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Vehicle Maintenance Shelters Meet Structural Requirements Through FEA Analysis

Anchor Industries supplies tents and fabric products to the outdoor amusement and entertainment industries, and municipalities. With their experience in producing portable structures, Anchor re-entered the military market of vehicle maintenance shelters (VMS). The first Anchor VMS, designed several years ago to compete with another company’s lightweight maintenance enclosure (LME), was overpriced compared to similar products in the U.S. and Europe, so the company sought to create a more competitive and efficient shelter.

Posted in: Manufacturing & Prototyping, Briefs

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Treatments To Produce Stabilized Aluminum Mirrors for Cryogenic Uses

Selected heat treatments are performed between and after fabrication steps.Five metallurgical treatments have been tested as means of stabilizing mirrors that are made of aluminum alloy 6061 and are intended for use in cryogenic applications. Aluminum alloy 6061 is favored as a mirror material by many scientists and engineers. Like other alloys, it shrinks upon cool-down from room temperature to cryogenic temperature. This shrinkage degrades the optical quality of the mirror surfaces. Hence, the metallurgical treatments were tested to determine which one could be most effective in minimizing the adverse optical effects of cooldown to cryogenic temperatures. Each of the five metallurgical treatments comprises a multistep process, the steps of which are interspersed with the steps of the mirror- fabrication process. The five metallurgical- treatment/fabrication–process combinations were compared with each other and with a benchmark fabrication process, in which a mirror is made from an alloy blank by (1) symmetrical rough machining, (2) finish machining to within 0.006 in. (˜ 0.15 mm) of final dimensions, and finally (3) diamond turning to a mirror finish. Two specimens ? a flat mirror and a spherical mirror ? were fabricated in each case. The blanks for all the specimens were cut from the same plate of aluminum alloy 6061-T651. (The suffix “T651” denotes a stress-relieving treatment that involves reducing residual stresses by mechanical stretching of the previously untreated alloy.) Of the five metallurgical-treatment/fabricationprocess combinations tested, the one found to exert the greatest stabilizing effect comprises the following ten steps:

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Portable Electron-Beam Free-Form Fabrication System

The electron beam in this system will be of relatively low voltage. A portable electron-beam free-form fabrication (EB F3) system, now undergoing development, is intended to afford a capability for manufacturing metal parts in nearly net sizes and shapes.

Posted in: Manufacturing & Prototyping, Briefs

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Improvements in Fabrication of Sand/Binder Cores for Casting

Cores can be made stronger and more consistent. Three improvements have been devised for the cold-box process, which is a special molding process used to make sand/binder cores for casting hollow metal parts. These improvements are:

Posted in: Manufacturing & Prototyping, Briefs

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Solid Freeform Fabrication of Composite-Material Objects

Parts specified by CAD data files could be fabricated as needed. Composite solid freeform fabrication (C-SFF) or composite layer manufacturing (CLM) is an automated process in which an advanced composite material (a matrix reinforced with continuous fibers) is formed into a freestanding, possibly complex, three-dimensional object. In CLM, there is no need for molds, dies, or other expensive tooling, and there is usually no need for machining to ensure that the object is formed to the desired net size and shape.

Posted in: Manufacturing & Prototyping, Briefs

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Program Predicts Time Courses of Human/Computer Interactions

CPM X is a computer program that predicts sequences of, and amounts of time taken by, routine actions performed by a skilled person performing a task. Unlike programs that simulate the interaction of the person with the task environment, CPM X predicts the time course of events as consequences of encoded constraints on human behavior. The constraints determine which cognitive and environmental processes can occur simultaneously and which have sequential dependencies. The input to CPM X comprises (1) a description of a task and strategy in a hierarchical description language and (2) a description of architectural constraints in the form of rules governing interactions of fundamental cognitive, perceptual, and motor operations. The output of CPM X is a Program Evaluation Review Technique (PERT) chart that presents a schedule of predicted cognitive, motor, and perceptual operators interacting with a task environment. The CPM X program allows direct, a priori prediction of skilled user performance on complex human-machine systems, providing a way to assess critical interfaces before they are deployed in mission contexts.

Posted in: Software, Briefs, TSP

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Chimera Grid Tools

Chimera Grid Tools (CGT) is a software package for performing computational fluid dynamics (CFD) analysis utilizing the Chimera-overset-grid method. For modeling flows with viscosity about geometrically complex bodies in relative motion, the Chimera-overset-grid method is among the most computationally cost-effective methods for obtaining accurate aerodynamic results. CGT contains a large collection of tools for generating overset grids, preparing inputs for computer programs that solve equations of flow on the grids, and post-processing of flow-solution data. The tools in CGT include grid editing tools, surface-grid generation tools, volume-grid-generation tools, utility scripts, configuration scripts, and tools for post-processing (including generation of animated images of flows and calculating forces and moments exerted on affected bodies). One of the tools, denoted OVERGRID, is a graphical user interface (GUI) that serves to visualize the grids and flow solutions and provides central access to many other tools. The GUI facilitates the generation of grids for a new flow-field configuration. Scripts that follow the grid generation process can then be constructed to mostly automate grid generation for similar configurations. CGT is designed for use in conjunction with a computer-aided-design program that provides the geometry description of the bodies, and a flowsolver program.

Posted in: Software, Briefs, TSP

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