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Article
Publication date: 6 May 2020

Mayyadah S. Abed, Payman S. Ahmed, Jawad K. Oleiwi and Basim M. Fadhil

Composite laminates are considered one of the most popular damage-resistant materials when exposed to impact force in civil and military applications. In this study, a comparison…

339

Abstract

Purpose

Composite laminates are considered one of the most popular damage-resistant materials when exposed to impact force in civil and military applications. In this study, a comparison of composites 12 and 20 layers of fabrics Kevlar and ultrahigh-molecular-weight poly ethylene (UHMWPE)-reinforced epoxy under low-velocity impacts represented by drop-weight impact and Izod pendulum impact has been done. During the Izod test, Kevlar-based composite showed damage at the composite center and fiber breakages. Whereas delamination was observed for UHMWPE reinforced epoxy (PE). The maximum impact strength was for Kevlar-reinforced epoxy (KE) and increases with the number of laminates. Drop-weight impact test showed the highest absorbed energy for (KE) composites. The results revealed that different behavior during the impact test for composites belongs to the impact mechanism in each test.

Design/methodology/approach

Aramid 1414 Kevlar 49 and UHMWPE woven fabrics were purchased from Yixing Huaheng High-Performance Fiber Textile Co. Ltd, with specifications listed in Table 1. Epoxy resin (Sikafloor-156) is supplied from Sika AG. Sikafloor-156 is a two-part, low-viscosity, solvent-free epoxy resin, with compressive strength ∼95 N/mm², flexural strength ∼30 N/mm² and shore D hardness 83 (seven days). The mixture ratio of A/B was one-third volume ratio. Two types of laminated composites with different layers 12 and 20 were prepared by hand layup: Kevlar–epoxy and UHMWPE–epoxy composites as shown in Figure 1. Mechanical pressure was applied to remove bubbles and excess resin for 24 h. The composites were left in room temperature for seven days, and then composite plates were cut for the desired dimensions. Low-velocity impact testing, drop-weight impact, drop tower impact system INSTRON CEAST 9350 (see Figure 2) was facilitated to investigate impact resistance of composites according to ASTM D7137M (Test Method for Compressive, 2005). Low-velocity impact tests have been performed at room temperature for composite with dimensions 10 × 15 cm2 utilizing a drop tower (steel indenter diameter 19.85 mm as shown in Figure 3), height (800 mm), drop mass (5 kg) and speed (3.96 m/s). Special impact equipment consisting of vertically falling impactor was used in the test. The energy is obtained from Drop tower impact systems, (2009) E = ½ mv2 (2.1). The relationship between force–time, deformation–time and energy–time and deformation was obtained. Energy–deformation and force–deformation relationships were also obtained. The depth of penetration and the radius of impactor traces were recorded. Izod pendulum impact test of plastics was applied according to ASTM D256 (Test Method for Compressive, 2005). Absorbed energy was recorded to compute the impact strength of the specimen. The specimen before the test is shown in Figure 4.

Findings

In order to investigate two types of impact: drop-weight impact and Izod impact on damage resistance of composites, the two tests were done. Drop-weight impact is dropping a known weight and height in a vertical direction with free fall, absorbed energy can be calculated. Izod impact measures the energy required to break a specimen by striking a specific size bar with a pendulum (Test Method for Compressive, 2005; Test Methods for Determining, 2018). The results obtained with the impact test are presented. Figure 5 shows the histogram bars of impact strength of composites. It can be noticed that Kevlar–epoxy (KE) composites give higher energy strength than UHMWPE–epoxy (PE) in 12 and 20 plies. The increasing percentage is about 18.5 and 5.7%. It can be observed in Figure 6 that samples are not destructed completely due to fiber continuity. Also, the delamination occurs obviously for UHMWPE–epoxy more than for Kevlar-based composite, which may due to weak binding between UHMWPE with an epoxy relative with Kevlar.

Practical implications

The force–time curves for Kevlar–epoxy (KE) and UHMWPE–epoxy (PE) composites with 12 and 20 plies are illustrated respectively in Figure 7. The contact duration between indenter and composite surface is repented by the force–time curves, so the maximum force reaches with certain displacement. It can be seen that maximum force was (13,209, 18,734.9, 23,271.07 and 19,825.38 N) at the time (3.97, 4.43, 3.791 and 4.198 ms) for 12 KE, 12 PE, 20 KE and 20 PE, respectively. The sharp peaks of KE composite are due to the lower ductility of Kevlar compared with UHMWPE. These results agree with the results of Ahmed et al. (2016). Kevlar-based composites (KE) showed lower impact force and crack propagates in the matrix with fast fiber breakage compared with PE composites, whereas the latter did not suffer from fabric breakage in 12 and 20 plies any more (see Figure 8). Figure 9 illustrates force–deformation curves, for 12 and 20 plies of Kevlar–epoxy (KE) and UHMWPE–epoxy (PE) composites. Curve's slop is considered the specimen's stiffness and the maximum displacement. To investigate the impact behavior of the four different composites, the comparison was made among the relative force–deformation curves. The maximum displacement was 5.119, 3.443, 1.173 and 1.17 mm for 12KE, 12 PE, 20 KE and 20 PE, respectively. It seems that UHMWPE-based composite (PE) presents lower deformation than Kevlar-based composites (KE) at a same number of laminates, although the maximum displacement is for 12 PE and 12 KE (see Figure 8). Kevlar-based composites (KE) showed more damage than UHMWPE-based composite (PE), so the maximum displacement is always higher for KE specimens with maximum indenter trace diameter (D∼11.27 mm). The onset of cracks begins along fibers on the impacted side for 20 KE and 20 PE specimens with lower indenter trace (D∼5.42 and 5.96 mm), respectively (see Table 2). These results refer to the lower stiffness of KE composites (see the slope of the curve) relative to PE composites. This result agreed with (Vieille et al., 2013) when they found that the theoretical stiffness of laminated composite during drop-weight impact depends significantly on fiber nature (Fadhil, 2013). The matrix cracking is the first type of damage that may not change stiffness of composites overall. Material stiffness changes due to the stress concentration represented by matrix cracks, delamination and fiber breakage (Hancox, 2000). Briefly, the histogram (see Figure 10) showed that the best impact behavior was for 20 KE, highest impact force with lower deformation, indenter trace diameter and contact time. Absorbed energy–time and absorbed energy–deformation curves for composites are shown in Figures 11 and 12, respectively. The maximum absorbed energy was (36.313, 29.952, 9.783 and 6.928 J) for 12 KE, 12 PE, 20 KE and 20 PE, respectively. Test period time is only 8 ms, but the time in which composites reached maximum absorbed energy was (4.413, 3.636, 2.394 and 2.408 ms). The maximum absorbed energy was for 12 KE with lower rebound energy because part of kinetic energy transferred to potential energy kept in the composite as material damage (see Figures 3 and 4). This composite absorbs more energy as material damage which kept as potential energy. Whereas other composites 12 PE, 20 PE and 20 KE showed less damage, lower absorbed energy and higher rebound energy, which appeared in different peak behavior as the negative value of energy. Also from the absorbed energy–time curves, it had been noticed significantly the maximum contact time of indenter with composite was 4.413 ms for 12 KE, which exhibits higher deformation (5.119 mm), whereas other composites 12 PE, 20 KE and 20 PE showed less damage, contact time and deformation as (3.443, 1.173, 1.17 mm), respectively.

Originality/value

The main goal of the current study is to evaluate the performances of armor composite made off of Kevlar and UHMWPE fabrics reinforced epoxy thermosetting resin under the low-velocity impact. Several plates of composites were prepared by hand layup. Izod and drop-weight impact tests were facilitated to get an indication about the absorbed energy and strength of the armors.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 6
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 9 October 2023

Goutam Kumar Jana, Sumit Bera, Ribhu Maity, Tithi Maity, Arjun Mahato, Shibayan Roy, Hemakesh Mohapatra and Bidhan Chandra Samanta

The manufacture of polymer composites with a lower environmental footprint requires incorporation of sustainably sourced components. In addition, the incorporation of novel…

Abstract

Purpose

The manufacture of polymer composites with a lower environmental footprint requires incorporation of sustainably sourced components. In addition, the incorporation of novel components should not compromise the material properties. The purpose of this paper is to demonstrate the use of a synthetic amine functional toluidine acetaldehyde condensate (AFTAC) as a modifier for fiber-reinforced epoxy composites. One of the fiber components was sourced from agricultural byproducts, and glass fiber was used as the fiber component for comparison.

Design/methodology/approach

The AFTAC condensate was synthesized via an acid-catalyzed reaction between o-toluidine and acetaldehyde. To demonstrate its efficacy as a toughening agent for diglycidyl ether bisphenol A resin composites and for the comparison of reinforcing materials of interest, composites were fabricated using a natural fiber (mat stick) and a synthetic glass fiber as the reinforcing material. A matched metal die technique was used to fabricate the composites. Composites were prepared and their mechanical and thermal properties were evaluated.

Findings

The inclusion of AFTAC led to an improvement in the mechanical strengths of these composites without any significant deterioration of the thermal stability. It was also observed that the fracture strengths for mat stick fiber-reinforced composites were lower than that of glass fiber-reinforced composites.

Originality/value

To the best of the authors’ knowledge, the use of the AFTAC modifier as well as incorporation of mat stick fibers in epoxy composites has not been demonstrated previously.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 11 January 2008

B.C. Samanta, T. Maity, S. Dalai and A.K. Banthia

The purpose of this paper is to evaluate the mechanical properties of glass fibre reinforced epoxy composites modified with amine‐terminated poly (ethylene glycol) benzoate…

Abstract

Purpose

The purpose of this paper is to evaluate the mechanical properties of glass fibre reinforced epoxy composites modified with amine‐terminated poly (ethylene glycol) benzoate (ATPEGB) along with their thermal stability.

Design/methodology/approach

ATPEGB prepared from poly (ethylene glycol) (PEG) of different molecular weights (200, 400, 600, 4,000 and 20,000) were used as modifiers for glass fibre epoxy composite here. For toughening, 12.5 parts per hundred grams (phr) of epoxy resin of each ATPEGB was added to epoxy and pre‐reacted with it. The impact, tensile and flexural strengths of modified and unmodified composite were characterised and compared for each ATPEGB.

Findings

Modified resin displayed a significant improvement in fracture toughness with glass fibre over unmodified epoxy. The modification caused the formation of oligomer domains having relatively round shapes in the matrix. These oligomer domains led to improved strength and toughness due mainly to the “rubber toughening” effect in the brittle epoxy matrix. The optimum results were obtained for composite modified with ATPEGB‐2 prepared from PEG of molecular weight 400.

Research limitations/implications

In the present context, only 12.5 phr concentration of each ATPEGB was used to modify composite and the composites were made sing three layers of glass fibre. Besides, modification could also be done using other concentrations and more layers of glass fibre could also be used to make composite.

Originality/value

The method for enhancing toughness of epoxy glass fibre composite was novel and finds numerous applications as surface coatings, casting and adhesive onto an intricate structure, etc.

Details

Pigment & Resin Technology, vol. 37 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 15 September 2023

Payman Sahbah Ahmed

Epoxy resins are widely used in a variety of engineering applications, including composite wind turbine blades used in the renewable energy industry, highly complex structural…

Abstract

Purpose

Epoxy resins are widely used in a variety of engineering applications, including composite wind turbine blades used in the renewable energy industry, highly complex structural components for aircraft, paints, coatings, industrial tooling, biomedical systems, adhesives, electronics and automotive. Epoxies' low fracture toughness is one of the key obstacles preventing its adoption in a wider range of applications. To address epoxy's low fracture toughness, this paper aims to examine the roles of intra-ply hybridization and nano reinforcing.

Design/methodology/approach

This paper investigates the role of intra-ply hybridization of glass-carbon woven fibers and adding 0.8 wt.% of multiwall carbon nanotube (MWCNT) nano reinforcement to overcome the low fracture toughness of epoxy. A bending test is used to calculate the composites elastic parameters, and a notched sample three-point bending test is used to show crack behavior in addition to using materials characterization methods to reveal the effect of the MWCNT on structure, bonding, glass transition temperature (Tg) and dispersion of MWCNT in the matrix. Furthermore, this paper suggests using the finite element method to overcome the difficulty in calculating the crack extension.

Findings

Intra-ply hybridization and MWCNT reinforcement decrease the crack extension of epoxy with time. The inclusion of high-strength carbon fiber increased the fracture toughness of glass composite. Furthermore, the existence of MWCNT in the surrounding area of the notch in epoxy composites hinders crack propagation and provides stiffness at the interface by bridging the crack and eventually enhancing its fracture toughness.

Originality/value

Studying the role of intra-ply hybridization of glass-carbon woven fibers and adding 0.8 wt.% of MWCNT nano reinforcement to overcome the low fracture toughness of epoxy. Additionally, this research recommends using the finite element method to overcome the challenge of computing the crack extension.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 30 January 2007

B. Das, S.K. Sahu and B.C. Ray

The objective of the present work is to ascertain the failure modes under different loading speeds along with change in percentage of constituents of FRP composites.

Abstract

Purpose

The objective of the present work is to ascertain the failure modes under different loading speeds along with change in percentage of constituents of FRP composites.

Design/methodology/approach

This involves experimental investigation of FRP composites with woven roving fibers and matrix. Different types of composites, i.e. glass: epoxy, glass: polyester and (carbon+glass): epoxy are used in the investigation with change in percentage of constituents. The variability of fiber content of the composite is in the range of 0.55‐0.65 weight fractions. The matrix dominated property, like inter laminar shear strength (ILSS) has been studied by three point bend test using INSTRON 1195 material testing machine with increasing five cross head velocities.

Findings

The variation of ILSS of laminates of FRP composites is significant for low loading speed and is not so prominent for high speed. The variation of ILSS are observed to be dependent on the type and amount of constituents present in the composites. The laminates with carbon fiber shows higher ILSS than that of glass fiber composites. The laminates with epoxy matrix shows higher ILSS than polyester matrix composites for the same fiber. There is no significant variation of ILSS beyond loading speed 200 mm/min and this can be used for specifications of testing. Matrix resins such as polyester and epoxy are known to be highly rate sensitive. Carbon fiber are relatively rate independent and E‐glass fibers are rate sensitive. Woven roving carbon glass fiber reinforced polymer shows small rate dependence and woven roving glass fiber reinforced polymer shows significant rate sensitivity.

Originality/value

The findings are based on original experimental investigations in the laboratories of the institute and can be used for characterization of composites.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 1
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 May 2019

Jenarthanan M.P., Karthikeyan Marappan and Giridharan R.

The need for seeking alternate materials with increased performance in the field of composites revived this research, to prepare and evaluate the mechanical properties of e-glass…

Abstract

Purpose

The need for seeking alternate materials with increased performance in the field of composites revived this research, to prepare and evaluate the mechanical properties of e-glass and aloe vera fiber-reinforced with polyester and epoxy resin matrices.

Design/methodology/approach

The composites are prepared by hand layup method using E-glass and aloe vera fibers with length 5-6 mm. The resin used in the preparation of composites was epoxy and polyester. Fiber-reinforced composites were synthesized at 18:82 fiber–resin weight percentages. Samples prepared were tested to evaluate its mechanical and physical properties, such as tensile strength, flexural strength, impact strength, hardness and scanning electron microscope (SEM).

Findings

SEM analysis revealed the morphological features. E-glass fiber-reinforced epoxy composite exhibited better mechanical properties than other composite samples. The cross-linking density of monomers of the epoxy resin and addition of the short chopped E-glass fibers enhanced the properties of E-glass epoxy fiber-reinforced composite.

Originality/value

This research work enlists the properties of e-glass and aloe vera fiber-reinforced with polyester and epoxy resin matrices which has not been attempted so far.

Details

Pigment & Resin Technology, vol. 48 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 6 March 2017

Arezoo Mamani, Morteza Ebrahimi and Maryam Ataeefard

The purpose of this paper is to investigate the effect of expandable graphite (EG) plates’ incorporation on the mechanical, thermal and fire-retardant properties of an epoxy

217

Abstract

Purpose

The purpose of this paper is to investigate the effect of expandable graphite (EG) plates’ incorporation on the mechanical, thermal and fire-retardant properties of an epoxy–aliphatic amine system. In addition, the optimum amount of EG in epoxy/EG composites is determined to achieve the best thermal and mechanical properties at the same time.

Design/methodology/approach

The epoxy/EG composites were prepared by using (1-4) phr of EG. The morphological structure of epoxy/EG composites was studied by using scanning electron microscopy. The thermal, flame-retardant and mechanical properties of epoxy/EG composites were evaluated by using thermogravimetric analysis (TGA), oxygen index test and dynamic mechanical analysis and tensile and impact test, respectively.

Findings

TGA results showed that the incorporation of EG to the epoxy resin increased the initial decomposition temperature and residue weight of the composites. It was found that, with increasing EG concentration up to 4 phr, the oxygen index, glass transition temperature and Young’s modulus of epoxy/EG composites increased up to 60 per cent, 4.1°C and 50 per cent, respectively. On the other hand, the sample with 2 phr EG provided the maximum values of tensile strength, storage modulus, cross-linking density, ultimate tensile strain and impact strength.

Practical implications

Prepared epoxy/EG composites can be used as halogen-free flame-retardant composites. The proposed process for the preparation of the composites is simple and can easily be implicated in the industry.

Originality/value

To the best of the authors’ knowledge, there is no other publication that considers mechanical, thermal and fire-retardant properties of epoxy/EG composites in one paper. In this work, the optimum concentration of EG in epoxy/EG composites was determined, considering all these properties.

Details

Pigment & Resin Technology, vol. 46 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 4 August 2021

Shailendra Singh Chauhan, Vaibhav Singh, Gauranshu Saini, Nitin Kaushik, Vishal Pandey and Anuj Chaudhary

The growing environmental awareness all through the world has motivated a standard change toward planning and designing better materials having good performance, which are very…

Abstract

Purpose

The growing environmental awareness all through the world has motivated a standard change toward planning and designing better materials having good performance, which are very much suited to the environmental factors. The purpose of this study is to investigate the impact on mechanical, thermal and water absorption properties of sawdust-based composites reinforced by epoxy, and the amount of sawdust in each form.

Design/methodology/approach

Manufacturing of the sawdust reinforced epoxy composites is the main area of the research for promoting the green composite by having good mechanical properties, biodegradability or many applications. Throughout this research work, the authors emphasize the importance of explaining the methodology for the evaluation of the mechanical and water absorption properties of the sawdust reinforced epoxy composites used by researchers.

Findings

In this paper, a comprehensive review of the mechanical properties of sawdust reinforced epoxy composite is presented. This study is reported about the use of different Wt.% of sawdust composites prepared by different processes and their mechanical, thermal and water absorption properties. It is studied that after optimum filler percentage, mechanical, thermal properties gradually decrease, but water absorption property increases with Wt.% of sawdust. The changes in the microstructure are studied by using scanning electron microscopy.

Originality/value

The novelty of this study lies in its use of a systematic approach that offers a perspective on choosing suitable processing parameters for the fabrication of composite materials for persons from both industry and academia. A study of sawdust reinforced epoxy composites guides new researchers in the fabrication and characterization of the materials.

Details

World Journal of Engineering, vol. 20 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 30 May 2023

Ravikantha Prabhu, Sharun Mendonca, Pavana Kumara Bellairu, Rudolf Charles DSouza and Thirumaleshwara Bhat

This paper aims to report the effect of titanium oxide (TiO2) particles on the physical, mechanical, tribological and water resistance properties of 5% NaOH-treated bamboo…

Abstract

Purpose

This paper aims to report the effect of titanium oxide (TiO2) particles on the physical, mechanical, tribological and water resistance properties of 5% NaOH-treated bamboo fiber–reinforced composites.

Design/methodology/approach

In this research, the epoxy/bamboo/TiO2 hybrid composite filled with 0–8 Wt.% TiO2 particles has been fabricated using simple hand layup techniques, and testing of the developed composite was done in accordance with the American Society for Testing and Materials (ASTM) standard.

Findings

The results of this study indicate that the addition of TiO2 particles improved the mechanical properties of the developed epoxy/bamboo composites. Tensile properties were found to be maximum for 6 Wt.%, and impact strength was found to be maximum for 8 Wt.% TiO2 particles-filled composite. The highest flexural properties were found at a lower TiO2 fraction of 2 Wt.%. Adding TiO2 filler helped to reduce the water absorption rate. The studies related to the wear and friction behavior of the composite under dry and abrasive wear conditions reveal that TiO2 filler was beneficial in improving the wear performance of the composite.

Originality/value

This research paper attempts to include both TiO2 filler and bamboo fibers to develop a novel composite material. TiO2 micro and nanoparticles are promising filler materials; it helps to enhance the mechanical and tribological properties of the epoxy composites and in literature, there is not much work reported, where TiO2 is used as a filler material with bamboo fiber–reinforced epoxy composites.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 23 June 2021

Radhwan Bin Hussin, Safian Bin Sharif, Shayfull Zamree Bin Abd Rahim, Mohd Azlan Bin Suhaimi, Mohd Tanwyn Bin Mohd Khushairi, Abdellah Abdellah EL-Hadj and Norshah Afizi Bin Shuaib

Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype…

Abstract

Purpose

Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts.

Design/methodology/approach

The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted.

Findings

Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles).

Research limitations/implications

The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available.

Originality/value

This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of over 2000