Modeling the dynamic behavior of laminated steels using a Fourier-based approach

A new magneto-dynamic model is proposed to approximate the dynamic hysteresis effect in laminated steels considering the static hysteresis, eddy-current field, and excess field. An accurate congruency-based hysteresis model is used to predict the static hysteresis field. The eddy-current is determined from the 1D diffusion equation and the well-known Bertotti empirical equation is utilized to model the excess-field effect. The dynamic lamination model obtained from coupling three field components is solved using a Fourier-based approach. In this approach, the flux density across the lamination thickness is approximated by a cosine-based Fourier series. The coefficients of the Fourier series are determined by solving a system of nonlinear equations through an iterative procedure. Owing to the employed congruency-based static hysteresis model, the proposed magneto-dynamic model offers high accuracy for arbitrary magnetization regimes. To validate the model accuracy, the model results are compared with sinusoidal and multi-harmonic measurements. The comparison shows that the proposed model predicts the dynamic hysteresis phenomenon in laminated steels with a relative energy error of less than 7%.

Effects of layer number and finger direction on bending behavior of glulam beams

Effects of the number of layers and the number and typology of finger joints were studied relative to the bending behavior of glulam beam made of Scots pine (Pinus sylvestris) laminates. The investigated parameters of glulam beams with constant overall dimensions (width × depth × length) of 90 mm × 90 mm × 1710 mm were lamination thickness (18 mm or 30 mm), the distance of the finger joints (200, 400, and 600 mm), and finger direction (horizontal and vertical). A total of 14 experimental samples were produced (12 different finger joint beams and two reference beams without finger joints) and tested under four-point bending tests. Taguchi orthogonal experimental design was used to evaluate and optimize test results using the S/N ratio. The effects of main and interactions between producing parameters on strength of glulam beam were determined by variance analysis. According to the results of the analysis, it was determined that the number of layers and the direction of the finger had a significant effect on the flexural strength of the beams, but the finger distance was not significant. Moreover, the highest strength values were obtained in 5-layer finger-jointed beams with vertical finger direction.

Application of Scanning Acoustic Microscopy for Micro Delamination Detection

This paper describes the detection capability of micro delamination in ICs according to the transducer frequency of SAM (Scanning Acoustic Microscopy) equipment through a case study of non-destructive failure analysis. The analysis of scanning acoustic microscopy is non-destructive, but is difficult to define micro de-lamination or micro crack. In this study, two SAM systems and various transducer frequencies were used to detect micro de-lamination on the lead finger area. In the results of non-destructive analysis by utilizing two systems, one SAM detected the micro delamination but the other SAM did not define micro delamination with C-scan mode. To confirm an accurate delamination phenomenon, we analyze the destructive analysis under cross-sectional inspection and the micro de-lamination was observed. The cause of non-detection for micro delamination is not due to the difference between equipments, but due to the transducer frequency. This paper will be concluded with a discussion on what kind of transducer frequency are selected according to distance from package surface to chip surface, package materials, and micro de-lamination thickness.

Finite Element Modeling and Analysis of Photovoltaic Modules

A Photovoltaic (PV) module consists of layers of different materials constrained together through an encapsulant polymer. During operation, it experiences mechanical and thermal loads due to seasonal and temperature variations, which cause breakage of interconnects owing to fatigue and laminate warpage. This is due to the fact that there is a coefficient of thermal expansion (CTE) mismatch because of the presence of unlike materials within the laminate. Therefore, thermo-mechanical stresses are induced in the module. Glass, being the thickest of all in the module, plays a significant role in the stressing of components. The lifetime of today’s PV module is expected to be 25 years and this period corresponds to the guarantee of the manufacturer. Its high reliability will help it to reach grid parity. But the problem is that it is not convenient to wait and assess its durability. Qualification standards such as ASTM E1171-09 are useful in predicting a module’s failure. In this work, material of each component of the PV module is characterized and then the implementation of material models is discussed. A Finite-Element (FE) model of 36 cell PV module is developed using 2D layered shell elements in ANSYS. A single temperature cycle of ASTM E1171-09 is simulated after lamination procedure and 24 hour storage at constant temperature. The FE model is validated by simulating an experimental procedure in the literature by determining change of cell gap during the temperature cycle. Finally, parametric studies are performed with respect to lamination thickness.

14C Dating of Laminated Sediments from Loch Ness, Scotland

Radiometric and AMS radiocarbon dating of a 6-m sediment core from Loch Ness, Scotland, indicates that it represents perhaps the very end of the Late Pleistocene, and the first ca. 7500 yr of the Holocene. Counts of laminations observed in the Holocene section of the core suggest that they are present in sufficient number to constitute annual laminations (varves), an hypothesis consistent with the pollen record, which contains a sequence of zones representative of the Early, Middle and part of the Late Holocene regional vegetation history. On the basis of BSEM and X-ray studies of sediments, and modern seston trap data, the laminations are believed to be produced by winter floods, which introduce increased silt loading into the Loch. Sediment for the rest of the year is mostly composed of clay-sized material. This hypothesis is being further tested, however, by continuing sedimentological and microfossil studies.Time-depth relations for the core based on calibrated 14C dates and lamination counts, respectively, illustrate the close correspondence between the two sets of data. The latter are therefore now being used to develop a varve chronology for the Holocene for Loch Ness. This will then in turn be used for further chronological studies, and for investigations of palaeoclimatic variations over the eastern North Atlantic, to which the signal of lamination thickness in the sediments is thought to be particularly sensitive. They may also eventually be used for calibration studies, employing 14C dating of specific carbon compounds, or groups of compounds extracted from the sediment using modern organic geochemical methods.

Integrated Damping Mechanics for Thick Composite Laminates and Plates

A method for predicting the damped dynamic characteristics of thick composite laminates and plates is presented. Unified damping mechanics relate the damping of composite plates to constituent properties, fiber volume ratio, fiber orientation, laminate configuration, plate geometry, temperature, and moisture. Discrete layer damping mechanics for thick laminates, entailing piecewise continuous displacement fields and including the effects of interlaminar shear damping, are described. A semi-analytical method for predicting the modal damping and natural frequencies of thick simply-supported specialty composite plates is included. Applications demonstrate the validity, merit, and ranges of applicability of the new theory. The applications further illustrate the significance of interlaminar shear damping, and investigate the effects of lamination, thickness aspect ratio, fiber content, and temperature.