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A Multidiscipline 35 kV Cable Failure Investigation
Orton Harry,Furst Gabor,Batho Joe,Rao Avaral,Salvida Candelario de,Morante Moises Gomes The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Electrophysics Vol.5C No.2
Cable failure investigations must evaluate all facets of cable technology to reach a complete understanding of why and how an underground power cable failed. This paper presents the salient points of a recent investigation into an in-service failure after only several weeks of operation.
S. Altai,S. L. Orton,F. M. Hussein,Z. Chen 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2
Prediction of possible structural collapse scenarios requires the experimental characterization of post-peak behaviors of structural members. The post-peak behavior of one member in a redundant structural system will influence the behaviors of the other members and ultimately the overall structural response. In this work, an experimental and numerical study was conducted to explore the failure behavior of structural systems consisting of three members arranged in parallel under tension. Twelve cylindrical A36 steel specimens with diameter (D) of 7.62 mm (0.3 in.) and length (L = 10D) of 76.2 mm (3 in.) were made for the experiments. Three specimens were used in single member tests to determine the base material properties. Three tests of three-member systems (Test-1, Test-2, and Test-3) were conducted using a special fixture that could rotate around a central pin in response to unbalanced forces produced due to unsymmetrical failure evolution in the three-member systems. A 3D DIC (three-dimensional Digital Image Correlation) measurement device was used to capture the deformations along the specimen length. The experimental results showed that all single members failed at approximately the same strength but with distinctly different displacement fields. In the three-member system tests, one system failed at 10% higher load, 21% lower displacement, and 13 times the rotation, as compared with the other two systems due to the softening of one outer member substantially before the other two members. The numerical results of the three-member system showed an acceptable correlation with the experiments. It could be concluded from this experimental study that the inconsistency of softening response, due to the inevitable imperfection of geometry, material and/or loading, can trigger the softening of one member before the others and significantly impact lateral displacement or rotation in a collapsing system.
Saif L. Altai,Sarah L. Orton,Zhen Chen 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.4
Constitutive modeling that could reasonably predict and effectively evaluate the post-peak structural behavior while eliminating the mesh-dependency in numerical simulation remains to be developed for general engineering applications. Based on the previous work, a simple one-dimensional modeling procedure is proposed to predict and evaluate the post-peak response, as characterized by the evolution of localized strain field, of a steel member to monotonically uniaxial tension. The proposed model extends the classic one-dimensional softening with localization model as introduced by (Schreyer and Chen 1986) to account for the localization length, and bifurcation and rupture points. The new findings of this research are as follows. Two types of strain-softening functions (bilinear and nonlinear) are proposed for comparison. The new failure criterion corresponding to the constitutive modeling is formulated based on the engineering strain inside the localization zone at rupture. Furthermore, a new mathematical expression is developed, based on the strain rate inside and outside the localization zone, to describe the displacement field at which bifurcation occurs. The model solutions are compared with the experimental data on four lowcarbon cylindrical steel bars of different lengths. For engineering applications, the model solutions are also compared to the experimental data of a cylindrical steel bar system (three steel bars arranged in series). It is shown that the bilinear and nonlinear softening models can predict the energy dissipation in the post-peak regime with an average difference of only 4%.
Kim, S.J.,Geballe, T.R.,Greathouse, T.K.,Yung, Y.L.,Miller, S.,Orton, G.S.,Minh, Y.C. Academic Press 2017 Icarus Vol.281 No.-
<P>We have derived homopause temperatures of 180-250 K for the 8-mu m north-polar hot spot (8NPHS) of Jupiter by fitting CH4 emission models to 3 and 8 mu m spectra of the 8NPHS obtained 24 days apart in 2013. From the fits, we find that CH4 mixing ratios at the 8NPHS are consistent with those reported by Kim et al. (2014) in equatorial regions. We propose possible mechanisms to account for the temperature of the 8NPHS homopause, which is relatively cool compared with the temperatures of other auroral regions, including locally-fixed and transient but energetic auroral particle precipitation. (C) 2016 Elsevier Inc. All rights reserved.</P>