The effect of loading rate on the compression properties of carbon fibre-reinforced epoxy honeycomb structures

The effect of varying strain rate on the compression strength and energy absorption characteristics of a carbon fibre-reinforced plastic honeycomb core has been investigated over a wide range of loading rates. The honeycombs were manufactured by infusing an epoxy resin through a carbon fibre fabric positioned in a dismountable honeycomb mould. The vacuum-assisted resin transfer moulding technique yielded honeycomb cores of a high quality with few defects. Compression tests were undertaken on single and multiple cells and representative volumes removed from the cores in order to assess how the compression strength and specific energy absorption vary with test rate. Crushing tests over the range of strain rates considered highlighted the impressive strength and energy-absorbing response of the honeycomb cores. At quasi-static rates of loading, the compression strength and specific energy absorption characteristics of the unidirectional samples exceeded those of the multidirectional cores. Here, extensive longitudinal splitting and fibre fracture were the predominant failure mechanisms in the cores. For all three stacking sequences, the single-cell samples offer higher compression strength than their five-cell counterparts. In contrast, the specific energy absorption values were found to be slightly higher in the five-cell cores. The experiments highlighted a trend of increased compression strength with loading rate in the multidirectional samples, whereas the strength of the [0°]4 samples was relatively insensitive to strain rate. Finally, the energy absorbing capacity of all structures studied was found to be reasonably constant at increasing rates of strain.

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Energy absorption in aluminium honeycomb cores reinforced with carbon fibre reinforced plastic tubes

Journal of Sandwich Structures & Materials ◽

10.1177/1099636217727145 ◽

2017 ◽

Vol 21 (8) ◽

pp. 2801-2815 ◽

Cited By ~ 3

Author(s):

A Alantali ◽

RA Alia ◽

R Umer ◽

WJ Cantwell

Keyword(s):

Carbon Fibre ◽

Energy Absorption ◽

Specific Energy ◽

Small Diameter ◽

Honeycomb Core ◽

Composite Tubes ◽

Specific Energy Absorption ◽

Reinforced Plastic ◽

Carbon Fibre Reinforced Plastic ◽

Energy Absorbing

The energy-absorbing behaviour of an aluminium honeycomb core reinforced with unidirectional and woven carbon fibre reinforced plastic composite tubes has been investigated experimentally at quasi-static rates of strain. Small diameter carbon fibre reinforced plastic tubes, with chamfered ends, were inserted into the cells of an aluminium honeycomb in order to yield a lightweight energy-absorbing material. The resulting data are compared with crushing tests on arrays of free-standing composite tubes, supported on a specially designed compression test fixture. The study continues with an investigation into size effects in the energy-absorbing response of these cellular materials, where compression tests are undertaken on four scaled sizes of reinforced honeycomb core. Crushing tests on the multi-tube arrays have shown that woven carbon fibre reinforced plastic tubes absorb significantly greater levels of energy than their unidirectional counterparts. Here, the specific energy absorption did not vary with the number of tubes in the array, with values for the woven tubes averaging 110 kJ/kg and those for the unidirectional tubes averaging 75 kJ/kg. Inserting composite tubes into aluminium honeycomb served to increase the measured specific energy absorption of the core, resulting in values of specific energy absorption of up to 100 kJ/kg being recorded in the woven-based system. Tests on four scaled sizes of core have shown that the measured SEA does not vary with specimen size, indicating that data generated on small samples can be used to represent the energy-absorbing response of larger, more representative components.

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The crushing characteristics of reinforced Nomex honeycomb

Journal of Reinforced Plastics and Composites ◽

10.1177/0731684418793211 ◽

2018 ◽

Vol 37 (20) ◽

pp. 1267-1276 ◽

Cited By ~ 4

Author(s):

RA Alia ◽

S Rao ◽

R Umer ◽

J Zhou ◽

C Zheng ◽

...

Keyword(s):

Energy Absorption ◽

Specific Energy ◽

Compression Strength ◽

Small Diameter ◽

Areal Density ◽

Mechanical Tests ◽

Stable Model ◽

Specific Energy Absorption ◽

Nomex Honeycomb ◽

Energy Absorbing

A Nomex honeycomb core has been reinforced with small diameter composite rods and tubes in order to enhance its compression properties and energy-absorbing characteristics. The influence of the areal density of the rods and tubes on the strength and energy-absorbing properties of the reinforced honeycomb was investigated by introducing increasing numbers of rods/tubes in square samples with bonded composite skins. An initial series of crushing tests on arrangements of small tubes and rods resulted in a stable model of failure yielding specific energy absorption values of approximately 45 kJ/kg for the tube and rod-based structures. A subsequent observation of the failed tubes highlighted the similar failure processes to those observed previously following the tests on much larger composite cylinders. Mechanical tests on the Nomex cores have shown that the compression strength and energy-absorbing characteristics of the reinforced honeycombs increase rapidly with increasing composite reinforcement. At low and intermediate values of core density, the rod and tube-reinforced cores exhibited similar properties, in terms of their compression strengths and specific energy absorption, an effect that is likely to be due to the dominance of the heavier Nomex core in these samples. At higher densities, the rod-reinforced systems tended to out-perform their tube-reinforced counterparts. Tests at impact rates of strain have shown that the compression strength and energy-absorbing capabilities of the reinforced cores are higher under the dynamic conditions, with the rod-reinforced cores offering values of specific energy absorption as high as 78 kJ/kg.

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Crashworthiness performance of concentric structures with different cross-sectional shapes under multiple loading conditions

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407020961885 ◽

2020 ◽

pp. 095440702096188

Author(s):

Sadjad Pirmohammad

Keyword(s):

Energy Absorption ◽

Specific Energy ◽

Absorption Maximum ◽

Element Model ◽

Hexagonal Structure ◽

Loading Conditions ◽

Cross Sectional ◽

Specific Energy Absorption ◽

Multiple Loading ◽

Energy Absorbing

This paper evaluates the crashworthiness performance of concentric structures with different numbers of tubes (i.e. one to five) and cross-sectional shapes (i.e. hexagon, octagon, decagon and circle) under the multiple loadings of θ = 0, 10, 20 and 30°. An experimentally validated finite element model generated in LS-DYNA is employed to calculate the crashworthiness parameters including the specific energy absorption, maximum crush force and crush force efficiency. A total of 20 concentric structures are analyzed to explore the effects of number of tubes and cross-sectional shapes on the crushing performance. A multi-criteria decision-making method known as TOPSIS is also used to compare and rank the concentric structures in terms of crushing performance. Based on the results, the hexagonal structure including two tubes and octagonal, decagonal and circular structures including three tubes demonstrate the best results among their corresponding cross-sectional shapes. These structures show 9, 39, 38 and 39% higher specific energy absorption compared to their corresponding single tubal cases, respectively. However, in comparison to single tubal cases, they generate 4, 57, 57 and 58% higher maximum crush force, respectively. As such, the values for the improvement of the crush force efficiency are 3, 26, 25 and 21%, respectively. Furthermore, the decagonal structure including three tubes provides the highest energy absorbing characteristics as compared with all the other structures studied in this research. Meanwhile, taking into account all the multiple loading conditions, this structure shows 50% higher specific energy absorption than the hexagonal structure including single tube (as the weakest structure).

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Effect of the Fine Recycled Aggregates on the Dynamic Compressive Behavior of Recycled Mortar

Materials Science Forum ◽

10.4028/www.scientific.net/msf.991.62 ◽

2020 ◽

Vol 991 ◽

pp. 62-69

Author(s):

Sallehan Ismail ◽

Mohamad Asri Abd Hamid ◽

Zaiton Yaacob

Keyword(s):

Compressive Strength ◽

Strain Rate ◽

Energy Absorption ◽

Specific Energy ◽

Split Hopkinson Pressure Bar ◽

Recycled Aggregates ◽

Fine Aggregate ◽

Peak Strain ◽

Specific Energy Absorption ◽

The Impact

This study aims to investigate the dynamic behavior of recycled mortar under impact loading using a split Hopkinson pressure bar (SHPB). Several mortar mixtures were produced by adding various fine recycled aggregates (FRA) to the mixture in replacement percentages of 0%, 25%, 50%, 75%, and 100% of the natural fine aggregate (NFA). The effects of strain rate on compressive strength and specific energy absorption were obtained. Results show that the dynamic compressive strength and specific energy absorption of recycled mortar are highly strain rate dependent; specifically, they increase nearly linearly with the increase in peak strain rate. However, the compressive strength and specific energy absorption of recycled mortar are generally lower than those of NFA mortar (reference samples) under similar high strain rates. The findings of this research can help researchers and construction practitioners to ascertain the appropriate mix design procedure to optimize the impact strength properties of recycled mortar for protective structural application.

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Experimental analysis on the axial crushing and energy absorption characteristics of novel hybrid aluminium/composite-capped cylindrical tubular structures

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420719843157 ◽

2019 ◽

Vol 233 (11) ◽

pp. 2234-2252 ◽

Cited By ~ 9

Author(s):

A Praveen Kumar

Keyword(s):

Energy Absorption ◽

Specific Energy ◽

Cylindrical Tube ◽

Tubular Structures ◽

Aluminium Composite ◽

Specific Energy Absorption ◽

Cylindrical Tubes ◽

Impact Crushing ◽

Energy Absorbing ◽

The Impact

In recent years, aluminium-composite hybrid tubular structures, which combine the stable and progressive plastic deformation of the aluminium metal with light-weight composite materials, are obtaining increased consideration for meeting the advanced needs of crashworthiness characteristics. This research article presents the experimental outcomes of novel aluminium/composite-capped cylindrical tubes subjected to quasi-static and impact axial loads. The influence of various capped geometries in the aluminium segment and three different fabrics of the composite segment in the cylindrical tube are investigated experimentally. The outcomes of the impact crushing test are also correlated with the quasi-static results of the proposed aluminium/composite-capped cylindrical tubes. The overall outcomes revealed that the crashworthiness characteristics of crushing force consistency and specific energy absorption of the aluminium-composite hybrid tubes are superior to those of the bare aluminium tubes. When the glass fabric/epoxy composite is wrapped to aluminium cylindrical tubes, the specific energy absorption increases about 23–30%, and the wrapping of hybrid glass/kenaf fabrics increases the specific energy absorption of almost 40–52%. Such a hybrid tubular structures would be of huge prospective to be used as effective energy-absorbing devices in aerospace and automotive applications. A further benefit of the composite-wrapping approach is that the composite might be retro-fitted to aluminium tubes, and the energy absorption capability is shown to be significantly enhanced by such utilization.

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Energy-Absorbing Characteristics of the Stiffened Thin-Walled Tubes Subjected to Axial Crushing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.437.158 ◽

2013 ◽

Vol 437 ◽

pp. 158-163

Author(s):

Wei Liang Dai ◽

Xu Guang Li ◽

Qing Chun Wang

Keyword(s):

Energy Absorption ◽

Specific Energy ◽

Absorption Capacity ◽

Test Results ◽

Energy Absorption Capacity ◽

Specific Energy Absorption ◽

Axial Crushing ◽

The Mean ◽

Thin Walled ◽

Energy Absorbing

Energy absorbing characteristics of the non-stiffened and stiffened single hat sections subjected to quasi-static axial crushing were experimentally investigated. First non-stiffened hat sections were axially crushed, then structures with different stiffened methods (stiffened in hat and stiffened in the plate) were tested, finally energy absorption capacities of these structures were compared. Test results showed that, for the appropriate designed stiffened tube, the mean crush force and mass specific energy absorption were increased significantly compared to the non-stiffened. Stiffened in hat section showed a little more energy absorption capacity than that stiffened in the plate, but the structure may sustain a global bending.

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Efficient crushable corrugated conical tubes for energy absorption considering axial and oblique loading

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406218806006 ◽

2018 ◽

Vol 233 (11) ◽

pp. 3917-3935 ◽

Cited By ~ 6

Author(s):

Alireza Ahmadi ◽

Masoud Asgari

Keyword(s):

Finite Element ◽

Energy Absorption ◽

Specific Energy ◽

Axial Loading ◽

Element Model ◽

Compression Tests ◽

Static Compression ◽

Specific Energy Absorption ◽

Thin Walled Structures ◽

Absorption Characteristics

Thin-walled structures are of much interest as energy absorption devices for their great crashworthiness and also low weight. Conical tubes are favorable structures because unlike most other geometries, they are also useful in oblique impacts. This paper investigated the effect of corrugations on energy absorption characteristics of conical tubes under quasi-static axial and oblique loadings. To do so, conical tubes with different corrugation geometries were analyzed using the finite element explicit code and the effects of corrugations on initial peak crushing force and specific energy absorption were studied. The finite element model was validated by experimental quasi-static compression tests on simple and corrugated aluminum cylinders. An efficient analytical solution for EA during axial loading was also derived and compared with the FEM solution. The crushing stableness was analyzed using the undulation of the load-carrying capacity parameter and it was shown that corrugations made collapsing mode, more predictable and controllable. The findings have shown that corrugated conical tubes have much better energy absorption characteristics compared with their non-corrugated counterparts. It was also discovered that during oblique loadings, introducing corrugations can significantly increase the specific energy absorption compared with simple cones.

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Comparative Research on the Crushing Behaviour of Aluminium Sheet Wrapped Square Carbon Fibre Reinforced Plastic (CFRP) Tubes

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.725.82 ◽

2016 ◽

Vol 725 ◽

pp. 82-87 ◽

Cited By ~ 6

Author(s):

Rafea Dakhil Hussein ◽

Dong Ruan ◽

Guo Xing Lu

Keyword(s):

Carbon Fibre ◽

Energy Absorption ◽

Specific Energy ◽

Deformation Mode ◽

Specific Energy Absorption ◽

Aluminium Sheet ◽

Reinforced Plastic ◽

Crushing Force ◽

Carbon Fibre Reinforced Plastic ◽

Cfrp Tubes

In this study, hollow square carbon fibre reinforced plastic (CFRP) tubes and aluminium sheet wrapped CFRP tubes have been axially crushed at a quasi-static loading velocity of 0.05 mm/s. A specially designed and manufactured platen with four cutting blades was used to cut and crush these two tubular structures. The four cutting blades had height of 5 mm and width of 3 mm with round tip to reduce the initial peak force and achieve a stable crushing deformation mode. Notches at one end of each tube were utilized to control the location of initial failure. The crashworthiness characteristics of hollow CFRP tubes and aluminium sheet wrapped CFRP tubes with notches that crushed by the platen with cutting blades were compared with those of tubes that crushed by a flat platen. Experimental results showed that using the platen with blades to crush the specimens with notches exhibited more stable deformation mode than the specimens without notches. Mean crushing force, energy absorption and specific energy absorption (SEA) increased when CFRP was wrapped with aluminium sheet and crushed by the platen with blades. The increase of average value of mean crushing force, energy absorption and specific energy absorption of aluminium sheet wrapped CFRP tube and crushed by the platen with blades are 16.5%, 17.3% and 5% respectively more than those for hollow tubes that crushed by a flat platen.

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Energy absorption characteristics of thin-walled steel tube filled with paper scraps

BioResources ◽

10.15376/biores.16.3.5985-6002 ◽

2021 ◽

Vol 16 (3) ◽

pp. 5985-6002

Author(s):

Peng Cheng ◽

Qingchun Wang ◽

Shi Ke

Keyword(s):

Finite Element ◽

Energy Absorption ◽

Specific Energy ◽

Steel Tube ◽

Specific Energy Absorption ◽

Crushing Force ◽

Thin Walled Tube ◽

The Mean ◽

Thin Walled ◽

Absorption Characteristics

The specific energy absorption of a thin-walled tube can be improved by filler. This study examined the potential use of a cheaper biomass filler, paper scraps, to enhance the energy absorption characteristics of the structure while reducing its cost, compared to that with a traditional filler such as foam material. Quasi-static crushing tests and finite element simulations were performed by using the explicit non-linear finite element software LS-DYNA to determine the improvements to the mean crushing force and specific energy absorption of the steel tube when filled with different densities of paper scraps. The mean crushing force and specific energy absorption of the empty tube, the paper scraps, and thin-walled tube filled with paper scraps were determined, and corresponding numerical simulations were performed. The simulation and test results showed that the impact performance of tube filled with paper scraps was greatly improved when paper scraps density was 0.35 g/cm3. By optimizing paper scraps filling structure, a new structure that could further enhance the specific energy absorption was obtained. The optimal scheme could increase the specific energy absorption of Q345 steel tube by 11.35%.

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