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The role of nonlinear viscoelasticity on the functionality of laminating shortenings
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In-situ synchrotron X-ray micro-diffraction investigation of ultra-low-strain deformation microstructure in laminated Ti-Al composites
An ultra-low-strain deformation microstructure was revealed for the first time non-destructively in the bulk interior of an annealed laminated Ti-Al composite-in the "fully recrystallized" Al layer-by a synchrotron-based micro-diffraction technique, namely differential aperture X-ray microscopy (DAXM), through real space mapping with a very high angular resolution (0.01 degrees). This ultra-low-strain deformation microstructure was found to result from the thermal stress, induced during cooling after annealing, due to the different coefficients of thermal expansion for the Ti and Al layers. The annealed sample was further tensile deformed to a strain of 1.66% and followed by in situ DAXM and analyzed by various misorientation mapping methods. The results pointed to the important effects of the initial microstructure and the interface constraint, as well as the grain size and crystal orientation, on the plastic deformation. A gradient in dislocation density from the layer interface to the center was found in the Al layer of the annealed sample, and this gradient increased slightly during tensile deformation. The variation of the dislocation density was further discussed based on the activation and interaction of dislocations in grains of different sizes and orientations during plastic deformation. The findings of this study provided valuable insights in understanding the constraint effect of the laminated metal composite and the design of novel composite materials. (c) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Irradiation effects in tungsten-copper laminate composite
Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410-780°C and fast neutron fluences of 0.02-9.0×1025 n/m2, E>0.1 MeV, 0.0039-1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22°C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22°C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.
Cross-Laminated Timber Workshop: Pathways and Priorities for Cross-Laminated Timber Building Systems
A virtual workshop titled "BTO Cross-Laminated Timber Workshop: Pathways and Priorities for CLT Building Systems," was held on April 19, 2021, to identify research and development pathways, including the embodied energy content, operational energy efficiency, wall moisture profiles, structural connector durability, and health monitoring systems for CLT wall systems. In the workshop, perspectives were gathered from a wide range of stakeholders across North America from academia, the mass timber industry, trade groups, and federal government departments. The participants had knowledge in one or more areas of CLT building performance, production and construction, supply and demand dynamics of CLT panels, building codes, and recycling of CLT panels. To capture potential research opportunities from the participants in the mass timber field, the workshop was structured with the following objectives: 1. Identify the research and development opportunities to overcome technology gaps, integration issues, and market adoption challenges that are currently preventing the greater deployment of CLT, and 2. Understand what priorities and pathways are needed to advance energy efficient, high- rise CLT building systems.
The natural armors of fish: A comparison of the lamination pattern and structure of scales
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Ultra-low radioactivity Kapton and copper-Kapton laminates
Polyimide-based materials, like Kapton, are widely used in flexible cables and circuitry due to their unique electrical and mechanical characteristics. This study is aimed at investigating the radiopurity of Kapton for use in ultralow background, rare-event physics applications by measuring the 238U, 232Th, and natK levels using inductively coupled plasma mass spectrometry. Commercial-off-the-shelf Kapton varieties, mea- sured at approximately 950 and 120 pg/g 238U and 232Th (1.2×104 and 490 µBq/kg), respectively, can be a significant background source for many current and next-generation ultralow background detectors. This study has found that the dominant contamination is due to the use of dicalcium phosphate (DCP), a nonessential slip additive added during manufacturing. Alternative Kapton materials were obtained that did not contain DCP and were determined to be significantly more radiopure than the commercially- available options with 12 and 19 pg/g 238U and 232Th (150 and 77 µBq/kg), respectively. The lowest radioactivity version produced (Kapton ELJ, which contains an adhesive) was found to contain single digit pg/g levels of 238U and 232Th, two-to-three orders of magnitude cleaner than commercial-off-the- shelf options. Moreover, copper-clad polyimide laminates employing Kapton ELJ as the insulator were obtained and measured and showed to be very radiopure at 8.6 and 22 pg/g 238U and 232Th (110 and 89 µBq/kg), respectively.
Enhanced Charge-Carrier Injection and Collection Via Lamination of Doped Polymer Layers p-Doped with a Solution-Processible Molybdenum Complex
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Convective heat transfer analysis of a laminated flux focusing magnetic gearbox
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Laser Shearography and Ultrasound Inspection of Composite Laminates with Overlapping Fiber Plies.
Abstract not provided.
Lamin A reassembly at the end of mitosis is regulated by its SUMO-interacting motif
Modification of proteins with small ubiquitin-related modifier (SUMO; SUMOylation) is involved in the regulation of various biological processes. Recent studies have demonstrated that noncovalent associations between SUMOylated proteins and co-operative proteins containing SUMO-interacting motifs (SIMs) are important for the spatiotemporal organization of many protein complexes. In this study, we demonstrate that interactions between lamin A, a major component of the nuclear lamina, and SUMO isoforms are dependent on one of the four SIMs (SIM3) resided in lamin A polypeptide in vitro. Live cell imaging and immunofluorescence staining showed that SIM3 is required for accumulation of lamin A on the chromosomes during telophase, and subsequent evaluation of a panel of deletion mutants determined that a 156-amino acid region spanning the carboxyl-terminal Ig-fold domain of lamin A is sufficient for this accumulation. Notably, mutation of SIM3 abrogated the dephosphorylation of mitosis-specific phosphorylation at Ser-22 of lamin A, which normally occurs during telophase, and the subsequent nuclear lamina reorganization. Furthermore, expression of a conjugation-defective SUMO2 mutant, which was previously shown to inhibit endogenous SUMOylation in a dominant-negative manner, also impaired the accumulation of wild type lamin A on telophase chromosomes. These findings suggest that interactions between SIM3 of lamin A and a putative SUMO2-modified protein plays an important role in the reorganization of the nuclear lamina at the end of mitosis. - Highlights: • Lamin A interacts with SUMO2 via a SUMO-interacting motif (SIM) in the Ig domain. • SIM3 of lamin A is responsible for chromosomal accumulation during telophase. • A 156-aa region spanning the Ig domain is sufficient for chromosomal accumulation. • Accumulation of lamin A is required for timely dephosphorylation on chromosomes. • A putative SUMO2-modified protein may mediate chromosomal accumulation of lamin A.
High expression of A-type lamin in the leading front is required for Drosophila thorax closure
Highlights: • Lamin C expression is high at the leading front of the closing tissue in pupal notum. • Lamin C is required for the coordinated movement of the leading front. • The closure defect by Lamin C knockdown correlates with insufficient F-actin formation. Tissue closure involves the coordinated unidirectional movement of a group of cells without loss of cell–cell contact. However, the molecular mechanisms controlling the tissue closure are not fully understood. Here, we demonstrate that Lamin C, the sole A-type lamin in Drosophila, contributes to the process of thorax closure in pupa. High expression of Lamin C was observed at the leading front of the migrating wing imaginal discs. Live imaging analysis revealed that knockdown of Lamin C in the thorax region affected the coordinated movement of the leading front, resulting in incomplete tissue fusion required for formation of the adult thorax. The closure defect due to knockdown of Lamin C correlated with insufficient accumulation of F-actin at the front. Our study indicates a link between A-type lamin and the cell migration behavior during tissue closure.
Investigation of the notch sensitivity of tailorable long fiber discontinuous prepreg composite laminates
Tailorable discontinuous fiber composite laminates provide relative formability beyond that of continuous fiber laminates, while achieving improved mechanical performance over comparable stochastic systems. Here, in this work, the notch sensitivity of engineered prepreg platelet molded composite (PPMC) laminates is investigated using the open-hole tension (OHT) test and compared to available data for stochastic PPMCs and continuous fiber laminates made with the same material. The press-formed thermoplastic composites (AS4/PEKK) were molded with a quasi-isotropic stacking sequence. The discontinuous PPMC laminate was found to be notch insensitive with OHT strengths ranging from 145.4 MPa (CV $=$ 7%) for d/w $=$ 0.5 to 229.3 MPa (CV $=$ 9%) for d/w $=$ 0.25. The highly ordered meso-structure of the engineered PPMC laminate yields comparatively excellent mechanical properties for relatively thin laminates in contrast to stochastic systems. Both net- and gross-section failures were observed for d/w $=$ 0.25, which suggests that the engineered PPMC laminates studied here maintain a degree of inherent, internal stress concentrations that compete with those caused by geometric features such as a circular hole. Computational simulations of the OHT tests with explicitly represented platelets were found to be in good agreement with experimental measurements. The progressive failure analysis was used to conduct a numerical investigation of the stacking sequence and platelet meso-morphology.
Highly-laminated, high-saturation-flux-density, magnetic cores for on-chip inductors in power converter applications
The objective of this project is development of a manufacturing process to realize thick highly-laminated metallic magnetic cores with suppressed eddy current losses for power applications and demonstration of integrated magnetic components using the process. The continual reduction in size and increase in functionality of portable electronic devices drives the development of ultracompact electrical power converters and therefore their associated inductors, which typically occupy the largest volume within the converter. This inductor size reduction can be achieved by increasing both the converter switching frequency as well as inductor operating flux density by utilizing appropriate magnetic core materials. Magnetically soft metallic alloys (e.g., NiFe and CoNiFe) are good core material candidates due to their superior magnetic properties (e.g., high saturation flux density and low coercivity) compared to conventional ferrite. However, to minimize eddy current losses, the core thickness is limited to the skin depth (typically less than 3 µm for 10 MHz operation); cores of this thickness are likely insufficient for handling high power (> 10W). Therefore, there is great interest in the development of highly-laminated metallic alloy cores with single lamination thickness in the sub-micron range to achieve suppressed eddy-current losses and high power handling capacity simultaneously. During the project, highly-laminated metallic alloy cores comprising up to 2000 layers of permalloy (Ni 80 Fe 20 ) or CoNiFe materials with single lamination thickness less than 1 µm have been fabricated based on automated multilayer electrodeposition technology compatible with CMOS manufacturing. The developed highly-laminated metallic cores preserve the high saturation flux density and low coercivity characteristics of metallic alloys, while suppressing eddy-current losses less than 1 W/cm3 at operation flux density of 0.5 T and frequency over 1 MHz. The developed highly-laminated metallic alloy cores have been further integrated into microfabricated windings to realize compact, on-chip inductors. Utilizing CMOS-compatible integration techniques, circular (toroid) and bar-shape (solenoid) microinductors have been fabricated exhibiting a constant inductance higher than 1 µH up to 50 MHz with peak quality factor as high as 35 at 5 MHz. The microfabricated inductor with highly-laminated core was tested in a power converter and demonstrated a converter efficiency of 93% at 5.5 MHz and 42 W under 100V input and 35V output operation.
Ultrafast (1‐5 sec) Lamination of Perovskite Solar Cells With Self‐Encapsulation Using Rapid Joule Heating
Perovskite solar cells (PSCs) are traditionally fabricated using sequential layer‐by‐layer deposition, in which each layer of the device is processed on top of the preceding layer. This constrains the processing techniques and selection of transport layer materials that can be used in the solar cell. To overcome these challenges, two half‐cells can be processed independently and then diffusion‐bonded through a lamination process. However, current lamination processes for perovskite solar cells suffer from relatively long process times, which can limit throughput when moving toward high‐volume manufacturing. In this study, a custom platform was designed for rapid‐joule heating of perovskite materials and devices. This enabled more than a 99% reduction in lamination time from 26 min to 1 s. Perovskite samples that were laminated in 1 s exhibited comparable values of percent bonded area, interfacial toughness, grain domain size, and X‐ray diffraction spectra to those laminated in greater than 10 min. As a proof‐of‐concept, 18.3% efficient devices were successfully laminated in 5 s. A transient heat transfer model was developed to describe the relationship between the perovskite temperature and the electrical power supplied to the heaters, establishing a baseline for predicting processing conditions in large‐scale manufacturing systems. Ultra‐fast lamination provides a pathway toward scalable roll‐to‐roll or sheet‐to‐sheet manufacturing of PSCs.
In-situ imaging of flexure-induced fracture in tape-laminate composites using high-resolution X-ray computed tomography
Here, this study presents development of an in-situ flexure test for imaging progressive inter- and intralaminar fracture in tape-laminate composites using X-ray computed tomography (CT). The intent of this test is to provide detailed experimental observations of ply-level damage that can be used to validate existing, and develop new, progressive damage analysis (PDA) tools. The test consists of a vertically mounted specimen which is flexed using two eccentric compressive loads using an in-situ uniaxial load stage. The flexure specimen contains a starter notch mid-span which promotes initiation of composite failure within the X-ray field of view. Specimens with two different laminate stacking sequences were tested, imaged, analyzed. For a quasi-isotropic laminate with large angle changes between adjacent plies, there was near simultaneous growth of transverse cracks and delaminations below the midplane of the laminate. For a laminate with small angles between adjacent plies, there was extensive formation of transverse crack networks which penetrated the laminate thickness without delamination growth. In addition to imaging fracture, the X-ray CT data from both specimen types were used to quantify the variability in thickness and analyze the local orientation of individual plies. Overall, the proposed test and the image-data analysis methodology provided an important insight into the fracture processes in tape laminates and highlights the inherent ply-level geometrical variabilities that should be accounted for in PDA simulations.
Understanding Process–Structure Relationships during Lamination of Halide Perovskite Interfaces
Fabrication of halide perovskite (HP) solar cells typically involves the sequential deposition of multiple layers to create a device stack, which is limited by the thermal and chemical incompatibility of top contact layers with the underlying HP semiconductor. One emerging strategy to overcome these restrictions on material selection and processing conditions is lamination, where two half-stacks are independently processed and then diffusion bonded to complete the device. Lamination reduces the processing constraints on the top side of the solar cell to allow new device designs, expanded use of deposition methods, and self-encapsulation of devices. While laminated perovskite solar cells with high efficiencies and novel interlayer combinations have been demonstrated, there is a limited understanding of how the lamination process parameters affect the diffusion-bond quality and material properties of the resulting HP layer. In this study, we systematically vary temperature, pressure, and time during lamination and quantify the resulting impacts on bonded area, grain domain size, and photoluminescence. A design of experiments is performed, and statistical analysis of the experimental results is used to quantitatively evaluate the resulting process–structure–property relationships. The lamination temperature is found to be the key parameter controlling these properties. Furthermore, a temperature of 150 °C enables successful bonding over 95% of the substrate area and also results in increases in apparent grain domain size and photoluminescence intensity. Based on these insights, the lamination temperature of functional perovskite solar cell devices is varied, demonstrating the importance of the resulting bond quality on device performance metrics.
Investigating Temperature Uniformity and Accuracy in PV Module Lamination: A Verification Study
This study investigates the temperature uniformity and accuracy of a photovoltaic (PV) module lamination process by addressing inconsistencies identified in 2017 data where irregular temperature changes were observed across setpoints. The 2017 data showed a notable drop in temperature upon bladder initiation, except for the 145 degrees Celsius profile. This inconsistency indicated potential inaccuracies in manual data recording methods. To address this concern, a verification experiment was conducted to evaluate temperature uniformity across the 2014 Bent River SPL2828 laminator platen and within test samples. Thermocouples, paired with Omega data acquisition software, were deployed to measure temperatures at multiple platen locations and within test samples. The experiment compared lamination temperatures of polyethylene-co-vinyl acetate (EVA) encapsulant when paired with solite glass or TPE backsheets. The methodology included verifying temperature uniformity directly on the platen and by using a large glass/EVA/glass sample using multiple thermocouples. Smaller samples were built with glass/EVA/glass and glass/EVA/backsheet configurations with one centered thermocouple to verify and compare sample temperatures. This verification aims to refine lamination temperature profiles, enhance data accuracy and provide insights into optimal process control for uniform module lamination. Ensuring consistent and uniform lamination may improve the accuracy and reliability of research outcomes.