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Pressurizer surge lines are essential pipeline structure in NPPs, and the thermal stratification in surge line is recognized as one of the possible cause of thermal fatigue. In this paper, a Computational Fluid Dynamic (CFD) method has been adopted to simulate temperature fluctuations on the process of temperature rising in a pressurizer surge line under rolling motion of single degree of freedom. This work focuses on a fundamental description of differences of thermal stratification between the surge line rolling around the coordinate X-axis condition and that in a static state. The Large-eddy simulation (LES) model is employed to capture the details of temperature change in surge line. Temperature distributions near the inner wall of a surge line pipe with or without swinging were monitored and compared. The temperature differences between the top and bottom of the pipe sections are employed to represent the maximum temperature differences at all the monitored sections. As the surge line swinging, the pattern of temperature distribution and the length of thermal stratification development are different from that in a static. Fluid temperature fluctuation in surge line occur periodically during the fluid temperature rising when the surge line is rotated with the X-axis, and the temperature difference between top and bottom of the surge line is reduced in the same motion mode compared with the static state.

The indentation behavior of metal/ceramic nanolayers is studied, with attention devoted to cyclic response under fixed maximum and minimum indentation loads. The primary objective is to examine the evolving plastic deformation in the ductile metal constrained by the hard ceramic layers. The model consists of alternating aluminum (Al) and silicon carbide (SiC) thin films on a silicon substrate, with the Al/SiC layered structure being indented by a diamond indenter. The rate-dependent viscoplastic response of Al is taken into account in the numerical model. It is shown that plastic deformation in the ductile Al layers continues to occur during the unloading phase of the first cycle, as well as during subsequent reload/unload processes. The cyclic plasticity results in an open load-displacement loop, and the indenter continues to move deeper with each cycle. For the control model of a homogeneous Al film, there is no hysteresis loop and the transient behavior soon approaches stabilization, showing repetitive elastic loading/unloading. The modeling results are also compared with cyclic nanoindentation experiments conducted on the same metal-ceramic multilayer system and control specimen.Copyright © 2012 by ASME

Misalignment of chips in three-dimensional (3D) integrated circuit (IC) packages subjects the bonding layer between chips to shear deformation. Chip warpage and thermal effects from chip processing can further compound the problem. In this study we perform a numerical assessment on the shear and thermally-induced deformations in and around the through-silicon vias (TSV) and solder micro-bumps. The 3D finite element model features a TSV/micro-bump bonding structure connecting two adjacent silicon chips, with and without an underfill layer in between. The possibility that the entire solder micro-bump may be transformed into an intermetallic is also considered in this study. We seek to parametrically explore the trend of stress and deformation fields due to misalignment-induced shear deformation and thermal expansion mismatch. Potential for damage initiation in the TSV/micro-bump is examined by the measure of plastic strain accumulation. The existence of an underfill layer around the TSV/micro-bump enhances the overall resistance to shear deformation, although with a higher buildup of local stresses. The TSV and silicon chip are less affected by misalignment than by thermal expansion mismatches.Copyright © 2012 by ASME