USA As Represented by Secretary of the Navy

United States of America, As Represented by the Secretary of Agriculture

George Mason University

John Michopoulos

Athanasios Iliopoulos

Dennis R Hardy

Samuel G Lambrakos

Nick E Tran

John Steuben

Nikos P Andrianopoulos

Andrew J Birnbaum

John C Hermanson

Athanasions Iliopoulos

A method for flexible functionally tailorable slicing for additive manufacturing includes the steps of receiving and parsing an input model of an object to be additively manufactured; reconstructing a domain boundary of the object; computing individual layer boundaries of the object; constructing, for each layer, layer domains from respective enclosing boundaries; computing, for each layer, a perimeter shell and a volumetric infill by finding level sets of a field function selected by a user; collecting and arranging into a coherent sequence each perimeter shell and volumetric infill; and formatting the coherent sequence as motion commands for an additive manufacturing system.

Implicit method and an algorithm for flexible functionally tailorable slicing for additive manufacturing

A method and apparatus for volumetric manufacture of three-dimensional physical objects from a precursor material based on plans, specifications, or virtual models. A build domain is provided comprising an enclosed three-dimensional wire grid in which the wires are connected to one or more electric power sources configured to controllably and addressably apply power to one or more individual wires to cause the wires to dissipate heat produced by Joule heating to the surrounding precursor material situated within the build domain, and to further allow for the control of the three-dimensional heat distribution and accordingly temperature distribution within the build domain. By activating and deactivating one or more predetermined subsets of the wires in the build domain, the precursor can be caused to melt and/or solidify so as to form a three-dimensional object within the build domain.

Method and apparatus for volumetric manufacture of composite objects

A method and system for measuring and determining the full-field spatial distributions of strain tensor field components in a two or three-dimensional space, as a consequence of deformation under generalized loading conditions. One or more digital cameras may be used to acquire successive images of a deforming body with optically distinctive features on its surface. A method for determining the location of characteristic points of the surface features and another one for tracking these points as deformation occurs. Elongations between neighboring points on the vicinity of a location of interest are computed. The elongation between points is calculated even though discontinuities may exist between them. Strain tensor fields are directly calculated as a tensor approximation from these elongations without determining or using the displacement vector distributions.

Method and system for direct strain imaging

A method and system for measuring full field deformation characteristics in three dimensions of a body upon which a pattern of visible marks has been applied. The method includes receiving images of the pattern of marks from at least two digital video cameras as the specimen deforms. A computer processor identifies the centroids of each of the two camera images of the body in a first frame, matches the centroids of the marks in the two images, and generates a three-dimensional representation of the centroids based on the two images, and repeats these steps for the images from the two cameras in a subsequent frame. The computer processor calculates the displacement vector between a three dimensional representation of the centroids and the subsequent three dimensional representation of the centroids, and calculates full field displacement and strain fields based on the displacement vector.

System and method for remote full field three-dimensional displacement and strain measurements

A recursive hexapod testing machine for mechanical testing of deformable material specimens under six degrees of freedom multiaxial loading. The machine includes a fixed base, a movable base connected to the fixed base at by a hexapod arrangement of six linearly extendable actuator linkages, with an end of each linkages attached to the movable base and the other end of the linkage attached to the fixed base. Each actuator linkage includes a hydraulic cylinder and piston, a digitally-controlled electro-hydraulic servo-valve for actuating the hydraulic cylinder in response to a digital command string, a load cell in line between the piston and the universal joint attached to the movable base, a linear variable displacement transducer for measuring extension of the piston, and a magneto-resistive position transducer for measuring a position of the piston. The servo-valves extend each hydraulic cylinder a predetermined amount to effect a desired motion of the material specimen.

Recursive hexapod system and method for multiaxial mechanical testing

A computer implemented method for directly determining parameters defining a Weierstrass-Mandelbrot (W-M) analytical representation of a rough surface scalar field with fractal character, embedded in a three dimensional space, utilizing pre-existing measured elevation data of a rough surface in the form of a discrete collection of data describing a scalar field at distinct spatial coordinates, is carried out by applying an inverse algorithm to the elevation data to thereby determine the parameters that define the analytical and continuous W-M representation of the rough surface. The invention provides a comprehensive approach for identifying all parameters of the W-M function including the phases and the density of the frequencies that must greater than 1. This enables the infinite-resolution analytical representation of any surface or density array through the W-M fractal function.

Algorithm and a method for characterizing surfaces with fractal nature

A computer-implemented method for measuring full field deformation characteristics of a deformable body. The method includes determining optical setup design parameters for measuring displacement and strain fields, and generating and applying a dot pattern on a planar side of a deformable body. A sequence of images of the dot pattern is acquired before and after deformation of the body. Irregular objects are eliminated from the images based on dot light intensity threshold and the object area or another geometrical cutoff criterion. The characteristic points of the dots are determined, and the characteristic points are matched between two or more of the sequential images. The displacement vector of the characteristic points is found, and mesh free or other techniques are used to estimate the full field displacement based on the displacement vector of the characteristic points. Strain tensor or other displacement-derived quantities can also be estimated using mesh-free or other analysis techniques.

System and method for remote measurement of displacement and strain fields

A method of: introducing hydrogen and a feed gas containing at least 50 vol % carbon dioxide into a reactor containing a Fischer-Tropsch catalyst; and heating the hydrogen and carbon dioxide to a temperature of at least about 190&#xb0; C. to produce hydrocarbons in the reactor. An apparatus having: a reaction vessel for containing a Fischer-Tropsch catalyst, capable of heating gases to at least about 190&#xb0; C.; a hydrogen delivery system feeding into the reaction vessel; a carbon dioxide delivery system for delivering a feed gas containing at least 50 vol % carbon dioxide feeding into the reaction vessel; and a trap for collecting hydrocarbons generated in the reaction vessel.

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Washington, DC, United States of America

John Michopoulos