Search NASA⌕ Search

SEARCH · Search NASA

Results for “ENERGY ABSORPTION”

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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Three-Dimensional High Fidelity Progressive Failure Damage Modeling of NCF Composites

Performance prediction of off-axis laminates is of significant interest in designing composite structures for energy absorption. Phenomenological models available in most of the commercial programs, where the fiber and resin properties are smeared, are very efficient for large scale structural analysis, but lack the ability to model the complex nonlinear behavior of the resin and fail to capture the complex load transfer mechanisms between the fiber and the resin matrix. On the other hand, high fidelity mesoscale models, where the fiber tows and matrix regions are explicitly modeled, have the ability to account for the complex behavior in each of the constituents of the composite. However, creating a finite element model of a larger scale composite component could be very time consuming and computationally very expensive. In the present study, a three-dimensional mesoscale model of non-crimp composite laminates was developed for various laminate schemes. The resin material was modeled as an elastic-plastic material with nonlinear hardening. The fiber tows were modeled with an orthotropic material model with brittle failure. In parallel, new stress based failure criteria combined with several damage evolution laws for matrix stresses were proposed for a phenomenological model. The results from both the mesoscale and phenomenological models were compared with the experiments for a variety of off-axis laminates.

Aitharaju, Venkat↗
NASA NTRS2018

High Kinetic Energy Penetrator Shielding and High Wear Resistance Materials Fabricated with Boron Nitride Nanotubes (BNNTS) and BNNT Polymer Composites

Boron nitride nanotubes (BNNTs), boron nitride nanoparticles (BNNPs), carbon nontubes (CNTs), graphites, or their combinations, are incorporated into matrices of polymer, ceramic or metals. Fibers, yarns, and woven or nonwoven mates of BNNTs are uses as toughening layers in penetration resistant materials to maximize energy absorption and/or high hardness layers to rebound or deform penetrators. They can be also uses as reinforcing inclusions combining with other polymer matrices to create composite layer like typical reinforcing fibers such as Kevlar (Registered Trademark), Spectra (Registered Trademark) ceramics and metals. Enhanced wear resistance and prolonged usage time, even under harsh conditions, are achieved by adding boron nitride nanomaterials because both hardness and toughness are increased. Such materials can be used in high temperature environments since the oxidation temperature of BNNTs exceeds 800 C in air. Boron nitride based composite materials are useful as strong structural materials for anti-micrometeorite layers for spacecraft and space suits, ultra strong tethers, protective gear for the human body as well as for vehicles, helmets, shields and safety suits/helmets for industry.

Kang, Jin Ho↗
NASA NTRSDate not supplied

Experimental Evaluation of Axial Crush Behavior of Woven Tubular Laminates with a Moving Support Condition

The objectives of the investigation were to measure the specific energy absorption (SEA) of the plain-weave carbon fiber reinforced polymer (CFRP) tubes, study the effect of tube length on SEA and stable crushing force, analyze the effect of using a crush trigger, and compare force-displacement data using different specimen support conditions. Dynamic crush testing of CFRP tubes was performed using the crash sled in the Impact Dynamics Laboratory at NASA Glenn Research Center.

Rudy T. Haluza↗
NASA NTRSDate not supplied

Impact of COVID-Global Shutdown on Earth's Radiation Budget

Climate is fueled by how much of the sun’s energy is absorbed by Earth. Changes in aerosol emissions have a direct impact how much solar energy is absorbed under clear-sky conditions, which occurs roughly one-third of the time globally. Aerosol emission changes can also indirectly influence clouds and further alter solar energy absorption. In this presentation, we examine the impact of the COVID-19 global shutdown on Earth’s radiation budget at global and regional scales and compare it with other changes that have had an influence on Earth's radiation budget during the past 20 years—including policy-related emission controls, wildfire events and changes in sea-ice extent in polar regions. We use a novel analysis technique together with data from NASA instruments on the Terra, Aqua and Aura satellites and reanalysis data from MERRA-2. We also compare results with state-of-the-art general circulation models that have been nudged to reanalysis data (winds, air temperature and surface 25 pressure) at all levels. Our preliminary results show that the largest COVID-19 impact occurs regionally over the East Asian Marginal Seas, just off the coast of China. We find a 30% reduction in aerosol optical depth according to the MODIS instrument, and an 8% reduction in reflected solar radiation according to the CERES radiation budget instrument. The climate model simulations show remarkable consistency with the observations and furthermore show no evidence of an indirect effect on cloud properties.

Norman G. Loeb↗
NASA NTRSDate not supplied

High Energy Dynamic Impact Testing of APC AS4/PEKK-FC and TC1225 LMPAEK T700G Thermoplastic Composite Materials

High energy dynamic impact tests were conducted on Solvay APC AS4D/PEKK-FC and Toray TC1225 LMPAEK T700Gthermoplastic composite laminates. The primary objective was to provide data for evaluation of computational composite impact models. Empirical results indicate an approximately 50% increase in penetration threshold velocity and over 100% increase in penetration energy threshold for the TC1225 LMPAEK T700Gcomposite compared to the APC AS4D/PEKK-FC composite. The velocity required to produce NDE-detectable delamination in the TC1225 LMPAEK T700Gcomposite was roughly twice that for the APC AS4D/PEKK-FC composite. Comparison of the normalized energy absorption showed similar results for the APC AS4D/PEKK-FC system compared to a previously studied IM7/8552 composite material. The TC1225 LMPAEK T700Gsystem absorbed approximately twice that of the other two systems when normalized by areal weight.

Impact↗
NASA NTRSDate not supplied

Simulation of Dynamic Crushing Behavior of Simulated Carbon/Epoxy Stanchions Using MAT58 and MAT213 in LS-DYNA

Carbon fiber-reinforced polymer (CFRP) composites have shown promise as a material for structures designed to absorb energy in crush-style impact loading. In complementing the lightweight and tailorable characteristics of CFRP structures, the benefits of impact energy absorption are particularly interesting in aerospace vehicles that require excellent crashworthiness performance. However, simulating the behavior of CFRP structures in dynamic, crushing-style impact loading is challenging because of the many damage and failure modes that are essential to capture in the model. For the present investigation, CFRP stanchions were tested using a crash sled experimental test rig. The stanchions were designed by the Composite Materials Handbook-17 (CMH-17) Crashworthiness Working Group for the purpose of comparing experimental crash sled tests to corresponding simulations of the tests. The stanchions are C-channel shaped and represent a geometry common in the interior of aerospace vehicle structures. Explicit simulations in LSDYNA were performed using a well-established composite material model (MAT58) and a next-generation material model (MAT213). Fully integrated shell elements were utilized instead of 3D solid elements to limit computation time. In all models, each of the sixteen plies were represented with individual layers of shell elements with tiebreak contact between each adjacent ply pair to simulate interlaminar fracture. Simulating the crushing of the stanchions occurred in two phases. First, the material models were calibrated using flat specimens that were manufactured with the same layup as the stanchions. While the original goal was calibration of material-related properties, meshdependent behavior was observed in simulations with either material model, and an unstructured mesh was selected to remediate undesirable mesh-dependent failure modes. Additionally, for both the MAT58 and MAT213 models, it was found that either the crush force or the failure mode could be modeled accurately, but no set of parameters could be identified to attain both results in the same model. Once satisfactory calibration was achieved, the same material parameters were applied to the stanchion crush simulations. The stanchion simulations showed that MAT213 more accurately predicted the experimentally determined crush force, and both material models predicted key aspects of the experimentally observed failure modes.

Composite Materials↗
NASA NTRSDate not supplied

Assessment of Pioneer Venus Entry Heating with Coupled Radiation and Ablation

The objective of this work is to reconstruct thermocouple temperature measurements taken at the stagnation point of the Pioneer Venus large probe using uncoupled and coupled ablation calculations. The time history of the large probe forebody entry heating was obtained from a trajectory-based analysis that employed a material response solver to model equilibrium and nonequilibrium ablation chemistry at the surface. In the uncoupled approach, equilibrium ablation chemistry was assumed in the material response calculations, but the material response outputs were not returned to the flowfield solver. Therefore, the effects of char and pyrolysis gas injection into the boundary layer due to ablation (e.g., convective blockage and radiative energy absorption) did not influence the flowfield solutions. In the coupled approach, nonequilibrium ablation chemistry was performed and the material response outputs were returned to the flowfield solver. Therefore, the effects of char and pyrolysis gas injection into the boundary layer were accounted for in the flowfield solutions. Both uncoupled and coupled approaches produced reconstructed temperatures that were within 10% of the flight measurements through the entry heat pulse, with the coupled results comparing more favorably with the measurements. Overall, the reconstructed thermocouple temperatures in this work significantly improved on the results of previous reconstructions for the large probe.

Jannuel V V Cabrera↗
NASA NTRSDate not supplied

Experimental Calibration of Flow Rule Coefficients for LS-Dyna Mat_213

Composite materials have become a popular choice in aerospace engineering applications due to their low weight, high specific stiffness, high specific energy absorption, and economic synthesis. As use of composite materials has proliferated, the need for accurate simulation under extreme loading conditions is of increasing importance. *MAT_213 is a tabulated plasticity and damage material model in LS-DYNA designed for such use cases. To account for the nonlinear material response, a plasticity algorithm is used, which employs a non-associative flow rule with coefficients requiring experimental calibration. This work outlines an experimental methodology for calibrating these coefficients using the macroscopic stress-strain response and microscopic in-plane strain measurements from coupon scale experiments. The model material used for the development and demonstration of this methodology is a plain weave woven fabric with T300 carbon fiber tows in the warp direction and Kevlar© 49 fiber tows in the weft direction, and an Epon© 828/Epikure© 3223 thermoset epoxy matrix. Coupon-scale tensile testing performed at multiple fiber angles (carbon fibers oriented 0º, 22.5º, 45º, 67.5º, and 90º relative to the loading axis) provides data for multiple calibration processes. The measured plastic strain increments in the principal material coordinate are used to set limits for ratios between flow rule coefficients. The identified ranges are used to bound the search for a set of coefficients, leading to convergence of different coupon responses in the effective stress – effective plastic strain space. Flow rule coefficients found by this methodology are then used as (i) input for LS-DYNA simulations of uniaxial tension coupon tests at varying fiber angles, and (ii) comparison of predicted values for the plastic Poisson’s ratio in global coordinates with the experimentally measured one for all off-axis orientations. These results are quantitatively and qualitatively compared to macroscopic stress-strain curves and experimental strain components. The conformity of the experimentally measured quantities with those derived from the simulations provide a means for assessing the quality of calibrated coefficients.

Polymer Matrix Composites↗
NASA NTRSDate not supplied

Aligned Boron Nitride Nanotube Reinforced Polyethylene Nanocomposite for Space Radiation Shielding

With NASA’s Artemis program aiming to establish a human presence on the Moon and eventually on Mars, protecting astronauts from radiation is necessary. Flight-heritage materials, like those with high hydrogen content, such as polyethylene (PE), have proven to be effective radiation shields. This is due to hydrogen’s high charge-to-mass ratio, low secondary radiation production, efficient energy absorption, and high cross-section, which increases the probability of particle interactions to slow or stop ionized particles. Boron nitride nanotubes (BNNTs) and other boron-rich materials offer more effective thermal neutron radiation-stopping capabilities due to their high cross-section and neutron absorption properties. BNNTs also enhance the mechanical properties of radiation shielding material due to their high strength-to-weight ratios. However, integrating high volumes of nanotubes in a matrix without defects presents significant manufacturing challenges. To address this, a bulk nanocomposite laminate fabricating technique, involving synthesizing millimeter-long vertically aligned BNNTs, densifying the nanotubes to high-volume fractions, and infusing the nanotubes with PE while applying heat and pressure was utilized to fabricate the BNNT-PE nanocomposite that was tested for its radiation shielding properties at NASA Langley Research Center’s neutron radiation exposure lab. Results from these experiments will be discussed in the presentation.

Palak B Patel↗
NASA NTRS2024

Scalability in SLA lattice through lattice orientation and hybrid frame and plate architectures

Lightweighting has been a key goal for engineers and designers, with lattice structures widely explored as the building blocks for structural components. Cellular structure-inspired lattice truss frame designs made of struts, have been extensively studied. All plate-based lattice designs have superior mechanical performance. Limits in scalability occur from formation of closed pockets limiting uv curing in processes like stereolithography (SLA). We examine hybrid frame and plate body-centered cubic-simply cubic (BCC-SC) lattices under compression. Unit cells and scaled up lattice exhibit an increase in yield stress and modulus with the addition of plates. The loading direction on the hybrid frame and plate unit cells affected the magnitude of improvement. Simulations and measurements indicated that the optimal lightweight lattice was determined to be when two plates were placed opposite each other with plates buttressing the struts, inhibiting buckling of the struts aligned with the loading direction. This lattice resulted in 63% improvement in specific modulus, a 137% improvement in specific yield point, and a 360% improvement in specific energy absorption (SEA) and the scaled up 4 × 4 × 4 scaled-up structures, showed a 107%, 148%, and 297% in specific modulus, specific yield point, and SEA, respectively A combined stretching-bending behavior was identified in optimal orientations reflecting the delayed buckling mechanism paired to a rising stress-strain curve past the elastic yield indicating bending resistance. The mass moment of inertia was found to be a key parameter correlating optimum orientation for the same number of plates added to the BCC-SC frame.

Mahan Ghosh↗
DOE OSTI2021

Method for Forming Hollow Profile Non-Circular Extrusions Using Shear Assisted Processing and Extrusion (ShAPE)

A process for forming extruded products using a device having a scroll face configured to apply a rotational shearing force and an axial extrusion force to the same preselected location on material wherein a combination of the rotational shearing force and the axial extrusion force upon the same location cause a portion of the material to plasticize, flow and recombine in desired configurations. This process provides for a significant number of advantages and industrial applications, including but not limited to extruding tubes used for vehicle components with 50 to 100 percent greater ductility and energy absorption over conventional extrusion technologies, while dramatically reducing manufacturing costs.

Joshi, Vineet V.↗
DOE OSTI2021

The Role of Interface in Additively Manufactured Interpenetrating Composites

Additively Manufactured Interpenetrating Composites (AMIPCs) are a relatively new metal-metal chain composite in development for use in high energy absorption systems. In this system, reinforcing phase of additively manufactured continuous lattice configurations 316L austenitic stainless-steel is in melt infiltrated with a matrix phase of A356 aluminum-silicon casting alloy. Measurements and observations of this material system have shown that weakly bonded or open/porous interface between the reinforcement and matrix phases exhibits dramatically different mechanical properties of AMIPCs, which is not currently well understood. In this work, Finite Element Models (FEM) are used to model the effects of interfaces between the composite phases. Mechanical tensile tests measurements of various composite volume fractions and varying degrees of casting infiltration are also examined and used to show consistency with the FEM results. The outcome provides insight into material design criteria and performance predictions for new hybrid material systems with exceptional damage tolerance.

Allen, Jason↗
DOE OSTI2022

Method for forming hollow profile non-circular extrusions using shear assisted processing and extrusion (ShAPE)

A process for forming extruded products using a device having a scroll face configured to apply a rotational shearing force and an axial extrusion force to the same preselected location on material wherein a combination of the rotational shearing force and the axial extrusion force upon the same location cause a portion of the material to plasticize, flow and recombine in desired configurations. This process provides for a significant number of advantages and industrial applications, including but not limited to extruding tubes used for vehicle components with 50 to 100 percent greater ductility and energy absorption over conventional extrusion technologies, while dramatically reducing manufacturing costs.

Joshi, Vineet V.↗
DOE OSTI2023

Crosslinked polymers with tunable coefficients of thermal expansion

Curatives and their resulting thermosets and other crosslinked polymers can reduce thermal expansion mismatch between an encapsulant and objects that are encapsulated. This can be accomplished by incorporating a negative CTE moiety into the thermoset resin or polymer backbone. The negative CTE moiety can be a thermal contractile unit that shrinks as a result of thermally induced conversion from a twist-boat to chair or cis/trans isomerization upon heating. Beyond CTE matching, other potential uses for these crosslinked polymers and thermosets include passive energy generation, energy absorption at high strain rates, mechanophores, actuators, and piezoelectric applications.

Redline, Erica Marie↗
DOE OSTI2024

Crosslinked polymers with tunable coefficients of thermal expansion

Curatives and their resulting thermosets and other crosslinked polymers can reduce thermal expansion mismatch between an encapsulant and objects that are encapsulated. This can be accomplished by incorporating a negative CTE moiety into the thermoset resin or polymer backbone. The negative CTE moiety can be a thermal contractile unit that shrinks as a result of thermally induced conversion from a twist-boat to chair or cis/trans isomerization upon heating. Beyond CTE matching, other potential uses for these crosslinked polymers and thermosets include passive energy generation, energy absorption at high strain rates, mechanophores, actuators, and piezoelectric applications.

Redline, Erica M.↗
DOE OSTI2025

Plasmon Dynamics Driven by Aggregation of Tris(2,2′-bipyridine)ruthenium(II)-Functionalized Gold Nanoparticles Probed by XANES and Transient Absorption Spectroscopy

Energy conversion dynamics is critical for advancing next-generation photovoltaics, optoelectronics, and light-harvesting technologies. Noble metal plasmonic nanoparticles play a pivotal role as nanoscale electromagnetic confinement structures, driving photon-induced chemical reactions. In this study, we explore the effects of [Ru(bpy) 3 ] 2+ functionalization and aggregation on citrate-capped gold nanoparticles (AuNPs) of 40 and 100 nm diameters, focusing on molecule-plasmon interactions and their influence on electronic and energy dissipation properties. X-ray absorption near-edge spectroscopy (XANES) revealed that [Ru(bpy) 3 ] 2+ functionalization induces controlled aggregation without altering the oxidation state of gold. A more pronounced white-line intensity is observed in 40 nm AuNPs, consistent with greater s–p–d hybridization and a higher density of surface states, likely influenced by both nanoparticle size and aggregation. Transient absorption (TA) spectroscopy highlights faster electron–phonon relaxation dynamics in aggregated 40 nm nanoparticles, which is attributed to increased electron delocalization and more efficient coupling to the phonon bath. In contrast, 100 nm nanoparticles exhibit minimal changes due to a lower degree of aggregation. Interestingly, we observe that enhanced electron–phonon coupling in aggregated nanoparticles coincides with a slowing of electron–electron scattering. These observations suggest a competitive interplay between the two relaxation pathways, where enhanced energy transfer to the lattice in aggregated systems can suppress electronic thermalization. In conclusion, these findings underscore the critical role of nanoparticle size, aggregation, and molecule–surface interactions in modulating plasmonic dynamics and excited-state lifetimes and further provide valuable insights into designing tailored plasmonic systems with transformative potential for sensing, catalysis, and energy conversion.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Self-absorption of high-energy Gamma-rays in Cygnus X-3

Absorption of high-energy gamma-rays from Cyg X-3 in its own photon field by the reaction gamma + gamma yields e(+) + e(-) is considered. It is found that gamma rays with an energy around 10 to the 12th eV are attenuated, and the observed flux has to be corrected. Gamma rays with energy greater than 10 to the 15th eV which are observed are not affected by the photon field.

Apparao, K. M. V.↗