Browsing by Subject "vibration isolation"
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Item Robust Design of Negative Stiffness Elements Fabricated by Selective Laser Sintering(University of Texas at Austin, 2011) Shahan, David; Fulcher, Ben; Seepersad, Carolyn ConnerConstrained negative stiffness structures have been shown to possess desirable vibration isolation properties because of their ability to provide low dynamic stiffness, resulting in low transmissibility over a wide range of frequencies. In this research, selective laser sintering (SLS) is an integral part of a model-design-build-test process for investigating the vibration isolation capabilities of negative stiffness structures in the form of axially compressed beams. SLS provides geometric design freedom and rapid fabrication capabilities for validating dynamic models of structural behavior and guiding the design process toward iterative improvements. SLS also introduces some geometric and dimensional variability that can significantly degrade the performance of the structure. In this paper, an iterative model-design-build-test process for negative stiffness structures is described and presented with an analysis of the impact of SLS-induced imperfections on the results.Item Sheareography - a Practical Optical Testing and Measuring Method(1995) Steinchen, W.Shearography is a laser optical method which is suited for either nondestructive testing or for strain analysis. Contrary to holography which measures surfach displacements, shearography measures derivatives of surface displacements. Since strains are functions of displacement derivatives, shearography allows strains to be determined without numerical differentiating displacement data. Defects in object normally create strain concentrations; it is easier using shearography to correlate defects with strain anomalies rather than displacement anomalies applying holography. Furthermore, rigid body motions do not produce strain, thus shearography is insensitive against such motions and does not need adopting any particular device for vibration isolation. It is an industrial tool suited very well for the following ares: 1. strain measurement and strain analysis 2. nondestructive testing and quality assurance system 3. optimization ofmachine parts and structures of any material