Path, theme and narrative in open plan exhibition settings

Three arguments are made based on the analysis of science exhibitions. First,sufficiently refined techniques of spatial analysis allow us to model the impact oflayout upon visitors' paths, even in moderately sized open plans which allow almostrandom patterns of movement and relatively unobstructed visibility. Second, newlydeveloped or adapted techniques of analysis allow us to make a transition frommodeling the mechanics of spatial movement (the way in which movement is affectedby the distribution of obstacles and boundaries), to modeling the manner in whichmovement might register additional aspects of visual information. Third, theadvantages of such purely spatial modes of analysis extend into providing us with asharper understanding of some of the pragmatic constrains within which exhibitioncontent is conceived and designed

An investigation of hydraulic-line resonance and its attenuation

An investigation of fluid resonance in high-pressure hydraulic lines has been made with two types of fluid dampers (or filters) installed in the line. One type involved the use of one or more closed-end tubes branching at right angles from a main line, and the other type was a fluid muffler installed in-line. These devices were evaluated in forced vibration tests with oscillatory disturbances over a 1000-Hz range applied to one end of the line and with oscillatory pressures measured at various stations along the main pipe. Limited applications of acoustic-wave theory to the branched systems are also included. Results show varying attenuations of pressure perturbations, depending on the number and location of branches and the type of muffler. Up to three branches were used in the branch-resonator study, and the largest frequency range with maximum attenuation was obtained for a three-branch configuration. The widest frequency ranges with significant attenuations were obtained with two types of fluid mufflers

Stress transfer modeling in viscoelastic polymer matrix composites

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76784/1/AIAA-1999-1344-540.pd

Viscoelastic hinge formation in beams

A constitutive equation for nonlinear viscoelasticity is used to model the mechanical response of solid polymers such as polycarbonate. The nonlinearity arises from a reduced time variable which causes stress relaxation to occur faster as strain increases. This constitutive equation is used to study the consequences of the interaction of the acceleration of stress relaxation with strain and the spatial variation of strain within the context of the structural theory of beams undergoing small displacements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41706/1/707_2005_Article_BF01182510.pd

Influence of thermally induced chemorheological changes on the torsion of elastomeric circular cylinders

When an elastomeric material is deformed and subjected to temperatures above some characteristic value T cr (near 100 ∘ C for natural rubber), its macromolecular structure undergoes time and temperature-dependent chemical changes. The process continues until the temperature decreases below T cr . Compared to the virgin material, the new material system has modified properties (reduced stiffness) and permanent set on removal of the applied load.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46097/1/161_2006_Article_9.pd

Residual stresses and web fracture in roller-straightened rail

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1991.Includes bibliographical references.by Sarah J. Wineman.Ph.D

Superposition of small shear deformations on large uniaxial extensions for viscoelastic materials

The equation for small amplitude torsional response superposed on a finite axial stretch history is derived for a material modelled by the BKZ constitutive equation. For the case of a uniaxial step stretch history, this equation contains a term generalizing the well known Rivlin result for nonlinear elasticity plus two additional terms. The equation is used to analyse a recent experiment which studies the relation between the period of free torsional oscillations, axial stretch and axial force in a material undergoing stress relaxation. It is shown that a 10% discrepancy which arises when the data is related by Rivlin's formula can be accounted for by the two additional terms associated with the BKZ formulation. Finally, an expression for the complex modulus for forced torsional oscillations is derived.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25639/1/0000189.pd

The influence of the representative volume element (RVE) size on the homogenized response of cured fiber composites

The influence of the representative volume element (RVE) size (in terms of fiber packing and number of fibers for a given fiber-volume fraction) on the residual stresses created during the curing process of a continuous fiber-reinforced polymer matrix tow is investigated with the ultimate goal of finding a minimum unit cell size that can be used later for a homogenization procedure to calculate the response of woven fiber textile composites and in particular, fiber tows. A novel network curing model for the solidification of epoxy is used to model the curing process. The model takes into account heat conduction, cure kinetics and the creation of networks in a continuously shape changing body. The model is applied to the curing of a fiber/matrix RVE. The results for the minimum size of the RVE, obtained on the basis of the curing problem, are compared with a similar RVE, modeled as an elastic–plastic solid subjected to external loads, in order to compare the minimum RVE sizes obtained on the basis of different boundary value problem solutions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98620/1/0965-0393_20_7_075007.pd

Elastomer bushing response: experiments and finite element modeling

 Elastomer bushings are essential components in tuning suspension systems since they isolate vibration, reduce noise transmission, accommodate oscillatory motions and accept misalignment of axes. This work presents an experimental study in which bushings are subjected to radial, torsional and coupled radial-torsional modes of deformation. The experimental results show that the relationship between the forces and moments and their corresponding displacements and rotations is nonlinear and viscoelastic due to the nature of the elastomeric material. An interesting feature of the coupling response is that radial force decreases and then increases with torsion. The experimental results were used to assess bushing behavior and to determine the strength of radial-torsional coupling. The experimental results were also compared to finite element simulations of a model bushing. While finite element analysis predicted small displacements at the relaxed state reasonably well, the response to larger radial deformations and coupled deformations was not well captured.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42461/1/31630025.pd