3D EVALUATION OF THE TOPOGRAPHY OF THE SURFACE BY ABRASIVE WATER JET MACHINING TECHNOLOGY

The article deals with contact and non-contact evaluation of surface roughness created by water jet cutting technology (AWJ). Non-contact surface measurement was performed using an LPM laser profilometer. The values measured by the laser profilometry method were compared with the values measured by the contact method, the Mitutoyo SJ 400 roughness meter. Six samples were produced. Three in stainless steel and three in structural steel. In order to achieve a different surface topography, different feed rates of the cutting head were used on the samples, which was reflected in the quality of the resulting surface. The evaluated parameters were the average arithmetic deviation of the assessed profile and the largest height of the profile inequality.

DEVELOPMENT OF A LASER PROFILOMETER FOR THE GENERATION OF 3D- MODELS TO MEASURE THE VOLUME OF FERTILIZER APPLIED BY FERTILIZER SOWERS

Laser profilometry based on triangulation is a method for measuring depth of points in space that uses a laser beam to scan the object. The image of a laser-line projected onto a surface of an object is captured and treated in image-analysis software, which calculates its profile. The union of a sequence of profiles allows the construction of the 3D-digital models of objects. The objective of this work was to develop a methodology and to build a prototype of a threedimensional scanner based on laser triangulation. A prototype was built, with a gantry structure containing a car on which are a laser diode and a camera. This car is driven by an endless shaft driven by an electric motor with variable speed. When moving the car, the laser module produces a line on the surface of the object that is filmed by a camera fixed at a known angle, obtaining the necessary information to generate the 3D model of the object. Tests were made on regular objects: hubcaps, pyramids and cobblestones and the results showed that the 3D-models produced had the same dimensions. Tests were also made on irregular objects such as soil surface and fruit. The prototype proved to be solid for generating 3D models of objects.

An Investigation of Corrosion Progression Using Laser Profilometry

Atmospheric corrosion progression characterisation on metal substrates is a major problem in the field of corrosion science and Non-destructive Evaluation (NDE). A laser profilometry has been used to characterise the corrosion on the mild steel plate at a low cost and high resolution. Four mild steel samples have been measured which exposed to the marine environment from 1 month to 10 months. Two features have been developed to characterise thickness variation in the corrosion layer. These features have been used to characterise corrosion progression through experimental studies. The relationship between these features and corrosion progression has been derived which is useful for corrosion progression measurement, early-stage corrosion prediction, and monitoring areas.

Characterization of Vacuum Arc Thruster Performance in Weak Magnetic Nozzle

Vacuum arc thruster performance in a magnetic nozzle configuration is experimentally characterized. Measurements are performed on a miniature coaxial thruster with an anode inner diameter of 1.8 mm. The magnetic field B is produced by a single air coil, 18 mm in diameter. Direct measurement of thrust, mass consumption and arc current are performed. To obtain statistically viable results ≈ 6000 arc pulses are analyzed at each operational point. Cathode mass erosion is measured using laser profilometry. To sustain thruster operation over several measurement cycles, an active cathode feeding system is used. For 0 < B ≤ 0.2 T, performance increase over the non-magnetic case is observed with the best thrust to arc power ratio T / P ≈ 9 μ N/W obtained at B ≈ 0.2 T. A parametric model is provided that captures the performance enhancement based on beam collimation and acceleration by the magnetic nozzle. For B > 0.2 T, the arc discharge is shown to be suppressed nullifying any additional gains by the nozzle effect.