Light emitting composite beams during matrix cracking

2017 ◽  
Vol 51 (30) ◽  
pp. 4251-4260 ◽  
Author(s):  
Kunal Joshi ◽  
Spandan Mishra ◽  
Chris Campbell ◽  
Tarik Dickens ◽  
Arda Vanli
Keyword(s):  
Glass Fiber ◽  
Composite Structures ◽  
Vinyl Ester ◽  
Failure Modes ◽  
Acoustic Emissions ◽  
Matrix Cracking ◽  
Waveform Analysis ◽  
Future Research ◽  
Vinyl Ester Resin ◽  
Flexural Loading

Defects in fiber-reinforced composite structures tend to initiate unpredictably and unalarmed due to local stress concentrations within a composite structure; this has given rise to active monitoring techniques that can quantify the mechanical stress within composites in order to evaluate the structural health. In this paper, triboluminescent mechanisms are used for damage monitoring of composite matrix under flexural loading. Vinyl ester resin is doped with ZnS:Mn phosphors and reinforced with glass fiber whiskers, were subjected to flexural loading while observing both the triboluminescent and acoustic response using a photo multiplier tube (PMT) and micro-mic respectively. Validity of triboluminescent emissions for determining structural integrity of glass fiber / vinyl ester resin composites through individual waveform analysis was examined. Understanding the failure modes through the captured waveform and observed triboluminescent emissions shows that the matrix cracking failure mode tends to lie in the natural frequency range of 2691–2813 Hz. High correlation between the triboluminescent and acoustic signals at matrix cracking at a frequency of 2800 Hz were found. Future research will discuss the triboluminescent and acoustic emissions behavior for delamination and fiber breakage failure modes.

scholarly journals Falling Weight Impact Damage Characterisation of Flax and Flax Basalt Vinyl Ester Hybrid Composites

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 806 ◽  
Author(s):  
Hom Nath Dhakal ◽  
Elwan Le Méner ◽  
Marc Feldner ◽  
Chulin Jiang ◽  
Zhongyi Zhang
Keyword(s):  
Vinyl Ester ◽  
Failure Modes ◽  
Hybrid Composites ◽  
Impact Damage ◽  
Matrix Cracking ◽  
Damage Mechanisms ◽  
Pull Out ◽  
Weight Impact ◽  
Falling Weight ◽  
The Impact

Understanding the damage mechanisms of composite materials requires detailed mapping of the failure behaviour using reliable techniques. This research focuses on an evaluation of the low-velocity falling weight impact damage behaviour of flax-basalt/vinyl ester (VE) hybrid composites. Incident impact energies under three different energy levels (50, 60, and 70 Joules) were employed to cause complete perforation in order to characterise different impact damage parameters, such as energy absorption characteristics, and damage modes and mechanisms. In addition, the water absorption behaviour of flax and flax basalt hybrid composites and its effects on the impact damage performance were also investigated. All the samples subjected to different incident energies were characterised using non-destructive techniques, such as scanning electron microscopy (SEM) and X-ray computed micro-tomography (πCT), to assess the damage mechanisms of studied flax/VE and flax/basalt/VE hybrid composites. The experimental results showed that the basalt hybrid system had a high impact energy and peak load compared to the flax/VE composite without hybridisation, indicating that a hybrid approach is a promising strategy for enhancing the toughness properties of natural fibre composites. The πCT and SEM images revealed that the failure modes observed for flax and flax basalt hybrid composites were a combination of matrix cracking, delamination, fibre breakage, and fibre pull out.

scholarly journals An Optimization Tool for Impact Analysis of Composite Structures

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Impact Loading ◽  
Composite Structures ◽  
Impact Analysis ◽  
Failure Modes ◽  
Drop Test ◽  
Matrix Cracking ◽  
Computational Time ◽  
Failure Behavior ◽  
Test Analysis ◽  
Plane Failure

Composite materials exhibit complex failure behavior under impact loading especially such as that for composite landing gear structure. Possible failure modes in composites may include matrix cracking, fiber breakage, kinking, fiber-matrix debonding or delamination between composite plies. In order to better understand the damage mechanisms and non-linear response of composite structures under impact, complex geometries, materials, ply orientations and stacking sequence need to be considered. However, general drop test analysis for composite structures usually takes a lot of computational efforts, and it may be even more expensive for failure analysis and optimization when various structural geometries and design configurations are taken into account. This paper proposes a new methodology for evaluation and optimization of failure behavior of composite structures subjected to impact loading, whereby drop test analysis of composite structures is modeled by explicitly dynamics analysis of two-dimensional structures and implicit analysis of three-dimensional solid structures to predict delamination or out-of-plane failure. The above-mentioned modeling strategy helps speed up the optimization process and considerably save computational time and efforts. The proposed methodology together with reliable optimization algorithms and failure theory criteria are integrated and coded into a FE optimization tool by Python script. It is shown that the optimization tool effectively helps engineers and researchers perform optimization of general composite structures and fully take into account of various geometries, materials, loading configurations, composite stack-up and sequences and individual ply's orientation.

Impact performances and failure modes of glass fiber reinforced polymers in different curvatures and stacking sequences

2021 ◽  
pp. 002199832110590
Author(s):  
Cihan Kaboglu ◽  
Taha Y Eken ◽  
Yakup Yurekturk
Keyword(s):  
Glass Fiber ◽  
Failure Modes ◽  
Impact Resistance ◽  
Matrix Cracking ◽  
Fiber Reinforced ◽  
Stacking Order ◽  
Glass Fiber Reinforced ◽  
The Impact

Recently, glass fiber reinforced polymer composites have been increasingly used in applications which are exposed to impact loads due to their high strength, low weight, and corrosion resistance properties. Therefore, the effect of curvature of composite laminate on their impact resistance is important. In this study, the mechanical properties of three curvature diameters and two stacking sequences, which have not been compared before, were examined and compared. The diameter of curved composites is 760 mm, 380 mm, and 304 mm and flat designated as A, B, C, and D, respectively. The fiber stacking orders are [0/0/-45/+45/90/90]S and [90/90/-45/+45/0/0]S designated as Type 1 and Type 2, respectively. The drop-weight impact tests were performed and failure modes of composites were examined. It was observed that the impact resistance decreases with the increase of curvature, where 760 mm diameter and Type 2 composites had the highest strength in all of the composites. In addition, delamination, fiber breakage, and matrix cracking failure modes were observed in the composites after impact. The reason why the strength decreases as the curvature of the composite increases is that the curved areas create an effect that increases the external force applied. The reason why Type 2 stacking order is more durable than Type 1 stacking order is that the 90° fiber direction in the bottom layer has a damping effect on the applied force. According to the results of this study, composite materials with larger diameter and stacking order starting with 0° provides more mechanical strength. [Formula: see text]

Investigation on resin interphase produced near silane-treated glass fiber in vinyl ester resin

2000 ◽  
Vol 7 (5-6) ◽  
pp. 511-515 ◽  
Author(s):  
N. Ikuta ◽  
A. Yanagawa ◽  
Y. Suzuki ◽  
S. Ochiai
Keyword(s):  
Glass Fiber ◽  
Vinyl Ester ◽  
Vinyl Ester Resin
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