RELFIT: A program for determining prony series fits to measured relaxation data

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Description

Viscoelastic materials are often characterized in terms of stress relaxation moduli which decay in time. Finite element programs which model viscoelastic materials frequently require that these relaxation functions be defined as an exponential series (i.e., Prony Series) to exploit the numerical advantages of developing recursive equations for evaluating hereditary integrals. Obtaining these data fits can be extremely difficult when the data is spread over many decades in the logarithm of time. RELFIT is a nonlinear optimization program that iteratively determines the Prony series coefficients and relaxation times so as to minimize the least squares error in the data fit. An ... continued below

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17 p.

Creation Information

Chambers, R.S. April 1, 1997.

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This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 94 times , with 11 in the last month . More information about this report can be viewed below.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

Viscoelastic materials are often characterized in terms of stress relaxation moduli which decay in time. Finite element programs which model viscoelastic materials frequently require that these relaxation functions be defined as an exponential series (i.e., Prony Series) to exploit the numerical advantages of developing recursive equations for evaluating hereditary integrals. Obtaining these data fits can be extremely difficult when the data is spread over many decades in the logarithm of time. RELFIT is a nonlinear optimization program that iteratively determines the Prony series coefficients and relaxation times so as to minimize the least squares error in the data fit. An overview of the code, a description of the required inputs (i.e., users`s instructions), and a demonstration problem are presented.

Physical Description

17 p.

Notes

OSTI as DE97005909

Source

  • Other Information: PBD: Apr 1997

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  • Other: DE97005909
  • Report No.: SAND--97-0371
  • Grant Number: AC04-94AL85000
  • DOI: 10.2172/469147 | External Link
  • Office of Scientific & Technical Information Report Number: 469147
  • Archival Resource Key: ark:/67531/metadc685134

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Creation Date

  • April 1, 1997

Added to The UNT Digital Library

  • July 25, 2015, 2:21 a.m.

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  • April 13, 2016, 6:48 p.m.

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Chambers, R.S. RELFIT: A program for determining prony series fits to measured relaxation data, report, April 1, 1997; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc685134/: accessed November 12, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.