Experimental and numerical investigation of abrasive waterjet polishing technology

The objective of this investigation is the development of the abrasive waterjet (AWJ) based polishing technology. The result of the investigation will assist the implementation of AWJ polishing for manufacturing processes and procedures. Experimental exploration of AWl polishing involving processing of difficultmachine materials such as Alumina ceramic and stainless steel. Surface improvement due to this processing is evaluated by measuring the roughness of the generated surfaces and examining the microhardness and micro-topography of the surfaces using Scanning Electronic Microscopy (SEM). The surface roughness of 0.3 micron was obtained at samples of ceramic and metal alloys at a reasonable rate using 500-mesh garnet. No surface defects are induced. The effect of various process variables on the topography of surfaces generated during AWJ polishing was evaluated, It is shown that the particles dimension and jet impact angle are two critical parameters controlling the process. The former determines the feasibility of AWJ polishing, and the later limits the extent of improvement in the surface topography. The force exerted on the sample surface is measured at various impingement angles. And, the effects of the tangential and normal component of the force on the surface topography is evaluated. The abrasive particles which constitute a machining tool in the AWJ polishing are collected after mixing and after impact, and analyzed using Laser Scanning Sizer and SEM. The acquired data reveal the details of the mechanism of AWJ polishing processes. Numerical simulation of the motion of particles prior and after the impingement are conducted. Numerical solutions of the differential equations as applied to the two-phase turbulent jet flow are obtained using FIDAP package. The numerical prediction of jet velocity and force exerted on the target surface comply with the experimental results. The simulation of particles trajectories reveals existence of five distinctive patterns of particles motion which determine the surface topography. This work pioneers the use of AWJ as a polishing tool. and identifies the principal features of AWJ polishing and its use of computational packages for evaluation of the behavior of ultrahigh speed two-phase flows

Virtual reality based creation of concept model designs for CAD systems

This work introduces a novel method to overcome most of the drawbacks in traditional methods for creating design models. The main innovation is the use of virtual tools to simulate the natural physical environment in which freeform. Design models are created by experienced designers. Namely, the model is created in a virtual environment by carving a work piece with tools that simulate NC milling cutters. Algorithms have been developed to support the approach, in which the design model is created in a Virtual Reality (VR) environment and selection and manipulation of tools can be performed in the virtual space. The desianer\u27s hand movements generate the tool trajectories and they are obtained by recording the position and orientation of a hand mounted motion tracker. Swept volumes of virtual tools are generated from the geometry of the tool and its trajectories. Then Boolean operations are performed on the swept volumes and the initial virtual stock (work piece) to create the design model. Algorithms have been developed as a part of this work to integrate the VR environment with a commercial CAD/CAM system in order to demonstrate the practical applications of the research results. The integrated system provides a much more efficient and easy-to-implement process of freeform model creation than employed in current CAD/CAM software. It could prove to be the prototype for the next-generation CAD/CAM system

Design and construction of a carbon fiber gondola for the SPIDER balloon-borne telescope

We introduce the light-weight carbon fiber and aluminum gondola designed for the SPIDER balloon-borne telescope. SPIDER is designed to measure the polarization of the Cosmic Microwave Background radiation with unprecedented sensitivity and control of systematics in search of the imprint of inflation: a period of exponential expansion in the early Universe. The requirements of this balloon-borne instrument put tight constrains on the mass budget of the payload. The SPIDER gondola is designed to house the experiment and guarantee its operational and structural integrity during its balloon-borne flight, while using less than 10% of the total mass of the payload. We present a construction method for the gondola based on carbon fiber reinforced polymer tubes with aluminum inserts and aluminum multi-tube joints. We describe the validation of the model through Finite Element Analysis and mechanical tests.Comment: 16 pages, 11 figures. Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 914

Investigation and development of a transverse deflecting structure: a beam separator for ELBE

The thesis described the development of a beam separator device for the ELBE accelerator in Dresden, Germany, facilitating simultaneous operation of multiple secondary user stations. After reviewing deflecting structures, an RF cavity was chosen as the optimal solution. Extensive electromagnetic and multiphysics analysis were conducted to optimize the cavity design. A copper deflecting cavity was manufactured and underwent rigorous high-power testing, successfully meeting the design requirements. The cavity is now ready for installation in the ELBE beamline.In dieser Arbeit wurde die Entwicklung einer Strahlseparatorvorrichtung für den ELBE-Beschleuniger in Dresden beschrieben, die den gleichzeitigen Betrieb mehrerer sekundärer Benutzerstationen ermöglicht. Nach der Prüfung von Ablenkungsstrukturen wurde eine HF-Kavität als optimale Lösung gewählt. Umfangreiche elektromagnetische und multiphysikalische Analysen wurden durchgeführt, um das Design des Hohlraums zu optimieren. Ein Ablenkungshohlraum aus Kupfer wurde hergestellt und strengen Hochleistungstests unterzogen, wobei die Designanforderungen erfolgreich erfüllt wurden

Deriving Functional Properties of Components from the Analysis of Digital Mock-ups

International audienceDigital Mock-ups (DMUs) are widespread and form a common basis for product description. However, DMUs produced by industrial CAD systems essentially contain geometric models and their exploitation often requires new input data to derive various simulation models. In this work, analysis and reasoning approaches are developed to automatically enrich DMUs with functional and kinematic properties. Indeed, interfaces between components form a key starting point to analyze their behaviours under operational reference states. This is a first stage in a reasoning process to progressively identify mechanical, kinematic as well as functional properties of the components. The overall process relying on the interfaces between components addresses also the emerging needs of conventional representations of components in industrial DMUs. Inferred semantics add up to the pure geometric representation provided by a DMU, to allow for easier exploitation of the model in different phases of a Product Development Process (PDP)