Contributions in the Study of Hybrid Layered Composites under Static and Variable Loads

The research work behind this paper focused a rather extensive assessment of hybrid composites made of pure aluminium sheets, alternating with GFRP and CFRP layers. Static, fatigue and low velocity impact tests were performed, combined with NDI on damaged samples, using Lockin thermography, on specimens obtained from the two hybrid laminates and from genuine GFRP and CFRP laminates, all having five layers. The static and fatigue tests were made on parallel specimens, un-notched and having a central 5 mm drilled hole, with various failure modes. The low velocity impact tests were followed by CAI tests, meant to evaluate residual mechanical performance and damage tolerance. Lockin thermography was used for prior assessment of damage.

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Effect of interlayer carbon fiber dispersion on the low-velocity impact performance of woven flax-carbon hybrid composites

Journal of Composite Materials ◽

10.1177/0021998318808355 ◽

2018 ◽

Vol 53 (12) ◽

pp. 1717-1734 ◽

Cited By ~ 10

Author(s):

M Ravandi ◽

U Kureemun ◽

M Banu ◽

WS Teo ◽

Liu Tong ◽

...

Keyword(s):

Damage Mechanics ◽

Mechanical Performance ◽

Hybrid Composites ◽

Weight Ratio ◽

Material Behavior ◽

Low Velocity Impact ◽

Low Velocity ◽

Fiber Dispersion ◽

Velocity Impact ◽

The Impact

This work investigates the effects of interlayer hybrid fiber dispersion on the impact response of carbon-flax epoxy hybrid laminates at low carbon volume fractions, and benchmarks the mechanical performance enhancement against the non-hybrid flax epoxy. Five hybrid laminate stacking sequences with similar carbon-to-flax weight ratio were fabricated and subjected to low-velocity impact at three different energy values, generating non-perforated and perforated damage states. A virtual drop-weight impact test that models intralaminar failure based on continuum damage mechanics approach, and delamination using cohesive elements, was also implemented to evaluate the material behavior and damage development in the composites. Simulation results were then verified against experimental data. Results suggested that positioning stiffer carbon plies at the impact face does not necessarily lead to enhancement of the hybrid's impact properties. On the contrary, flax plies at the impacted side lead to significant improvement in impact resistance compared to the non-hybrid flax composite with similar thickness. Results of finite element analysis showed that carbon plies play a significant role in the hybrid laminate's energy absorption characteristics due to lower failure strain.

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Low-Velocity Impact Behavior of Interlayer/Intralayer Hybrid Composites Based on Carbon and Glass Non-Crimp Fabric

Materials ◽

10.3390/ma11122472 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2472 ◽

Cited By ~ 9

Author(s):

Chen Zhang ◽

Yunfei Rao ◽

Zhe Li ◽

Wei Li

Keyword(s):

Hybrid Composite ◽

Composite Laminates ◽

Hybrid Composites ◽

Low Velocity Impact ◽

Hybrid Structures ◽

Impact Behavior ◽

Absorbed Energy ◽

Low Velocity ◽

Velocity Impact ◽

Impact Tests

Composites have gained wide use in structural applications; however, they are sensitive to impact damage. The use of hybrid composites is an effective way to overcome this deficiency. The effects of various hybrid structures of interlayer and intralayer warp-knitted fabrics with carbon and glass fibers on the low-velocity impact behavior of composite laminates were studied. Drop-weight impact tests were conducted on two types of interlayer, sandwich and intralayer hybrid composite laminates, which were compared with homogenous composite laminates. During low-velocity impact tests, the time histories of impact forces and absorbed energy by laminate were recorded. The failure modes were analyzed using the micro-CT (computed tomography) and C-scan techniques. The results revealed that the hybrid structure played an important role in peak force and the absorbed energy, and that the hybrid interface had an influence on damage modes, whereas the intralayer hybrid composite laminate damage was affected by the impact location. The intralayer hybrid laminate with C:G = 1:1 exhibited better impact resistance compared to the other hybrid structures.

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Study upon the Damage Tolerance of Thick Sandwich Materials

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.266.287 ◽

2017 ◽

Vol 266 ◽

pp. 287-291

Author(s):

Nicolae Constantin ◽

Marin Sandu ◽

Adriana Sandu ◽

Paulina Spânu ◽

Dorin Roşu ◽

...

Keyword(s):

Mechanical Performance ◽

Damage Tolerance ◽

Green Energy ◽

Low Velocity Impact ◽

Sandwich Composite ◽

Low Velocity ◽

Energy Unit ◽

Velocity Impact ◽

Impact Tests ◽

Post Impact

Sandwich composite materials are widely used in various applications, due to their advanced flexibility in responding to special design requirements. This paper presents the evaluation of thick sandwiches, aimed to be imbedded in platforms of a green energy unit, accommodating storage water tanks. The evaluation of the damage tolerance was made having in view previous studies on similar materials and covered assessment of results obtained during low velocity impact tests and post-impact tests, aimed to establish the residual mechanical performance. Ways to increase the damage tolerance, by diminishing the invasive effect of low velocity impact, were also explored.

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Simulations of Low-Velocity Impact on Fibre Metal Lanimate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.813.63 ◽

2015 ◽

Vol 813 ◽

pp. 63-71

Author(s):

Yun Wan ◽

Hao Jiang ◽

Zhen Qing Wang ◽

Li Min Zhou

Keyword(s):

Contact Force ◽

Failure Modes ◽

Hybrid Composites ◽

Low Velocity Impact ◽

Absorbed Energy ◽

Low Velocity ◽

Velocity Impact ◽

Mesh Density ◽

Fibre Metal ◽

Simulation Results

During the last decades the application of composite materials in various structures has become increasingly popular. Advanced hybrid composites are useful in marine and aerospace engineering. In this contribution, impact response and damage process by a drop-weight instrument on glass reinforced (GLARE) 5 fibre-metal laminates (FMLs) with different impacted energy were presented. After comparing and analyzing the histories of contact force, central displacement, absorbed energy and force-deflection for GLARE 5 (2/1) with impacted energy of 8J, 10J and 15J, respectively. The fact that aluminium layers play an important role in absorbing energy was proved. Moreover, A numerical methodology including user material subroutine VUMAT, Johnson–Cook flow stress model is employed to simulate the response of the contact force, deflection, absorbed energy and corresponding failure modes in low-velocity impact of FML. After comparing the five simulation results with different mesh density, the influence of mesh density on simulation results was investigated and presented. The optimalizing mesh size which considered both computational efficiency and accuracy was found.

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Residual bending behaviour of sandwich composites after impact

Journal of Sandwich Structures & Materials ◽

10.1177/1099636218757164 ◽

2018 ◽

Vol 22 (2) ◽

pp. 402-422 ◽

Cited By ~ 3

Author(s):

Ismet Baran ◽

Wouter Weijermars

Keyword(s):

Polyethylene Terephthalate ◽

Failure Modes ◽

Sandwich Panels ◽

Low Velocity Impact ◽

Bending Test ◽

Low Velocity ◽

Velocity Impact ◽

Three Point Bending ◽

Impact Tests ◽

Styrene Acrylonitrile

This work investigates the residual mechanical behaviour of composite sandwich panels in bending after impact loading conditions. The sandwich panels were made of an epoxy/glass face sheet with three different core materials: styrene acrylonitrile foam, polyethylene terephthalate foam and Balsa wood. A three-point bending test was performed in order to determine the reference stiffness. A low-velocity impact test and thereafter the three-point bending test were performed with the same specimens. The failure modes during bending tests were captured using a high-speed camera. It was found that multiple shear cracks with progressive failure were present in the core of styrene acrylonitrile and polyethylene terephthalate panels in bending after impact tests, whereas single shear crack with sudden failure was the case for Balsa panels. The initial bending stiffness decreased approximately 30.5, 35.2 and 55.6% for Balsa, styrene acrylonitrile and polyethylene terephthalate panels, respectively, in bending after impact tests due to the influence of the pre-damage from the low-velocity impact tests. The reduction in collapse force was also quantified for Balsa, styrene acrylonitrile and polyethylene terephthalate panels as 22.8, 4.9 and 22.1%, respectively.

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Response and failure modes of biaxial warp-knitted flexible composite subject to low-velocity impact

Journal of Industrial Textiles ◽

10.1177/15280837211015477 ◽

2021 ◽

pp. 152808372110154

Author(s):

Ziyu Zhao ◽

Tianming Liu ◽

Pibo Ma

Keyword(s):

Impact Energy ◽

Linear Density ◽

Failure Modes ◽

Impact Response ◽

Low Velocity Impact ◽

Minor Effect ◽

Low Velocity ◽

Velocity Impact ◽

Flexible Composites ◽

The Impact

In this paper, biaxial warp-knitted fabrics were produced with different high tenacity polyester linear density and inserted yarns density. The low-velocity impact property of flexible composites made of polyurethane as matrix and biaxial warp-knitted fabric as reinforcement has been investigated. The effect of impactor shape and initial impact energy on the impact response of flexible composite is tested. The results show that the initial impact energy have minor effect on the impact response of the biaxial warp-knitted flexible composites. The impact resistance of flexible composite specimen increases with the increase of high tenacity polyester linear density and inserted yarns density. The damage morphology of flexible composite materials is completely different under different impactor shapes. The findings have theoretical and practical significance for the applications of biaxial warp-knitted flexible composite.

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