پژوهشکده پژوهشکده پژوهشکده مهرستان (مطالعات حکمرانی) | سامانه جامع پژوهشی دانشگاه اصفهان

The formation of multiple delaminations is a frequently observed damage mechanism in composite materials, exerting a more pronounced influence on their strength properties compared to single delaminations. To tackle this issue, the incorporation of nanoparticles has been investigated as a means to enhance composite materials. This study aims to examine the effects of nano-additives, specifically carbon nanotubes and nanosilica, on the flexural behavior of glass/epoxy composites containing multiple embedded delaminations. The acoustic emission technique is employed to gain deeper insights into the damage mechanisms associated with flexural failure. Artificial delaminations of varying sizes, arranged in a triangular pattern, were introduced into four interlayers of a [(0/90)2]s oriented glass/epoxy composite. The findings reveal a notable reduction in flexural properties due to the presence of multiple delaminations. However, the addition of nanoparticles demonstrates a significant improvement in the flexural behavior of the multi-delaminated specimens. The most substantial enhancement is observed in the composite incorporating 0.3 wt% nanosilica + 0.5 wt% carbon nanotubes. Furthermore, genetic K-means and hierarchical clustering techniques are employed to classify different damage mechanisms based on the peak frequency and amplitude of the acoustic emission signals. The results indicate that the hierarchical clustering method outperforms the genetic K-means method in accurately clustering the acoustic emission signals. Moreover, the incorporation of nanoparticles' impact on the occurrence of distinct damage mechanisms is evaluated through the analysis of acoustic signals using Wavelet Packet Transform. By investigating the flexural behavior of nanomodified multi-delaminated composites and employing the acoustic emission technique, this study offers valuable insights into the role of nanoparticles in enhancing the mechanical properties and monitoring the damage mechanisms of composite materials. © 2024 Elsevier B.V.

Multi-scale modeling and experimental study on electrosprayed multicore microcapsule-based self-healing polymers

( Article )

Barbaz isfahani, R., Saber-samandari, S., Salehi, M.

Publication Date: 2024

Mechanics of Advanced Materials and Structures (15210596)31(12)pp. 2581-2594

Optimal flammability and thermal buckling resistance of eco-friendly abaca fiber/polypropylene/egg shell powder/halloysite nanotubes composites

( Article )

Kamarian, S., Barbaz isfahani, R., Tran, T.M.N., Song, J.

Publication Date: 2024

Advances in Nano Research (2287237X)16(2)pp. 127-140

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young’s modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness. Copyright © 2023 Techno-Press, Ltd.

Synergistic effects of egg shell powder and halloysite clay nanotubes on the thermal and mechanical properties of abacá/polypropylene composites

( Article )

Barbaz isfahani, R., Khalvandi, A., Tran, T.M.N., Kamarian, S., Saber-samandari, S., Song, J.

Publication Date: 2023

Industrial Crops and Products (09266690)205

Experimental and analytical investigation on forced and free vibration of sandwich structures with reinforced composite faces in an acidic environment

( Article . Green • Gold )

Rahmani, F., Barbaz isfahani, R., Saber-samandari, S., Salehi, M.

Publication Date: 2023

Heliyon (24058440)9(10)

Effect of corrosive environment on mechanical properties of polymer-based nanocomposite: Analytical and experimental study

( Article )

Rahmani, F., Barbaz isfahani, R., Saber-samandari, S., Salehi, M.

Publication Date: 2023

Materials Today Communications (23524928)36

Indentation, finite element modeling and artificial neural network studies on mechanical behavior of GFRP composites in an acidic environment

( Article . Gold )

Dadras, H., Teimouri, A., Barbaz isfahani, R., Saber-samandari, S.

Publication Date: 2023

Journal of Materials Research and Technology (22387854)24pp. 5042-5058

A comprehensive investigation of the low-velocity impact response of enhanced GFRP composites with single and hybrid loading of various types of nanoparticles

( Article . Gold • Green )

Barbaz isfahani, R., Dadras, H., Saber-samandari, S., Taherzadeh-fard, A., Liaghat, G.

Publication Date: 2023

Heliyon (24058440)9(5)

Synergistic effect of graphene nanosheets and copper oxide nanoparticles on mechanical and thermal properties of composites: Experimental and simulation investigations

( Article )

Safaei, M., Abedinzadeh, R., Khandan, A., Barbaz isfahani, R., Toghraie, D.

Publication Date: 2023

Materials Science and Engineering: B (09215107)289

In this study, the synergetic effects of graphene nanosheets (Gr) and copper oxide (CuO) nanoparticles and the hybrid incorporation of both nanoparticles on the mechanical and thermal properties of 8-layer glass/epoxy composites are investigated. Also, the method of hand-lay-up is used and the tensile strength, three-point bending, and low velocity impact tests are performed to study their mechanical properties. Also, the X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis are conducted to study the structure and the morphological behavior of nanoparticles. Finally, the obtained result is that by adding the combination of both nanoparticles to the polymer and fibers, the tensile properties increase about 32 %, its flexural properties increase about 30%. The SEM images show that the less diffuse the copper nanoparticles on the sample surface, the better the activity and dispersion of the graphene nanosheets. The obtained results show that the stress–strain diagram for the sample containing the simultaneous combination of copper and graphene has the lowest stress and yield stress while the pure sample with the highest load tolerance and then the sample contain copper nanoparticles. Also, the interpretation of the obtained results in comparison with the results of other researches shows that the heat transfer behavior is uniformly about 0.1 to 0.3 and the maximum heat transfer rate is 0.38. The results showed that the addition of hybrid CuO and Gr nanoparticles into composite specimens can enhanced both mechanical and thermal properties of fabricated specimens, simultaneously. The equivalent properties of the matrix and graphene nanosheet obtained from the FEM validated by experimental experiments are considered as independent parameters. This equivalent property along with the mechanical properties of the fibers is placed in a quasi-experimental Halpin-Tsai equation to obtain an estimate of the mechanical properties of the whole nanocomposite. © 2022 Elsevier B.V.