Paradigm Shift in Materials Processing - The Intelligent Processing Revolution

During the last several decades, the importance of materials processing in the control of microstructure and materials properties has been recognized and, accordingly, the materials engineering community has dedicated much effort to studying the physics of the process. These endeavors have provided an understanding of the phenomena which are relevant. However, a paradigm shift is taking place in that the physics oriented approach to materials processing is being replaced by a control oriented approach. What is needed today is the ability to control the process and, thus, the trajectory of the controllable variables in a temporal space. Such a knowledge based approach to materials processing which requires understanding, sensors, and controls is the revolution taking place in the materials engineering field. The essence is a process which can learn and develop \u27\u27intelligence\u27\u27 as it progresses. This address will present and discuss the basis and the need for a knowledge based approach to materials processing. Furthermore, specific industrial examples will be given to illustrate implementation of intelligent processing. Finally, the challenges ahead and the impediments we face as a community will also be addressed

Structure-property characterization of rheocast and VADER processed IN-100 superalloy

Two recent solidification processes have been applied in the production of IN-100 nickel-base superalloy: rheocasting and vacuum arc double electrode remelting (VADER). A detailed microstructural examination has been made of the products of these two processes; associated tensile strength and fatigue crack propagation (FCP) rate at an elevated temperature were evaluated. In rheocasting, processing variables that have been evaluated include stirring speed, isothermal stirring time and volume fraction solid during isothermal stirring. VADER processed IN-100 was purchased from Special Metals Corp., New Hartford, NY. As-cast ingots were subjected to hot isostatic pressing (HIP) and heat treatment. Both rheocasting and VADER processed materials yield fine and equiaxed spherical structures, with reduced macrosegregation in comparison to ingot materials. The rheocast structures are discussed on the basis of the Vogel-Doherty-Cantor model of dendrite arm fragmentation. The rheocast ingots evaluated were superior in yield strength to both VADER and commercially cast IN-100 alloy. Rheocast and VADER ingots may have higher crack propagation resistance than P/M processed material

Resonant Oscillation of a Liquid Metal Column Driven by Electromagnetic Lorentz Force Sources

In this paper, a theoretical study is conducted in order to establish the feasibility of a liquid metal acoustic resonator (liquid gallium or liquid aluminum) for high-amplitude acoustic oscillations. The fundamental resonant frequency typically lies between 5 and 40 kHz. The oscillations are induced by an alternating Lorentz force density applied directly to the liquid metal volume. Depending on the boundary conditions, two different resonator types (open-closed and open-open) are theoretically investigated. The analysis incorporates the effects of impedance termination, volume absorption, wall friction, acoustic radiation from the open end, and nonlinear inflow-outflow losses. The actual elasticity of the container, either a ceramic or quartz tube, and the coupled solid-liquid interactions are taken into consideration. Based on this investigation, theoretical predictions are conducted for the quality factor and the pressure level for the liquid metal resonator under various geometric and boundary conditions. They indicate that resonant amplitudes of 10-20 arm can be achieved using commercially available high-current audio amplifiers

Flexible body dynamic stability for high performance aircraft

Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration