Infrared Thermographic Flaw Detection in Composite Laminates

1987 ◽  
Vol 109 (2) ◽  
pp. 146-150 ◽  
Author(s):  
P. V. McLaughlin ◽  
M. G. Mirchandani ◽  
P. V. Ciekurs
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Thermal Field ◽  
Impact Damage ◽  
Flaw Detection ◽  
Fiber Composites ◽  
Surface Cracks ◽  
Glass Fiber Composites ◽  
Detection Tool ◽  
Detection Capabilities

Research performed to develop thermography as a routine rapid flaw detection tool for large composite structures is presented. The externally applied thermal field (EATF) technique is described whereby surface cracks or sub-surface impact damage creates detectable surface temperature perturbations when heated. EATF thermographic procedures and flaw detection capabilities in multidirectional and unidirectional graphite and glass fiber composites are described. The method’s advantages and limitations are outlined.

Sensing of Damage in Glass Fiber Composites by Adding Carbon Nanotubes

2013 ◽  
Vol 330 ◽  
pp. 68-76 ◽  
Author(s):  
Li Min Gao ◽  
Xin Lin Qing
Keyword(s):  
Carbon Nanotubes ◽  
Glass Fiber ◽  
Composite Structures ◽  
Fiber Composites ◽  
Damage Initiation ◽  
Micro Scale ◽  
Glass Fiber Composites ◽  
Specific Strength ◽  
Fiber Reinforced Polymer Composites ◽  
Structural Applications

Advanced fiber-reinforced polymer composites are known to possess outstanding specific strength and stiffness and their use in structural applications continues to expand. Most structural composites are susceptible to the formation of micro-scale damage in polymer matrix under adverse conditions which has significant implications on the durability and performance of fiber composites. Thus, it is imperative to detect the initiation and evolution of damage in composites long before their catastrophic failure. In this report, our recent research in sensing of micro-crack in matrix in situ and in real time for glass fiber composites was reviewed. Carbon nanotubes were dispersed into glass fiber composites by three roll mill technique. A resistance parameter was utilized to quantitatively characterize damage initiation and propagation. Damage mechanisms and development were investigated under tension, fatigue loadings. This research demonstrates the feasibility and benefits of electrical resistance measurements in the sensing of micro-scale damage for fiber composites using carbon nanotubes and offers the potential for in-service health monitoring of composite structures.

scholarly journals Mechanical and Impact Damage Analysis on Carbon/Natural Fibers Hybrid Composites: A Review

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 517 ◽  
Author(s):  
Carlo Santulli
Keyword(s):  
Composite Laminates ◽  
Natural Fiber ◽  
Hybrid Composites ◽  
Impact Damage ◽  
Natural Fibers ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
Impact Performance ◽  
Modes Of Failure ◽  
Post Impact

Hybrid composite laminates including carbon fibers and natural fibers, hence basalt and/or vegetable ones, draw on the experiences accumulated in studying the hybridization of fiberglass with carbon or natural fibers. Yet, in the case of carbon/natural fiber composites, the sense is different: in particular, the idea is to accept the reduction of properties from bare carbon fiber composites and the unavoidable complication in processing, induced by hybridization. The compensation obtained, which offers a rationale to this operation, is the improved toughness and a significant modification of the different modes of failure. This would bring a higher energy absorption and a substantially more effective damage tolerance. The aforementioned characteristics are particularly of interest in the case of flexural properties, impact properties, and residual post-impact performance.

Environmental, mechanical and materialistic effects on delamination damage of glass fiber composites: Analysis and optimization

2019 ◽  
Vol 53 (26-27) ◽  
pp. 3671-3680 ◽  
Author(s):  
Ali Tabatabaeian ◽  
Mohammad Baraheni ◽  
Saeid Amini ◽  
Ahmad R Ghasemi
Keyword(s):  
Glass Fiber ◽  
Ultrasonic Vibration ◽  
Thermal Fatigue ◽  
Composite Structures ◽  
Fiber Composites ◽  
Machining Process ◽  
High Tech ◽  
Glass Fiber Composites ◽  
Cutting Velocity ◽  
Delamination Damage

Machining process of glass fiber composites usually induces delamination damage. The presence of delamination may cause changes in the mechanical characteristics of the composite structures. In this research, a comprehensive experimental study is performed to analyze the influence of different parameters such as thermal fatigue, lay-up arrangement, resin type, feed rate and cutting velocity on the delamination of glass fiber composites under different drilling processes. Besides, influence of ultrasonic vibration exerting on the tool as a new and high-tech process is investigated. To follow this aim, different composite specimens with various resin types and lay-up arrangements are fabricated and a thermal fatigue condition is provided. Additionally, the Taguchi method is employed to obtain the optimized damage reduction condition in terms of mentioned parameters. The results indicated that thermal fatigue and unsymmetrical lay-up arrangement result in more delamination damage. It was also established that the influence of mentioned parameters is more considerable in higher cutting velocities. Moreover, ultrasonic vibration application is suggested to have the least delamination damage.

scholarly journals Effect of polycaprolactone nanofibers on the vibratory behaviour and the damage resistance of composite laminates

2018 ◽  
Vol 211 ◽  
pp. 19003 ◽  
Author(s):  
Cristobal Garcia ◽  
Irina Trendafilova ◽  
Andrea Zucchelli
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Natural Frequencies ◽  
Impact Damage ◽  
Damping Ratio ◽  
Element Model ◽  
Nano Composites ◽  
Civil Structures ◽  
Damage Resistance ◽  
Fibre Composites

Aircrafts, bridges, wind turbines and other civil structures made of composite materials are frequently subjected to vibrations, which are responsible for a considerable number of accidents. One of the methods to reduce the vibrations is the incorporation of nanofibers in the composite structures. The main purpose of this study is to investigate the effect of the inclusion of polycaprolactone nanofibers on the vibratory behaviour of composite laminates. For this purpose, the vibratory behaviour of nano composites (with nanofibers) and standard composites (without nanofibers) is investigated with the purpose of acquiring their natural frequencies and the damping ratio. The results indicated that the inclusion of polycaprolactone nanofibers in composites increased the damping ratio, however it did not change significantly the natural frequencies. Furthermore, the paper investigates the effect of polycaprolactone nanofibers on the damage resistance of glass fibre composites. For this purpose, a finite element model is used to simulate the damage caused by mechanical impact in standard and nano composites. The numerical simulations show that the interleaving with nanofibers increased the damage resistance considerably. This study contributes to the knowledge about the vibration behaviour and the damage resistance of composites interleaved with polycaprolactone nanofibers. It is demonstrated that the interleaving with polycaprolactone fibres can play an important role for reducing the vibrations and increasing their impact damage resistance in composite structures as aircrafts.

Comparison of tensile properties and impact damage tolerance of hemp and glass fiber composites

2011 ◽  
Vol 30 (22) ◽  
pp. 1877-1893 ◽  
Author(s):  
Asim Shahzad
Keyword(s):  
Glass Fiber ◽  
Tensile Properties ◽  
Damage Tolerance ◽  
Impact Damage ◽  
Fiber Composites ◽  
Hemp Fiber ◽  
Glass Fiber Composites ◽  
Chopped Strand Mat ◽  
Strength And Stiffness ◽  
Intrinsic Strength

Tensile properties and impact damage tolerance of hemp fiber and chopped strand mat (CSM) glass fiber composites have been evaluated and compared. The absolute and specific tensile properties of CSM glass fiber composites were found to be much superior to hemp fiber composites. Impact damage tolerance of hemp fiber composites was also quite low compared to CSM glass fiber composites. They lost almost half of their intrinsic strength and stiffness following an impact of 2 J energy. Considerable evidence of matrix fracture, interfacial debonding, and fiber fracture was found in the fracture surface. Following an impact at 4 J energy, hemp fiber composites lost almost 70% of their intrinsic strength and stiffness. In comparison, CSM glass fiber composites were able to endure an impact of 20 J energy for 70% reduction in their intrinsic strength and stiffness.

Elastic Guided Waves in Bistable Composite Structures – Experimental and Numerical Investigation

2021 ◽  
Vol 01 ◽  
Author(s):  
D.M. Saad ◽  
S. Mustapha ◽  
A. Firouzian ◽  
A. Abdul Aziz
Keyword(s):  
Wave Propagation ◽  
Health Monitoring ◽  
Composite Laminates ◽  
Composite Structures ◽  
Guided Waves ◽  
Flaw Detection ◽  
Composite Plates ◽  
Stable Configuration ◽  
Propagation Behavior ◽  
Wave Modes

Background: Bistable composite laminates are emerging as smart structures in automotive and aerospace applications. However, the behavior of the wave propagation within such laminates has not been investigated, which hinders their implementation in structural health monitoring (SHM) and non-destructive evaluation (NDE). Objective: As a result, this manuscript examines the propagation behavior of guided waves in bistable composite structures. By understanding the effect of pre-stressing in bistable composite laminates on the characteristics of propagating waves, such as velocity and amplitude, a more knowledgeable decision about their applications in flaw detection and assessment can be made. Methods: The fundamental symmetric (S0) and anti-symmetric (A0) Lamb wave modes were investigated during propagation in two bistable composite laminates, [0/90]T and [02/902]T, and were assessed experimentally and numerically using ABAQUS. For the tested frequencies, which ranged from 60 kHz to 250 kHz, the behavior of the propagating wave was evaluated for both stable configurations and across two different actuators that were lined up with the fiber directions. Signal processing techniques were thus extensively used to enhance the measured signals and identify both the group velocities and the amplitudes’ trend of the S0 and A0 wave modes. Results: Our results showed that there is a minimal variation (typically below 1%) in the amplitude and velocity of the A0 and S0 modes when the composite plates switch between the first stable configuration and the second stable configuration in both composite plates. These results were numerically validated by replicating the bi-stability of the composites. The numerical data were in relatively close agreement (10% average error) with the experimental values and trends. Furthermore, the bistable effect was examined in detail relative to a reference numerical flat (monostable) plate. Although the bistable effect induced a notable amount of internal residual stress, this did not significantly impact the propagating wave modes, with a maximum difference of about 2% when comparing wave velocities. Conclusions: The effect on the wave propagation behavior along different directions of both stable configurations was shown to be minimal. These results, which were validated numerically, clear the ambiguity on the usage of these laminates in experimental health monitoring.

The Probabilistic Compliance Methodology for Damage Tolerance Design of Thicker Composite Structure

2011 ◽  
Vol 239-242 ◽  
pp. 872-875
Author(s):  
Tian Chun Zou ◽  
Peng Hao ◽  
Jia Rui Zhang ◽  
Zhen Yu Feng
Keyword(s):  
Impact Energy ◽  
Composite Structure ◽  
Composite Laminates ◽  
Composite Structures ◽  
Damage Tolerance ◽  
Impact Damage ◽  
Tolerance Design ◽  
Research Results ◽  
Certification Requirements

In this paper, the probabilistic compliance methodology for damage tolerance design of thicker composite structures were investigated, and the research results show that for the composite laminates withstanding impact energy below 90J, if it cannot produce barely visible impact damage (BVID), then using the probabilistic methodology can meet certification requirements of damage tolerance.

scholarly journals Enhancing Impact Energy Absorption, Flexural and Crash Performance Properties of Automotive Composite Laminates by Adjusting the Stacking Sequences Layup

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3404
Author(s):  
Hassan Alshahrani ◽  
Azzam Ahmed
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Failure Modes ◽  
Volume Fraction ◽  
Impact Damage ◽  
Flexural Modulus ◽  
Stacking Sequence ◽  
Performance Properties ◽  
Impact Tests ◽  
Crash Performance

In response to the high demand for light automotive, manufacturers are showing a vital interest in replacing heavy metallic components with composite materials that exhibit unparalleled strength-to-weight ratios and excellent properties. Unidirectional carbon/epoxy prepreg was suitable for automotive applications such as the front part of the vehicle (hood) due to its excellent crash performance. In this study, UD carbon/epoxy prepreg with 70% and 30% volume fraction of reinforcement and resin, respectively, was used to fabricate the composite laminates. The responses of different three stacking sequences of automotive composite laminates to low-velocity impact damage and flexural and crash performance properties were investigated. Three-point bending and drop-weight impact tests were carried out to determine the flexural modulus, strength, and impact damage behavior of selected materials. Optical microscopy analysis was used to identify the failure modes in the composites. Scanning electron microscopy (SEM) and C-scan non-destructive methods were utilized to explore the fractures in the composites after impact tests. Moreover, the performance index and absorbed energy of the tested structures were studied. The results showed that the flexural strength and modulus of automotive composite laminates strongly depended on the stacking sequence. The highest crash resistance was noticed in the laminate with a stacking sequence of [[0, 90, 45, −45]2, 0, 90]S. Therefore, the fabrication of a composite laminate structure enhanced by selected stacking sequences is an excellent way to improve the crash performance properties of automotive composite structures.

In situ sensing of impact damage in epoxy/glass fiber composites using percolating carbon nanotube networks

Carbon ◽  
2011 ◽  
Vol 49 (10) ◽  
pp. 3382-3385 ◽  
Author(s):  
Limin Gao ◽  
Tsu-Wei Chou ◽  
Erik T. Thostenson ◽  
Zuoguang Zhang ◽  
Magali Coulaud
Keyword(s):  
Carbon Nanotube ◽  
Glass Fiber ◽  
Impact Damage ◽  
Fiber Composites ◽  
Glass Fiber Composites ◽  
In Situ Sensing ◽  
Carbon Nanotube Networks
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