of a physical model. The moment-rotation relationship for a complete single bay of the physical model has been measured and the overall behavior is predicted well by the model, however the model predicts the residual rotation at zero moment to be zero and so it is concluded that a more refined model for the latch will need to be developed

Thermal Deformation of Very Slender Triangular Rollable and Collapsible Booms

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

MEMS 411: Vehicle Entry Aid

Handicapped individuals such as those with prosthetic legs or diabetes can struggle greatly with entering large vehicles such as trucks. In this struggle, a client uses a rigid step stool with a rope tied through it to lift himself and then the stool into the vehicle. This report outlines an initiative to design and manufacture a better solution to this problem. A collapsible, two-step step stool was fabricated with a spring loaded retraction system. The design process for this solution is outline from start to finish, showing the extensive thought process that was followed to create the final product

The Road to Redemption: Reclaiming the Value in Assessment Retention Exams

A good assessment plan combines many direct and indirect measures to validate the collected data. One often controversial assessment measure comes in the form of retention exams. Although assessment retention exams may come with faults, others advocate for their inclusion in program assessment. Objective-based tests may offer insight to instructors about course objectives that students comprehend well and other concepts that need more attention. This research shows that using retention exams as an assessment measure can generate useful and meaningful data for both the students and the program. Students can learn strengths and weaknesses based on scores. Faculty and programs can learn where gaps may exist within the program. But, whenever a program decides to use retention exams as an assessment tool, faculty members need to be included in the process. Discussions about content need to occur constantly. Exams need to consistently reflect current standards and student learning objectives. And faculty need to stay involved in the process to know exactly where any inconsistencies may lie within their courses, and how they contribute to the students’ overall experience within the program

Hospitals to celebrate living : a therapeutic environment for long term care

Thesis. 1978. M.Arch--Massachusetts Institute of Technology. Dept. of Architecture.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 83-84.by Thomas Joseph Stohlman, Jr.M.Arc

Volume 1: Eudaimonia

PSYCHE Eudaimonia at Smith College seeks to encourage human flourishing among undergraduate students by opening them to the pursuit of wisdom that is strongly encouraged by Smith’s liberal art curriculum. Moreover, since today’s various disciplines originated from the study of “philosophy”, Smith’s philosophy department seeks to bring together the different disciplines into unique synergies.https://scholarworks.smith.edu/satya_archive/1000/thumbnail.jp

Advances in Low-Cost Manufacturing and Folding of Solar Sail Membranes

Solar sail membranes must have a high area-to-mass ratio and high solid volume fraction when stowed. In order to meet mission requirements, current solar sail projects, such as NASAs Near Earth Asteroid Scout, require metallized sail membranes with thicknesses on the order of 2-3 m. These very thin membranes do not retain creases like thicker membranes, solar panels, or paper models. For Cubesat-class spacecraft, volume, rather than mass, is often the driving requirement for deployable structural elements. These two factors make it both difficult and highly desirable to characterize the practical differences between solar sail membrane packaging methods with laboratory demonstrations. This paper presents lessons gathered from lab work with solar sail membranes at a 10-meter scale

Durability Characterization of Mechanical Interfaces in Solar Sail Membrane Structures

The construction of a solar sail from commercially available metallized film presents several challenges. The solar sail membrane is made by seaming together strips of metallized polymer film. This requires seaming together a preselected width and thickness of a base material into the required geometry, and folding the assembled sail membranes into a small stowage volume prior to launch. The sail membranes must have additional features for connecting to rigid structural elements (e.g., sail booms) and must be electrically grounded to the spacecraft bus to prevent charge build up. Space durability of the material and mechanical interfaces of the sail membrane assemblies will be critical for the success of any solar sail mission. In this study, interfaces of polymer/metal joints in a representative solar sail membrane assembly were tested to ensure that the adhesive interfaces and the fastening grommets could withstand the temperature range and expected loads required for mission success. Various adhesion methods, such as surface treatment, commercial adhesives, and fastening systems, were experimentally evaluated and will be discussed

Shape Accuracy of a Joint-Dominated Deployable Mast

This paper presents a study to capture and model friction related changes in the un-loaded configuration of deployable masts with articulated joints. A finite model of a rep-resentative mast structure is described. This model includes a detailed treatment of the latching mechanism. The parameters of the computational model are based on direct mea-surements on components of a physical model. The moment-rotation relationship for a complete single bay of the physical model has been measured and the overall behavior is predicted well by the model, however the model predicts the residual rotation at zero moment to be zero and so it is concluded that a more refined model for the latch will need to be developed