M. V. Gandhi

On boundary conditions for a certain class of problems in mixture theory

Abstract An additional boundary condition is proposed for solid-fluid mixtures for the situation in which a mixture boundary is in a saturated state. This condition on the boundary is derived from a thermodynamic characterization of the state and takes the form of a relationship between the total stress tensor, the stretch tensor and the volume fraction of the solid. This additional condition is sufficient to make several boundary value problems involving mixtures, determinate.

Automated design of modular fixtures for flexible manufacturing systems

Abstract The absence of adequate flexible fixturing methodologies is a significant impediment to the evolution of truly flexible manufacturing systems. Modular fixturing is one of the principal emerging technologies which addresses this void in computer integrated manufacturing. A methodology is proposed herein for the automated design and robotic assembly of these modular fixturing systems based on the integration of state-of-the-art methodologies from several distinctly different disciplines. The complexity of this challenging frontier problem is discussed and the interdisciplinary nature of the solution philosophy is emphasized.

The computer-aided design of modular fixturing systems

The flexibility of modular fixturing systems can be exploited to significantly enhance the productivity of computer integrated manufacturing facilities. A major impediment to the implementation of this philosophy is the absence of viable methodologies for the automated design and assembly of these fixturing systems. This paper addresses this technological void by proposing a CAD/CAM tool for the automated design and robotic assembly of modular fixturing systems which can form the basis for a fully automated design system. The development of automated flexible fixturing technologies that transcend the traditional time-consuming and expensive practice of manual assembly would significantly contribute to the evolution to the factory-of-the-future.

A new generation of innovative ultra-advanced intelligent composite materials featuring electro-rheological fluids: an experimental investigation

A new generation of revolutionary, intelligent, ultra-advanced composite materials featuring electro-rheological fluids is proposed herein for the active continuum vibrational control of structural and mechanical systems. This paper reports on a pioneer ing proof-of-concept experimental investigation focussed on evaluating the static and elastodynamic transient response characteristics of cantilevered beams fabricated in this new class of materials. The results of this investigation clearly demonstrate for the first time the ability to dramatically change the vibrational characteristics of beam-like speci mens fabricated in ultra-advanced composite materials by changing the electrical field im posed on the fluid. The capability of these materials to interface with modem solid-state electronics can be exploited by extending the fundamental phenomenological work pre sented herein by the successful incorporation of intelligent sensor technologies and modern control strategies in order to significantly accelerate the evolution of this in novative class of multi-functional, dynamically-tunable, ultra-advanced, intelligent com posite materials for military, aerospace, advanced manufacturing applications.

Some nonlinear diffusion problems within the context of the theory of interacting continua

Abstract Recently, a method for generating additional boundary conditions which are required for solving boundary value problems within the context of the theory of interacting continua, has been developed by Rajagopal, Wineman and Gandhi (Int. J. Engng Sci. 24, 1453, 1986). In this paper, using these boundary conditions the problems of radial diffusion of a fluid through a hollow non-linear elastic cylinder, and the diffusion through a sheared non-linear elastic layer, are studied in detail. It is found that shearing and stretching have qualitatively different effects on the diffusion process.

Vibration control of flexible linkage mechanisms using piezoelectric films

Abstract A control methodology for suppressing the elastodynamic responses of high-speed flexible linkage mechanism is presented by adopting the concept of smart structures featuring piezoelectric films. The dynamics of piezoelectric actuators and sensors bonded on the flexible link are developed for a one-dimensional beam model. The linear optimal feedback control law with a Luenberger observer is employed. The instability caused by the combined effect of control and observation spillover is investigated and carefully prevented. Numerical simulation is performed to evaluate the improvement of elastodynamic responses.

Adaptable Fixture Design: An Analytical and Experimental Study of Fluidized-Bed Fixturing

Computer-integrated flexible manufacturing systems are designed to respond quickly and economically to varying production requirements. Since an essential ingredient of all manufacturing operations is fixturing, if these modern manufacturing systems are to be truly flexible, then the fixturing must be adaptable also. Traditional design philosophies focused on dedicated fixtures are clearly inadequate for these applications. This paper reports on an innovative class of adaptable fixtures based on particulate fluidized beds. This mode of fixturing exploits the ability of these devices to change from a solid phase to a liquid phase and vice versa. Design criteria for the holding ability of this novel class of fixtures is established herein, and the proposed design philosophy is validated by an experimental program.

An experimental and analytical study of a four bar mechanism with links fabricated from a fiber-reinforced composite material

Abstract Computer simulations and experimental response data are presented for a 4-bar linkage made from a graphite-epoxy composite material with a ply layup of ±45°. A continuum theory is employed to model this fiber-reinforced laminate, and it accomodates orthotropic materials with differing densities, thickness and elastic properties. This mathematical model is embodied in a mixed variational principle which is the basis for a finite element analysis.

An Experimental and Analytical Study of the Dynamic Response of a Linkage Fabricated from a Unidirectional Fiber-Reinforced Composite Laminate

A large class of industrial machinery and commercial equipment is operated at high speed to satisfy the demands for high productivity. In order to further improve performance, it is proposed herein that the designer should consider fabricating the mechanism components in one of the commercially available composite materials because they offer many desirable characteristics with the promise of even higher speeds of operation. This paper presents an experimental and computational study of a flexible planar four-bar linkage fabricated from one of these composites. This fiber-reinforced material is modeled as an elastic solid by using a continuum theory which accommodates laminae with orthotropic properties, and differing densities, thicknesses, and elastic moduli. The theory is embodied in a variational theorem which serves as the basis for a finite element analysis of the mechanism.

A review of flexible fixturing systems for computer integrated manufacturing

Abstract Computer-integrated flexible manufacturing systems arc designed to manufacture a wide variety of parts ancl subassemblies by integrating the capabilities of computer-controlled machine tools, automated material-handling systems, and computer technology. Phe signilicant productivity payoffs that accrue from the implementation of state-of-the-art computer-integrated flexible manufacturing systems have been well documented. However, there are several major technical obstacles that prevent these systems from achieving the desired degree of flexibility. One of the significant impediments to the evolution of truly flexible computer-integrated manufacturing systems is the absence of truly adaptable flexible fixturing systems. This article presents a coherent overview of research activities dedicated to developing viable universal flexible fixturing systems, ancl technologies for fixturing parts of various shapes and sizes. Phase-change fixturing, modular fixture kits, ancl other innovative concepts are ...