Search NASA⌕ Search

SEARCH · Search NASA

Results for “Soft composites”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Investigations of room temperature multiferroic and magneto-electric properties of (1-Φ) PZTFT-Φ CZFMO particulate composites

Multiferroic composites consisting of a single-phase multiferroic [0.6(PbZr 0.53 Ti 0.47 O 3 )-0.4(PbFe 0.5 Ta 0.5 )O 3 ] as a matrix and a magnetostrictive phase (Co 0.6 Zn 0.4 Fe 1.7 Mn 0.3 O 4 ) dispersed in the matrix are fabricated via hybrid synthesis technique. The structure and surface morphology studies using x-ray diffraction and field emission scanning electron microscopy techniques indicate the formation of 3-0 type particulate composites. Coexistence of soft-magnetic behavior and ferroelectric characteristics are confirmed for composites from magnetization vs magnetic field (M–H) and polarization vs electric field (P–E) measurements, respectively. Magneto-dielectric (MD) measurement shows significant changes in the dielectric properties with the application of a magnetic field, indicating the existence of strong MD behavior. The biquadratic nature of magneto-electric (ME) coupling is described by the Landau free energy equation arising from the strain transfer at the interfaces between the constituent phases. The direct magneto-electric voltage coefficient measurement also confirms very strong coupling between ferroelectricity and magnetism and supports the strain-mediated magneto-electric effect in composites. The Φ = 0.3 composite exhibits the maximum ME coefficient of 20.72 mV/cm Oe with M S = 24.62 emu/g, H C = 59.66 Oe, and piezoelectric coefficient value d 33 = 19 pC/N. In conclusion, the strong magneto-electric effect along with low dielectric loss at room temperature in these composites suggests their suitability for multifunctional magneto-electric device applications such as magnetic sensors, etc.

36 MATERIALS SCIENCE↗
DOE OSTI2023

All-Polyhydroxyalkanoate Triblock Copolymers via a Stereoselective-Chemocatalytic Route

Biodegradable polyhydroxyalkanoate (PHA) homopolymers and statistical copolymers are ubiquitous in microbially produced PHAs, but the step-growth polycondensation mechanism the biosynthesis operates on presents a challenge to access well-defined block copolymers (BCPs), especially higher-order tri-BCP PHAs. We report a stereoselective-chemocatalytic route to produce discrete hard–soft–hard ABA all-PHA tri-BCPs based on the living chain-growth ring-opening polymerization of racemic (rac) 8-membered diolides (rac-8DL R ; R denotes the two substituents on the ring). Depending on the composition of the soft B block, originated from rac-8DL R (R = Et, n Bu), and its ratio to the semicrystalline, high-melting hard A block, derived from rac-8DL Me , the resulting all-PHA tri-BCPs with high molar mass (M n up to 238 kg mol –1 ) and low dispersity (&#208: = 1.07) exhibit tunable mechanical properties characteristic of a strong and tough thermoplastic, elastomer, or a semicrystalline thermoplastic elastomer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

A state-of-the-art review of experimental and computational studies of granular materials: Properties, advances, challenges, and future directions

Modeling of heterogeneous materials and media is a problem of fundamental importance to a wide class of phenomena and systems, ranging from condensed matter physics, soft materials, and composite media to porous media, biological systems, geosystems, ceramic engineering, pharmaceutical science and even in space discoveries. Among the most important materials are granular systems, which have received intense interest from the engineering, physics, and mathematics communities. In this review paper, the recent developments and new advances in experimental, and computational methods on a variety of scales and physics that extend understanding to a wide range of materials and phenomena are reviewed. Experimental advances include computed neutron and nanometer-scale tomography, magnetic resonance imaging, refractive index matching, digital image correlation, acoustic emission analysis, and the most recent 4D techniques. Furthermore, a tremendous shift has occurred from the continuum scale to micro-scale and developing multiscale approaches. As such, various computational methods, including, constitutive modeling, discrete modeling, and multiscale approaches, have been developed. In conclusion, aside from all these evolutions, more complicated modeling called coupled, or multiphysics, systems representing a simultaneous presence of heat, fluid, chemical variation, and mechanical effect are also explored.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Loosely bound composite dark matter

We investigate loosely bound composite states made of dark matter, where the binding energy for constituent particles is considerably less than the constituent mass. We focus on models of nuclear and molecular dark matter, where constituents are separated by length scales larger than the inverse constituent mass, just like nuclei and atoms in the Standard Model. The cosmology, structure, and interactions at underground experiments are described. We find that loosely bound composites can have a very large cross section for scattering with nuclei that scales with nucleon number like ∼ A 4 . For some couplings, these composites produce extremely soft (≪ keV) individual atomic recoils while depositing a large amount of total recoil energy (≫ keV) in a single passage through a detector, implying an interesting new class of signatures for low threshold direct detection.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Carbon Fiber and Polymer Composites

Tooling is an integral part of composites manufacturing. Composite tools, also called ‘soft’ tools, are more easily constructed than ‘hard’ metal tools and, because they are made from materials similar to the manufactured composite part, they can be made in-house and have a good co-efficient of thermal expansion match. However, as the ‘soft’ designation suggests, they are more vulnerable to wear and typically find application in relatively low-volume production. Additive manufacturing of thermoplastics has proven to be a lucrative option that can help improve the tooling functionalities, as it offers more design flexibility. Owing to the inherent nature of additive manufacturing, the possibility of printing sensors within the tool material and at proximity to otherwise inaccessible areas of the tool become a reality. Continuous carbon fiber (CCF)-reinforced three-dimensional (3D) printing of engineering thermoplastics has proven to be a viable option to strengthen a part well beyond the ideal moduli of unmodified thermoplastic. Furthermore, adding nanotubes or graphene to the thermoplastic matrix will also improve both the thermal conductivity and interlaminar shear strength within the tool. Carbon nanotubes (CNTs) and carbon fibers (CFs) are microwave susceptors; exploiting the physics of Joule heating to increase the energy efficiency of tool hardening and cure rates is a core goal of this project. Because of the rapid volumetric heating enabled by the absorption of microwave or radio frequency energy and electromagnetic (EM) annealing presents an attractive opportunity to significantly reduce manufacturing cycle times while improving part performance.

Craps, Matthew G.↗
DOE OSTI2020

Resilient, untethered soft robot

A pneumatically powered, fully untethered mobile soft robot is described. Composites consisting of silicone elastomer, polyaramid fabric, and hollow glass microspheres were used to fabricate a sufficiently large soft robot to carry the miniature air compressors, battery, valves, and controller needed for autonomous operation. Fabrication techniques were developed to mold a 0.65 meter long soft body with modified Pneumatic network actuators capable of operating at the elevated pressures (up to 138 kPa) required to actuate the legs of the robot and hold payloads of up to 8 kg. The soft robot is safe to handle, and its silicone body is innately resilient to a variety of adverse environmental conditions including snow, puddles of water, direct (albeit limited) exposure to flames, and the crushing force of being run over by an automobile.

42 ENGINEERING↗
DOE OSTI2021

Generation of Bright Soft X-ray Laser Beams (Final Report)

The project goal was to demonstrate new compact soft x-ray lasers emitting high energy ultrashort pulses at shorter wavelengths and increased repetition rates by amplification in atomic transitions in high density laser-created plasmas. To demonstrate these lasers we developed new high power solid state lasers. The project succeeded in demonstrating the shortest wavelength compact soft x-ray laser to date, 6.85 nm wavelength, and the highest repetition rate table-top soft x-ray laser, 400 Hz. We also applied these compact soft x-ray laser sources to determine the composition of materials with nanoscale resolution using a new technique that combines soft x-ray laser ablation with mass spectrometry, and we demonstrated that these lasers are capable of acquiring nanoscale resolution holograms with picosecond time resolution. The combination of an increased pumping efficiency with increased repetition rates can yield soft x-ray laser beams with an unprecedented average power on a table-top for applications demanding a high photon flux. We have demonstrated that the efficiency of plasma-based laser-pumped soft x-ray lasers can be significantly increased by detailed pulse shaping of the pump laser using a new pulse synthesizer. Results include the demonstration of 18.9 nm wavelength laser operation at a record 400 Hz repetition rate, and the extension of repetitive gain-saturated plasma-based table-top x-ray lasers to the shortest wavelength to date, 6.85 nm. Laser amplification was also observed at wavelengths as short at 5.8 nm by isolectronic scaling in Ni-like lanthanide ions. We have also conducted simulations to explore the possibility of demonstrating gain saturated atomic x-ray lasers near the carbon K-edge, in the “carbon window” for the first time. The work conducted under this program also includes the use of compact soft x-ray lasers in applications to problems of chemical interest, such as isotopic composition mapping of micron-size uranium particles with nanoscale resolution, and nanoscale resolution depth profiling analysis of CoNCN-coated electrodes for water oxidation catalysis. We also demonstrated single-shot high resolution soft x-ray Fourier transform holography over a broad 7 µm diameter field of view with ~ 5 ps temporal resolution.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Evading strength and ductility trade-off in an inverse nacre structured magnesium matrix nanocomposite

Mimicking nacre structure is an often-used strategy for developing materials which combine high strength and high toughness. Here, a novel strategy, named inverse nacre structure, is proposed where elongated and curled soft constituents are embedded in a matrix of hard constituent to form an ordered brick-and-mortar arrangement. This strategy is demonstrated in a particle reinforced metal matrix composite, using pure Mg as the soft phase and SiC nanoparticle reinforced Mg as the hard phase. In this work, the resulting nanocomposite yields high strength, and especially high tensile elongation which is five times that of the homogeneous counterpart. The superior comprehensive strengthening-toughening effect originates from the tailored inverse nacre structure which enables a stable microcrack-multiplication process by sufficiently promoting strain hardening so as to avoid any significant decrease in post-ultimate tensile strength. This strategy, while demonstrated here for the specific case of particle reinforced Mg, is not restricted to any particular material system but constitutes a generic pathway for the development of high-performance materials for engineering applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Deformation Rate‐Adaptive Conducting Polymers and Composites

Abstract Materials are more easily damaged during accidents that involve rapid deformation. Here, a design strategy is described for electronic materials comprised of conducting polymers that defies this orthodox property, making their extensibility and toughness dynamically adaptive to deformation rates. This counterintuitive property is achieved through a morphology of interconnected nanoscopic core–shell micelles, where the chemical interactions are stronger within the shells than the cores. As a result, the interlinked shells retain material integrity under strain, while the rate of dissociation of the cores controls the extent of micelle elongation, which is a process that adapts to deformation rates. A prototype based on polyaniline shows a 7.5‐fold increase in ultimate elongation and a 163‐fold increase in toughness when deformed at increasing rates from 2.5 to 10 000% min −1 . This concept can be generalized to other conducting polymers and highly conductive composites to create “self‐protective” soft electronic materials with enhanced durability under dynamic movement or deformation.

Hernandez, Victor↗
DOE OSTI2023

The phantom menace of dynamic soft-shorts in solid-state battery research

Solid-state batteries with lithium metal anodes present the highest energy density batteries for applications in electric vehicles, leading to massive R&D investments over the past decade. Although most research focuses on preventing lithium metal dendrites that eventually short the battery, the nature of these shorts remains elusive. Soft-shorts, in particular, receive little attention or are not recognized, even in published data. Here, in this study, we present a comprehensive outline of the detection and analysis of soft -shorts in solid-state lithium metal cells with composite polymer electrolytes as well as a fundamental understanding of the dynamics of soft -shorts. Transient un-shorting of soft -shorts that occurs on the micro-to-millisecond timescale-driven by joule heating, chemical reactivity, and other processes-limits one's ability to determine whether the cell was or is still shorted. We provide numerous experimental methods to detect and analyze soft-shorts in any battery type as a resource to all battery researchers.

25 ENERGY STORAGE↗
DOE OSTI2021

Characterize traction–separation relation and interfacial imperfections by data-driven machine learning models

Abstract Interfacial mechanical properties are important in composite materials and their applications, including vehicle structures, soft robotics, and aerospace. Determination of traction–separation (T–S) relations at interfaces in composites can lead to evaluations of structural reliability, mechanical robustness, and failures criteria. Accurate measurements on T–S relations remain challenging, since the interface interaction generally happens at microscale. With the emergence of machine learning (ML), data-driven model becomes an efficient method to predict the interfacial behaviors of composite materials and establish their mechanical models. Here, we combine ML, finite element analysis (FEA), and empirical experiments to develop data-driven models that characterize interfacial mechanical properties precisely. Specifically, eXtreme Gradient Boosting (XGBoost) multi-output regressions and classifier models are harnessed to investigate T–S relations and identify the imperfection locations at interface, respectively. The ML models are trained by macroscale force–displacement curves, which can be obtained from FEA and standard mechanical tests. The results show accurate predictions of T–S relations ( R 2 = 0.988) and identification of imperfection locations with 81% accuracy. Our models are experimentally validated by 3D printed double cantilever beam specimens from different materials. Furthermore, we provide a code package containing trained ML models, allowing other researchers to establish T–S relations for different material interfaces.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Minimizing Crinkling of Soft Specimens Using Holey Gold Films on Molybdenum Grids for Cryogenic Electron Microscopy

We introduce a novel composite holey gold support that prevents cryo-crinkling and reduces beam-induced motion of soft specimens, building on the previously introduced all-gold support. The composite holey gold support for high-resolution cryogenic electron microscopy of soft crystalline membranes was fabricated in two steps. In the first step, a holey gold film was transferred on top of a molybdenum grid. In the second step, a continuous thin carbon film was transferred onto the holey gold film. This support (Au/Mo grid) was used to image crystalline synthetic polymer membranes. The low thermal expansion of Mo is not only expected to avoid cryo-crinkling of the membrane when the grids are cooled to cryogenic temperatures, but it may also act to reduce whatever crinkling existed even before cooling. Here, the Au/Mo grid exhibits excellent performance with specimens tilted to 45°. This is demonstrated by quantifying beam-induced motion and differences in local defocus values. In addition, images of specimens on the Au/Mo grids that are tilted at 45° show high-resolution information of the crystalline membranes that, after lattice-unbending, extends beyond 1.5 Å in the direction perpendicular to the tilt axis.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Stretchable and Self‐Healable Semiconductive Composites Based on Hydrogen Bonding Cross‐linked Elastomeric Matrix

Abstract Semiconductors with both high stretchability and self‐healing capability are highly desirable for various wearable devices. Much progress has been achieved in designing highly stretchable semiconductive polymers or composites. The demonstration of self‐healable semiconductive composite is still rare. Here, an extremely soft, highly stretchable, and self‐healable hydrogen bonding cross‐linked elastomer, amide functionalized‐polyisobutylene (PIB‐amide) is developed, to enable a self‐healable semiconductive composite through compounding with a high‐performance conjugated diketopyrrolopyrrole (DPP‐T) polymer. The composite, consisting of 20% DPP‐T and 80% PIB‐amide, shows record high crack‐onset strain (COS ≈1500%), extremely low elastic modulus (E≈1.6 MPa), and unique ability to spontaneously self‐heal atroom temperature within 5 min. Unlike previous works, these unique composite materials also show strain‐independent charge mobility. An in‐depth morphological study based on multi‐model techniques indicate that all composites show blending ratio‐ and stretching‐independent fibril‐like aggregation due to the strong hydrogen bond in elastomer to enable the unique stable charge mobility. This study provides a new direction to develop highly healable and electronically stable semiconductive composite and will enable new applications of stretchable electronics.

Chemistry↗
DOE OSTI2024

Digital Multiphase Composites via Additive Manufacturing

Abstract Mechanical properties of traditional engineering materials are typically coupled to each other, presenting a challenge to practitioners with multi‐dimensional material property requirements. In this work, continuous, independent control over multiple mechanical properties is demonstrated in composite materials realized using additive manufacturing. For the first time, composites additively manufactured from rigid plastic, soft elastomer, and liquid constituents are experimentally characterized, demonstrating materials which span four orders of magnitude in modulus and two orders of magnitude in toughness. By forming analytical mappings between relative concentrations of constituents at the microscale and resulting macroscale material properties, inverse material design is enabled; the method is showcased by printing artifacts with prescribed toughness and elasticity distributions. The properties of these composites are placed in the context of biological tissues, showing they have promise as mechanically plausible tissue mimics.

Smith, Lawrence T.↗
DOE OSTI2021

Ribbon Wrinkling Origin and Its Effect on Tape-Wound Core Shape

Improved understanding of advanced manufacturing techniques is needed to fabricate next- generation soft magnetic tape-wound cores. These utilize metal amorphous nano-composites (MANCs) in the form of long thin ribbons. MANCs exhibit attractive soft magnetic properties for use in high frequency and high power density magnetic components. Of particular interest here, the permeability and hysteresis of MANC ribbons can be tuned in a strain annealing process. An unexpected consequence is that wider ribbons develop longitudinal wrinkle patterns. This can substantially reduce the tape-wound core stacking factor. However, when winding a wrinkled ribbon into a toroidal core, the wrinkles can completely flatten, or crinkle. By this phenomenon, the stacking factor can be recovered. To understand the crinkling effect we have developed analytical and finite element analysis (FEA) models. Experiments with known boundary conditions demonstrate the transition from wrinkled to crinkled versus winding curvature. The models utilize an elastic modulus measured via ribbon tensile testing and a ribbon thickness value measurement made by profilometry. The analytical model provides insight into the crinkling effect but cannot explain the length of the transition region from wrinkling to crinkling. With FEA, we successfully predict the transition region and depending on wrinkling amplitude can determine when a ribbon will wind into a useable core. Such mechanics-based insight provides critical feedback for allowable processing parameters in the strain annealing process.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2022

Structural stability of thin overhanging walls during material extrusion additive manufacturing of thermoset-based ink

Recent developments have enabled material extrusion additive manufacturing of thermoset-based composite inks on the large scale. In addition, printing out-of-plane components is of broad interest to the polymer material extrusion community. Here, we address some of the challenges associated with both large-scale and out-of-plane thermoset material extrusion additive manufacturing by studying the height at which thin overhanging walls collapse. Walls at a range of overhang angles were printed until they collapsed. An optical camera captured the profile of each wall throughout the print, allowing the collapse height to be identified and the geometric fidelity to the programmed angle to be evaluated. Using previously measured rheological properties, predictive models were generated to approximate the collapse height and profile of the deflected walls. First, an analytical model was created to predict the height at which the walls would yield. The analytical model assumes the walls exhibit a perfectly linear profile; however, experiments proved this assumption to be false. Therefore, a finite element simulation was developed to account for the elastic deflection that occurs during printing. The finite element simulation predicts both the yield height and the deflected profile after the deposition of each layer. For the properties of the thermoset ink used here, the yield height predicted by the analytical model and finite element simulation are virtually identical. These predictions match experimental data reasonably well, but minor errors are observed. Accounting for the fully plastic moment appears to explain the small mismatch between experimental data and predictions. Additionally, the finite element simulation provides an excellent prediction of the deflected profile before the wall begins to collapse. Finally, by demonstrating that the collapse height and deflected profile of thin overhanging walls can be predicted, this work illustrates how the soft viscoelastic properties of thermoset-based composite inks limit the scale of a key feature required to print some nonplanar components. It also provides a basis to tailor in-process curing systems to suppress deflection and collapse of thin overhanging walls.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Chiral, Topological, and Knotted Colloids in Liquid Crystals

The geometric shape, symmetry, and topology of colloidal particles often allow for controlling colloidal phase behavior and physical properties of these soft matter systems. In liquid crystalline dispersions, colloidal particles with low symmetry and nontrivial topology of surface confinement are of particular interest, including surfaces shaped as handlebodies, spirals, knots, multi-component links, and so on. These types of colloidal surfaces induce topologically nontrivial three-dimensional director field configurations and topological defects. Director switching by electric fields, laser tweezing of defects, and local photo-thermal melting of the liquid crystal host medium promote transformations among many stable and metastable particle-induced director configurations that can be revealed by means of direct label-free three-dimensional nonlinear optical imaging. The interplay between topologies of colloidal surfaces, director fields, and defects is found to show a number of unexpected features, such as knotting and linking of line defects, often uniquely arising from the nonpolar nature of the nematic director field. This review article highlights fascinating examples of new physical behavior arising from the interplay of nematic molecular order and both chiral symmetry and topology of colloidal inclusions within the nematic host. Furthermore, the article concludes with a brief discussion of how these findings may lay the groundwork for new types of topology-dictated self-assembly in soft condensed matter leading to novel mesostructured composite materials, as well as for experimental insights into the pure-math aspects of low-dimensional topology.

chirality↗
DOE OSTI2020

Additive manufacturing of two-phase lightweight, stiff and high damping carbon fiber reinforced polymer microlattices

Carbon fiber reinforced polymer (CFRP) composite is known for its high stiffness-to-weight ratio and hence is of great interest in several engineering fields such as aerospace, automotive, defense, etc. However, such a composite is not suitable for energy dissipation as failure occurs with very little or no plastic deformation. Herein, we present an extendable multi-material projection microstereolithography process capable of producing carbon-fiber-reinforced cellular materials that achieve simultaneously high specific stiffness and damping coefficient. Inspired by the upper bounds of stiffness-loss coefficient in a two-phase composite, we designed and additively manufactured CFRP microlattices with soft phases architected into selected stiff-phase struts. Our results, confirmed by experimental and analytical calculations, revealed that the damping performance can be significantly enhanced by the addition of only a small fraction of the soft phase. The presented design and additive manufacturing strategy allow for optimizing mutually exclusive properties. As a result, these CFRP microlattices achieved high specific stiffness comparable to commercial CFRP, technical ceramics, and composites, while being dissipative like elastomers.

36 MATERIALS SCIENCE↗