Low-velocity impact behavior of flexible sandwich composite with polyurethane grid sealing shear thickening fluid core

2019 ◽  
Vol 22 (4) ◽  
pp. 1274-1291 ◽  
Author(s):  
Liwei Wu ◽  
Jing Wang ◽  
Qian Jiang ◽  
Zhenqian Lu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Shear Thickening ◽  
Compression Modulus ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Sandwich Composite ◽  
Control Group ◽  
Dynamic Impact ◽  
Low Velocity ◽  
Static Compression ◽  
The Impact

In this study, a new type of flexible sandwich composite with nonwoven facesheets and core reinforced by polyurethane (PU) grid sealing shear thickening fluid (STF) has been presented. With the specific design, the STF was sealed into PU grids as the core to provide shear thickening effect against impact. Rheological property of STF with different mass ratio and PU morphology after first and second foaming were evaluated and optimized for sandwich composite preparation. Both static compression and dynamic impact tests were carried out to obtain the impact dynamic response and investigate the effects of typical parameters including STF volume, core thickness and striker height on low-velocity impact behavior. The test results showed that the optimal concentration of STF was 20 wt.%, whose critical shear rate was 100s−1. The presence of STF had a positive influence on the static compression strength and dynamic impact strength. In particular, the 70% STF volume fraction contributed to the highest compression modulus. The compression modulus was 445 MPa and 466 MPa when the sample thickness was 2 cm and 3 cm, respectively. As for dynamic impact strength with corresponding STF volume fractions, it was 4535.31 mJ for 30%, 4599.72 mJ for 50%, and 4827.46 mJ for 70%, all of which were much higher than that (2348 mJ) of control group (without STF). Regardless of whether the STF volume being 30%, 50% and 70%, the impact displacement of composite was within 10 mm, showing better impact resistance than control group (13.16 mm). Besides, this composite with special PU grid sealing, STF structure demonstrated a certain strain rate effect. The higher the impact energy, the greater the energy absorption was. Specifically, impact energy absorption rate of composite with a thickness of 3 cm was as high as 52.3% under 350 mm impact height.

Low Velocity and Compression-After-Impact Response of Pin-Reinforced Sandwich Composites

1999 ◽  
Author(s):  
Uday K. Vaidya ◽  
Mohan V. Kamath ◽  
Mahesh V. Hosur ◽  
Anwarul Haque ◽  
Shaik Jeelani
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Static Compression ◽  
Velocity Impact ◽  
Transverse Stiffness ◽  
Impact Studies ◽  
Compression After Impact ◽  
The Impact

Abstract In the current work, sandwich composite structures with innovative constructions referred to as Z-pins, or truss core pins are investigated, in conjunction with traditional honeycomb and foam core sandwich constructions, such that they exhibit enhanced transverse stiffness, high damage resistance and furthermore, damage tolerance to impact. While the investigations pertaining to low velocity impact have appeared recently in Vaidya et al. 1999, the current paper deals with compression-after-impact studies conducted to evaluate the residual properties of sandwich composites “with” and “without” reinforced foam cores. The resulting sandwich composites have been investigated for their low velocity (< 5 m/sec) impact loading response using instrumented impact testing at energy levels ranging from 5 J to 50 J impact energy. The transverse stiffness of the cores and their composites has also been evaluated through static compression studies. Compression-after-impact studies were then performed on the sandwich composites with traditional and pin-reinforcement cores. Supporting vibration studies have been conducted to assess the changes in stiffness of the samples as a result of the impact damage. The focus of this paper is on the compression-after-impact (CAI) response and vibration studies with accompanying discussion pertaining to the low velocity impact.

scholarly journals Experimental and numerical analysis of high and low velocity impacts against neat and shear thickening fluid (STF) impregnated weave fabrics

2018 ◽  
Vol 183 ◽  
pp. 01044
Author(s):  
Djalel Eddine Tria ◽  
Larbi Hemmouche ◽  
Abdelhadi Allal ◽  
Abdelkader Benouali
Keyword(s):  
High Velocity ◽  
Shear Thickening ◽  
Force Sensor ◽  
Low Velocity Impact ◽  
Dynamic Force ◽  
Low Velocity ◽  
Shear Thickening Fluid ◽  
Velocity Impact ◽  
Pull Out ◽  
The Impact

This investigation aims to study the efficiency of STF impregnated plain-weave fabric made of Kevlar under high and low velocity impact conditions. The shear thickening fluid (STF) was prepared by ultrasound irradiation of silica nanoparticles (diameter ≈30 nm) dispersed in liquid polyethylene glycol polymer. STF impregnation effect was determined from single yarn pull-out test and penetration at low velocity using drop weight machine equipped with hemi-spherical penetrator and dynamic force sensor. Force-displacement curves of neat and impregnated Kevlar were analysed and compared. Also, the STF impregnation effect on Kevlar multilayers was analysed from high velocity impact tests using 9mm FMJ bullet at 390 m/s. After impact, Back face deformation (BFD) of neat and impregnated Kevlar layers were measured and compared. Results showed that STF impregnated fabrics have better energy absorption and penetration resistance as compared to neat fabrics without affecting the fabric flexibility. When relative yarn translations are restricted (e.g. at very high levels of friction), windowing and yarn pull-out cannot occur, and the fibres engaged with the projectile fail in tension that leads to fabric penetration. Microscopy of these fabrics after testing have shown pitting and damage to the Kevlar filaments caused by the hard silica particles used in the STF. Mesoscopic 3D Finite Element models were developed using explicit LS-DYNA hydrocode to account for STF impregnation by employing the experimental results of yarn pull-out tests, low and high velocity impacts. It was found that friction between fibers and yarns increase the dissipation of energy upon impact by restricting fiber mobility, increasing the energy required for relative yarn translations and transferring the impact energy to a larger number of fibers.

Preparation of auxetic warp-knitted spacer fabric impregnated with shear thickening fluid for low-velocity impact resistance

2020 ◽  
pp. 152808372092701 ◽  
Author(s):  
Wanli Xu ◽  
Biao Yan ◽  
Dongmei Hu ◽  
Pibo Ma
Keyword(s):  
Shear Rate ◽  
Energy Absorption ◽  
Impact Resistance ◽  
Shear Thickening ◽  
Weight Fraction ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Shear Thickening Fluid ◽  
Spacer Fabric ◽  
The Impact

This paper reports the preparation of auxetic warp-knitted spacer fabric impregnated with shear thickening fluid and studied its impact behavior under low-velocity impact loading. The shear thickening fluids have been prepared by mechanically dispersing 12 nm silica particles with weight fraction of 10, 15, 20, and 25% in various carriers (PEG200, PEG400, and PEG600). Rheological results indicate that shear thickening fluid experiences shear thickening transition at a specific shear rate. The critical shear rate reduces, and initial viscosity and maximum viscosity increase with the increase of silica weight fraction. The higher molecular weight of polyethylene glycols can lead to lower critical shear rate. The impact process of composite under impact loading can be divided into three stages. The warp-knitted spacer fabric with different negative Poisson’s ratio has a significant effect on the impact behavior. The warp-knitted spacer fabric with better auxetic performance endows composite better impact resistance, the specific performance is the deformation depth, and energy absorption and peak load increase with the increase of auxetic effect of fabric. The silica weight fraction of shear thickening fluid can increase the energy absorption of composite due to the shear thickening transition of shear thickening fluid. Shear thickening fluid has a synergistic effect with the auxetic warp-knitted spacer fabric on impact resistance of composite. The various carriers have no obvious influence on the overall energy absorption and impact load of composites.

Dynamic Characterization of Multi-Functional Sandwich Composites

2000 ◽  
Author(s):  
Uday K. Vaidya ◽  
Scott P. Nelson ◽  
Biju Mathew ◽  
Renee M. Rodgers ◽  
Mahesh V. Hosur
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Initiation ◽  
The Impact

Abstract This paper deals with an innovative integrated hollow (space) E-glass/epoxy core sandwich composite construction that possesses several multi-functional benefits in addition to the providing light-weight and bending stiffness advantages. In comparison to traditional foam and honeycomb cores, the integrated space core provides a means to route wires/rods, embed electronic assemblies, and store fuel and fire-retardant foam, among other conceivable benefits. In the current work the low velocity impact (LVI) response of innovative integrated sandwich core composites was investigated. Three thickness of integrated and functionality-embedded E-glass/epoxy sandwich cores were considered in this study — including 6mm, 9mm and 17 mm. The low-velocity impact results indicated that the hollow and functionality embedded integrated core suffered a localized damage state limited to a system of core members in the vicinity of the impact. Stacking of the core was an effective way of improving functionality and limiting the LVI damage in the sandwich plate. The functionality-embedded cores provided enhanced LVI resistance due to energy additional energy absorption mechanisms. The high strain rate (HSR) impact behavior of these sandwich constructions is also studied using a Split Hopkinson Pressure Bar (SHPB) at strain rates ranging from 163 to 653 per second. The damage initiation, progression and failure mechanisms under low velocity and high strain rate impact are investigated through optical and scanning electron microscopy.

scholarly journals Improvement of Impact Damage Resistance of Epoxy-Matrix Composites Using Ductile Hollow Fibers

2013 ◽  
Vol 8 (1) ◽  
pp. 155892501300800
Author(s):  
Mohammad Nasr-Isfahani ◽  
Masoud Latifi ◽  
Mohammad Amani-Tehran
Keyword(s):  
Impact Damage ◽  
Fiber Composites ◽  
Filament Winding ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Experimental Investigations ◽  
Matrix Composites ◽  
Transverse Impact ◽  
Low Velocity ◽  
The Impact

Fiber reinforced polymer structures typically respond very poorly to transverse impact events. In this study, some experimental investigations are performed on the low velocity impact behavior of unidirectional hollow, solid and hybrid (hollow/solid) polyester fiber composites. The materials are fabricated in a curved shape using filament winding method. The impact tests are applied on the simply supported specimens by a drop weight impact test apparatus at five levels of energy. To present a proper comparison on the results, the various densities of the materials are considered as normalizing coefficients. It is observed that in the hollow fiber composites cracks appear at an appreciably higher amount (93%) of impact energy than the solid ones.

scholarly journals Simulation of Low Velocity Impact on Composite Hemispherical Shell

2014 ◽  
Vol 564 ◽  
pp. 406-411
Author(s):  
Parnia Zakikhani ◽  
R. Zahari ◽  
Mohamed Thariq Hameed Sultan
Keyword(s):  
Finite Element ◽  
Energy Absorption ◽  
Experimental Testing ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Element Analysis ◽  
Velocity Impact ◽  
Hemispherical Shell ◽  
The Impact

Impact simulation with finite element analysis is an appropriate manner to reduce the cost and time taken to carry out an experimental testing on a component. In this study, the impact behavior of the composite hemispherical shell induced by low velocity impact is simulated in ABAQUS software with finite element method. To predict the responses of Kevlar fabric/polyester, glass fabric/polyester and carbon fabric/polyester in the form of a hemisphere, once as one layer and then as a three-layered composite under applied force by an anvil. The sequences of layers are changed, to investigate and compare the occurred alternations in the amount of energy absorption, impact force and specific energy absorption (SEA). The comparison of results showed that the highest and the lowest quantity of energy absorption and SEA belong to Carbon/Glass/Kevlar (CGK) and Kevlar/Carbon/Glass (KCG) respectively.

Low Velocity Impact Analysis on GFRP Laminates under Different Temperatures

2011 ◽  
Vol 110-116 ◽  
pp. 632-636
Author(s):  
K. Pazhanivel ◽  
G.B. Bhaskar ◽  
S. Arunachalam ◽  
V. Hariharan ◽  
A. Elayaperumal
Keyword(s):  
Composite Materials ◽  
Impact Analysis ◽  
Failure Modes ◽  
Laminated Composites ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Aerospace Applications ◽  
Different Temperatures ◽  
The Impact

Composite materials have a number of properties that make them attractive for use in aerospace applications. The impact behavior of fiber reinforced composite materials is much more complex than conventional metallic structures due to a number of different failure modes on the inter laminar and intra laminar level. The aim of this study is to investigate the effects of temperature and thermal residual stresses on the impact behavior and damage of glass/epoxy laminated composites. To this end, thermal stress analyses of the laminates with lay-ups [90/0/0/90] s, [90/0/45/45] s, [0/90/45/-45] s, [45/0/-45/90] s are carried out under different temperatures by using ANSYS software. Also, the impact analysis on the laminated composites was performed at the different range of impact energies under different temperatures. The specific energy values and impact parameters were obtained and compared for each type of specimens and temperatures.

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