The effect of microfibrils cellulose modified epoxy on the quasi-static and fatigue behaviour of open hole carbon textile composites

2018 ◽  
Vol 52 (24) ◽  
pp. 3365-3380 ◽  
Author(s):  
Valter Carvelli ◽  
Toru Fujii ◽  
Kazuya Okubo
Keyword(s):  
Mechanical Performance ◽  
Fatigue Behaviour ◽  
Textile Composites ◽  
Image Correlation ◽  
Cellulose Microfibrils ◽  
Micro Computed Tomography ◽  
The Matrix ◽  
Open Hole ◽  
Static Tensile ◽  
Modified Epoxy

The extensive experimental investigation aimed to assess the effects of hybrid epoxy resin with micro-fibrillated cellulose on tensile quasi-static and fatigue behaviour of open hole carbon plain weave composites. The hybridization of the matrix allowed an improved damage tolerance of the composite leading to increase of the quasi-static tensile strength and extension of the fatigue life. The enhanced mechanical performance of the notched composites was connected to the bridging effect of cellulose microfibrils preventing or delaying the cracks propagation in the matrix and along the fibres interface. The better distribution of the stress state was assessed by digital image correlation strain maps around the hole and the imparted fatigue damage was analysed by scanning electron microscope and X-ray micro-computed tomography visualizations.

scholarly journals Effects of Knit Stretching and Matrix Crystallinity on the Fatigue Behaviour of Knitted Fabric-Reinforced Gf/Pet Composites

1997 ◽  
Vol 6 (3) ◽  
pp. 096369359700600 ◽  
Author(s):  
E. Moos ◽  
J. Karger-Kocsis
Keyword(s):  
Endurance Limit ◽  
Damage Zone ◽  
Stress Transfer ◽  
Fatigue Behaviour ◽  
Knitted Fabric ◽  
The Matrix ◽  
Static Tensile ◽  
Matrix Morphology ◽  
Number Of Cycles ◽  
Fatigue Endurance

In this study the tension-tension fatigue behaviour of weft-knitted glass fibre fabric-reinforced polyethylene terephthalate (GF/PET) composites was studied as a function of the stretching ratio of the knit The knits were stretched prior to consolidation in wale direction in 0, 25, 50 and 73%, respectively, in order to increase the anisotropy and to alter the mechanical properties of the composites. The influence of the matrix morphology (crystalline, amorphous) on the fatigue response was also investigated by using a composite with unstretched knit reinforcement. The results, displayed in normalized maximum fatigue stress Ms number of cycles (S-N) diagrams showed that the fatigue endurance limit of the GF/PET composites did not depend either on the knit stretching or the matrix crystallinity. The fatigue endurance limit, normalized to the static tensile strength, was found at ≍27 and ≍50 % for the knitted fabric-reinforced composite sheets tested in wale (W) and course (C) direction, respectively. The damage zone seemed to be localized for 1 and 2 rows of loops in C-and W-directions, respectively. This failure mode reflects the stress transfer and redistribution capability of the plain weft-knit reinforcement

scholarly journals An Experimental and Numerical Investigation to Characterize an Aerospace Composite Material with Open-Hole Using Non-Destructive Techniques

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4148 ◽  
Author(s):  
Norberto Feito ◽  
José Vicente Calvo ◽  
Ricardo Belda ◽  
Eugenio Giner
Keyword(s):  
Strain Distribution ◽  
Stress Concentrator ◽  
Image Correlation ◽  
Fiber Waviness ◽  
Static Tests ◽  
Manufacturing Defects ◽  
Open Hole ◽  
Static Tensile ◽  
Non Destructive ◽  
Non Destructive Techniques

In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze the behavior of this material. We aim at characterizing the influence of the manufacturing defects and the stress concentrator through the temperature variation and strain distribution during fatigue and quasi-static tests. On the one hand, the fatigue specimens were tested in two main perpendicular directions of the laminate. The results revealed that manufacturing defects such as fiber waviness can have a major impact than open-hole stress concentrator on raising the material temperature and causing fracture. In addition, the number of plies with fibers oriented in the load direction can drastically reduce the temperature increment in the laminate. On the other hand, the quasi-static tensile tests showed that the strain distribution around the hole is able to predict the crack initiation and progression in the external plies. Finally, the experimental quasi-static tests were numerically simulated using the finite element method showing good agreement between the numerical and experimental results.

scholarly journals Mechanical Performance and Environmental Assessment of Sustainable Concrete Reinforced with Recycled End-of-Life Tyre Fibres

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 256
Author(s):  
Magdalena Pawelska-Mazur ◽  
Maria Kaszynska
Keyword(s):  
Tensile Strength ◽  
Mechanical Performance ◽  
Image Correlation ◽  
The Novel ◽  
Micro Computed Tomography ◽  
Fibre Concrete ◽  
Wedge Splitting Test ◽  
Splitting Test ◽  
Wide Range ◽  
Physical Features

The presented research’s main objective was to develop the solution to the global problem of using steel waste obtained during rubber recovery during the tire recycling. A detailed comparative analysis of mechanical and physical features of the concrete composite with the addition of recycled steel fibres (RSF) in relation to the steel fibre concrete commonly used for industrial floors was conducted. A study was carried out using micro-computed tomography and the scanning electron microscope to determine the fibres’ characteristics, incl. the EDS spectrum. In order to designate the full performance of the physical and mechanical features of the novel composite, a wide range of tests was performed with particular emphasis on the determination of the tensile strength of the composite. This parameter appointed by tensile strength testing for splitting, residual tensile strength test (3-point test), and a wedge splitting test (WST), demonstrated the increase of tensile strength (vs unmodified concrete) by 43%, 30%, and 70% relevantly to the method. The indication of the reinforced composite’s fracture characteristics using the digital image correlation (DIC) method allowed to illustrate the map of deformation of the samples during WST. The novel composite was tested in reference to the circular economy concept and showed 31.3% lower energy consumption and 30.8% lower CO2 emissions than a commonly used fibre concrete.

scholarly journals Strengthening of Wood-like Materials via Densification and Nanoparticle Intercalation

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 478 ◽  
Author(s):  
David Novel ◽  
Simone Ghio ◽  
Andrea Gaiardo ◽  
Antonino Picciotto ◽  
Vincenzo Guidi ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Structural Modification ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Stress Transfer ◽  
Giant Reed ◽  
Cellulose Microfibrils ◽  
Viable Solution ◽  
The Matrix ◽  
Physical Treatments

Recently, several chemical and physical treatments were developed to improve different properties of wood. Such treatments are applicable to many types of cellulose-based materials. Densification leads the group in terms of mechanical results and comprises a chemical treatment followed by a thermo-compression stage. First, chemicals selectively etch the matrix of lignin and hemicellulose. Then, thermo-compression increases the packing density of cellulose microfibrils boosting mechanical performance. In this paper, in comparison with the state-of-the-art for wood treatments we introduce an additional nano-reinforcemeent on densified giant reed to further improve the mechanical performance. The modified nanocomposite materials are stiffer, stronger, tougher and show higher fire resistance. After the addition of nanoparticles, no relevant structural modification is induced as they are located in the gaps between cellulose microfibrils. Their peculiar positioning could increase the interfacial adhesion energy and improve the stress transfer between cellulose microfibrils. The presented process stands as a viable solution to introduce nanoparticles as new functionalities into cellulose-based natural materials.

Damage development in woven carbon fibre thermoplastic laminates with PPS and PEEK matrices: A comparative study

2016 ◽  
Vol 51 (5) ◽  
pp. 637-647 ◽  
Author(s):  
Sergey G Ivanov ◽  
Dries Beyens ◽  
Larissa Gorbatikh ◽  
Stepan V Lomov
Keyword(s):  
Fracture Toughness ◽  
Carbon Fibre ◽  
Mechanical Performance ◽  
Textile Composites ◽  
Interlaminar Fracture Toughness ◽  
Carbon Fabric ◽  
Interlaminar Fracture ◽  
Peek Composite ◽  
The Matrix ◽  
Carbon Fibre Composites

In this work, we investigate the effect of the matrix on the mechanical performance of woven carbon fibre composites. More specifically, composites with the same 5-harness satin carbon fabric reinforcement and different thermoplastic matrices, PPS and PEEK, are compared in various mechanical tests (tensile, interlaminar fracture toughness and compression-after-impact tests). The results of tension tests show the influence of the matrix type on the development of cracks in yarns. The cracks in carbon fabric/PEEK composite appear later than in carbon fabric/PPS composite. Their density is also lower. A correlation between cumulative acoustic emission energy and transverse crack appearance in tensile tests is shown. The most evident difference is demonstrated for the Double Cantilever Beam tests and End Notch Flexure tests. The interlaminar fracture toughness for both mode I and mode II is more than 1.5 times higher for carbon fabric/PEEK laminates as compared to carbon fabric/PPS ones. The higher fracture toughness of carbon fabric/PEEK results in its higher residual compressive strength after impact (∼25%). Thus, the study concludes that the performance of textile composites is highly sensitive to the performance of the matrix. Matrices that have higher strength, ductility and fracture toughness lead to structural composites with lower crack densities, better performance in the bias direction, higher resistance to delaminations and higher residual strength after impact.

scholarly journals Performance of Friction Stir Welded Tailor Welded Blanks in AA5059 and AA6082 Alloys for Marine Applications

2016 ◽  
Vol 710 ◽  
pp. 91-96
Author(s):  
Eduardo E. Feistauer ◽  
Luciano Bergmann ◽  
Jorge Fernandez Dos Santos
Keyword(s):  
Rotational Speed ◽  
Mechanical Performance ◽  
Local Strain ◽  
Tensile Tests ◽  
Image Correlation ◽  
Friction Stir ◽  
Tailor Welded Blanks ◽  
Weld Properties ◽  
Static Tensile ◽  
Marine Applications

Tailor welded blank (TWB) concepts in aluminum alloys, welded by friction stir welding (FSW), are an attractive solution to reduce structural weight of structures applied on the transportation sector. In the present work the mechanical performance and microstructural features of dissimilar friction stir welded TWBs were assessed. Welds were produced with alloys of particular interest to the shipbuilding sector (AA6082 and AA5083, with a thickness combination of 6 and 8 mm respectively) and the effect of rotational speed on the weld properties was investigated. A digital image correlation system (DIC) was used to characterize the local strain fields during the quasi-static tensile tests. Microstructure analysis revealed the presence of a remnant oxide line (ROL) at the stir zone. Moreover, the rotational speed directly affected the ROL distribution and consequently the mechanical properties of the welds. The TWB produced with low rotation speed and high force (600 rpm and 20kN) has shown the highest mechanical performance and failed at the thermo-mechanical affected zone of the AA6082 plate. The micromechanisms of fracture were assessed by SEM and revealed a ductile fracture with large amounts of dimples spread out on the fracture surface.

scholarly journals Mechanical Response and Analysis of Cracking Process in Hybrid TRM Composites with Flax Textile and Curauá Fibres

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 715 ◽  
Author(s):  
Giuseppe Ferrara ◽  
Marco Pepe ◽  
Romildo Dias Toledo Filho ◽  
Enzo Martinelli
Keyword(s):  
Mechanical Response ◽  
Mechanical Performance ◽  
Crack Pattern ◽  
Image Correlation ◽  
Dissipated Energy ◽  
Sustainable Improvement ◽  
The Matrix ◽  
Linear Behaviour ◽  
Cracking Process ◽  
Composite Response

In recent years, the use of plant fibres in Textile-Reinforced Mortar (TRM) composites emerged as a valuable solution to increase their sustainability. Several studies carried out to mechanically characterize the so-called Natural TRMs, although showing promising results, also emphasised some drawbacks due to a severe deformability of the system and to durability issues. This study aims at improving the mechanical behaviour of Natural TRMs including impregnated flax textile (Flax TRMs) by the addition of short curauá fibres within the matrix. Flax TRM specimens were tested in tension to assess the influence of the fibre-reinforced mortar on the composite response. The crack pattern developed during the test was investigated via Digital Image Correlation analysis and by means of an analytical simplified model proposed by the authors. The addition of curauá fibres resulted in a denser crack pattern and in a significant decrease of the mean crack width (around 20%). The overall tensile response of Flax TRMs including curauá fibres resulted closer to the ideal three-linear behaviour of strain-hardening TRM composites with respect to the conventional Flax TRMs by also presenting an increase of dissipated energy of around 45%. This study paves the way for further analysis aimed at enhancing the mechanical performance of Natural TRMs adopting sustainable improvement techniques.

scholarly journals Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1124
Author(s):  
Zhifang Liang ◽  
Hongwu Wu ◽  
Ruipu Liu ◽  
Caiquan Wu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Mechanical Performance ◽  
Tensile Elongation ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
The Matrix ◽  
Blending Process ◽  
Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

scholarly journals Characterization and ballistic performance of thin pre-damaged resin-starved aramid-fiber composite panels

2021 ◽  
pp. 004051752110134
Author(s):  
Cerise A Edwards ◽  
Stephen L Ogin ◽  
David A Jesson ◽  
Matthew Oldfield ◽  
Rebecca L Livesey ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Plane Deformation ◽  
Ballistic Impact ◽  
Image Correlation ◽  
Composite Panel ◽  
Composite Panels ◽  
Micro Computed Tomography ◽  
Ballistic Performance ◽  
Low Level ◽  
Out Of Plane

Military personnel use protective armor systems that are frequently exposed to low-level damage, such as non-ballistic impact, wear-and-tear from everyday use, and damage during storage of equipment. The extent to which such low-level pre-damage could affect the performance of an armor system is unknown. In this work, low-level pre-damage has been introduced into a Kevlar/phenolic resin-starved composite panel using tensile loading. The tensile stress–strain behavior of this eight-layer material has been investigated and has been found to have two distinct regions; these have been understood in terms of the microstructure and damage within the composite panels investigated using micro-computed tomography and digital image correlation. Ballistic testing carried out on pristine (control) and pre-damaged panels did not indicate any difference in the V50 ballistic performance. However, an indication of a difference in response to ballistic impact was observed; the area of maximal local out-of-plane deformation for the pre-damaged panels was found to be twice that of the control panels, and the global out-of-plane deformation across the panel was also larger.

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