Impact of Next Generation Electrode Materials on Abuse Response.
Abstract not provided.
Fenton, Kyle R↗
SEARCH · Search NASA
Results for “responsive material”
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.
Impact of Next Generation Electrode Materials on Abuse Response.
Abstract not provided.
Fenton, Kyle R↗
Modeling the high-strain-rate failure response of granular materials.
Abstract not provided.
Demaske, Brian James↗
Evaluation of Finite-Rate Gas/Surface Interaction Models for a Carbon Based Ablator
Two sets of finite-rate gas-surface interaction model between air and the carbon surface are studied. The first set is an engineering model with one-way chemical reactions, and the second set is a more detailed model with two-way chemical reactions. These two proposed models intend to cover the carbon surface ablation conditions including the low temperature rate-controlled oxidation, the mid-temperature diffusion-controlled oxidation, and the high temperature sublimation. The prediction of carbon surface recession is achieved by coupling a material thermal response code and a Navier-Stokes flow code. The material thermal response code used in this study is the Two-dimensional Implicit Thermal-response and Ablation Program, which predicts charring material thermal response and shape change on hypersonic space vehicles. The flow code solves the reacting full Navier-Stokes equations using Data Parallel Line Relaxation method. Recession analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities with heat fluxes ranging from 45 to 1100 wcm2 are performed and compared with data for model validation. The ablating material used in these arc-jet tests is Phenolic Impregnated Carbon Ablator. Additionally, computational predictions of surface recession and shape change are in good agreement with measurement for arc-jet conditions of Small Probe Reentry Investigation for Thermal Protection System Engineering.
Ablation↗
A stable numerical solution method in-plane loading of nonlinear viscoelastic laminated orthotropic materials
In response to the tremendous growth in the development of advanced materials, such as fiber-reinforced plastic (FRP) composite materials, a new numerical method is developed to analyze and predict the time-dependent properties of these materials. Basic concepts in viscoelasticity, laminated composites, and previous viscoelastic numerical methods are presented. A stable numerical method, called the nonlinear differential equation method (NDEM), is developed to calculate the in-plane stresses and strains over any time period for a general laminate constructed from nonlinear viscoelastic orthotropic plies. The method is implemented in an in-plane stress analysis computer program, called VCAP, to demonstrate its usefulness and to verify its accuracy. A number of actual experimental test results performed on Kevlar/epoxy composite laminates are compared to predictions calculated from the numerical method.
Gramoll, K. C.↗
In Pursuit of 2D Materials for Maximum Optical Response
Despite being only a few atoms thick, single-layer two-dimensional (2D) materials display strong electron–photon interactions that could be utilized in efficient light modulators on extreme subwavelength scales. In various applications involving light modulation and manipulation, materials with strong optical response at different wavelengths are required. Using qualitative analytical modeling and first-principles calculations, we determine the theoretical limit of the maximum optical response such as absorbance ($A$) and reflectance ($R$) in 2D materials and also conduct a computational survey to seek out those with best $A$ and $R$ in various frequency ranges, from mid-infrared to deep-ultraviolet. We find that 2D boron has broadband reflectance R > 99% for >100 layers, surpassing conventional thin films of bulk metals such as silver. Moreover, we identify 2D monolayer semiconductors with maximum response, for which we obtain quantitative estimates by calculating quasiparticle energies and accounting for excitonic effects by solving the Bethe–Salpeter equation. We found several monolayer semiconductors with absorbances ≳30% in different optical ranges, which are more than half of the maximum possible value, Alim = 1/2, for a freestanding 2D material. Our study predicts 2D materials which can potentially be used in ultrathin reflectors and absorbers for optoelectronic application in various frequency ranges.
36 MATERIALS SCIENCE↗
In situ dynamic compression wave behavior in additively manufactured lattice materials
Explore the source record for details and available documents.
Lind, Jonathan (ORCID:0000000164060617)↗
Correlation Between Bulk Material Defects and Spectroscopic Response in Cadmium Zinc Telluride Detectors
One of the critical challenges for large area cadmium zinc telluride (CdZnTe) detector arrays is obtaining material capable of uniform imaging and spectroscopic response. Two complementary nondestructive techniques for characterizing bulk CdZnTe have been developed to identify material with a uniform response. The first technique, infrared transmission imaging, allows for rapid visualization of bulk defects. The second technique, x-ray spectral mapping, provides a map of the material spectroscopic response when it is configured as a planar detector. The two techniques have been used to develop a correlation between bulk defect type and detector performance. The correlation allows for the use of infrared imaging to rapidly develop wafer mining maps. The mining of material free of detrimental defects has the potential to dramatically increase the yield and quality of large area CdZnTe detector arrays.
Parker, Bradford H.↗
Response of spacecraft window materials to hypervelocity projectile impact
This paper presents the results of an investigation of the response of window materials to hypervelocity projectile impact. Window impact damage is characterized according to the nature and extent of surface and internal damage. Analysis of the test data indicates that, for single-pane specimens, the extent of the damage to the test specimens can be written as functions of the impact parameters of the original projectile and the geometric and material properties of the projectile/ window system. These functions can be used to perform parameter-sensitivity studies and to evaluate hypothetical design applications and configurations.
Schonberg, William P.↗
Attribution of gamma-ray background collected by a mobile detector system to its surroundings using panoramic video
Mobile radiation detector systems are important tools for detecting radiological and nuclear sources outside of regulatory control, but due to their mobility, they are subject to complex and varying backgrounds in most realistic operational scenarios. Recent work has found correlations between non-radiological contextual information and gamma-ray spectral features that can be used to decrease false alarm rates, however a more complete understanding of background source terms has been elusive. A measurement campaign developed a full radiological characterization of a controlled facility that roughly corresponded to two city blocks. As part of the campaign, the Radiological Multi-sensor Analysis Platform (RadMAP) collected extensive multi-sensor data. In this work, RadMAP’s panoramic video data were used to visually identify several different materials and quantify the detector response to each material. A linear model was fit between the material responses and radiological features, and the results demonstrate reasonable agreement with ground truth flux measurements for each material. This paper will describe the data collection, processing, and analysis of the gamma-ray and video data from RadMAP. The paper will conclude with perspectives on the applicability of such a method to less controlled environments both with respect to achieving better understanding the sources of variability of background radiation in urban environments and whether such methods could be leveraged in operational scenarios.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Sensitivity of tire response to variations in material and geometric parameters
A computational procedure is presented for evaluating the analytic sensitivity derivatives of the tire response with respect to material and geometric parameters of the tire. The tire is modeled by using a two-dimensional laminated anisotropic shell theory with the effects of variation in material and geometric parameters included. The computational procedure is applied to the case of uniform inflation pressure on the Space Shuttle nose-gear tire when subjected to uniform inflation pressure. Numerical results are presented showing the sensitivity of the different response quantities to variations in the material characteristics of both the cord and the rubber.
Noor, Ahmed K.↗
Shock behavior of materials
The physics governing the response of materials to shock loading has many applications in various fields, ranging from Earth and planetary science to engineering and ballistics. Elucidating the behavior of materials experiencing the passage of shock waves motivates active research worldwide, including experimental developments with in situ and time-resolved measurements, modern computational approaches, and multi-scale simulations.
36 MATERIALS SCIENCE↗
Mechanical Erosion Modeling of TPS Materials
The goal of this work is to predict the mechanical response of TPS materials, and specifically, to determine if there is additional surface recession in the heat shield’s surface as a result of mechanical erosion due to the mechanical and thermal loads experienced during atmospheric entry. To accomplish this, a solid mechanics module was integrated within the PATO material response code, enabling it to model the potential mechanical erosion in three steps: first, having the effective mechanical properties as function of temperature, the implemented stress analysis solver computes the stress and the displacement fields for the TPS material using the wall shear stress tensor, computed with the DPLR hypersonic CFD code, as boundary conditions; then, regions on the surface where the stress meets the failure criteria are identified; finally, the failed material is removed and the mesh is redistributed accordingly. The outcome is a model capable of predicting the total recession in the TPS material due to surface chemistry and mechanical erosion.
Stress Analysis↗
On computing the evolution of temperature for materials under dynamic loading
Modeling and simulation of the dynamic response of materials is important to many applications including the development of armor systems, understanding the safety of explosives, and assessing the crashworthiness of vehicles. Within such applications it is often critical to accurately compute the evolution of the temperature because it is a state variable that affects the kinetics of competing active processes within the material (e.g., dislocation motion, phase transformation, decomposition). Depending on the selection of an independent state variable, e.g. temperature or entropy, the approach for computing temperature is well understood based on the thermodynamic framework attributed to Coleman and Noll. However, different computational codes used for modeling the dynamic response of materials adopt different independent state variables. In this work, two thermodynamically consistent strategies for computing the temperature of a coupled thermodynamic state are compared and implemented into two different Lagrangian computational codes. The equivalence of these two approaches is established through the numerical solutions of several test problems. Finally, the implication of various approximations made to each of these approaches within the literature are assessed in the context of uniaxial stress conditions (split Hopkinson pressure bar experiments) and uniaxial strain conditions (plate impact experiments). Here, it is shown that the temperature rate or energy partition approaches are equivalent when implemented in their complete forms, but that several common simplifying assumptions, that are warranted in the case of uniaxial stress, lead to significant errors in the resulting Hugoniot state for plate impact.
36 MATERIALS SCIENCE↗
Investigating compression failure mechanisms in composite laminates with a transparent fiberglass-epoxy birefringent materials
The response and failure of a + or - 45s class laminate was studied by transparent fiberglass epoxy composite birefringent material. The birefringency property allows the laminate stress distribution to be observed during the test and also after the test if permanent residual stresses occur. The location of initial laminate failure and of the subsequent failure propagation are observed through its transparency characteristics. Experimental results are presented.
Shuart, M. J.↗
Predicting the Cyclic Response of High-Temperature Materials
Simplified analytical procedure for estimating local stress/strain response in high-temperature structural component developed. Simplified procedure relies on assumption local inelastic response in hightemperature structure constrained by surrounding elastic material. Procedure assumes local response composed of elastic, time-independent plastic, and creep components. Conventional yield surface concept used to determine onset of plastic action.
Moreno, V.↗
Simulating Meteor Ablation at the Hypersonic Materials Environmental Test System
The ablation mechanisms of stony meteorite material and a terrestrial analog were investigated at the Hypersonic Materials Environmental Test System (HyMETS) facility at NASA’s Langley Research Center. The primary analyte (Tamdakht-H5) and arc-jet test conditions were chosen to simulate the entry of an ordinary chondrite through the Earth’s mesosphere. Basalt was selected to compare the meteorite response against material with enhanced polymerization and an elevated concentration of volatile species. The initial ablation process for each material commences with the vaporization of volatile species and germination of a viscous melt layer on the stagnation surface. However, each material exhibited distinct mass loss mechanisms, with basalt recessing at twice the rate of Tamdakht. Inspection of high-speed video and chemical analysis of the post-test melt layer suggests the dominant mode of mass loss of Tamdakht is expressed through the vaporization of volatile compounds. Vaporization rates of Tamdakht are 18x higher than basalt under the most severe test conditions which provides enhanced thermal shielding. Furthermore, Tamdakht produces a relatively stable melt flow, as evidenced by perpetual growth at the sidewall and the exiguous detachment of molten material into the flow. The ablation mechanism of basalt is markedly different from Tamdakht and is governed by volatile species in the virgin material. The dominant mode of mass loss for basalt is attributed to the detachment of large sections of the stagnation surface near the edge radius. An additional but subordinate mode of mass loss is assigned to the removal of melt flow as it passes over the edge radius, where shear forces overcome the rheological properties of the molten matter. Finally, mechanistic details will be discussed in terms of designing future test campaigns, developing meteorite-based materials response models, and impacting the broader scope of the Asteroid Threat Assessment Project (ATAP).
Meteor Ablation↗