Effect of resin crosslink density on the impact damage resistance of laminated composites

1997 ◽  
Vol 18 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Alan J. Lesser
Keyword(s):  
Crosslink Density ◽  
Impact Damage ◽  
Laminated Composites ◽  
Damage Resistance ◽  
The Impact

Impact Damage Resistance, Response, and Mechanisms of Laminated Composites Reinforced by Through-Thickness Stitching

2011 ◽  
Vol 21 (1) ◽  
pp. 51-80 ◽  
Author(s):  
K. T. Tan ◽  
N. Watanabe ◽  
Y. Iwahori
Keyword(s):  
Crack Propagation ◽  
Impact Damage ◽  
Laminated Composites ◽  
Low Velocity Impact ◽  
Response Curves ◽  
Damage Resistance ◽  
Delamination Growth ◽  
Matrix Cracks ◽  
Stitch Density ◽  
The Impact

In this article, the study of impact damage of laminated composites reinforced by through-thickness stitching is investigated and presented in threefold. Specimens stitched with varying stitch density and stitch thread thickness are subjected to low-velocity impact via a drop-weight machine. Impact damage resistance is first studied by examining the extent of delamination area in damaged specimens using ultrasonic C-scan analysis. It is revealed that higher stitch density is more capable of impeding delamination growth by arresting cracks at closer interval and suppressing crack propagation. The use of thicker stitch thread offers slight improvement to damage resistance by marginal reduction in delamination propagation, and is more pertinent at high impact energy levels. Impact damage response is then analyzed from the impact history response curves of impacted laminates. The impact response of load–time graphs demonstrates that the onset of delamination is not influenced by stitch density and stitch thread thickness, but the maximum residual impact force is related to the delamination size of the laminates, which is sequentially related to stitch parameters. Finally, impact damage mechanisms are elucidated by employing X-ray radiography and micro-Computed Tomography to reveal subsurface damages, primarily dominated by intralaminar matrix cracks, interlaminar delamination, and stitch fiber/matrix debonding. It is revealed that stitches act as crack initiation sites, due to the presence of weak resin-rich pockets around stitch threads, thus inadvertently resulting in densely stitched composites having more stitch-induced matrix cracks upon impact loading. Contrarily, specimens with higher stitch density and thread thickness are more capable of impeding delamination growth by effectively bridging delamination cracks and arresting crack propagation. Principal mechanisms responsible for impact resistance performance of stitching namely crack arresting and crack bridging are presented and discussed.

Simulation of Impact Damage in Foam-Based Sandwich Composites

2013 ◽  
Vol 569-570 ◽  
pp. 25-32
Author(s):  
Dian Shi Feng ◽  
Francesco Aymerich
Keyword(s):  
Impact Damage ◽  
Element Model ◽  
Fracture Mechanisms ◽  
Sandwich Composites ◽  
Typically Developing ◽  
Damage Resistance ◽  
Damage And Fracture ◽  
Closed Cell ◽  
Impact Energies ◽  
The Impact

The paper describes the application of a 3D finite element model for prediction of impact induced damage in sandwich composites consisting of laminated skins bonded to a closed cell foam core. The major damage and fracture mechanisms typically developing in transversally loaded sandwich composites were simulated in the model. The model was implemented in the FE package ABAQUS/Explicit and used to predict the impact damage resistance of sandwich panels with different core densities, core thicknesses, and skins layups. Numerical results obtained by FE simulations were compared with experimental data and observations collected through impact tests carried out at various impact energies.

Damage Development in CFRP Laminates under Impact Loading

2006 ◽  
Vol 326-328 ◽  
pp. 1833-1836 ◽  
Author(s):  
Seung Min Jang ◽  
Tadaharu Adachi ◽  
Akihiko Yamaji
Keyword(s):  
Impact Damage ◽  
Stacking Sequence ◽  
Absorbed Energy ◽  
Damage Development ◽  
Damage Resistance ◽  
Cfrp Laminates ◽  
Impact Tester ◽  
Weight Impact ◽  
The Impact ◽  
Delamination Area

The development characteristics of impact-induced damage in carbon-fiber-reinforcedplastics (CFRP) laminates were experimentally studied using a drop-weight impact tester. Five types of CFRP laminates were used to investigate the effect of stacking sequences and thicknesses. The efficiency of absorbed energy to impact energy was different for CFRP laminates with different stacking sequences or thicknesses. The DA/AE ratio of delamination area (DA) to absorbed energy (AE) was almost the same for CFRP laminates with the same stacking sequence regardless of the thickness. We found that the DA/AE ratio could be used as a parameter to characterize the impact damage resistance in CFRP laminates with different stacking sequences.

scholarly journals Effect of Temperature and Water Absorption on Low-Velocity Impact Damage of Composites with Multi-Layer Structured Flax Fiber

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 453 ◽  
Author(s):  
Yiou Shen ◽  
Junjie Zhong ◽  
Shenming Cai ◽  
Hao Ma ◽  
Zehua Qu ◽  
...  
Keyword(s):  
Water Absorption ◽  
Structural Damage ◽  
Impact Damage ◽  
Damage Threshold ◽  
Flax Fiber ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Damage Resistance ◽  
The Impact

Temperature and moisture can cause degradation to the impact properties of plant fiber-based composites owing to their complex chemical composition and multi-layer microstructure. This study focused on experimental characterization of the effect of important influencing factors, including manufacturing process temperature, exposure temperature, and water absorption, on the impact damage threshold and damage mechanisms of flax fiber reinforced composites. Firstly, serious reduction on the impact damage threshold and damage resistance was observed, this indicated excessive temperature can cause chemical decomposition and structural damage to flax fiber. It was also shown that a moderate high temperature resulted in lower impact damage threshold. Moreover, a small amount of water absorption could slightly improve the damage threshold load and the damage resistance. However, more water uptake caused severe degradation on the composite interface and structural damage of flax fiber, which reduced the impact performance of flax fiber reinforced composites.

scholarly journals Palliatives for Low Velocity Impact Damage in Composite Laminates

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Mubarak Ali ◽  
S. C. Joshi ◽  
Mohamed Thariq Hameed Sultan
Keyword(s):  
Composite Laminates ◽  
Impact Damage ◽  
Laminated Composites ◽  
Low Velocity Impact ◽  
Normal Operation ◽  
Fibre Reinforcement ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Initiation ◽  
The Impact

Fibre reinforced polymer laminated composites are susceptible to impact damage during manufacture, normal operation, maintenance, and/or other stages of their life cycle. Initiation and growth of such damage lead to dramatic loss in the structural integrity and strength of laminates. This damage is generally difficult to detect and repair. This makes it important to find a preventive solution. There has been abundance of research dealing with the impact damage evolution of composite laminates and methods to mitigate and alleviate the damage initiation and growth. This article presents a comprehensive review of different strategies dealing with development of new composite materials investigated by several research groups that can be used to mitigate the low velocity impact damage in laminated composites. Hybrid composites, composites with tough thermoplastic resins, modified matrices, surface modification of fibres, translaminar reinforcements, and interlaminar modifications such as interleaving, short fibre reinforcement, and particle based interlayer are discussed in this article. A critical evaluation of various techniques capable of enhancing impact performance of laminated composites and future directions in this research field are presented in this article.

Impact Damage Behavior of Glass/Epoxy Laminates for Railway Vehicle at Low Temperature

2006 ◽  
Vol 326-328 ◽  
pp. 1793-1796
Author(s):  
Ki Weon Kang ◽  
Seung Yong Yang ◽  
J.H. Kim ◽  
Jung Kyu Kim ◽  
Heung Seob Kim ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Impact Damage ◽  
Testing Machine ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Railway Vehicle ◽  
Low Velocity ◽  
Damage Resistance ◽  
Damage Behavior ◽  
The Impact

This paper deals with the damage behavior of glass/epoxy composite laminates subjected to low-velocity impact at various temperatures. For this goal, the impact tests were performed by using an instrumented impact-testing machine at three temperatures: +20°C, -10°C and -40°C. And the resultant damages were inspected through the scanning acoustic microscope (SAM). Also, based on the impact force history and the damage configuration of the laminates, the impact resistance parameters were employed to evaluate damage resistance of glass/epoxy laminates. As results, it was found that the temperature changes affect the damage resistance capacity of glass/epoxy laminates.

Evaluation of Impact Damage Resistance in Laminated Composites Using Resins with Different Crosslink Densities

1996 ◽  
Vol 434 ◽  
Author(s):  
A. J. Lesser
Keyword(s):  
Fracture Toughness ◽  
Molecular Weight ◽  
Composite Laminates ◽  
Impact Damage ◽  
Laminated Composites ◽  
Resin Matrix ◽  
Low Velocity ◽  
Compression After Impact ◽  
Overall Resistance ◽  
The Impact

AbstractIt is generally recognized that fiber-reinforced laminated composites are susceptible to damage resulting from low-velocity impacts. Over recent years, many strategies have been devised to increase the fracture toughness of resin matrix materials with the aim of improving the composites overall resistance to impact damage. One popular strategy for enhancing the fracture toughness of thermosets involves increasing its molecular weight between crosslinks which, in turn, enhances the resins ductility. In this paper, we investigate the efficiency of this toughening approach with regard to resisting damage in composite laminates subjected to lowvelocity impacts. Generic damage characteristics and mechanisms are reviewed and it is shown that two different events occur during the impact process. First, the laminate experiences a local failure which resembles a Hertzian fracture process followed by subsequent delamination between the plies. Results are presented illustrating the effects that systematically increasing the molecular weight between crosslinks of the resin has on each of these mechanisms. Also, the residual compressive strength (Compression After Impact) of the laminates made with these resins is presented.

Study on the Low-Velocity Impact Behavior of CFRP with Nanoclay-Filled Epoxy Matrix

2008 ◽  
Vol 47-50 ◽  
pp. 1205-1208 ◽  
Author(s):  
Iqbal Kosar ◽  
Khan Shafi Ullah ◽  
Jang Kyo Kim ◽  
Arshad Munir
Keyword(s):  
Impact Damage ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Damage Resistance ◽  
Velocity Impact ◽  
Compression After Impact ◽  
The Impact ◽  
Carbon Fiber Epoxy ◽  
Insight Into

The influence of nanoclay on the impact damage resistance of carbon fiber-epoxy (CFRP) composites has been investigated using the low-velocity impact and compression after impact tests. The load-energy vs time relations were analyzed to gain insight into the damage behaviors of the materials. Compression-after-impact (CAI) test was performed to measure the residual compressive strength. The CFRPs containing organoclay brought about a significant improvement in impact damage resistance and damage tolerance. The composites containing organoclay exhibited an enhanced energy absorption capability with less damage areas and higher CAI strengths compared to those made from neat epoxy. A 3wt% phr was shown to be an optimal content with the highest damage resistance.

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