Effect of Multi-Impact on QIQH Carbon/Epoxy Composite Laminate

This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy traditional impact tests don’t allow to see the evolution of the damage and don’t permit also to compare the best tolerance to impact between different stratifications. The multi-impact tests made it possible to find a solution to this problem. In this work, multi-impact tests are performed on three carbon/epoxy stratifications. The final goal is to predict the durability of the composite structures during impact loading for their design. This study brings to light the response of multi-impact tests through force-time and force-displacement curves obtained experimentally. On the other hand, a parameter D has introduced following the experimental results. This made it possible to rank the three stratifications from their tolerance to multi-impact tests. To evaluate the post impact damage, ultrasonic testing techniques are used. The results allow to find the relationship between the damaged surface obtained by the ultrasonic control and the parameter D and to rank the three laminates configurations.

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Determination of impact events on a plate-like composite structure

The Aeronautical Journal ◽

10.1017/aer.2016.36 ◽

2016 ◽

Vol 120 (1228) ◽

pp. 984-1004 ◽

Cited By ~ 4

Author(s):

L. Xu ◽

Y. Wang ◽

Y. Cai ◽

Z. Wu ◽

W. Peng

Keyword(s):

Composite Structures ◽

Transfer Functions ◽

Flat Glass ◽

Time History ◽

Identification Algorithm ◽

Impact Location ◽

Force Time ◽

The Impact ◽

The Relationship ◽

Impact Events

ABSTRACTComposite materials have been increasingly used in aircraft structures. However, these composite structures are susceptible to damage from external low-velocity impacts. In this paper, an impact identification algorithm is proposed to estimate the impact location and force time history simultaneously. A localisation method based on basis vectors is proposed, and the impact force time history is reconstructed by simplified transfer functions. The basis vector stands for the relationship between the impact location and the sensor signals, and the transfer function shows the relationship of the sensor signal and the force time history. An experiment is conducted on a flat glass fibre-epoxy matrix composite plate to verify the developed algorithm using only four sensors. The soft impactor and hard impactor are two typical impactors for impact events; therefore, the impact experiment is performed by the rubber and the steel impactors, respectively. The experimental results indicate that the proposed algorithm is feasible for the identification of impact events on plate-like composite structures.

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Развитие вибротермографии как метода неразрушающего контроля изделий из полимерных конструкционных материалов с использованием принудительных механических вибраций

Дефектоскопия ◽

10.31857/s013030822106004x ◽

2021 ◽

Vol 6 ◽

pp. 35-45

Author(s):

С.В. Дубинский ◽

Е.А. Казьмин ◽

И.Е. Ковалев ◽

А.Б. Корнилов ◽

Г.А. Корнилов ◽

...

Keyword(s):

Composite Structures ◽

Impact Damage ◽

Thermal Excitation ◽

Ultrasonic Frequency ◽

Non Destructive Testing ◽

Destructive Testing ◽

Internal Damage ◽

Mechanical Oscillations ◽

Testing Techniques ◽

Non Destructive

The method of vibrothermography may be considered as one of the promising thermal non-destructive testing techniques, which can be applied for the detection of internal damage in composite structures. The thermal excitation of the structure in case of vibrothermography is caused by the mechanical oscillations on the sonic or ultrasonic frequency, and the change in temperature field of the object is controlled by thermography methods. The present paper considers the method of vibration testing and presents the results of thermography studies focused on the behavior of composite structure with impact damage subjected to vibration loading.

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

Polymers ◽

10.3390/polym13193404 ◽

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.

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Active Health Monitoring of Thick Composite Structures by Embedded and Surface-Mounted Piezo Diagnostic Layer

Sensors ◽

10.3390/s20123410 ◽

2020 ◽

Vol 20 (12) ◽

pp. 3410

Author(s):

Tianyi Feng ◽

Dimitrios Bekas ◽

M. H. Ferri Aliabadi

Keyword(s):

Composite Structures ◽

Guided Waves ◽

Impact Damage ◽

Effective Means ◽

Laser Doppler Vibrometer ◽

Mechanical Impedance ◽

Bonding Process ◽

Ultrasonic Guided Waves ◽

Impedance Technique ◽

The Relationship

An effective approach for an embedded piezo diagnostic layer into thick composite material is presented. The effectiveness of the approach is assessed in comparison to the surface-mounted layer. The proposed manufacturing alleviates difficulties associated with trimming edges of composites when embedding wires. The Electro-Mechanical Impedance technique is used to access the integrity of the piezoelectric sensors bonding process. Comparisons of ultrasonic guided waves are made between embedded and surface-mounted diagnostic layers and their penetration through and across the thickness of the composites. Temperature influences with the range from −40 °C up to 80 °C on embedded and surface-mounted guided waves are investigated. An investigation is carried out into the relationship between amplitude and time-of-flight with temperature at different excitation frequencies. The temperature has significant but different effects on amplitude and phase-shift of guided waves for the embedded layer compared to the surface-mounted layer. A Laser Doppler Vibrometer is used to identify the blue tack and impact damage. Both embedded and surface-mounted layers are shown to be an effective means of generating detectable wave scatter from damage.

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Impact response in polymer composites from embedded optical fibers

Journal of Composite Materials ◽

10.1177/0021998318763274 ◽

2018 ◽

Vol 52 (25) ◽

pp. 3415-3427 ◽

Cited By ~ 7

Author(s):

Lorianne K Batte ◽

Rani W Sullivan ◽

Vipul Ranatunga ◽

Kevin Brown

Keyword(s):

Optical Fibers ◽

Composite Laminates ◽

Composite Structures ◽

Impact Damage ◽

Energy Levels ◽

Impact Testing ◽

Low Velocity Impact ◽

Low Velocity ◽

Impact Surface ◽

Post Impact

This study investigates the feasibility of using embedded optical fibers in polymer matrix composite laminates to characterize delaminations caused by low-velocity impacts with energies between 30 J and 50 J. Impact damage can occur in composite structures during manufacture, in-service, storage and routine maintenance. Because of their small size and light weight, optical fibers can be embedded in composite structures during the manufacture of composite parts, allowing the structure to be monitored for impact-induced delaminations without being removed from service. In this study, optical fibers are embedded in a grid configuration at four selected locations (one-third from impact surface, midplane, two-thirds from impact surface, and farthest ply from impact) in thick autoclave-cured graphite/epoxy laminates. Low-velocity impact testing is performed at four energy levels. Manufacturing procedures for embedding the optical fibers within the composite laminates are investigated. The strain distribution from the optical fibers is correlated with ultrasonic C-scans of the laminates in which they are embedded. X-ray computed tomography scan images are also compared to those from ultrasonic C-scans. Results indicate that embedded optical fibers can provide post-impact strain responses and delamination area from each embedded site within the impacted laminates.

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Selection of Materials and Sensors for Health Monitoring of Composite Structures

MRS Proceedings ◽

10.1557/proc-785-d11.1 ◽

2003 ◽

Vol 785 ◽

Cited By ~ 5

Author(s):

Seth S. Kessler ◽

S. Mark Spearing

Keyword(s):

Health Monitoring ◽

Lamb Wave ◽

Composite Structures ◽

Structural Damage ◽

Performance Metrics ◽

Full Range ◽

Transportation Systems ◽

Health Monitoring Systems ◽

The Relationship ◽

Selection Of

ABSTRACTEmbedded structural health monitoring systems are envisioned to be an important component of future transportation systems. One of the key challenges in designing an SHM system is the choice of sensors, and a sensor layout, which can detect unambiguously relevant structural damage. This paper focuses on the relationship between sensors, the materials of which they are made, and their ability to detect structural damage. Sensor selection maps have been produced which plot the capabilities of the full range of available sensor types vs. the key performance metrics (power consumption, resolution, range, sensor size, coverage). This exercise resulted in the identification of piezoceramic Lamb wave transducers as the sensor of choice. Experimental results are presented for the detailed selection of piezoceramic materials to be used as Lamb wave transducers.

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