scholarly journals Experimental and numerical study of the response to various impact energy levels for composite sandwich plates with different face thicknesses

2019 ◽  
Vol 21 (5) ◽  
pp. 1654-1682
Author(s):  
Moeen S Rajput ◽  
Magnus Burman ◽  
Fredrik Forsberg ◽  
Stefan Hallström
Keyword(s):  
Impact Energy ◽  
Impact Damage ◽  
Energy Levels ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Absorbed Energy ◽  
Low Velocity ◽  
Composite Sandwich ◽  
The Impact ◽  
Dent Depth

Composite sandwich structures find wide application in the aerospace sector thanks to their lightweight characteristics. However, composite structures are highly susceptible to low-velocity impact damage and therefore thorough characterization of the impact response and damage process for the used material configurations is necessary. The present study investigates the effect of face-sheet thickness on the impact response and damage mechanisms, experimentally and numerically. A uni-directional, non-crimp fabric is used as reinforcement in the face-sheets, and a closed cell Rohacell 200 Hero polymer foam is used as core material. Low-velocity impact tests are performed in a novel instrumented drop-weight rig that is able to capture the true impact response. A range of impact energies are initially utilized in order to identify when low level damage (LLD), barely visible impact damage (BVID) and visible impact damage (VID) occur. A thorough fractography investigation is performed to characterize the impact damage using both destructive and non-destructive testing. The damage from the impacts in terms of dent depth, peak contact force, deflection and absorbed energy is measured. The results show bilinear responses in dent depth vs. impact energy and absorbed energy vs. impact energy. It is found than the BVID energy works well as an indication for the onset of excessive damage. Fractography reveals that there is a failure mode shift between the LLD and the VID energy levels, and that delaminations predominantly grow along the fiber direction and rotate in a spiral pattern through the thickness, following the laminate ply orientations. Finally, a progressive damage finite element model is developed to simulate both the impact response and the delamination extent, incorporating both intra-laminar and inter-laminar damage modes. The simulation shows good agreement with the experiments.

scholarly journals Experimental Investigation of Impactor Diameter Effect on Low-Velocity Impact Response of CFRP Laminates in a Drop-Weight Impact Event

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4131 ◽  
Author(s):  
Hongyi Cao ◽  
Mengyuan Ma ◽  
Mingshun Jiang ◽  
Lin Sun ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Internal Damage ◽  
Velocity Impact ◽  
Damage Characteristics ◽  
The Impact ◽  
Dent Depth ◽  
Delamination Area

The present study delved into the effect of impactor diameter on low velocity impact response and damage characteristics of CFRP. Moreover, the phased array ultrasonic technique (PAUT) was adopted to identify the impact damages based on double-sided scanning. Low-velocity impact tests were carried out using three hemispherical impactors with different diameters. The relationship of impact response and impactor diameters was analyzed by ultrasonic C-scans and S-scans, combined with impact response parameters. Subsequently, the damage characteristics were assessed in terms of dent depth, delamination area and extension shape via the thickness, and the relationships between absorbed energy, impactor displacement, dent depth and delamination area were elucidated. As revealed from experiment results, double-sided PAUT is capable of representing the internal damage characteristics more accurately. Moreover, the impactor diameter slightly affects the impact response under small impact energy, whereas it significantly affects the impact response under large impact energy.

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

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.

Impact Damage Detection in GFRP Laminates through Ultrasonic Imaging

2012 ◽  
Vol 585 ◽  
pp. 337-341 ◽  
Author(s):  
H. Rama Murthy Naik ◽  
J. Jerald ◽  
N. Rajesh Mathivanan
Keyword(s):  
Impact Energy ◽  
Ultrasonic Testing ◽  
Energy Levels ◽  
Low Velocity Impact ◽  
Image Processing Technique ◽  
Sound Waves ◽  
Low Velocity ◽  
Immersion Method ◽  
Pulse Echo ◽  
The Impact

Composite materials are increasingly used in aerospace, naval and automotive vehicles due to their high specific strength and stiffness. In the area of Non destructive testing, ultrasonic C-scans are used frequently to detect defects in composite components caused during fabrication and damage resulting from service conditions. Ultrasonic testing uses transmission of high frequency sound waves into a material to detect imperfections or to locate changes in material properties. The most commonly used ultrasonic testing technique is pulse echo and through transmission wherein sound is introduced into a test object and reflections (echoes) are returned to a receiver from internal imperfections. Under low-velocity impact loading delaminating is observed to be a major failure mode. This report presents the use of above two techniques to detect the damage in glass fiber reinforced plastic (GFRP) laminates. Pulse echo is used to locate the exact position of damage and through transmission is used to know the magnitude of damage in composite. This paper work will be carried out on two different thicknesses and at impact energy levels varying from 7 to 53J. The ensuring delamination damage will be determined by ultrasonic C-scans using the pulse-echo immersion method for through transmission. Delamination areas were quantified accurately by processing the raw image data using a digital image processing technique. Based on the data obtained, correlation will be established between the delamination area and the impact energy.

Compressive Strength of CCF300/QY8911 Composite Laminates with LVI Damage

2012 ◽  
Vol 583 ◽  
pp. 203-206
Author(s):  
Hai Ming Hong ◽  
Ming Li ◽  
Jian Yu Zhang ◽  
Yi Ning Zhang
Keyword(s):  
Compressive Strength ◽  
Impact Energy ◽  
Composite Laminates ◽  
Inflection Point ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Damage Area ◽  
Compressive Performance ◽  
The Impact ◽  
Dent Depth

A series of low-velocity impact tests and residual compressive strength tests after impacts on CCF300/QY8911 composite materials were carried out to study the mechanism of compression failure of the laminates after low-velocity impact. The curves of impact energy verse dent depth and impact energy verse the damage area was obtained. And the residual compressive strength and stiffness after impact verse damage parameters were analyzed. The results showed that when the impact energy exceeded the inflection point, as the impact energy increased, the dent depth on the impacted surface of the laminates notably increased while the damage area of the internal layers merely increased slowly. If the impact energy was continued to increase, the expansion of the laminates' internal damage mainly consisted of fiber breaks. The main reason for the decrease in compressive performance of composite laminates was inside delamination between layers, while in the case in which impact energy exceeded the inflection point, there were no obvious changes in delamination damage area for different energy, so the residual compressive performance kept almost stable.

scholarly journals Low Velocity Impact Assessment of a Carbon Fiber Bicycle Wheel

2021 ◽  
Author(s):  
Karmanya Ratra
Keyword(s):  
Carbon Fiber ◽  
Energy Absorption ◽  
Impact Energy ◽  
Damage Evolution ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Test Protocol ◽  
Velocity Impact ◽  
The Impact

Carbon fiber bicycle wheels were tested under low velocity impact to monitor the damage evolution of the impact event. A wheel model designed by KQS Inc. (industrial partner) with eight different configurations, including spoke tension, number of spokes, and location of impact on the rim were investigated. IR thermography combined with PCA was used to monitor the damage during impact. Results showed that wheels in line with spokes had 16% higher impact energy absorption compared to those impacted in between spokes on average (58.9 J vs 70.2 J). The 20 spoked wheels had a slightly higher (6%) impact energy absorption than the 24 spoked wheels. The added stiffness due to the extra spokes reduced the impact energy absorption of rim. Wheels with higher spoke tension also had slightly improved impact energy absorption (4%). The test protocol established in this study provides a good understanding of the wheel’s impact damage evolution.

Effect of Foam Core Density and Facesheet Thickness on the Low Velocity Impact Response of Foam Core Sandwich Composites

2000 ◽  
Author(s):  
M. Motuku ◽  
R. M. Rodgers ◽  
S. Jeelani ◽  
U. K. Vaidya
Keyword(s):  
Impact Energy ◽  
Maximum Load ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Foam Core ◽  
Low Velocity ◽  
Core Density ◽  
Failure Characteristics ◽  
Velocity Impact ◽  
The Impact

Abstract The effect of foam core density and facesheet thickness on the low velocity impact response and damage evolution in homogeneous foam core sandwich composites was studied. The failure characteristics, initiation and evolution of damage as well as the effect of impact energy were investigated. A Dynatup 8210 Impact Test Machine was utilized to conduct the low-velocity impact tests. Characterization of the impact response was performed by comparing the impact load histories, impact plots and failure characteristics. Fractography analysis was conducted through the use of scanning electron microscopy (SEM) and optical microscopy. Three types of foam cores with different densities, namely Airlite B12.5, Rohacell IG-71R63 and Airex R63.5 foam cores, were used to study the effect of core density. Considering four groups of facesheets made of different layers of cross-ply carbon prepregs performed the effect of facesheet thickness. For all the facesheet thicknesses (0.011-0.894-cm thick) and impact energy (11-40 J) range considered in this study, the maximum load (Pm), deflection-at-maximum load (δm) and time-to-maximum load (tm) exhibited strong influence or dependence on the type of foam core as opposed to the facesheet thickness. The energy-to-maximum load (Em), total energy absorbed (Et) and total energy-to-impact energy (Et/Eimp) ratio became less sensitive on the foam core density (or type) with increasing facesheet thickness. A transition point from foam core to facesheet controlled impact behavior as a function of impact energy level was observed. The impact parameters varied either linearly or parabolically with impact energy depending on the impact energy level, type of foam core and facesheet thickness. Excellent repeatability of impact data was generally obtained with increase in foam core density.

scholarly journals Impactor Shape Effect on Low Velocity Impact Response of Woven Glass Epoxy Composites

2012 ◽  
Vol 21 (5) ◽  
pp. 096369351202100 ◽  
Author(s):  
Bulent Murat Icten ◽  
Binnur Gören Kıral
Keyword(s):  
Energy Levels ◽  
High Energy ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Shape Effect ◽  
Test Machine ◽  
Low Velocity ◽  
Impact Characteristics ◽  
The Impact ◽  
Maximum Contact

This study deals with the effect of impactor shape on the impact response of plain woven glass-epoxy laminates. Impact tests were performed by using Fractovis Plus test machine with seven different impactor noses grouped as hemispherical, conical and flat. Specimens were impacted at low (5 J) to high energy levels (45 J) enough to obtain perforation of the composite at the room temperature. Variation of the impact characteristics such as maximum contact load, maximum deflection, total contact time and absorbed energy versus impact energy are depicted in Figs. Results indicated that the projectile shape highly affects the impact response of composite materials.

The Low-Velocity Impact Response of Sandwich Panels

2010 ◽  
Vol 168-170 ◽  
pp. 1149-1152
Author(s):  
Xiao Xiong Zha ◽  
Hong Xin Wang
Keyword(s):  
Impact Force ◽  
Energy Levels ◽  
Impact Resistance ◽  
Sandwich Panels ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Weight Impact ◽  
The Impact

The low velocity impact response of sandwich panels at different energy levels has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Impact parameters like maximum impact force and the extent of the damage were evaluated and compared for different types of sandwich panels. Finite elements simulations have been undertaken using the LS-DYNA software; the results of FE simulations have a good agreement with the experiments. It shows that, the impact force increased with thickness of face-sheets and foam core, the extent of the damage increased with the impact energy, sandwich panels with steel face sheet has a good impact resistance in comparison with sandwich panel with aluminum face sheets.

Effect of Graphene Platelets/Fiber on Plastics Nanocomposites under Low-Velocity Impact Response

2016 ◽  
Vol 852 ◽  
pp. 23-28
Author(s):  
S. Subha ◽  
Battu Sai Krishna ◽  
Dalbir Singh ◽  
R. Gokulnath
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Laminate Plate ◽  
Absorption Capacity ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Energy Absorption Capacity ◽  
Velocity Impact ◽  
The Impact

In this study, an attempt has made to explore the low-velocity impact response of a Carbon/epoxy laminate (CFRP) and E-Glass/epoxy laminates (GFRP). The composite was reinforced with Graphene Nanoplatelets (GnPs) and impact energy absorption capacity was studied. The plain GFRP and plain CFRP were served as a baseline for comparison. These composite laminate plates were fabricated using hand layup technique. The tests were carried out on the laminate plate as per ASTM D5628 FD. Impact tests were performed using a specially designed vertical drop-weight testing machine with an impactor mass of 1.926 kg. The result shows that laminate plate reinforced with GnPs reinforcement enhances the impact energy absorption capacity of the composites almost 4.5 % in the case Carbon/epoxy laminate and 3.5 % in the case of and E-glass/epoxy laminate. The enhanced impact resistance could be attributed to increased interlaminar fracture toughness of the fibres.

Experimental Research on the Low Velocity Impact Damage of CCF300/QY8911 Composite Laminates

2012 ◽  
Vol 583 ◽  
pp. 179-182
Author(s):  
Hai Ming Hong ◽  
Ming Li ◽  
Jian Yu Zhang ◽  
Yi Ning Zhang
Keyword(s):  
Impact Energy ◽  
Composite Laminates ◽  
Low Velocity Impact ◽  
Test Machine ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Pattern ◽  
The Impact ◽  
Dent Depth ◽  
Delamination Damage

A group of low-velocity impact tests on CCF300/QY8911 composite laminates were implemented by the low-velocity drop hammer test machine. The dent depth and the internal damage pattern with corresponding impact energy were studied, the internal delamination damage state of laminates after impact were observed through thermal layer exposing tests, and the mechanism of low-velocity impact delamination damage were discussed. The results indicated that there existed a significant inflection point in the curve of impact energy verse dent depth of CCF300/QY8911 composite material, which was also the transition point of different damage patterns. When the impact energy was smaller than the inflection energy, the damage pattern consisted mainly of matrix flaws and delamination damages, but when the impact exceeded the inflection energy, delamination damage hardly expanded while the expansion of damage was mainly fiber break.

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