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Damaged Structures (damaged + structure)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

A structural damage identification method based on genetic algorithm and vibrational data

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2007
Carlos C. H. Borges
Abstract The problem of damage identification in framed structures using vibrational data is considered. The identification problem is modelled as an optimization task and the use of measured natural frequencies as well as modeshape information in the construction of objective functions is discussed. In a first attempt, a standard genetic algorithm is shown to be ineffective in obtaining the correct damage distribution in test problems. Using domain knowledge, modifications are introduced in the coding process, in the initial population generation, in the fitness function, and in the genetic operators, leading to a promising tool to solve this class of problems. Synthetic problems, with the addition of noise in the simulated measured data associated with the damaged structure, are analysed in order to assess the capability of the proposed technique. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Development of the extended parametric meshless Galerkin method to predict the crack propagation path in two-dimensional damaged structures

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 7 2009
M. MUSIVAND-ARZANFUDI
ABSTRACT The parametric meshless Galerkin method (PMGM) enhances the promising features of the meshless methods by utilizing the parametric spaces and parametric mapping, and improves their efficiency from the practical viewpoints. The computation of meshless shape functions has been usually a time-consuming and complicated task in the meshless methods. In the PMGM, the meshless shape functions are mapped from the parametric space to the physical space, and therefore, the necessary computational time to generate the meshless shape functions is saved. The extended parametric meshless Galerkin method (X-PMGM) even improves the parametric property of the PMGM by incorporating the partition of unity concepts. In this paper, the development of the X-PMGM is extended by incorporating a crack-tip formulation in X-PMGM for fracture analysis and prediction of crack propagation path in the damaged structures. In this formulation, meshless shape functions are enriched by discontinuous enrichment function as well as crack-tip enrichment functions. The obtained results show that the predicted crack growth path is in good agreement with the experimental results. [source]

Rescue robots for mudslides: A descriptive study of the 2005 La Conchita mudslide response

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1-2 2008
Robin R. Murphy
The Center for Robot-Assisted Search and Rescue (CRASAR) assisted the Ventura County Fire Rescue Department with the January 2005 La Conchita, California, mudslide response. CRASAR provided commercially available urban search and rescue robots and expert operators which were deployed twice into damaged structures. The waterproof robots were able to tolerate wet conditions but proved unable to handle the densely packed rubble, vegetation, and soil and failed within two and four minutes, respectively on their two deployments. Informal interviews were conducted with responders as well. The experience forms a descriptive study of what mudslide responses are like, what tasks robots are needed for, how the rescue robots performed, and how responders viewed the robots. Our observations are captured in fourteen findings on robot performance (3), domain characteristics of mudslides (8), and general rescue robot design issues (3). These findings are expected to be of interest to robot designers, software developers, and the human-robot interaction communities. The experience at La Conchita illustrates that terrain understanding, critical for both robot design and for control, remains an important open research question for rescue robotics. © 2008 Wiley Periodicals, Inc. [source]