A Novel Method to Measure Dynamic Properties of Composite Materials

Kadıoğlu, Ferhat; Sekerci, Halil Ulas; Coskun, Taner

doi:10.2514/6.2018-0226

Cited by 4 publications

(6 citation statements)

References 16 publications

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“…Thus, f n is also named as “resonant frequency”. Based on the ASTM E756 standard, it is stated in the literature 31 that, by using this f n value and the geometric parameters and the boundary conditions, “dynamic modulus, E Dyn ” also named as “dynamic stiffness” of the specimens can be calculated by using the following equation: where t , l , b , ρ , and I are the thickness, length, width, density, and moment of inertia of the specimens, respectively; while λ 1 is the first eigenvalue of the clamped-free specimens taken as 1.88. 32…”

Section: Methodsmentioning

confidence: 99%

“…Thus, f n is also named as "resonant frequency". Based on the ASTM E756 standard, it is stated in the literature 31 that, by using this f n value and the geometric parameters and the boundary conditions, "dynamic modulus, E Dyn " also named as "dynamic stiffness" of the specimens can be calculated by using the following equation:…”

Section: Vibration Damping Analysismentioning

confidence: 99%

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Contribution of carbon nanotubes to vibration damping behavior of epoxy and its carbon fiber composites

Avil

Kadıoğlu

Kaynak

2020

Journal of Reinforced Plastics and Composites

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The main objective of this study was to investigate contribution of the non-functionalized multi-walled carbon nanotubes on the vibration damping behavior of first neat epoxy resin and then unidirectional and bidirectional continuous carbon fiber reinforced epoxy matrix composites. Epoxy/carbon nanotubes nanocomposites were produced by ultrasonic solution mixing method, while the continuous carbon fiber reinforced composite laminates were obtained via resin-infusion technique. Vibration analysis data of the specimens were evaluated by half-power bandwidth method; and the mechanical properties of the specimens were determined with three-point bending flexural tests, including morphological analyses under scanning electron microscopy. It was generally concluded that when even only 0.1 wt% carbon nanotubes were incorporated into neat epoxy resin, they have contributed not only to the mechanical properties (flexural strength and modulus), but also to the vibration behavior (damping ratio) of the epoxy. When 0.1 or 0.5 wt% carbon nanotubes were incorporated into continuous carbon fiber reinforced epoxy matrix composites, although they have no additional contribution to the mechanical properties, their contribution in terms of damping ratio of the composites were significant.

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Section: Methodsmentioning

confidence: 99%

Section: Vibration Damping Analysismentioning

confidence: 99%

Contribution of carbon nanotubes to vibration damping behavior of epoxy and its carbon fiber composites

Avil

Kadıoğlu

Kaynak

2020

Journal of Reinforced Plastics and Composites

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“…The storage modulus and loss factor can be used to evaluate the energy dissipation capacity of the composite materials. The storage modulus can be obtained using natural frequencies achieved from the experimental studies, and is calculated using the Euler-Bernoulli beam theory 32 as seen in Equation ( 2).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

The influences of low‐velocity impact loading on the vibration responses of the carbon/glass fiber‐reinforced epoxy composites interleaved with various non‐woven thermoplastic veils

Tarih

Coskun

Yar

et al. 2023

J of Applied Polymer Sci

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Time‐dependent variable stresses that occur in composites subjected to mechanical and dynamic loads have devastating impacts on the material properties. Since these stresses reduce the service life, it is critical to detect and enhance structural responses before and after dynamic loadings. Therefore, the present study aimed to increase the toughness and delamination resistance of the conventional fiber‐reinforced composites by means of thermoplastic veil interleaves, thereby improving the vibration responses both before and after low‐velocity impact (LVI). In this context, carbon fiber (CF) and glass fiber (GF) reinforced epoxy composites interleaved with five different thermoplastic veils as Polyamide (PA), Polyetheretherketone (PEEK), Polyetherimide (PEI), Polyimide (PI) and Poly‐Phenylene Sulphide (PPS) were manufactured, and machined in accordance with the LVI standard. Composite specimens were subjected to the LVI tests, and then vibration tests were carried out for the non‐impacted and impacted specimens to determine dynamic properties. As a result, although thermoplastic veils generally have favorable effects on damping ratios of the GF composites, it has been revealed that these veils other than PPS and PI cause deterioration in CF composites. On the other hand, since vibration reduction depends on inherent damping and structural stiffness, this study also examined the storage‐to‐loss modulus ratios which denote the loss factors. In this respect, it was discovered that, while PPS, PEEK, PA, and PI thermoplastic veils included among the GF laminates ascend the loss factors of composites, only PI and PPS thermoplastic veils were shown to be positively effective in CF laminates. Moreover, CF and GF reinforced composites interleaved with thermoplastic veils generally exhibited higher natural frequency and lower damping ratio compared to the entirely CF or GF laminated composites. These results show that composite specimens gained bending stiffness due to local deformation hardening, and improved dynamic properties thanks to thermoplastic veil interleaved was attributed to increased toughness and delamination resistance.

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“…As far as the vibration test is concerned, the specimens under the test somehow are interacted with measuring and exciting devices, and also with boundary conditions of the test set-up. Kadioglu and Coskun 21 carried out vibration tests under free-free boundary conditions by using a non-contact mechanism, with aiming to get reliable results. In the experimental set-up, specimens were stimulated by induced airflow and response was picked up with a laser Doppler vibrometer.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and dynamic responses of unidirectional/woven carbon fiber reinforced thermoset and thermoplastic composites after low velocity impact

Kayaaslan

Coskun

Şahi̇n

et al. 2022

Polymers and Polymer Composites

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It is highly important to determine how mechanical and dynamic properties of composite materials will change after impact loads considering the coupled effects of composite design parameters. For these reasons, three-point bending and vibration tests have been carried out for the carbon fiber reinforced thermoset and thermoplastic composites with various stacking sequences before and after low velocity impact, and it is expected that these results achieved from the current study will be beneficial for applications where high damping and impact resistance are demanded together. In this context, vibration tests were carried out under free-free boundary conditions, and their natural frequencies, flexural moduli and structural damping were obtained. Furthermore, three-point tests were conducted in the elastic region with 1 mm/min crosshead speed using a universal test machine, and thus flexural moduli of the composite specimens were obtained. The results were validated by comparing the flexural moduli obtained from the both vibration and three-point bending tests, found to be reliable and comparable. As a result of the current study, it was concluded that woven fabric reinforced composite specimens exhibited 50% higher specific damping capacity (SDC) but 70% lower flexural modulus than unidirectional specimens thanks to biaxially fiber alignment. On the other hand, specific damping capacities of the thermoset and thermoplastic composites with different stacking sequences have been examined, and it was observed that thermoset specimens exhibited unexpectedly 192% higher SDC compared to the thermoplastics. This was interpreted as even though thermoplastics are normally expected to exhibit more damping than thermosets, stacking sequence being more effective on damping responses. Apart from that, although there were slight changes in material properties due to degradation in structural integrity after 2 m/s and 3 m/s low-velocity impacts, it was not found to be significantly effective due to the limited damage areas.

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A Novel Method to Measure Dynamic Properties of Composite Materials

Cited by 4 publications

References 16 publications

Contribution of carbon nanotubes to vibration damping behavior of epoxy and its carbon fiber composites

Contribution of carbon nanotubes to vibration damping behavior of epoxy and its carbon fiber composites

The influences of low‐velocity impact loading on the vibration responses of the carbon/glass fiber‐reinforced epoxy composites interleaved with various non‐woven thermoplastic veils

Mechanical and dynamic responses of unidirectional/woven carbon fiber reinforced thermoset and thermoplastic composites after low velocity impact

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