A H M Abdul Moudood (original) (raw)
Papers by A H M Abdul Moudood
Applied Mechanics and Materials, Dec 1, 2013
Journal of Natural Fibers, Aug 23, 2018
Development of environment-friendly natural fiber composites has been a recent trend. However, du... more Development of environment-friendly natural fiber composites has been a recent trend. However, due to the fact that natural fibers permit high level of moisture absorption from the surroundings, it can lead to weak bindings and degradation of composite properties. This paper presents an experimental study on the dynamic performance of flax fiber composite beams manufactured at different relative humidity (RH) levels. Five types of flax fiber-reinforced composite materials were made under different RH values, i.e., dry, 35%, 50%, 70%, and 95% RH, and beam samples were prepared using the composite. Impact hammer testing was conducted to measure the natural frequencies and damping of the beams. It was found that for the first three modes, while the resonant frequencies are very close for most samples, there is a clear drop of frequencies for the composite fabricated at 95% RH. Along with an increase of the RH level, the damping ratios for all the three modes have reported a slight increase, but the variation is not significant.
Advanced Materials Research, Jul 1, 2015
This paper investigates the average surface roughness (Ra) in micro-electrical discharge machinin... more This paper investigates the average surface roughness (Ra) in micro-electrical discharge machining of electrically nonconductive zirconium oxide (ZrO2) ceramic using powder mixed dielectric. The gap voltage and concentration of tantalum carbide (TaC) powder are considered as the variable parameters for the investigation while other conditions are kept constant. Response surface methodology is used for design of experiments and to analyze the results for a better surface finish. The study shows that both the gap voltage and powder concentration have a significant effect on the average surface roughness of ZrO2. However, voltage has the higher effect than powder concentration on the surface integrity. The optimized values of gap voltage and powder concentration are found to be 94.39 V and 6.28g/l respectively for a minimum surface roughness in micro-EDM of ZrO2.
Flax fibre composite is a bio-material that can meet the requirements in many engineering applica... more Flax fibre composite is a bio-material that can meet the requirements in many engineering applications. It has been used especially in applications for the automotive industry due to the several excellent specific properties which are similar to composites manufactured with glass fibres. However, due to the hydrophilic nature of flax fibre, this material is prone to absorb water and moisture from the environment, and therefore, they are not reliable for outdoor applications. The growing demand for flax composites in the field of bio-material research enforces the researchers to have in-depth knowledge in their processing into a useful final product. However, the correlation between the environmental effects and the performance of the flax fibre bio-composites is not well established. The main focus of this study is to address the specific environmental issues and their effects on flax fibre composites manufactured by the vacuum infusion method. First of all, the effect of the moisture content in the fibres on the mechanical performance and overall quality of the manufactured composites is studied. Flax composites are manufactured with fibres having different moisture content and they are compared to composites manufactured with dry fibres. This work begins with measuring moisture absorption kinetics of the flax fibres. Flax fibres absorb moisture almost linearly from 0% to 70% RH (relative humidity) environments, however, this absorption almost double from 70% to 95% RH. The tensile strength of the flax fibre reinforced composites increases until a certain RH value (50% RH) and then it decreases as the RH of the environment is raised up to the maximum value (95% RH). However, the tensile modulus, flexural strength and modulus of the composite samples continuously decrease with the increasing RH values. The microstructural tests of the composites confirmed the presence of micro-cracks and pores and debonding in the fibre-matrix interface. In addition, a study about the dynamic response of the flax composites manufactured with fibres stored at different RH levels ensures that dry composites have better vibration and damping properties. The damping ratios of the flax composites manufactured with fibres with different RH values are slightly increased with the increasing rates of moisture absorption although this change is not notable. Moreover, the mechanical properties of the flax composites manufactured with fibres at different RH environments are predicted by analytical models. The geometric and displacement potential function approaches are proposed to estimate the tensile properties of the flax composites. The proposed models demonstrate greater accuracy when validated with experimental observations. Secondly, the consequence of different environmental conditions on the performance and durability of flax composites is analysed. Composites made by vacuum infusion using dry fibres are immersed in water, exposed to warm humid environments and subjected to freeze-thaw (F/T) cycles. During exposure to different environments, the mechanical performance (tensile and flexural properties), moisture content and physical changes (dimensional stability) of the composites are analysed. The water absorption trend is partially Fickian for the samples immersed in water at room temperature and these samples are greatly affected and degraded. Furthermore, the mechanical properties of the water saturated (WS) samples are clearly degraded in contrast to the as manufactured (AM) samples. Compared to AM samples, the tensile strength and modulus are decreased approximately by 9% and 57%, respectively for WS samples and their flexural strength and modulus is decreased by 64% and 70%, respectively. However, some of these properties could be recovered, to some extent, by drying the WS samples. On the other hand, the reduction of tensile strength and modulus for the humidity saturated (HS) samples is only 0.8% and 3%, respectively, when compared to the AM composite samples. It was found that freezing-thawing cycles have almost no effects on the flax bio-composites.
Flax fibre composite is a bio-material that can meet the requirements in many engineering applica... more Flax fibre composite is a bio-material that can meet the requirements in many engineering applications. It has been used especially in applications for the automotive industry due to the several excellent specific properties which are similar to composites manufactured with glass fibres. However, due to the hydrophilic nature of flax fibre, this material is prone to absorb water and moisture from the environment, and therefore, they are not reliable for outdoor applications. The growing demand for flax composites in the field of bio-material research enforces the researchers to have in-depth knowledge in their processing into a useful final product. However, the correlation between the environmental effects and the performance of the flax fibre bio-composites is not well established. The main focus of this study is to address the specific environmental issues and their effects on flax fibre composites manufactured by the vacuum infusion method. First of all, the effect of the moistu...
Advances in Materials Science and Engineering, 2020
The moisture absorption behavior of flax fiber-reinforced epoxy composites is deliberated to be a... more The moisture absorption behavior of flax fiber-reinforced epoxy composites is deliberated to be a serious issue. This property restricts their usage as outdoor engineering structures. Therefore, this study provides an investigation of moisture in flax fibers on the performance of the flax/epoxy composite materials based on their shear responses. The ±45° aligned flax fibers exposed to different relative humidities (RH) and the vacuum infusion process was used to manufacture the composite specimens. The optimum shear strength (40.25 ± 0.75 MPa) was found for the composites manufactured with 35% RH-conditioned flax fibers, but the shear modulus was reduced consistently with increasing RH values. Although shear strength was increased because of fiber swelling with increased moisture absorption rate until 35% RH environments with good microstructures, nonetheless, strength and modulus both started to decrease after this range. A very poor microstructure has been affirmed by the SEM imag...
Advanced Materials Research, 2015
This paper investigates the average surface roughness (Ra) in micro-electrical discharge machinin... more This paper investigates the average surface roughness (Ra) in micro-electrical discharge machining of electrically nonconductive zirconium oxide (ZrO2) ceramic using powder mixed dielectric. The gap voltage and concentration of tantalum carbide (TaC) powder are considered as the variable parameters for the investigation while other conditions are kept constant. Response surface methodology is used for design of experiments and to analyze the results for a better surface finish. The study shows that both the gap voltage and powder concentration have a significant effect on the average surface roughness of ZrO2. However, voltage has the higher effect than powder concentration on the surface integrity. The optimized values of gap voltage and powder concentration are found to be 94.39 V and 6.28g/l respectively for a minimum surface roughness in micro-EDM of ZrO2.
IOP Conference Series: Materials Science and Engineering, 2013
ABSTRACT
Applied Mechanics and Materials, 2013
Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process... more Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process, is used for structuring of nonconductive ZrO2 ceramic. In this study copper foil as a conductive layer is adhered on the workpiece surface to initiate the sparks and kerosene is used as dielectric for creation of continuous conductive pyrolytic carbon layer on the machined surface. Voltage (V) and capacitance (C) are considered as the parameters to investigate the process capability of machining parameters in continuous micro-EDM of ZrO2. Different voltage pulses are studied to examine the causes of lower material removal rate (MRR) in micro-EDM of nonconductive ceramics. The results showed that in micro-EDM of ZrO2 MRR increases with the increase of voltage and capacitance initially, but decreases at higher values and no significant materials are removed at capacitances higher than 1nF.
International Journal of Automotive and Mechanical Engineering, 2014
In this study, microelectro-discharge (micro-ED) milling of nonconductive ZrO 2 ceramicsis invest... more In this study, microelectro-discharge (micro-ED) milling of nonconductive ZrO 2 ceramicsis investigated using a Cu tool electrode in kerosene dielectric. An adhesive Cu foil is firmly attached on the workpiece to initiate the sparks. After the machining of Cu foil, an electrically conductive carbonic layer is formed on the ceramic workpiece disassociating the kerosene dielectric, which allows micro-ED milling to be continued on ZrO 2 .A micro-channel of 1500 µm length, 920 µm width and 150 µm depth is created. Energy-dispersive X-ray spectroscopy showed evidence of higher C precedence on the workpiece surface, which is the main element of the carbonic layer. It is shown that material removal rate increases with the increase of capacitance and voltage initially but it decreases at higher values. MRR and average surface roughness of the micro-channel are found to be 1.29×10-5 mm 3 /s and 0.25 µm, respectively, when machined with a capacitance of 0.1 nF and voltage of 80 V. This study shows that micro-ED milling is applicable for creating micro-channels on nonconductive ZrO 2 ceramic with the assisting electrode technique.
Polymer Composites, 2020
Due to the good mechanical properties, flax fiber‐reinforced epoxy composites are being widely us... more Due to the good mechanical properties, flax fiber‐reinforced epoxy composites are being widely used as a green alternative to glass fiber composites. However, plant fibers absorb moisture from the environment, being in a higher moisture uptake as the relative humidity (RH) increases. This absorbed moisture deteriorates the mechanical properties of the composites. In this study, geometric and displacement potential function (DPF) approaches are used to predict the mechanical properties of flax fiber‐reinforced epoxy composites under environmental conditions, in particular, different RH values. The tensile properties that were measured experimentally strongly agreed with the analytical findings. Almost similar results were found for the tensile strain those were measured experimentally and the one predicted by the geometric function. However, the predicted strain values were 38% and 42% less than the experimental ones for 0% and 95% RH conditioned composites, respectively, when DPF was used. Good conformity between the experimental, analytical, and DPF formulation for predicting mechanical properties ensures the practical applicability of this study. The formulations established in this work could, therefore, be utilized to analytically solve laminated composites under specific boundary conditions in structural applications.
Journal of Natural Fibers, 2018
Development of environment-friendly natural fiber composites has been a recent trend. However, du... more Development of environment-friendly natural fiber composites has been a recent trend. However, due to the fact that natural fibers permit high level of moisture absorption from the surroundings, it can lead to weak bindings and degradation of composite properties. This paper presents an experimental study on the dynamic performance of flax fiber composite beams manufactured at different relative humidity (RH) levels. Five types of flax fiber-reinforced composite materials were made under different RH values, i.e., dry, 35%, 50%, 70%, and 95% RH, and beam samples were prepared using the composite. Impact hammer testing was conducted to measure the natural frequencies and damping of the beams. It was found that for the first three modes, while the resonant frequencies are very close for most samples, there is a clear drop of frequencies for the composite fabricated at 95% RH. Along with an increase of the RH level, the damping ratios for all the three modes have reported a slight increase, but the variation is not significant.
Composites Part B: Engineering, 2019
The growing usage of bio-composite materials in different engineering applications demands a thor... more The growing usage of bio-composite materials in different engineering applications demands a thorough understanding of their performance during their service. Extreme environmental conditions, such as warm, humid, and freezing environments, among others, can degrade the mechanical properties of the bio-composites when they are exposed to harsh environmental conditions. In addition, the use of these composites in underwater applications can also shorten their life cycle. In this work, the durability and mechanical performance (tensile and flexural behavior) of flax/bio-epoxy composites exposed to different environmental conditions were evaluated. These conditions were chosen to replicate those found outdoors that can affect the durability of these materials: water immersion, warm humid environment and freeze-thaw conditions. Moisture and water absorption behavior were evaluated and the water content (or exposure time) was related to the physical changes and mechanical properties. Results show that the mechanical properties of flax/bio-epoxy composites are clearly degraded by water ageing when they are compared to the "as manufactured" composites. The tensile strength and modulus is decreased approximately by 9% and 57%, respectively for water saturated (immersed in water until saturation) samples compared to as manufactured samples. On contrary, this reduction rate is only 0.8% and 3%,
Journal of Reinforced Plastics and Composites, 2018
Contemporary researchers have specified that natural flax fiber is comparable with synthetic fibe... more Contemporary researchers have specified that natural flax fiber is comparable with synthetic fibers due to its unique physical and mechanical characteristics which have been recognized for decades. Flax fiber-reinforced composites have the potential for wide usage in sport and maritime industries, and as automotive accessories. In addition, this composite is in the development stages for future applications in the aeronautical industry. However, designing the flax composite parts is a challenging task due to the great variability in fiber properties. This is caused by many factors, including the plant origin and growth conditions, plant age, location in the stem, fibers extraction method, and the fact that there is often a non-uniform cross section of the fibers. Furthermore, the water and moisture absorption tendency of the flax fibers and their composites and the consequent detrimental effects on their mechanical performance are also major drawbacks. Fibers may soften and swell wi...
Journal of Natural Fibers, 2017
Moisture present in plant fibres is considered to be detrimental to the performance of composites... more Moisture present in plant fibres is considered to be detrimental to the performance of composites. In general, a drying stage is performed on the plant fibre fabrics before manufacturing the composites since it is seemed to allow better output. This work provides an analysis about the effect of moisture in flax fibres on the overall quality of epoxy/flax biocomposites. Flax fibre fabrics were conditioned at different relative humidity (RH) environments and composites were manufactured by vacuum infusion technique. Composites were characterized by mechanical and microstructural analysis. Results showed that manufacturing composites with highly humid fabrics (95% RH) generates post processing deformation of finished parts and also leads to poor microstructural quality. The moisture in the fibres with different RH reduced the stiffness (from 23.74 to 17.67 GPa for Young's modulus and from 16.28 to 11.82 GPa for flexural modulus) but increased their fracture strain (from 1.87 to 2.64). Tensile strength displayed an optimum value (287.96 MPa) for fabrics conditioned at 50% RH, but flexural strength decreases continuously from 225.12 to 152.34 MPa as the moisture in the fabric increases.
Applied Mechanics and Materials, Dec 1, 2013
Journal of Natural Fibers, Aug 23, 2018
Development of environment-friendly natural fiber composites has been a recent trend. However, du... more Development of environment-friendly natural fiber composites has been a recent trend. However, due to the fact that natural fibers permit high level of moisture absorption from the surroundings, it can lead to weak bindings and degradation of composite properties. This paper presents an experimental study on the dynamic performance of flax fiber composite beams manufactured at different relative humidity (RH) levels. Five types of flax fiber-reinforced composite materials were made under different RH values, i.e., dry, 35%, 50%, 70%, and 95% RH, and beam samples were prepared using the composite. Impact hammer testing was conducted to measure the natural frequencies and damping of the beams. It was found that for the first three modes, while the resonant frequencies are very close for most samples, there is a clear drop of frequencies for the composite fabricated at 95% RH. Along with an increase of the RH level, the damping ratios for all the three modes have reported a slight increase, but the variation is not significant.
Advanced Materials Research, Jul 1, 2015
This paper investigates the average surface roughness (Ra) in micro-electrical discharge machinin... more This paper investigates the average surface roughness (Ra) in micro-electrical discharge machining of electrically nonconductive zirconium oxide (ZrO2) ceramic using powder mixed dielectric. The gap voltage and concentration of tantalum carbide (TaC) powder are considered as the variable parameters for the investigation while other conditions are kept constant. Response surface methodology is used for design of experiments and to analyze the results for a better surface finish. The study shows that both the gap voltage and powder concentration have a significant effect on the average surface roughness of ZrO2. However, voltage has the higher effect than powder concentration on the surface integrity. The optimized values of gap voltage and powder concentration are found to be 94.39 V and 6.28g/l respectively for a minimum surface roughness in micro-EDM of ZrO2.
Flax fibre composite is a bio-material that can meet the requirements in many engineering applica... more Flax fibre composite is a bio-material that can meet the requirements in many engineering applications. It has been used especially in applications for the automotive industry due to the several excellent specific properties which are similar to composites manufactured with glass fibres. However, due to the hydrophilic nature of flax fibre, this material is prone to absorb water and moisture from the environment, and therefore, they are not reliable for outdoor applications. The growing demand for flax composites in the field of bio-material research enforces the researchers to have in-depth knowledge in their processing into a useful final product. However, the correlation between the environmental effects and the performance of the flax fibre bio-composites is not well established. The main focus of this study is to address the specific environmental issues and their effects on flax fibre composites manufactured by the vacuum infusion method. First of all, the effect of the moisture content in the fibres on the mechanical performance and overall quality of the manufactured composites is studied. Flax composites are manufactured with fibres having different moisture content and they are compared to composites manufactured with dry fibres. This work begins with measuring moisture absorption kinetics of the flax fibres. Flax fibres absorb moisture almost linearly from 0% to 70% RH (relative humidity) environments, however, this absorption almost double from 70% to 95% RH. The tensile strength of the flax fibre reinforced composites increases until a certain RH value (50% RH) and then it decreases as the RH of the environment is raised up to the maximum value (95% RH). However, the tensile modulus, flexural strength and modulus of the composite samples continuously decrease with the increasing RH values. The microstructural tests of the composites confirmed the presence of micro-cracks and pores and debonding in the fibre-matrix interface. In addition, a study about the dynamic response of the flax composites manufactured with fibres stored at different RH levels ensures that dry composites have better vibration and damping properties. The damping ratios of the flax composites manufactured with fibres with different RH values are slightly increased with the increasing rates of moisture absorption although this change is not notable. Moreover, the mechanical properties of the flax composites manufactured with fibres at different RH environments are predicted by analytical models. The geometric and displacement potential function approaches are proposed to estimate the tensile properties of the flax composites. The proposed models demonstrate greater accuracy when validated with experimental observations. Secondly, the consequence of different environmental conditions on the performance and durability of flax composites is analysed. Composites made by vacuum infusion using dry fibres are immersed in water, exposed to warm humid environments and subjected to freeze-thaw (F/T) cycles. During exposure to different environments, the mechanical performance (tensile and flexural properties), moisture content and physical changes (dimensional stability) of the composites are analysed. The water absorption trend is partially Fickian for the samples immersed in water at room temperature and these samples are greatly affected and degraded. Furthermore, the mechanical properties of the water saturated (WS) samples are clearly degraded in contrast to the as manufactured (AM) samples. Compared to AM samples, the tensile strength and modulus are decreased approximately by 9% and 57%, respectively for WS samples and their flexural strength and modulus is decreased by 64% and 70%, respectively. However, some of these properties could be recovered, to some extent, by drying the WS samples. On the other hand, the reduction of tensile strength and modulus for the humidity saturated (HS) samples is only 0.8% and 3%, respectively, when compared to the AM composite samples. It was found that freezing-thawing cycles have almost no effects on the flax bio-composites.
Flax fibre composite is a bio-material that can meet the requirements in many engineering applica... more Flax fibre composite is a bio-material that can meet the requirements in many engineering applications. It has been used especially in applications for the automotive industry due to the several excellent specific properties which are similar to composites manufactured with glass fibres. However, due to the hydrophilic nature of flax fibre, this material is prone to absorb water and moisture from the environment, and therefore, they are not reliable for outdoor applications. The growing demand for flax composites in the field of bio-material research enforces the researchers to have in-depth knowledge in their processing into a useful final product. However, the correlation between the environmental effects and the performance of the flax fibre bio-composites is not well established. The main focus of this study is to address the specific environmental issues and their effects on flax fibre composites manufactured by the vacuum infusion method. First of all, the effect of the moistu...
Advances in Materials Science and Engineering, 2020
The moisture absorption behavior of flax fiber-reinforced epoxy composites is deliberated to be a... more The moisture absorption behavior of flax fiber-reinforced epoxy composites is deliberated to be a serious issue. This property restricts their usage as outdoor engineering structures. Therefore, this study provides an investigation of moisture in flax fibers on the performance of the flax/epoxy composite materials based on their shear responses. The ±45° aligned flax fibers exposed to different relative humidities (RH) and the vacuum infusion process was used to manufacture the composite specimens. The optimum shear strength (40.25 ± 0.75 MPa) was found for the composites manufactured with 35% RH-conditioned flax fibers, but the shear modulus was reduced consistently with increasing RH values. Although shear strength was increased because of fiber swelling with increased moisture absorption rate until 35% RH environments with good microstructures, nonetheless, strength and modulus both started to decrease after this range. A very poor microstructure has been affirmed by the SEM imag...
Advanced Materials Research, 2015
This paper investigates the average surface roughness (Ra) in micro-electrical discharge machinin... more This paper investigates the average surface roughness (Ra) in micro-electrical discharge machining of electrically nonconductive zirconium oxide (ZrO2) ceramic using powder mixed dielectric. The gap voltage and concentration of tantalum carbide (TaC) powder are considered as the variable parameters for the investigation while other conditions are kept constant. Response surface methodology is used for design of experiments and to analyze the results for a better surface finish. The study shows that both the gap voltage and powder concentration have a significant effect on the average surface roughness of ZrO2. However, voltage has the higher effect than powder concentration on the surface integrity. The optimized values of gap voltage and powder concentration are found to be 94.39 V and 6.28g/l respectively for a minimum surface roughness in micro-EDM of ZrO2.
IOP Conference Series: Materials Science and Engineering, 2013
ABSTRACT
Applied Mechanics and Materials, 2013
Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process... more Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process, is used for structuring of nonconductive ZrO2 ceramic. In this study copper foil as a conductive layer is adhered on the workpiece surface to initiate the sparks and kerosene is used as dielectric for creation of continuous conductive pyrolytic carbon layer on the machined surface. Voltage (V) and capacitance (C) are considered as the parameters to investigate the process capability of machining parameters in continuous micro-EDM of ZrO2. Different voltage pulses are studied to examine the causes of lower material removal rate (MRR) in micro-EDM of nonconductive ceramics. The results showed that in micro-EDM of ZrO2 MRR increases with the increase of voltage and capacitance initially, but decreases at higher values and no significant materials are removed at capacitances higher than 1nF.
International Journal of Automotive and Mechanical Engineering, 2014
In this study, microelectro-discharge (micro-ED) milling of nonconductive ZrO 2 ceramicsis invest... more In this study, microelectro-discharge (micro-ED) milling of nonconductive ZrO 2 ceramicsis investigated using a Cu tool electrode in kerosene dielectric. An adhesive Cu foil is firmly attached on the workpiece to initiate the sparks. After the machining of Cu foil, an electrically conductive carbonic layer is formed on the ceramic workpiece disassociating the kerosene dielectric, which allows micro-ED milling to be continued on ZrO 2 .A micro-channel of 1500 µm length, 920 µm width and 150 µm depth is created. Energy-dispersive X-ray spectroscopy showed evidence of higher C precedence on the workpiece surface, which is the main element of the carbonic layer. It is shown that material removal rate increases with the increase of capacitance and voltage initially but it decreases at higher values. MRR and average surface roughness of the micro-channel are found to be 1.29×10-5 mm 3 /s and 0.25 µm, respectively, when machined with a capacitance of 0.1 nF and voltage of 80 V. This study shows that micro-ED milling is applicable for creating micro-channels on nonconductive ZrO 2 ceramic with the assisting electrode technique.
Polymer Composites, 2020
Due to the good mechanical properties, flax fiber‐reinforced epoxy composites are being widely us... more Due to the good mechanical properties, flax fiber‐reinforced epoxy composites are being widely used as a green alternative to glass fiber composites. However, plant fibers absorb moisture from the environment, being in a higher moisture uptake as the relative humidity (RH) increases. This absorbed moisture deteriorates the mechanical properties of the composites. In this study, geometric and displacement potential function (DPF) approaches are used to predict the mechanical properties of flax fiber‐reinforced epoxy composites under environmental conditions, in particular, different RH values. The tensile properties that were measured experimentally strongly agreed with the analytical findings. Almost similar results were found for the tensile strain those were measured experimentally and the one predicted by the geometric function. However, the predicted strain values were 38% and 42% less than the experimental ones for 0% and 95% RH conditioned composites, respectively, when DPF was used. Good conformity between the experimental, analytical, and DPF formulation for predicting mechanical properties ensures the practical applicability of this study. The formulations established in this work could, therefore, be utilized to analytically solve laminated composites under specific boundary conditions in structural applications.
Journal of Natural Fibers, 2018
Development of environment-friendly natural fiber composites has been a recent trend. However, du... more Development of environment-friendly natural fiber composites has been a recent trend. However, due to the fact that natural fibers permit high level of moisture absorption from the surroundings, it can lead to weak bindings and degradation of composite properties. This paper presents an experimental study on the dynamic performance of flax fiber composite beams manufactured at different relative humidity (RH) levels. Five types of flax fiber-reinforced composite materials were made under different RH values, i.e., dry, 35%, 50%, 70%, and 95% RH, and beam samples were prepared using the composite. Impact hammer testing was conducted to measure the natural frequencies and damping of the beams. It was found that for the first three modes, while the resonant frequencies are very close for most samples, there is a clear drop of frequencies for the composite fabricated at 95% RH. Along with an increase of the RH level, the damping ratios for all the three modes have reported a slight increase, but the variation is not significant.
Composites Part B: Engineering, 2019
The growing usage of bio-composite materials in different engineering applications demands a thor... more The growing usage of bio-composite materials in different engineering applications demands a thorough understanding of their performance during their service. Extreme environmental conditions, such as warm, humid, and freezing environments, among others, can degrade the mechanical properties of the bio-composites when they are exposed to harsh environmental conditions. In addition, the use of these composites in underwater applications can also shorten their life cycle. In this work, the durability and mechanical performance (tensile and flexural behavior) of flax/bio-epoxy composites exposed to different environmental conditions were evaluated. These conditions were chosen to replicate those found outdoors that can affect the durability of these materials: water immersion, warm humid environment and freeze-thaw conditions. Moisture and water absorption behavior were evaluated and the water content (or exposure time) was related to the physical changes and mechanical properties. Results show that the mechanical properties of flax/bio-epoxy composites are clearly degraded by water ageing when they are compared to the "as manufactured" composites. The tensile strength and modulus is decreased approximately by 9% and 57%, respectively for water saturated (immersed in water until saturation) samples compared to as manufactured samples. On contrary, this reduction rate is only 0.8% and 3%,
Journal of Reinforced Plastics and Composites, 2018
Contemporary researchers have specified that natural flax fiber is comparable with synthetic fibe... more Contemporary researchers have specified that natural flax fiber is comparable with synthetic fibers due to its unique physical and mechanical characteristics which have been recognized for decades. Flax fiber-reinforced composites have the potential for wide usage in sport and maritime industries, and as automotive accessories. In addition, this composite is in the development stages for future applications in the aeronautical industry. However, designing the flax composite parts is a challenging task due to the great variability in fiber properties. This is caused by many factors, including the plant origin and growth conditions, plant age, location in the stem, fibers extraction method, and the fact that there is often a non-uniform cross section of the fibers. Furthermore, the water and moisture absorption tendency of the flax fibers and their composites and the consequent detrimental effects on their mechanical performance are also major drawbacks. Fibers may soften and swell wi...
Journal of Natural Fibers, 2017
Moisture present in plant fibres is considered to be detrimental to the performance of composites... more Moisture present in plant fibres is considered to be detrimental to the performance of composites. In general, a drying stage is performed on the plant fibre fabrics before manufacturing the composites since it is seemed to allow better output. This work provides an analysis about the effect of moisture in flax fibres on the overall quality of epoxy/flax biocomposites. Flax fibre fabrics were conditioned at different relative humidity (RH) environments and composites were manufactured by vacuum infusion technique. Composites were characterized by mechanical and microstructural analysis. Results showed that manufacturing composites with highly humid fabrics (95% RH) generates post processing deformation of finished parts and also leads to poor microstructural quality. The moisture in the fibres with different RH reduced the stiffness (from 23.74 to 17.67 GPa for Young's modulus and from 16.28 to 11.82 GPa for flexural modulus) but increased their fracture strain (from 1.87 to 2.64). Tensile strength displayed an optimum value (287.96 MPa) for fabrics conditioned at 50% RH, but flexural strength decreases continuously from 225.12 to 152.34 MPa as the moisture in the fabric increases.