The effects of loading direction on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

Nettles, Alan T.; Guin, William E.; Sadowski, Isabelle Jacot

doi:10.1177/10996362221116572

Cited by 3 publications

(12 citation statements)

References 9 publications

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“…This is consistent with the results found in. 1 The +22.5⁰ QI and À22.5⁰ QI CAI specimens had essentially the same average CAI strength results which negates the assumption that the À22.5⁰ QI specimens would have a higher average CAI strength value since all four load bearing plies were "tucked into" the center of the face sheet.…”

Section: Compression After Impact Testingmentioning

confidence: 98%

“…The impact energy (14.1 J) was selected based on what used in a previous study. 1 An example of the visual damage that was formed is shown in Figure 3. Note that the aluminum honeycomb that crushes under the impact location tends to "hold" a dent approximately 30 mm in diameter around the impact location.…”

Section: Impact Damage Testingmentioning

confidence: 99%

“…During a program examining what material and layup to use to manufacture a payload adapter fitting (PAF) for NASA’s Space Launch System (SLS) rocket, compression-after-impact (CAI) tests were performed on specimens cut from a large aluminum honeycomb sandwich structure with T1100/3960 carbon/epoxy quasi-isotropic face sheets. 1 During this testing, some specimens were cut in both the 0⁰ and 90⁰ directions to give two different layup sequences of a quasi-isotropic laminate. In theory the results should have been the same (as long as the rotation did not cause the outermost plies of the face sheet to be oriented parallel to the loading direction).…”

Section: Introductionmentioning

confidence: 99%

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The effects of off-axis loading on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

Nettles

Barnes

Guin

et al. 2023

Jnl of Sandwich Structures & Materials

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This study presents experimental results of compression after impact (CAI) testing of aluminum honeycomb core sandwich structure with face sheets made of co-cured T1100/3960 quasi-isotropic carbon/epoxy when tested at +22.5⁰ and −22.5⁰ with respect to the 0⁰ fibers. In a previous study examining the CAI strengths of honeycomb sandwich structure, it was found that specimens had different CAI strengths, based on a [−45/90/+45/0]S layup, depending on whether they were tested in the 0⁰ direction (face sheet layup of [−45/90/+45/0]S) or 90⁰ direction (face sheet layup of [+45/0/-45/90]S). The CAI strength results showed that the specimens tested in the 90⁰ direction had a 19% drop in CAI strength compared to specimens tested in the 0⁰ direction. This was attributed to the 0⁰ load bearing plies in the 0⁰ direction specimens being “tucked in” at the center of the specimen thus providing more stability against microbuckling. This raised the question as to what CAI strength would specimens tested at +22.5⁰ (face sheet layup of [−22.5/−67.5/+67.6/+22.5]S) and −22.5⁰ (face sheet layup of [−67.5/+67.5/+22.5/-22.5]S) have compared to specimens tested in the 0⁰ and 90⁰ direction. Results presented in this study show that the specimens loaded at +22.5⁰ and −22.5⁰ have a similar average CAI strength compared to the specimens loaded in the 0⁰ direction. The specimens loaded in the 90⁰ direction exhibit 16% lower average CAI strength. Additional specimens were tested in the +45⁰ direction to put the 0⁰ load bearing fibers on the outside of the specimen to see if this would decrease the strength as has been documented for undamaged strength. These specimens have average CAI strength values between the 0⁰ direction average CAI strength values and the 90⁰ direction average CAI strength values.

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Section: Compression After Impact Testingmentioning

confidence: 98%

Section: Impact Damage Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effects of off-axis loading on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

Nettles

Barnes

Guin

et al. 2023

Jnl of Sandwich Structures & Materials

View full text Add to dashboard Cite

show abstract

“…Furthermore, compared with the original hexagonal unit cell, the irregular folding wave is observed in higher order hexagonal unit cells, owing to the increased wall constraint, which agrees with Fang 16 and Kim 25 's findings. A threshold is therefore proposed for the ratio of wall thickness to edge length of the first order unit cell to achieve a regular progressive folding wave, as shown in equation (7).…”

Section: Uniaxial Tensile Characteristics Of Parent Materialsmentioning

confidence: 99%

“…1,2 Because of the high strength/stiffness to density ratio and the excellent energy absorption capacity, honeycomb cores have been extensively applied for crash resistance. [3][4][5][6][7][8] Wadley 9 reported that honeycombs possess the higher compressive strength, elastic modulus and energy absorption capacity along the out-of-plane orientation under a quasistatic compression, than corrugated and lattice truss topologies.…”

Section: Introductionmentioning

confidence: 99%

Out-of-plane crashworthiness of hierarchical cellular topology with different wall thicknesses in hierarchies

Zhang

Liu

et al. 2023

Jnl of Sandwich Structures & Materials

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Hierarchical honeycomb is a topology presenting better weight-efficiency than the conventional honeycomb. However, the existing research are mainly conducted based on an assumption of uniform in-plane wall thickness. Rare studies consider the effect of different wall thicknesses in hierarchies. This paper investigates the out-of-plane crashworthiness of vertex hexagonal-based hierarchical honeycombs with non-uniform wall thickness in distinct hierarchies experimentally and theoretically. The coupons with parent material of 316L steel are obtained using Selective Laser Melting fabricating technique. The experimental results indicate that the first order honeycombs with uniform wall thickness experience a failure mechanism transition from local elastic buckling to local plastic buckling of cell walls at the critical density of 0.0772. A progressive folding wave can be identified when relative density is lower than 0.0386. At any edge length ratio, the plateau crushing stress increases monotonously as the increase of the wall thickness ratio, but not for the half wavelength. Both the half wavelength and maximum plateau crushing stresses are linearly related to relative density. For the first order honeycombs, the effect of edge length ratio is more considerable on the plateau crushing stress than the wall thickness ratio. The second order honeycombs exhibit higher half wavelengths and maximum plateau crushing stresses than the first order honeycombs owing to the more considerable cell wall constraint among the hierarchies. Compared to the hierarchical honeycombs with uniform wall thicknesses at relative densities of 0.005∼0.0386, the non-uniform wall thickness enhances the maximum plateau crushing stress significantly, especially at a low relative density, and the maximum improvements for first order and second order honeycombs are 71.5 and 48.6%, respectively. However, the absolute improvements are similar, averaging approximately 1.18 MPa. This work provides a foundation for developing ultralight hierarchical material candidates applied in passive protection equipment, such as aircrafts and vehicles.

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Experimental and numerical investigation of core splicing configurations in an advanced composite sandwich structural system

Aqel

Severson

Elhajjar

2023

Journal of Reinforced Plastics and Composites

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In this study, an investigation is presented on the effects of the honeycomb core splice gaps on the performance of advanced composite sandwich structures consisting of aluminum honeycomb core and carbon-fiber/epoxy facesheets. The experimental and numerical investigation explores the effects of core thickness, facesheet thickness, splice gap width, and the presence of core splice adhesive on the structural response of the composite sandwich structure. The specimens fabricated with the splices exposed to primarily bending and shear to understand further how the core splice interacts with the overall structural response under such loading conditions. In addition, 3D finite element models investigated the failure modes in the specimens by examining the strain fields for core-spliced sections of the sandwich structure under the experimentally observed loading conditions. Various failure modes are observed in the experiments ranging from core shear failure, facesheet debonding, or fracture depending on the location of the core splice, core, and the facesheet properties. The results illustrate the importance of proper detailing and analysis of core splices in composite structures made from sandwich designs.

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The effects of loading direction on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

Cited by 3 publications

References 9 publications

The effects of off-axis loading on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

The effects of off-axis loading on the compression after impact strength of quasi-isotropic face sheet honeycomb core sandwich structure

Out-of-plane crashworthiness of hierarchical cellular topology with different wall thicknesses in hierarchies

Experimental and numerical investigation of core splicing configurations in an advanced composite sandwich structural system

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