Design Concepts and Process Analysis for Transmuter Fuel Manufacturing: Quarterly Progress Report #2

This report discusses mainly the fabrication of inert matrix fuels. There are three fabrication routes to obtain inert matrix fuels (IMF). IMF is a dispersion-type fuel in which the actinide phase is distributed as a separate phase in a so called inert matrix. This concept has evolved as one of the most promising in the field of transmutation. The following section discusses each manufacturing route aside

Inverse Dynamics Based Tuning of a Fuzzy Logic Controller for a Single-Link Flexible Manipulator

Abstract: Since its introduction to engineering applications, fuzzy logic has attracted many researchers because of its simplicity and robustness. Experience with a system is translated into heuristic rules which can be used to control that system. This article proposes a novel method for a generalized inverse dynamics based fuzzy logic controller (FLC) of a single-link flexible manipulator. The deflection of the flexible link was modeled using the assumed modes method. The control action is distributed between two FLCs: A joint angle controller and a tip controller. Each controller produces a torque value. The torque values are summed, and the resulting control action is used to drive the manipulator. A novel method for varying the ranges of the variables of the two controllers as a function of the motion parameters and the inverse dynamics of the system is presented. The relative shapes and distribution of the fuzzy membership sets (with respect to each other) are kept fixed. Simulation results show that joint trajectory tracking is accomplished, and that the residua

Inverse Dynamics Based Fuzzy Logic Controller for a Single-Link Flexible Manipulator

This paper presents a novel method for an inverse dynamics based fuzzy logic controller (FLC) of a single-link flexible manipulator. The control action is distributed between two FLCs: a joint angle controller and a tip controller. A method for varying the ranges of the variables of the two controllers as a function of the motion parameters and the inverse dynamics of the system is presented. Simulation results show that the joint trajectory tracking is accomplished and the residual vibration of the flexible link is suppressed

Optimising stop-bands in periodic waveguides using genetic algorithms and wave finite element method

In this paper, we propose using the wave finite element method and genetic algorithms to design periodic waveguide structures with optimal stop-bands. Instead of modelling waveguides using the standard finite element method, we use the wave finite element method to model the waveguides. The wave and finite element method is based on using periodic structure theory and the finite element model of a unit cell of the waveguide to describe the waveguide's motion in terms of wave amplitudes rather than in terms of physical degrees of freedom. This results in a numerically efficient model of the waveguide which can be used in optimisation studies. In particular, the focus of this paper is on the optimisation of stop-bands in the waveguides which leverage this property of periodic structures. Genetic algorithms will be used to optimise the stop-bands. A numerical example where analytical models can be obtained will be used to demonstrate the efficacy of the proposed approach and its potential.</p

Transmuter Fuel Fabrication: Design and Analysis of Robotic Manufacturing Processes

The large-scale deployment of remote fabrication and refabrication processes will be a requirement for the implementation of transmutation (Meyer, 2001). Fabrication processes for different fuel types differ in terms of equipment types, throughput, and cost. A comprehensive assessment of the issue is presented in NEA, 2000. Many aspects of manufacturing will be common to both powder-based and metallic fuels manufacturing. These comprise: fuel pin assembly, welding of the cladding tubes, and dimensional inspection of slugs, pellets, and completed fuel pins. The paper describes the design of robot arms, control strategies and end effectors for material handling in a hot cell, such as pellet insertion into fuel rods and fuel rod handling. The dynamics of the robots and the objects handled by them are analyzed in detail using state of the art software tools. In addition to the evaluation and testing of normal assembly operations, the simulation provides for a comprehensive analysis of forces and loads, including those occurring during atypical events such as collisions. The results are to form part of a decision support data base for the selection of the most suitable manufacturing process

Vibration modelling of helical springs with non-uniform ends

Helicalsprings constitute an integral part of many mechanical systems. Usually, a helicalspring is modelled as a massless, frequency independent stiffness element. For a typical suspension spring, these assumptions are only valid in the quasi-static case or at low frequencies. At higher frequencies, the influence of the internal resonances of the spring grows and thus a detailed model is required. In some cases, such as when the spring is uniform, analytical models can be developed. However, in typical springs, only the central turns are uniform; the ends are often not (for example, having a varying helix angle or cross-section). Thus, obtaining analytical models in this case can be very difficult if at all possible. In this paper, the modelling of such non-uniformsprings are considered. The uniform (central) part of helicalsprings is modelled using the wave and finite element (WFE) method since a helicalspring can be regarded as a curved waveguide. The WFE model is obtained by post-processing the finite element (FE) model of a single straight or curved beam element using periodic structure theory. This yields the wave characteristics which can be used to find the dynamic stiffness matrix of the central turns of the spring. As for the non-uniformends, they are modelled using the standard finite element (FE) method. The dynamic stiffness matrices of the ends and the central turns can be assembled as in standard FE yielding a FE/WFE model whose size is much smaller than a full FE model of the spring. This can be used to predict the stiffness of the spring and the force transmissibility. Numerical examples are presente

Modeling and control of membrane mirror strip using single piezoelectric bimorph

This paper presents an improved finite-element model of a membrane strip actuated by a single piezoelectric bimorph. The paper also treats the static shape control problem of the structure under study. The membrane strip is modeled as an Euler—Bernoulli beam under tension, with non-uniform physical properties. The finite-element method allows the development of a model that accounts for the actuator dynamics. The static shape control problem is formulated as a disturbance rejection problem and solved using a proportional-integral (PI) controller. The PI control gains are obtained using the linear quadratic regulator theory. The proposed model is verified experimentally, and the closed loop system is simulated to demonstrate the effectiveness of the control law