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Series

Mechanical Engineering

1997

Articles 1 - 2 of 2

Full-Text Articles in Engineering Science and Materials

Part Form Errors Predicted From Machine Tool Performance Measurements, R. G. Wilhelm, N. Srinivasan, F. Farabaugh, R. Hocken Jan 1997

Part Form Errors Predicted From Machine Tool Performance Measurements, R. G. Wilhelm, N. Srinivasan, F. Farabaugh, R. Hocken

Department of Mechanical and Materials Engineering: Faculty Publications

Machine tool performance testing, as defined by IS0 230 and ANSI B5.54 has been successfully used to maintain and improve the accuracy and repeatability of production-level machine tools. In this study, a controlled series of experiments have been used to test the efficacy of these performance tests in the prediction of part form errors. Results are shown for flatness, squareness, position, and profile tolerances. The experimental results suggest that standard machine tool performance tests can also be used to predict the “best-case” tolerances that can be achieved for particular part features.

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Molecular-Level Modeling Of The Viscoelasticity Of Crosslinked Polymers: Effect Of Time And Temperature, P. P. Simon, Harry J. Ploehn Jan 1997

Molecular-Level Modeling Of The Viscoelasticity Of Crosslinked Polymers: Effect Of Time And Temperature, P. P. Simon, Harry J. Ploehn

Faculty Publications

We present a new molecular-level picture of chain dynamics for describing the viscoelasticity of crosslinked polymers. The associated mathematical model consists of a time-dependent momentum balance on a representative polymer segment in the crosslinked network, plus phenomenological expressions for forces acting on the segments. These include a cohesive force that accounts for intermolecular attraction, an entropic force describing the thermodynamics governing chain conformations, and a frictional force that captures the temperature dependence of relative chain motion. We treat the case of oscillatory uniaxial deformation. Solution of the model equations in the frequency domain yields the dynamic moduli as functions of …

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