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The current study aims to forecast and analyze wind data such as wind speed at a test site called “Urumsill” on Deokjeok Island, South Korea. The measured wind data available at the aforementioned test site are only for two years (2015 and 2016), making it impossible to analyze the long-term wind characteristics. In order to overcome this problem, two measure-correlate-predict (MCP) techniques were adopted using long-term wind data (2000–2016), measured by a meteorological mast (met-mast) installed at a distance of 3 km from the test site. The wind data measured at the test site in 2016 were selected as training data to build the MCP models, whereas wind data of 2015 were used to test the accuracy of MCP models (test data). The wind data at both sites were measured at a height of 10 m and showed a good agreement for the year 2016 (training period). Using the comparison results of the year 2016, wind speed predictions were made for the rest of the years (2000–2016) at the test site. The forecasted values of wind speed had maximum relative error in the range of ±0.8 m/s for the test year of 2105. The predicted wind data values were further analyzed by estimating the mean wind speed, the Weibull shape, and the scale parameters, on a seasonal and an annual basis, in order to understand the wind behavior in the region. The accuracy and presence of possible errors in the forecasted wind data are discussed and presented.

We aimed to embed silica optical fibers in composites (epoxy vinyl ester matrix reinforced with E-glass unidirectional fibers in mass fraction of 60%) in order to further monitor the robustness of civil engineering structures (such as bridges). A simple system was implemented using two different silica optical fibers (F1-uble coating of 172 μm diameter and F2-ngle coating of 101.8 μm diameter respectively). The optical fibers were dynamically tensile tested and Weibull plots were traced. Interfacial adhesion stress was determined using pull-out test and stress values were correlated to fracture mechanisms based on SEM observations. In the case of the optical fiber (OF) (F1)/resin system and OF (F1)/composite system, poor adhesion was reported that may be correlated to interface fracture at silica core level. Relevant applicable results were determined for OF (F2)/composite system. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study is to address the rolling contact fatigue (RCF) life and behavior of thermal sprayed coatings. The Fe–Cr alloy coatings and Ni–Al alloy coatings were prepared by a plasma spray device as the surface coating and undercoating on steel substrates, respectively. RCF tests were conducted using the ball-on-disc tester under four kinds of loading conditions. The failure mechanisms were investigated on the basis of worn surface observations of failed coated specimens. The RCF lives of Fe–Cr coatings were evaluated by means of Weibull distribution plots. The results show that the contact stress obviously influences the RCF life and failure behavior of the Fe–Cr coatings. The lives decreased as the contact stress increased. At the same time, the main failure modes of the coatings changed from abrasion and spalling to delamination. The failure mechanisms of coatings are associated with the micro-defects, the bond strength of the coatings and the orthogonal shear stress (OSS) within the coatings. The S–N curve, based on RCF life data by using statistical approach, is helpful for the design of hard coatings. [Copyright &y& Elsevier]

Material damage by several erosion processes is caused mainly by high, local, and repetitive loading, resulting in fatigue, cracking, and erosion. One of the surface treatments used to increase material resistance to erosion damage is shot peening. This process induces compressive stresses on the treated surface layer, and increases its resistance to fatigue loading. Cumulative erosion-time curves of shot-peened specimens clearly indicate their increased erosion resistance compared to that of machined specimens. However, this comparison does not yield any information about the causes for the improved performance. Cumulative erosion-time plots in the Weibull domain of machined specimens, tested by five different erosion methods, are very similar. The common plot shape is bimodal with a decreasing slope. These plots enable an extensive study of machined and shot-peened specimens. This study explains the improvement process, and quantifies it during test duration and beyond it. This method is illustrated by testing of two AISI-316 specimens by the vibratory cavitation erosion method. Analysis of test results confirms the effectiveness of this method for erosion testing of machined and shot-peened specimens. Shot peening was found to restore some of the erosion properties of the boundary layer, bringing them closer to those of the base material. [ABSTRACT FROM AUTHOR]

Erosion and abrasion-time curves of laboratory tests are of various forms. Most of these curves have a typical form, and are considered to be representative of erosion and abrasion phenomena. Other curves are considered anomalous; however, no definite explanations are offered for these irregularities. Analysis of the anomalous curves enables detection of the causes for these anomalies. The main causes detected for curve shape variation are: faulty test equipment, improper test procedure, variation in test specimen structure and properties, and wrong evaluation of test results. [ABSTRACT FROM AUTHOR]

Manufacturers of consumer electronic products are continuously striving to confer greater functionality to smaller, lighter, and less expensive packages, and flip-chip is an important enabling technology for these product trends. Underfill between the die and an organic substrate is necessary to compensate for the coefficient of thermal expansion mismatch. The underfill dispense and cure step is not a typical process for a surface-mount technology (SMT) factory, and demands additional capital equipment, floor space, cycle time, and headcount. An alternate approach to traditional capillary underfill is wafer-applied underfill. The underfill is applied after wafer bumping and sawing, but prior to the picking of the individual die from the saw tape. This paper describes the coating and assembly processes. Liquid-to-liquid thermal cycle shock tests (-55 to +125°C) have been performed on test vehicles assembled with the wafer-applied underfill. First failures were at over 1000 cycles. Weibull plots of the data and failure analysis are presented. [ABSTRACT FROM PUBLISHER]