Water Impact Test and Simulation of a Composite Energy Absorbing Fuselage Section

Fasanella, Edwin L.; Jackson, Karen E.; Sparks, Chad E.; Sareen, Ashish K.

doi:10.4050/1.3092852

Cited by 26 publications

(17 citation statements)

References 7 publications

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“…A similar fuselage section with an integrated crushable foam subfloor concept and simulated payload was used in previous studies involving vertical drop tests on various impact surfaces [7,8]. Sareen et al [7] studied the response of the fuselage section during a 25-fps vertical drop on a hard surface and soft soil (sand) and Fasanella et al [8] reported on the response of the same fuselage section during a 25-fps vertical drop on water.…”

Section: Discussionmentioning

confidence: 99%

“…Sareen et al [7] studied the response of the fuselage section during a 25-fps vertical drop on a hard surface and soft soil (sand) and Fasanella et al [8] reported on the response of the same fuselage section during a 25-fps vertical drop on water. Therefore, a loose comparison of the two concepts can be made for corresponding impact surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…In essence, this is a similar approach to the one previously proposed by Kellas [6] where most of the crash energy is dissipated by crushable structure placed between a rigid floor and a flexible aerodynamic cowling and, therefore, for both concepts, stroking is limited by the available subfloor space. The multi-terrain capability of the concept, proposed by Kellas [6], was investigated by Sareen et al [7] for hard and soft surface impacts, and Fasanella et al [8] for water impact. While concepts with integrated subfloor energy absorption capability can help mitigate impact loads, their performance is limited by the crush stroke capacity -an area in which externally deployable energy absorbers have a clear advantage.…”

Section: Introductionmentioning

confidence: 99%

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Multiterrain Vertical Drop Tests of a Composite Fuselage Section

Kellas¹,

Jackson²

2010

J. Am. Helicopter Society

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A 5-ft-diameter composite fuselage section was retrofitted with four identical blocks of deployable honeycomb energy absorber and crash tested on two different surfaces: soft soil, and water. The drop tests were conducted at the 70-ft. drop tower at the Landing and Impact Research (LandIR) Facility of NASA Langley. Water drop tests were performed into a 15-ft-diameter pool of water that was approximately 42-in. deep. For the soft soil impact, a 15-ft-square container filled with fine-sifted, unpacked sand was located beneath the drop tower. All drop tests were vertical with a nominally flat attitude with respect to the impact surface. The measured impact velocities were 37.4, and 24.7-fps for soft soil and water, respectively. A fuselage section without energy absorbers was also drop tested onto water to provide a datum for comparison with the test, which included energy absorbers. In order to facilitate this type of comparison and to ensure fuselage survivability for the noenergy-absorber case, the velocity of the water impact tests was restricted to 25-fps nominal. While all tests described in this paper were limited to vertical impact velocities, the implications and design challenges of utilizing external energy absorbers during combined forward and vertical impact velocities are discussed. The design, testing and selection of a honeycomb cover, which was required in soft surface and water impacts to transmit the load into the honeycomb cell walls, is also presented. IntroductionHelicopter designers face major challenges in establishing crashworthiness due to the multitude of possible impact orientations and the unknown morphology of the crash site, with surfaces such as concrete and water being at the extreme. For hard and non-yielding impact surfaces, the vehicle's kinetic energy has to be managed by the airframe, and internal and/or external energy absorbing devices to ensure load attenuation and adequate post-crash cabin volume. Often, legacy airframes have little or no internal structure designed for crash energy management. Consequently, external energy absorbers with large stroke capability are often necessary.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiterrain Vertical Drop Tests of a Composite Fuselage Section

Kellas¹,

Jackson²

2010

J. Am. Helicopter Society

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“…The specimens do not collapse after maximum loading is achieved and exhibit a complex unloading response. The composite fuselage section was developed during a three-year research program in the late 1990's and has since been used as a test bed to evaluate structural scaling effects, multi-terrain impacts, seat and occupant loadings, and model correlation studies [22][23][24][25][26][27][28][29][30][31]. A pre-test photograph of the test article is shown in Figure 21 …”

Section: Three-point Bend: Test/analysis Correlationmentioning

confidence: 99%

Deployable System for Crash—Load Attenuation

Kellas¹,

Jackson²

2010

J. Am. Helicopter Society

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An externally deployable honeycomb structure is investigated with respect to crash energy management for light aircraft. The new concept utilizes an expandable honeycomb-like structure to absorb impact energy by crushing. Distinguished by flexible hinges between cell wall junctions that enable effortless deployment, the new energy absorber offers most of the desirable features of an external airbag system without the limitations of poor shear stability, system complexity, and timing sensitivity. Like conventional honeycomb, once expanded, the energy absorber is transformed into a crush efficient and stable cellular structure. Other advantages, afforded by the flexible hinge feature, include a variety of deployment options such as linear, radial, and/or hybrid deployment methods. Radial deployment is utilized when omnidirectional cushioning is required. Linear deployment offers better efficiency, which is preferred when the impact orientation is known in advance. Several energy absorbers utilizing different deployment modes could also be combined to optimize overall performance and/or improve system reliability as outlined in the paper. Results from a series of component and full scale demonstration tests are presented as well as typical deployment techniques and mechanisms. LS-DYNA analytical simulations of selected tests are also presented.

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“…A lot of research was conducted with respect to composite sine wave beams in the subfloor structure that are crushed under vertical crash loads [4][5][6][7][8][9]. Further concepts are based on foam [10] or honeycomb absorbers [11,12] in the subfloor structure. Illustration of aircraft fuselage drop test for crashworthiness evaluation.…”

Section: Introductionmentioning

confidence: 99%

Composite crash absorber for aircraft fuselage applications

Heimbs¹,

Strobl²,

Middendorf³

et al. 2010

WIT Transactions on the Built Environment

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A composite crash absorber element for potential use in z-struts of commercial aircraft fuselage structures was developed, which absorbs energy under crash loads by cutting the composite strut into stripes and crushing the material under bending. The design concept of this absorber element is described and the performance is evaluated experimentally in static, crash and fatigue test series on component and structural level under normal and oblique impact conditions. The physics of the energy absorption by high rate material fragmentation and delamination interactions are explained and numerical modelling methods in explicit finite element codes for the simulation of the crash absorber are assessed.

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Water Impact Test and Simulation of a Composite Energy Absorbing Fuselage Section

Cited by 26 publications

References 7 publications

Multiterrain Vertical Drop Tests of a Composite Fuselage Section

Multiterrain Vertical Drop Tests of a Composite Fuselage Section

Deployable System for Crash—Load Attenuation

Composite crash absorber for aircraft fuselage applications

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