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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.

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At least 109 records · Page 6

The European Spacelab structural design evolution

Spacelab is a manned, reusable laboratory which is being developed for the European Space Agency (ESA). In its working mode it will fly in low earth orbit in the cargo bay of the Shuttle Transportation System (STS) Orbiter. A description is presented of the structural development of the various features of Spacelab. System requirements are considered along with structural requirements, quasi-static loads, acoustic loads, pressure loads, crash loads, ground loads, and the fatigue profile. Aspects of thermal environment generation are discussed, and questions regarding the design evolution of the pallet structure are examined. Details of pallet structure testing are reported, taking into account static strength tests, acoustic tests, the modal survey test, crash tests, and fatigue/fracture mechanics testing.

Thirkettle, A. J.↗

An Advanced Meso-Scale Peridynamic Modeling Technology using High-Performance Computing for Cost-Effective Product Design and Testing of Carbon Fiber Reinforced Polymer Composites in Light-weight Vehicles

We study a peridynamic composite modeling technology based on the discontinuous Galerkin finite element method, implemented in the commercial LS-DYNA software, for modeling and prediction of failure in carbon fiber reinforced polymer composites. The proposed technology is developed for the material failure analysis at the meso-scale, which provides the prevailing fiber-matrix interaction mechanism, without adoption of the representative volume element method and thus avoiding complicated numerical calibration procedures. Three types of experimental tests—in-plane coupon test, out-of-plane coupon test, and a component crash test—are simulated in a high-performance computing environment to assess the performance of the proposed peridynamic composite modeling technology.

36 MATERIALS SCIENCE↗

Comparison Between THOR Anthropomorphic Test Device and THOR Finite Element Model

Extended time spent in reduced gravity can cause physiologic deconditioning of astronauts, reducing their ability to sustain excessive forces during dynamic phases of spaceflight such as landing. To make certain that the crew is safe during these phases, NASA must take caution when determining what types of landings are acceptable based on the accelerations applied to the astronaut. In order to test acceptable landings, various trials have been run accelerating humans, cadavers, and Anthropomorphic Test Devices (ATDs), or crash test dummies, at different acceleration and velocity rates on a sled testing platform. Using these tests, risks of injury will be created and metrics will be developed for the likelihood of injuries due to the acceleration. A finite element model (FEM) of the Test Device for Human Occupant Restraint (THOR) ATD has been developed that can simulate these test trials and others (Putnam, 2014), reducing the need for human and ATD testing. Additionally, this will give researchers a more effective way to test the accelerations and orientations encountered during spaceflight landings during design of new space vehicles for crewed missions. However, the FEM has not been proven and must be validated by comparing the forces, accelerations, and other measurements of all parts of the body between the physical tests already completed and computer simulated trials. The purpose of my research was to validate the FEM for the ATD using previously run trials with the physical THOR ATD.

Moore, Erik↗

A Comparative Analysis of Occupant Response Between Component and Full Vehicle Tests of Fokker F28 Aircraft Hardware

In 2019, the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) conducted a full-scale crash test of a Fokker F28 MK1000 aircraft. This test concluded a multi-year research effort in which two component fuselage sections of a matching Fokker F28 aircraft were previously tested under similar vertical impact conditions. Due to facility and cost constraints of full-scale testing, aircraft are typically evaluated through component level tests (i.e. vertical drops of fuselage subsections or isolated seat tests). Although more practical, these tests are limited in their ability fully replicate the complex multi-axis loading environment induced on the occupants during a full-aircraft crash event. Because of this, there is risk that component level testing does not provide a complete assessment of vehicle crashworthiness. Comparative analysis between full-scale and component level testing of the Fokker F28 aircraft provides an excellent opportunity to evaluate differences in crashworthiness prediction made between these levels of test fidelity. In this study, Anthropomorphic Test Device (ATD, a.k.a crash test dummies) responses measured during the Fokker full scale impact test were compared to those measured in the component fuselage section drops. A variety of ATD configurations (5th, 50th, 95th) and positions (upright, braced) were tested in both the full-scale and component tests. ATD injury metric response comparisons were made across these ATD variations in addition to comparisons made with respect to ATD location within the vehicle. Results found the addition of horizontal impact velocity, achieved in the full-scale testing, along with aircraft structural effects altered ATD based crashworthiness assessment of the vehicle.

Crashworthiness↗

Correlation and assessment of structural airplane crash data with flight parameters at impact

Crash deceleration pulse data from a crash dynamics program on general aviation airplanes and from transport crash data were analyzed. Structural airplane crash data and flight parameters at impact were correlated. Uncoupled equations for the normal and longitudinal floor impulses in the cabin area of the airplane were derived, and analytical expressions for structural crushing during impact and horizontal slide out were also determined. Agreement was found between experimental and analytical data for general aviation and transport airplanes over a relatively wide range of impact parameter. Two possible applications of the impulse data are presented: a postcrash evaluation of crash test parameters and an assumed crash scenario.

Carden, H. D.↗

A Summary of Results from Vertical Drop Testing of Hybrid III and WIAMan ATDs

With the development and maturation of the Urban Air Mobility (UAM) market, many new types of electric vertical take-off and landing (eVTOL) vehicles will be flying in the national airspace carrying goods, people or conducting operations for a variety of missions. These types of vehicles are unlike current aircraft due to their novel design and operational profile. Several considerations must be examined in areas including noise, comfort and safety in order for these vehicles to be utilized and accepted into the current airspace system. Researchers at NASA Langley Research Center (LaRC) have conducted sub-scale and full-scale tests on representative eVTOL airframes and seats under a variety of dynamic impact conditions. These tests were conducted to generate data necessary to inform the development of standards in the areas specific to crashworthiness of eVTOL vehicle systems and safety. The data in this report relates to occupant responses obtained during a test campaign utilizing various makes, models, and sizes of Anthropomorphic Test Devices (ATD’s, a.k.a. crash test dummies) undergoing vertical impacts in a variety of seats. The data is intended to provide occupant behavior response and injury metrics for several anticipated impact scenarios that may occur in eVTOL operations. This report will present test data highlighting the effects of several variables on the test results. Discussions on the ATD sizes, along with comparisons between different ATD makes and types will be included. The performance of an in-house developed energy absorbing seat will be detailed, and discussions pertaining to the applicability in various loading conditions will be presented. Finally, a discussion as to the applicability of the tested results to eVTOL full-scale conditions will be included.

Dynamic Drop Testing↗

Suited Occupant Injury Potential During Dynamic Spacecraft Flight Phases

In support of the Constellation Space Suit Element [CSSE], a new space-suit architecture will be created for support of Launch, Entry, Abort, Microgravity Extra- Vehicular Activity [EVA], and post-landing crew operations, safety and, under emergency conditions, survival. The space suit is unique in comparison to previous launch, entry, and abort [LEA] suit architectures in that it utilizes rigid mobility elements in the scye (i.e., shoulder) and the upper arm regions. The suit architecture also utilizes rigid thigh disconnect elements to create a quick disconnect approximately located above the knee. This feature allows commonality of the lower portion of the suit (from the thigh disconnect down), making the lower legs common across two suit configurations. This suit must interface with the Orion vehicle seat subsystem, which includes seat components, lateral supports, and restraints. Due to the unique configuration of spacesuit mobility elements, combined with the need to provide occupant protection during dynamic vehicle events, risks have been identified with potential injury due to the suit characteristics described above. To address the risk concerns, a test series has been developed in coordination with the Injury Biomechanics Research Laboratory [IBRL] to evaluate the likelihood and consequences of these potential issues. Testing includes use of Anthropomorphic Test Devices [ATDs; vernacularly referred to as "crash test dummies"], Post Mortem Human Subjects [PMHS], and representative seat/suit hardware in combination with high linear acceleration events. The ensuing treatment focuses on test purpose and objectives; test hardware, facility, and setup; and preliminary results.

Dub, Mark O.↗

Large Field Photogrammetry Techniques in Aircraft and Spacecraft Impact Testing

The Landing and Impact Research Facility (LandIR) at NASA Langley Research Center is a 240 ft. high A-frame structure which is used for full-scale crash testing of aircraft and rotorcraft vehicles. Because the LandIR provides a unique capability to introduce impact velocities in the forward and vertical directions, it is also serving as the facility for landing tests on full-scale and sub-scale Orion spacecraft mass simulators. Recently, a three-dimensional photogrammetry system was acquired to assist with the gathering of vehicle flight data before, throughout and after the impact. This data provides the basis for the post-test analysis and data reduction. Experimental setups for pendulum swing tests on vehicles having both forward and vertical velocities can extend to 50 x 50 x 50 foot cubes, while weather, vehicle geometry, and other constraints make each experimental setup unique to each test. This paper will discuss the specific calibration techniques for large fields of views, camera and lens selection, data processing, as well as best practice techniques learned from using the large field of view photogrammetry on a multitude of crash and landing test scenarios unique to the LandIR.

Littell, Justin D.↗

Data Reduction and Its Impact on Test-Analysis Correlation

A research project has been initiated to improve crash test and analysis correlation. The research has focused on two specimen types: simple metallic beams and plates; and a representative composite fuselage section. Impact tests were performed under carefully controlled conditions. In addition, the specimens were densely instrumented to enable not only correlation with finite element simulations, but to also assess the repeatability of the data. Simulations utilizing a detailed finite element model were executed in a nonlinear transient dynamic code. The results presented in this paper concentrate on the effect of several data reduction processes, to include filtering frequency and sampling rate, on the correlation accuracy.

Lyle, Karen H.↗

Testing Instrument Extremes in the TREAT Facility

TREAT is a transient power-shaping reactor whose primary mission is to enhance safety performance by testing nuclear fuels and materials under thermodynamic and neutronic conditions ranging from off-normal to extreme. Transient testing of nuclear fuels is analogous to car crash testing, in that the dramatic changes commonly seen when comparing the test specimens' initial and final state points necessitate in-situ measuring in order to interpret and understand the evolution of the experiment. TREAT’s experiment design strategy utilizes a highly reconfigurable and accessible reactor core that affords flexibility when installing experiment devices, thanks to the lack of a primary coolant boundary and the inclusion of multiple access points in the reactor bioshield. Within the experiment devices, the test specimens (which are integrated with their test environments), desired instrumentation diagnostics, and safety considerations are all contained in a single engineered package. The experiments encompass various types of environments (e.g., water, sodium, and gas at temperature and pressure), as well as a range of control options (e.g., static or flowing coolants). The experimental conditions are uniquely representative of advanced reactors, providing challenges to sensor performance but also affording a unique opportunity for development and qualification of sensors suited to these environments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA, Langley Impact Dynamics Facility

Description of an impact dynamics facility that will be used to crash test full-scale light aircraft. The aircraft are crashed into the ground as free bodies, using a pendulum swing method to obtain desired flightpath angles and velocities. The aircraft are unrestrained during impact to obtain realistic reactions. Accelerations and strains of the aircraft structure are measured during impact. The crash sequence and structural deformations are obtained by external and internal camera coverage.

Vaughan, V. L., Jr.↗

Project Morpheus: Lessons Learned in Lander Technology Development

NASA's Morpheus Project has developed and tested a prototype planetary lander capable of vertical takeoff and landing, that is designed to serve as a testbed for advanced spacecraft technologies. The lander vehicle, propelled by a LOX/Methane engine and sized to carry a 500kg payload to the lunar surface, provides a platform for bringing technologies from the laboratory into an integrated flight system at relatively low cost. Designed, developed, manufactured and operated in-house by engineers at Johnson Space Center, the initial flight test campaign began on-site at JSC less than one year after project start. After two years of testing, including two major upgrade periods, and recovery from a test crash that caused the loss of a vehicle, flight testing will evolve to executing autonomous flights simulating a 500m lunar approach trajectory, hazard avoidance maneuvers, and precision landing, incorporating the Autonomous Landing and Hazard Avoidance (ALHAT) sensor suite. These free-flights are conducted at a simulated planetary landscape built at Kennedy Space Center's Shuttle Landing Facility. The Morpheus Project represents a departure from recent NASA programs and projects that traditionally require longer development lifecycles and testing at remote, dedicated testing facilities. This paper expands on the project perspective that technologies offer promise, but capabilities offer solutions. It documents the integrated testing campaign, the infrastructure and testing facilities, and the technologies being evaluated in this testbed. The paper also describes the fast pace of the project, rapid prototyping, frequent testing, and lessons learned during this departure from the traditional engineering development process at NASA's Johnson Space Center.

Olansen, Jon B.↗

Impact Testing and Simulation of a Sinusoid Foam Sandwich Energy Absorber

A sinusoidal-shaped foam sandwich energy absorber was developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research project. The energy absorber, designated the "sinusoid," consisted of hybrid carbon- Kevlar® plain weave fabric face sheets, two layers for each face sheet oriented at +/-45deg with respect to the vertical or crush direction, and a closed-cell ELFOAM(TradeMark) P200 polyisocyanurate (2.0-lb/ft3) foam core. The design goal for the energy absorber was to achieve an average floor-level acceleration of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in the design were assessed through quasi-static and dynamic crush testing of component specimens. Once the design was finalized, a 5-ft-long subfloor beam was fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorber prior to retrofit into TRACT 2. Finite element models were developed of all test articles and simulations were performed using LSDYNA ®, a commercial nonlinear explicit transient dynamic finite element code. Test analysis results are presented for the sinusoid foam sandwich energy absorber as comparisons of load-displacement and acceleration-time-history responses, as well as predicted and experimental structural deformations and progressive damage for each evaluation level (component testing through barrel section drop testing).

Jackson, Karen E.↗

Development of an energy absorbing passenger seat for the B-720 test aircraft

An evaluation is made of the experimental results obtained in the 720B airliner flight crash testing of an energy-absorbing passenger seat design, which has been derived through modification of a standard three-passenger commercial aviation seat. The highly instrumented 720B aircraft was crashed at the end of a remotely controlled flight on a specially prepared, gravel-covered ground site. In order to limit acceleration upon impact, the seat tested had been designed and fabricated to collapse under a controlled load. The aircraft impact's shock pulse is absorbed by tubes which crush under load as axial columns.

Eichelberger, C. P.↗

Crashworthy design considerations for general aviation seats

This report summarizes the experimental research conducted at the NASA Langley Research Center on general aviation seat and occupant crash response and discusses seat design considerations. Included are typical floor acceleration pulses from general aviation airplane crash tests, the performance of typical general aviation seats in a simulated crash environment, and the performance of prototype energy absorbing (EA) seat designs. Static and dynamic seat testing procedures and test facilities are discussed. Also presented are results from a series of dynamic tests of typical general aviation seats and prototype EA seats.

Alfaro-Bou, E.↗

Impact data from a transport aircraft during a controlled impact demonstration

On December 1, 1984, the FAA and NASA conducted a remotely piloted air-to-ground crash test of a Boeing 720 transport aircraft instrumented to measure crash loads of the structure and the anthropomorphic dummy passengers. Over 330 time histories of accelerations and loads collected during the Full-Scale Transport Controlled Impact Demonstration (CID) for the 1-sec period after initial impact are presented. Although a symmetric 1 deg. nose-up attitude with a 17 ft/sec sink rate was planned, the plane was yawed and rolled 13 deg. at initial (left-wing) impact. The first fuselage impact occurred near the nose wheel well with the nose pitched down 2.5 deg. Peak normal (vertical) floor accelerations were highest in the cockpit and forward cabin near the nose wheel well and were approximately 14G. The remaining cabin floor received normal acceleration peaks of 7G or less. The peak longitudinal floor accelerations showed a similar distribution, with the highest (7G) in the cockpit and forward cabin, decreasing to 4G or less toward the rear. Peak transverse floor accelerations ranged from about 5G in the cockpit to 1G in the aft fuselage.

Fasanella, E. L.↗

Simulating the Response of a Composite Honeycomb Energy Absorber: Full-Scale Impact Testing - Part 2

NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark) honeycomb. The DEA has a flexible hinge that allows the honeycomb to be stowed collapsed until needed during an emergency. Evaluation of the DEA began with material characterization of the Kevlar(Registered TradeMark)-129 fabric/epoxy, and ended with a full-scale crash test of a retrofitted MD-500 helicopter. During each evaluation phase, finite element models of the test articles were developed and simulations were performed using the dynamic finite element code, LS-DYNA(Registered TradeMark). The paper will focus on simulations of two full-scale impact tests involving the DEA, a mass-simulator and a full-scale crash of an instrumented MD-500 helicopter. Isotropic (MAT24) and composite (MAT58) material models, which were assigned to DEA shell elements, were compared. Based on simulations results, the MAT58 model showed better agreement with test.

Fasanella, Edwin L.↗

Design and Test of an Improved Crashworthiness Small Composite Airframe

The purpose of this small business innovative research (SBIR) program was to evaluate the feasibility of developing small composite airplanes with improved crashworthiness. A combination of analysis and half scale component tests were used to develop an energy absorbing airframe. Four full scale crash tests were conducted at the NASA Impact Dynamics Research Facility, two on a hard surface and two onto soft soil, replicating earlier NASA tests of production general aviation airplanes. Several seat designs and restraint systems including both an air bag and load limiting shoulder harnesses were tested. Tests showed that occupant loads were within survivable limits with the improved structural design and the proper combination of seats and restraint systems. There was no loss of cabin volume during the events. The analysis method developed provided design guidance but time did not allow extending the analysis to soft soil impact. This project demonstrated that survivability improvements are possible with modest weight penalties. The design methods can be readily applied by airplane designers using the examples in this report.

Terry, James E.↗