Rafi Muhanna
In the present era of modern technology, engineering computing plays a fundamental role among all other engineering activities. Engineering computing comprises two main steps, simulation/analysis and optimization/design. The reliability of these two steps depends on how effectively we predict the system behavior and how successfully we achieve optimal solutions not limited to local optima but extend beyond that to obtain global optima.
Reliable Engineering Computing (REC) requires that computing systems accommodate several sources of errors. Looking at a system model as an example, uncertainty can be introduced in four ways:
- The appropriateness of the mathematical model to describe the physical system;
- The discretization of mathematical model into a computational framework;
- The inexact knowledge of input parameters of a problem;
- Errors introduced by the nature of computer finite arithmetic.
Center for Reliable Engineering Computing
Formulation of Fuzzy Finite-Element Methods for Solid Mechanics Problems
Rafi Muhanna, Robert Mullen
Accounting for uncertainties in mechanics problems has been accomplished previously by probabilistic methods that may require highly repetitive and time-consuming computations to analyze the behavior of mathematical models. In addition to the repetitions, knowledge of the probability distribution of state variables is often incomplete. This article introduces a new treatment of uncertainties in continuum mechanics based on fuzzy set theory.
Influence of Creep on the Stability of Pultruded E-Glass/Polyester Composite Columns at Elevated Service Temperatures
Evan A. Bennett, M.S.C.E.; Advisor: Dr. David Scott
The objectives of the research program were to expand on the existing body of work concerning the long-term behavior of full-scale FRP structural components; to investigate the short-term buckling strength of FRP columns and the creep behavior of FRP columns subjected to sustained loads and elevated service temperatures; to develop a semi-empirical predictive model to accurately predict creep displacements of FRP columns subjected to elevated service temperatures; and to investigate the post-recovery buckling strength of FRP columns.
Slide Handouts (Bennett) [PDF] | Research Handout (Bennett) [PDF]
Compression Creep of a Pultruded E-Glass/Polyester Composite at Elevated Service Temperatures
Kevin J. Smith, M.S.C.E.,; Advisor: Dr. David Scott
The goals of this research program were to expand upon previous research to include temperature effects; select temperatures that represent service conditions; successfully model experimental creep strain; and formulate a time and temperature-dependent predictive equation for the modulus of elasticity.
Slide Handouts (Smith) [PDF] | Research Handout (Smith) [PDF]
Flexural Strengthening of Timber Members with Mechanically Fastened FRP Strips
Dwight Dempsey, M.S.C.E.; Advisor: Dr. David Scott
The objective of the research program was to develop a rapid repair technique to strengthen members of existing timber bridges in military and civilian applications where viable mobilization and transport routes are required. The ability for application in a wide range of tactical and environmental conditions was of equal importance. This technique utilized an automatic screw gun to mechanically fasten fiber reinforced polymer (FRP) strips to the wood specimens and required less time for fabrication compared to conventional bonding techniques previously studied. The strengthened members were tested under static flexural loads to evaluate the structural behavior of the strengthened system. Upon analysis of experimental results, the rapid repair technique was shown to be an effective method to increase the flexural strength, stiffness, and ductility of the wood members. With the addition of the FRP strips, the strengthened members displayed a gradual failure with increased deflections, a marked improvement over that sudden brittle collapse as found for wood members that were not strengthened.
Slide Handouts (Dempsey) [PDF]
