An investigation into a system linking a computer solid modeler to an active stereo imaging inspection station is presented. Given the computer solid model of a surface, a projected pattern can be encoded so that the reflections from the object's surface exhibit a uniformly simple pattern when the object's surface and the modeled surface are identical. Research concerning the method of generating projection patterns, as well as the sensitivity of the system, is discussed. A prototype system consisting of a computer graphics workstation; a flexible projector, and a machine vision system was used to inspect two different manufactured parts. >

Encoded moire inspection based on a computer solid model

Bulk strain and grain strain in axisymmetric deformation

The development of good material models, accurate nonlinear finite element codes, and computer- controlled presses makes practical the application of control techniques to metal forging. This paper considers the problem of selecting a ram velocity profile to produce a desired microstructure, given a specified die and preform geometry and forging temperature. Two approaches for doing so are successfully applied to a simple but representative problem. The first is based on classical numerical optimization techniques. The second is based on inverse neural networks, and offers potential savings in critical computations. A method for choosing the forging temperature is also presented.

Optimal Control of Metal Forging

Assessment of Notch Effect Based on Finite Element Analysis and Digital Image Correlation Technique

Tensile Test Evaluation Using Vision Extender and Image Processing

The projection moire technique affords an accurate method of measuring the geometry of the necked region in a tensile specimen. Corrections to the measured stress, necessary to account for the triaxiality introduced by the neck, require values for the radius of curvature of the specimen at the minimum section. The spacing of fringes resulting from the interference between a grating projected on the specimen surface and a master grating not only provide information which permits calculation of the radius but also demonstrates any changes in symmetry resulting from plastic deformation. Results obtained by testing specimens of copper and mild steel having initially straight and initially curved profiles indicate that Bridgman's approach provides a self-consistent correction for triaxiality. However, comparison of incremental tests with continuous tests indicates that the development of neck geometry may be sensitive to the strain rate.

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J. Clave

Papers

Measurement of Neck Development in Tensile Testing Using Projection Moire