Unraveling the ultrahigh modulus of resilience of Core-Shell SU-8 nanocomposite nanopillars fabricated by vapor-phase infiltration
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36 MATERIALS SCIENCE↗
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Results for “elastic modulus”
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Elastic-Plastic J-Integral Solutions or Surface Cracks in Tension Using an Interpolation Methodology
No closed form solutions exist for the elastic-plastic J-integral for surface cracks due to the nonlinear, three-dimensional nature of the problem. Traditionally, each surface crack must be analyzed with a unique and time-consuming nonlinear finite element analysis. To overcome this shortcoming, the authors have developed and analyzed an array of 600 3D nonlinear finite element models for surface cracks in flat plates under tension loading. The solution space covers a wide range of crack shapes and depths (shape: 0.2 less than or equal to a/c less than or equal to 1, depth: 0.2 less than or equal to a/B less than or equal to 0.8) and material flow properties (elastic modulus-to-yield ratio: 100 less than or equal to E/ys less than or equal to 1,000, and hardening: 3 less than or equal to n less than or equal to 20). The authors have developed a methodology for interpolating between the goemetric and material property variables that allows the user to reliably evaluate the full elastic-plastic J-integral and force versus crack mouth opening displacement solution; thus, a solution can be obtained very rapidly by users without elastic-plastic fracture mechanics modeling experience. Complete solutions for the 600 models and 25 additional benchmark models are provided in tabular format.
Allen, P. A.↗
Elastic-Plastic J-Integral Solutions or Surface Cracks in Tension Using an Interpolation Methodology. Appendix C -- Finite Element Models Solution Database File, Appendix D -- Benchmark Finite Element Models Solution Database File
No closed form solutions exist for the elastic-plastic J-integral for surface cracks due to the nonlinear, three-dimensional nature of the problem. Traditionally, each surface crack must be analyzed with a unique and time-consuming nonlinear finite element analysis. To overcome this shortcoming, the authors have developed and analyzed an array of 600 3D nonlinear finite element models for surface cracks in flat plates under tension loading. The solution space covers a wide range of crack shapes and depths (shape: 0.2 less than or equal to a/c less than or equal to 1, depth: 0.2 less than or equal to a/B less than or equal to 0.8) and material flow properties (elastic modulus-to-yield ratio: 100 less than or equal to E/ys less than or equal to 1,000, and hardening: 3 less than or equal to n less than or equal to 20). The authors have developed a methodology for interpolating between the goemetric and material property variables that allows the user to reliably evaluate the full elastic-plastic J-integral and force versus crack mouth opening displacement solution; thus, a solution can be obtained very rapidly by users without elastic-plastic fracture mechanics modeling experience. Complete solutions for the 600 models and 25 additional benchmark models are provided in tabular format.
Allen, Phillip A.↗
Young’s modulus of V 3 O 5 thin films
Vanadium oxide V 3 O 5 exhibits an insulator-to-metal transition (IMT) near 430 K, which is the highest value for all vanadium oxides exhibiting IMTs. This makes it interesting for advanced electronic applications. However, the properties of V 3 O 5 have been little studied, and, in particular, there are no reports of experimentally determined mechanical properties. In this work, Young’s modulus of sputter-deposited V 3 O 5 thin films has been determined by measuring the fundamental resonant frequency of V 3 O 5 -coated silicon microcantilevers using a laser beam deflection technique. After deposition, the films were characterized by x-ray diffraction, resistivity measurements, and atomic force microscopy. The value of Young’s modulus experimentally determined for V 3 O 5 was 198 ± 14 GPa, which is slightly lower than the computationally derived values for bulk crystal V 3 O 5 .
36 MATERIALS SCIENCE↗
Method for measuring static Young's modulus of tungsten to 1900 K
An instrument system was developed and tested to measure static Young's modulus of elasticity of refractory metals in tension at temperatures to 1900 K. The extensometer uses capacitance displacement sensors for measuring total elongation of a specimen and incorporates a unique high-resolution remote zero-adjusting mechanism. Details of a method for calibrating capacitance displacement sensors at temperatures to 800 K are included. The system was built to adapt to a vacuum furnace on a tensile machine and was tested on unalloyed tungsten rod specimens. The test results show that the system can measure the modulus of tungsten to 1900 K to within a precision of + or - 5 percent. The uncertainty of the measurement is estimated to be of the same order as the precision.
Harrigill, W. T., Jr.↗
Single-beam plasma source deposition of carbon thin films
A single-beam plasma source was developed and used to deposit hydrogenated amorphous carbon (a-C:H) thin films at room temperature. The plasma source was excited by a combined radio frequency and direct current power, which resulted in tunable ion energy over a wide range. The plasma source could effectively dissociate the source hydrocarbon gas and simultaneously emit an ion beam to interact with the deposited film. Using this plasma source and a mixture of argon and C 2 H 2 gas, a-C:H films were deposited at a rate of ~26 nm/min. The resulting a-C:H film of 1.2 µm thick was still highly transparent with a transmittance of over 90% in the infrared range and an optical bandgap of 2.04 eV. Young’s modulus of the a-C:H film was ~80 GPa. The combination of the low-temperature high-rate deposition of transparent a-C:H films with moderately high Young’s modulus makes the single-beam plasma source attractive for many coatings applications, especially in which heat-sensitive and soft materials are involved. Here, the single-beam plasma source can be configured into a linear structure, which could be used for large-area coatings.
14 SOLAR ENERGY↗
Synthesis of Poly(ionic Liquid)s-block-poly(methyl Methacrylate) Copolymer-Grafted Silica Particle Brushes with Enhanced CO 2 Permeability and Mechanical Performance
Poly(ionic liquid) (PIL)-based block copolymers are of particular interest as they combine the specific properties of PILs with the self-assembling behaviors of block copolymers, broadening the range of potential applications for PIL-based materials. In this work, three particle brushes: SiO 2 -g-poly(methyl methacrylate) (PMMA), SiO 2 -g-PIL, and SiO 2 -g-PMMA-b-PIL were prepared through surface-initiated atom transfer radical polymerization. Unlike the homogeneous homopolymer particle brushes, the block copolymer particle brush SiO 2 -g-PMMA-b-PIL exhibited a bimodal chain architecture and unique phase-separated morphology, which were confirmed by size-exclusion chromatography and transmission electron microscopy. In addition, the influence of the introduction of the PMMA segment on the gas separation and mechanical performance of the PIL-containing block copolymer particle brushes were investigated. A significant improvement of Young’s modulus was observed in the SiO 2 -g-PMMA-b-PIL compared to the SiO 2 -g-PIL bulk films; meanwhile, their gas separation performances (CO 2 permeability and CO 2 /N 2 selectivity) were the same, which demonstrates the possibility of improving the mechanical properties of PIL-based particle brushes without compromising their gas separation performance.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Determination of Material Properties Near the Glass Transition Temperature for an Isogrid Boom
Experiments were performed and results obtained to determine the temperature dependence of the modulus of elasticity for a thermoplastic isogrid tube. The isogrid tube was subjected to axial tensile loads of 0-100 lbf and strain was measured at room and elevated temperatures of 100, 120, 140, 160, 180, 190, and 200 F. These were based on tube manufacturer specifying an incorrect glass transition temperature of 210 F. Two protocols were used. For the first protocol the tube was brought to temperature and a tensile test performed. The tube was allowed to cool between tests. For the second protocol the tube was ramped to the desired test temperature and held. A tensile test was performed and the tube temperature ramped to the next test temperature. The second protocol spanned the entire test range. The strain rate was constant at 0.008 in/min. Room temperature tests resulted in the determination of an average modulus of 2.34 x 106 Psi. The modulus decreased above 100 F. At 140 F the modulus had decreased by 7.26%. The two test protocols showed good agreement below 160 F. At this point the glass transition temperature had been exceeded. The two protocols were not repeated because the tube failed.
Blandino, Joseph R.↗
A fundamental approach to the sticking of insect residues to aircraft wings
The aircraft industry is concerned with the increase of drag on planes due to the sticking of insects on critical airfoil areas. The objectives of the present study were to investigate the effects of surface energy and elasticity on the number of insects sticking onto the polymer coatings on a modified aircraft wing and to determine the mechanism by which insects stick onto surfaces during high velocity impact. Analyses including scanning electron microscopy, electron spectroscopy for chemical analysis and contact angle measurements of uncoated and polymer coated aluminum surfaces were performed. A direct relation between the number of insects sticking on a sample and its surface energy was obtained. Since the sticky liquid from a burst open insect will not spread on the low energy surface, it will ball up providing poor adhesion between the insect debris and the surface. The incoming air flow can easily blow off the insect debris and thus reducing the number of insects that remain stuck on the surface. Also a direct relation between the number of insect sticking onto a surface and their modulus of elasticity was obtained.
Yi, O.↗
Development of a High-Pressure Fuel Injection System for Use with Propane-DME
Paper details the design approach and performance of a high-pressure common rail fuel injection system used with Propane-DME mixtures targeting high injection pressures on a light duty 2.2L inline-4 compression ignition engine. The study estimates the bulk modulus of elasticity based on the hardware geometry and operating pressures to assess the compressibility of Propane and DME across a range of pressures typical of the LD engine application. The compressibility factor ranges from 500 to 3000 bar, significantly lower than the theoretical values for the conditions tested. The high-pressure pump performance is optimized via the implementation of an inlet metering valve operated on a crank-angle open/close sequence to control pressure at the common rail. The application of a model-based controller and the use of high-speed sampling of rail pressure indicate that pressure at the rail can be attained with the pump metering valve, and without use of the pressure relieve valve present in the rail. Results show a significant reduction on pumping work parasitics and of fuel heating, on the order of 40°C, at typical working conditions with the proposed approach. Injector rates of injection with Propane-DME are very similar to those of Diesel. Paper compares bench data of rates of injection versus simulation predictions across operating pressures of 200 to 1000bar and from injection commands spanning 0.20 to 2.0ms. Furthermore, the accuracy of the model predictions are attributed in part by to the updated fuel compressibility modulus descriptions attained during the testing.
42 ENGINEERING↗
Reassessing early-age strength development of high-volume fly ash concretes for precast buildings
Increasing beneficial use of fresh or landfilled fly ash as a replacement for Portland cement can be more challenging for the construction of precast buildings or similar applications requiring rapid strength development. Therefore, the framework presented in this paper aims to reassess high-volume fly ash concretes but in the context of facilitating more sustainable precast buildings. More specifically, the framework was used to characterize strength development of concrete mixes with a target minimum 24-hour compressive strength of 24.1 MPa (3500 psi), selected as an example strength development metric to demonstrate the framework, and comprised of 40% Class C, Class F, and landfilled (harvested) fly ash – as a high-volume replacement of Type III or Type IL cement. High-early strength was driven by optimized dosages of commercial grade gypsum and accelerating admixtures, in addition to optimal aggregate packing and mix proportioning strategies. Early-age mechanical properties including compressive strength, modulus of rupture, and modulus of elasticity were reevaluated within 24 hours of batching with respect to common precast production demands. Simple data analyses were then used to highlight cases where currently accepted design provisions for the aforementioned properties are either overly-conservative or unconservative with respect to test data. Furthermore, the framework and demonstration of example mixes presented herein aim to promote confidence for using larger fractions of fresh or landfilled fly ashes for precast buildings to further enhance environmental benefits without sacrificing pertinent early-age structural performance.
42 ENGINEERING↗
Development of high‐performance partially biobased thermoset polyester using renewable building blocks from isosorbide, 1,3‐propanediol, and fumaric acid
Abstract Research on biobased thermoset resins has been overlooked when compared with the rapid progress on biobased thermoplastics. The objective of this work was to develop unsaturated polyester prepolymers based on building blocks derived from renewable raw materials, namely, biobased isosorbide, 1,3‐propanediol, and fumaric acid, with petroleum‐derived phthalic anhydride. The prepolymers developed herein behaved as low‐molecular weight macromolecules (oligoesters), with M n varying between 1.2 and 1.5 kDa, but achieved a high bio‐content of up to 87.1 wt%. The prepolymers were incorporated into reactive diluents comprising a blend of 2‐hydroxyethyl methacrylate and styrene, formulated to be eco‐friendlier and less toxic than typical styrene‐only incorporation approach, thus resulting in resins with viscosities between 750 and 950 cP. These resins are suitable for use in various fiber‐reinforced polymer production techniques, such as manual lamination, vacuum infusion, and pultrusion, having the benefit of presenting over 50 wt% of bio‐content in some formulations. Moreover, the crosslinked polyester resins (thermosets) exhibit comparable mechanical and thermomechanical behavior to their petrochemical‐based counterparts, with modulus of elasticity and tensile strength of up to 3.9 GPa and 62.1 MPa, respectively, and glass transition temperatures of up to 106°C, making them greener alternatives for high‐performance structural applications.
Hofmann, Mateus↗
Material selection and manufacturing for high‐temperature heat exchangers: Review of state‐of‐the‐art development, opportunities, and challenges
Abstract Many energy systems demand heat transfer at high temperatures to keep up with high demand for power, so high‐temperature material that can perform and last under these harsh conditions is needed for heat exchangers. The engineering requirements for these high‐temperature heat exchanger material call for high thermal conductivity, high resistance to fracture, high resistance to creep deformation, environmental stability in environments associated with the application, and high modulus of elasticity while maintaining low cost to make and maintain. Naturally, ceramics are a good solution for this endeavor. In the past, high‐temperature heat exchangers made from ceramics have been used. We provide examples of ceramics in relevant heat exchange applications and provide motivation where additive manufacturing (AM) can improve efficiency. AM for the relevant material is under development, and we provide insight on the AM of ceramic materials and examples of AM heat exchangers keeping cost in mind. The motivation of the review paper is to provide a framework for material and manufacturing selection for high‐temperature heat exchangers for AM to keep up with the demand for better efficiency, better material, better manufacturing, and cost moving forward with AM technology in high‐temperature ceramic heat exchangers.
36 MATERIALS SCIENCE↗
Defoliation‐induced compensatory transpiration is compromised in SUT4 ‐RNAi Populus
Abstract The tonoplast sucrose transporter PtaSUT4 is well expressed in leaves of Populus tremula × Populus alba (INRA 717‐IB4), and its inhibition by RNA‐interference (RNAi) alters leaf sucrose homeostasis. Whether sucrose partitioning between the vacuole and the cytosol is modulated by PtaSUT4 for specific physiological outcomes in Populus remains unexplored. In this study, partial defoliation was used to elicit compensatory increases in photosynthesis and transpiration by the remaining leaves in greenhouse‐grown poplar. Water uptake, leaf gas exchange properties, growth and nonstructural carbohydrate abundance in source and sink organs were then compared between wild‐type and SUT4 ‐RNAi lines. Partial defoliation increased maximum photosynthesis rates similarly in all lines. There was no indication that source leaf sugar levels changed differently between wild‐type and RNAi plants following partial defoliation. Sink levels of hexose (glucose and fructose) and starch decreased similarly in all lines. Interestingly, plant water uptake after partial defoliation was not as well sustained in RNAi as in wild‐type plants. While the compensatory increase in photosynthesis was similar between genotypes, leaf transpiration increased less robustly in RNAi than wild‐type plants. SUT4‐RNAi and wild‐type source leaves differed constitutively in their bulk modulus of elasticity, a measure of leaf turgor, and storage water capacitance. The data demonstrate that reduced sucrose partitioning due to PtaSUT4 ‐RNAi altered turgor control and compensatory transpiration capacity more strikingly than photosynthesis and sugar export. The results are consistent with the interpretation that SUT4 may control vacuolar turgor independently of sink carbon provisioning.
54 ENVIRONMENTAL SCIENCES↗
Nonlinear viscoelastic response of silicone additively manufactured direct ink write (DIW) foams under repetitive compression
To investigate dynamic fatigue behavior of foam in military protective applications, such as helmets, additively manufactured (AM) foams were compressively strained into the plateau region using a reduced design of experiments. A simple power law was found to govern the decline in dynamic stiffness (complex modulus) as the foams underwent the purchase order requirement of 10,000 cycles of small deformation in the plateau region. This rate of decline was newly found to correlate with the degree of nonlinearity in the material’s deformation, quantified using total harmonic distortion. Materials with low nonlinearity exhibited relatively stable stiffness across cycles, while those with high nonlinearity experienced greater losses. The observed nonlinearity depended on both applied stress and strain rate. A strong linear correlation (R 2 = 0.78) was identified between second-order nonlinearity and the time-dependent stiffness response. Two lattice structures were examined: face-centered tetragonal (FCT) and simple cubic (SC). The SC material exhibited higher total harmonic distortion (5%) and lower stiffness retention than the FCT (2%). In conclusion, these results suggest that for cyclic compression applications in a wide variety of industries such as packaging, personal protective equipment, or aerospace, selecting materials with lower stress and greater structural uniformity can enhance the stability of dynamic performance.
42 ENGINEERING↗
Development of Aluminum Scandium Nitride Molecular Dynamics Force Fields with Scalable Multi-Objective Bayesian Optimization
Scandium (Sc)-doped aluminum nitride (AlN) exhibits improved piezoelectric properties, which is favorable for sensor applications. Although many experimental studies exist to fine tune the material properties for design purposes, an atomistic level understanding of the structure-property (S-P) relationships is needed, which is the aim of this work. Molecular dynamics can be used to understand the S-P relationships. However, the limited availability of suitable force fields has been a major challenge for accurate property predictions. In this article, a robust force field calibration method using a scalable multi-objective Bayesian optimization approach is presented. Optimizations with three, six, and eight objectives are applied to calibrate aluminum scandium nitride force fields based on the piezoelectric characteristics, modulus of elasticity, and lattice parameters at different Sc-doped levels. Furthermore, the performances of the different force fields are compared, and the performance of the higher dimensional objective problems is discussed. The highly scalable molecular dynamics force field development method is successfully implemented, resulting in the creation of several aluminum scandium nitride molecular dynamics force fields for piezoelectric applications at varying Sc dope levels.
36 MATERIALS SCIENCE↗
Damage development in neutron-irradiated concrete in a test reactor: Hygro-thermal and mechanical simulations
This paper reports the development of a 3D mesoscale hygro-thermal-mechanical simulation approach to predict damage in concrete irradiated in a test reactor. This framework, developed in MOOSE, considers the effects of elevated temperature, moisture content, and high neutron fluence (energy threshold, E > 0.1 MeV) on the mortar and aggregates separately. The first-stage simulation implements hygro-thermal analysis to determine the temperature and RH inside the specimen as a function of imposed radiation energy. These are used as inputs to the second stage, which considers radiation-induced volumetric expansion (RIVE) of aggregates, and creep, shrinkage, and stress-strain response of mortar to predict the expansion, stresses, and damage in specimens made using different coarse aggregates and subjected to different irradiation times. The irradiation time-dependent damage in the mortar is expressed using an isotropic damage parameter. This multi-physics model serves as a predictive tool for damage quantification in concrete due to neutron irradiation.
36 MATERIALS SCIENCE↗