eman eltahan | Alexandria University (original) (raw)
Papers by eman eltahan
Journal of industrial textiles, 2024
Traditional silk, known for its strength, flexibility, and comfort, shows promise as a lightweigh... more Traditional silk, known for its strength, flexibility, and comfort, shows promise as a lightweight, comfortable material for stab-resistant armor. This study explores enhancing silk's knife-stabbing resistance for soft body armor through surface treatments. This study aims to augment the knife-stabbing resistance of silk fabric for soft body armor. Designed a falling tower setup to investigate fabric responses under impact. Exploring the addition of layers with coatings like silicon dioxide deposition, rice ash deposition, and aluminum oxide particles, the investigation revealed significant enhancements. A solitary silk layer exclusively coated with resin exhibited improvements of approximately 37.07%, 29.21%, and 13.47% in stab resistance for rice ash, aluminum oxide, and silicon oxide particles, respectively. The specific knife penetration depth indicated that the coating is more effective in diminishing penetration depth. The research identified that 7 layers of pure silk and 3 layers coated with rice ash satisfy National Institute of Justice Standard-0115.00, S1 as 26 layers of silk fabric, demonstrating a reduction without compromising protective efficacy.
Fouth International Conference on Advances in Civil, Structural and Construction Engineering - CSCE 2016, 2016
Natural fibers, including the Bamboo, are environment friendly materials. They require a low degr... more Natural fibers, including the Bamboo, are environment friendly materials. They require a low degree of industrialization and a small energy for their processing and production, and hence the total fabricating cost is also low. The main purpose of this paper is to cover the lack of information about Bamboo; its mechanical properties, interaction with concrete, strength and durability, and to investigate its validity of replacing steel as a reinforcement of concrete beams. This possibility is investigated through experimental results of bamboo reinforced concrete beams compared with others reinforced using steel. The experimental results were verified and expanded using the FE package called ANSYS. In this research, the Bamboo was used without any treatment or stirrups. It was found that untreated Bamboo must not be used as reinforcement in concrete beams, although its mechanical properties may be considered as comparable to steel.
Journal of Engineering Research and Reports
This research work studies the effects of fabric structure on the mechanical properties of fabric... more This research work studies the effects of fabric structure on the mechanical properties of fabric cement composites. Seven fabric structures from the same fabric material were used. In this work different sets of specimens were made with different fabric layers after that these specimens were tested on tensile, bending and compression testing machines. It was found that the mechanical properties of the composite materials were influenced by the properties of the reinforced fabric. Fabric tensile strength, which is determined by the fabric's structure, construction, and the number of reinforced fabric layers, is the key factor influencing both tensile and flexural strength of the cement composites. Additionally, when the number of fabric layers increases, some attributes of composites, such as tensile and bending strength, increase while compressive strength decreases.
The inherent complexity of textile preforms and a high degree of consistency in dry fabrics and y... more The inherent complexity of textile preforms and a high degree of consistency in dry fabrics and yarns present a number of modeling challenges, including uncertainty in geometrical characteristics under external loads, non-elastic deformations of fibrous media, and multiple deformation modes at the fiber and yarn scales. The prediction of the compaction reaction for different preforms is still possible thanks to the direct measurements of yarn compaction. The data are checked against compression stressthickness curves that were produced by compacting yarns and preforms. The yarn and fabric compaction model given in this article demonstrates the final characteristics of woven preforms. The yarn compaction curve exhibits asymptotic hardening with a restricted compaction state attained at high compression stress and as the limit deformations are being approached. The yarn count, yarn fiber volume ratio, and the spinning method all affected the compression modulus. The transverse compression behaviour of yarns and fabrics was studied both analytically and experimentally. Mechanisms of fabric compressibility have been found to be reliant on both fabric and yarn specifications of warp and weft Young's modulus. Investigations were made into the fabric's fiber volume fraction under compression stress. When producing composite with low fiber volume fraction preforms, it may be more efficient to use more compression, according to research on the link between compressive stress and fabric volume fraction.
Journal of Industrial Textiles
Punching resistance properties of the fabric are vital for several applications such as slash-res... more Punching resistance properties of the fabric are vital for several applications such as slash-resistant clothing. In this paper, the penetration of a puncher through a plain Kevlar woven fabric was analyzed to recognize the process of punching and the mechanism of yarn breakage. The model focused on the study of the difference between fabric that is woven from the continuous multifilament yarn or the spun yarn and the effects of their yarn structure on punching resistance. The relation between the warp and weft yarns and the punching resistance force of the fabric at different punching speeds was investigated. This work focused on the potentiality to use fabric from coarse Kevlar spun yarns instead of continuous filament yarns to enhance the punching resistance. Samples of fabrics were tested on a specially designed set-up to investigate the behaviour of warp and weft yarns under punching load. A basic understanding of the damage to the fabric under punching has been developed. The ...
Journal of Industrial Textiles, 2021
In several applications, the industrial and protective fabrics might be subjected to punching by ... more In several applications, the industrial and protective fabrics might be subjected to punching by the rigid sharp spikes. Fabric resistance to the penetration of the puncher at a constant rate was studied. The analysis of the factors influencing the resistance of the fabric and an explanation of the puncture mechanism were generated. Punching force-displacement curves were obtained and four noticeable fabric failure modes were observed. A special setup was designed so that the fabric sample can be subjected to the biaxial stresses during the puncture tests. This paper studies the puncture behaviors of the plain, twill 1/3, and twill 2/2 woven fabric designs. It was found that the increase in the number of fabric layers from one to three and the number of picks/cm from 17.6 to 27.2 would elevate the punching resistance and the punching energy by 354% and 333%, respectively, with the insignificant change in the values of specific punching force and energy. Plain weave design proved to ...
Alexandria Engineering Journal, 2017
The tearing strength is more vital in heavy duty fabrics. So it is important to know the effects ... more The tearing strength is more vital in heavy duty fabrics. So it is important to know the effects of the fabric structural parameters on the tearing resistance of these types of fabrics. In this work the effects of some fabric structural parameters were studied on the tearing properties of fabrics used in tents. The experimental work was divided into two parts; the first part was to study the effect of fabric design on the tearing strength. Six fabric designs of the same type of fiber were used. They were of different specific tightness. The second part was to produce fabrics which are used in tents with different specifications. Different sets of fabric specimens were prepared. These specimens were tested for tearing resistance, to study the effects of these structural parameters on the tearing resistance of the fabrics. The effects of the structural parameters on the tearing strength were deduced.
Alexandria Engineering Journal, 2016
After fabric relaxation, there is a reduction in wale and course density due to a reduction in lo... more After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is useful to find a relation between loop length and courses and wales per unit length as well as the yarn thickness because wales and courses per unit length can be easily measured at any state while it is difficult to measure the loop length in the knitted fabrics. Therefore, it is required to find an equation, through which the value of loop length can be easily calculated from the measured values of courses and wales per unit length at any state after the knitting process. In this work estimated equations to calculate the knitted loop length for open to normal structure and for normal to compact structure are developed. By comparing the value of the loop length predicted from this work with the other mentioned models, it was found that the calculated values are very near to the L value of the case study; so the developed equations are acceptable. The tightness factor and the porosity of single jersey fabrics were also calculated theoretically.
Alexandria Engineering Journal, 2014
This study shows the effect of fabric tightness and fabric material on the mechanical properties ... more This study shows the effect of fabric tightness and fabric material on the mechanical properties of fabric-cement composites. Six fabric designs from the same fabric material were used. These fabric designs are vary in the specific tightness. Also, three fabric materials with the same fabric design were used in this work. Different sets of specimens were made, after that these specimens were tested on tensile and bending testing machines. It was found that the mechanical properties of the composite materials were influenced by the length of the warp thread float, i.e. the longer is the yarns float in the fabric, the greater is the tensile strength properties of the reinforced fabric, its construction and the material of the reinforced fabric. Therefore, it is recommended to use fabric with yarns with higher tenacity in the direction of the application of load and with either long float or minimum number of intersections.
Journal of Industrial Textiles, 2014
Protective body armors, providing protection against stab threats, have long been in a focus of s... more Protective body armors, providing protection against stab threats, have long been in a focus of substantial interest. Lightweight fabric for flexible body armors that satisfy the customized fit, comfort, and protection should be considered. Sharp impact experiments were conducted on single and multilayer fabrics of Kevlar29, Vectran, and Polyester triaxial woven fabrics and compared with polyester woven and knitted fabrics. The experimental results evaluate the energy absorption of the different triaxial woven fabrics for stab resistance. An index was developed to evaluate the capability of fibers to absorb the impact energy which indicated that high fiber tenacity and Young’s modulus and low density lead to high rate of punching resistance force. The present work indicates that Vectran triaxial weave fabrics propose to improve the impact performance when used in developing multilayer fabrics for designing lightweight soft body armor with enhanced stab performance adding flexibility...
Journal of Composites, 2016
Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts... more Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts. Knit fabric can more easily deform or stretch by compressing or elongating the individual stitches that form the fabric. Cotton yarns, which are not elastomeric, do not have the ability of recovery to rearrange the stitches. As a consequence, single-knit fabrics may have permanent deformation. To improve the recovery performance of circular single-knit fabrics, it is now a common practice to knit a small amount of spandex fiber or yarn with companion cotton yarn. In this study the physical, dimensional, and mechanical properties of back plaited cotton/spandex single jersey knitted fabrics were investigated and the results are compared with knitted fabrics made from 100% cotton and the effect of spandex percentage was also studied. It was found that as the loop length increases, the wales density was not affected and specific fabric hand and extension increased, but bursting strength an...
Abstract Protective body armors, providing protection against stab threats, have long been in a f... more Abstract
Protective body armors, providing protection against stab threats, have long been in a
focus of substantial interest. Lightweight fabric for flexible body armors that satisfy the
customized fit, comfort, and protection should be considered. Sharp impact experiments
were conducted on single and multilayer fabrics of Kevlar29, Vectran, and
Polyester triaxial woven fabrics and compared with polyester woven and knitted fabrics.
The experimental results evaluate the energy absorption of the different triaxial woven
fabrics for stab resistance. An index was developed to evaluate the capability of fibers to
absorb the impact energy which indicated that high fiber tenacity and Young’s modulus
and low density lead to high rate of punching resistance force. The present work
indicates that Vectran triaxial weave fabrics propose to improve the impact performance
when used in developing multilayer fabrics for designing lightweight soft body
armor with enhanced stab performance adding flexibility and comfort.
After fabric relaxation, there is a reduction in wale and course density due to a reduction in lo... more After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is useful to find a relation between loop length and courses and wales per unit length as well as the yarn thickness because wales and courses per unit length can be easily measured at any state while it is difficult to measure the loop length in the knitted fabrics. Therefore, it is required to find an equation, through which the value of loop length can be easily calculated from the measured values of courses and wales per unit length at any state after the knitting process. In this work estimated equations to calculate the knitted loop length for open to normal structure and for normal to compact structure are developed. By comparing the value of the loop length predicted from this work with the other mentioned models, it was found that the calculated values are very near to the L value of the case study; so the developed equations are acceptable. The tightness factor and the porosity of single jersey fabrics were also calculated theoretically.
This study shows the effect of fabric tightness and fabric material on the mechanical properties ... more This study shows the effect of fabric tightness and fabric material on the mechanical properties of fabric–cement composites. Six fabric designs from the same fabric material were used. These fabric designs are vary in the specific tightness. Also, three fabric materials with the same fabric design were used in this work. Different sets of specimens were made, after that these specimens were tested on tensile and bending testing machines. It was found that the mechanical properties of the composite materials were influenced by the length of the warp thread float, i.e. the longer is the yarns float in the fabric, the greater is the tensile strength properties of the reinforced fabric, its construction and the material of the reinforced fabric. Therefore, it is recommended to use fabric with yarns with higher tenacity in the direction of the application of load and with either long float or minimum number of intersections. ª 2014 Production and hosting by Elsevier B.V. on behalf
The paper deals with the application of triaxial fabric from different high tenacity fibers as so... more The paper deals with the application of triaxial fabric from different high tenacity fibers as soft body armor .
Journal of industrial textiles, 2024
Traditional silk, known for its strength, flexibility, and comfort, shows promise as a lightweigh... more Traditional silk, known for its strength, flexibility, and comfort, shows promise as a lightweight, comfortable material for stab-resistant armor. This study explores enhancing silk's knife-stabbing resistance for soft body armor through surface treatments. This study aims to augment the knife-stabbing resistance of silk fabric for soft body armor. Designed a falling tower setup to investigate fabric responses under impact. Exploring the addition of layers with coatings like silicon dioxide deposition, rice ash deposition, and aluminum oxide particles, the investigation revealed significant enhancements. A solitary silk layer exclusively coated with resin exhibited improvements of approximately 37.07%, 29.21%, and 13.47% in stab resistance for rice ash, aluminum oxide, and silicon oxide particles, respectively. The specific knife penetration depth indicated that the coating is more effective in diminishing penetration depth. The research identified that 7 layers of pure silk and 3 layers coated with rice ash satisfy National Institute of Justice Standard-0115.00, S1 as 26 layers of silk fabric, demonstrating a reduction without compromising protective efficacy.
Fouth International Conference on Advances in Civil, Structural and Construction Engineering - CSCE 2016, 2016
Natural fibers, including the Bamboo, are environment friendly materials. They require a low degr... more Natural fibers, including the Bamboo, are environment friendly materials. They require a low degree of industrialization and a small energy for their processing and production, and hence the total fabricating cost is also low. The main purpose of this paper is to cover the lack of information about Bamboo; its mechanical properties, interaction with concrete, strength and durability, and to investigate its validity of replacing steel as a reinforcement of concrete beams. This possibility is investigated through experimental results of bamboo reinforced concrete beams compared with others reinforced using steel. The experimental results were verified and expanded using the FE package called ANSYS. In this research, the Bamboo was used without any treatment or stirrups. It was found that untreated Bamboo must not be used as reinforcement in concrete beams, although its mechanical properties may be considered as comparable to steel.
Journal of Engineering Research and Reports
This research work studies the effects of fabric structure on the mechanical properties of fabric... more This research work studies the effects of fabric structure on the mechanical properties of fabric cement composites. Seven fabric structures from the same fabric material were used. In this work different sets of specimens were made with different fabric layers after that these specimens were tested on tensile, bending and compression testing machines. It was found that the mechanical properties of the composite materials were influenced by the properties of the reinforced fabric. Fabric tensile strength, which is determined by the fabric's structure, construction, and the number of reinforced fabric layers, is the key factor influencing both tensile and flexural strength of the cement composites. Additionally, when the number of fabric layers increases, some attributes of composites, such as tensile and bending strength, increase while compressive strength decreases.
The inherent complexity of textile preforms and a high degree of consistency in dry fabrics and y... more The inherent complexity of textile preforms and a high degree of consistency in dry fabrics and yarns present a number of modeling challenges, including uncertainty in geometrical characteristics under external loads, non-elastic deformations of fibrous media, and multiple deformation modes at the fiber and yarn scales. The prediction of the compaction reaction for different preforms is still possible thanks to the direct measurements of yarn compaction. The data are checked against compression stressthickness curves that were produced by compacting yarns and preforms. The yarn and fabric compaction model given in this article demonstrates the final characteristics of woven preforms. The yarn compaction curve exhibits asymptotic hardening with a restricted compaction state attained at high compression stress and as the limit deformations are being approached. The yarn count, yarn fiber volume ratio, and the spinning method all affected the compression modulus. The transverse compression behaviour of yarns and fabrics was studied both analytically and experimentally. Mechanisms of fabric compressibility have been found to be reliant on both fabric and yarn specifications of warp and weft Young's modulus. Investigations were made into the fabric's fiber volume fraction under compression stress. When producing composite with low fiber volume fraction preforms, it may be more efficient to use more compression, according to research on the link between compressive stress and fabric volume fraction.
Journal of Industrial Textiles
Punching resistance properties of the fabric are vital for several applications such as slash-res... more Punching resistance properties of the fabric are vital for several applications such as slash-resistant clothing. In this paper, the penetration of a puncher through a plain Kevlar woven fabric was analyzed to recognize the process of punching and the mechanism of yarn breakage. The model focused on the study of the difference between fabric that is woven from the continuous multifilament yarn or the spun yarn and the effects of their yarn structure on punching resistance. The relation between the warp and weft yarns and the punching resistance force of the fabric at different punching speeds was investigated. This work focused on the potentiality to use fabric from coarse Kevlar spun yarns instead of continuous filament yarns to enhance the punching resistance. Samples of fabrics were tested on a specially designed set-up to investigate the behaviour of warp and weft yarns under punching load. A basic understanding of the damage to the fabric under punching has been developed. The ...
Journal of Industrial Textiles, 2021
In several applications, the industrial and protective fabrics might be subjected to punching by ... more In several applications, the industrial and protective fabrics might be subjected to punching by the rigid sharp spikes. Fabric resistance to the penetration of the puncher at a constant rate was studied. The analysis of the factors influencing the resistance of the fabric and an explanation of the puncture mechanism were generated. Punching force-displacement curves were obtained and four noticeable fabric failure modes were observed. A special setup was designed so that the fabric sample can be subjected to the biaxial stresses during the puncture tests. This paper studies the puncture behaviors of the plain, twill 1/3, and twill 2/2 woven fabric designs. It was found that the increase in the number of fabric layers from one to three and the number of picks/cm from 17.6 to 27.2 would elevate the punching resistance and the punching energy by 354% and 333%, respectively, with the insignificant change in the values of specific punching force and energy. Plain weave design proved to ...
Alexandria Engineering Journal, 2017
The tearing strength is more vital in heavy duty fabrics. So it is important to know the effects ... more The tearing strength is more vital in heavy duty fabrics. So it is important to know the effects of the fabric structural parameters on the tearing resistance of these types of fabrics. In this work the effects of some fabric structural parameters were studied on the tearing properties of fabrics used in tents. The experimental work was divided into two parts; the first part was to study the effect of fabric design on the tearing strength. Six fabric designs of the same type of fiber were used. They were of different specific tightness. The second part was to produce fabrics which are used in tents with different specifications. Different sets of fabric specimens were prepared. These specimens were tested for tearing resistance, to study the effects of these structural parameters on the tearing resistance of the fabrics. The effects of the structural parameters on the tearing strength were deduced.
Alexandria Engineering Journal, 2016
After fabric relaxation, there is a reduction in wale and course density due to a reduction in lo... more After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is useful to find a relation between loop length and courses and wales per unit length as well as the yarn thickness because wales and courses per unit length can be easily measured at any state while it is difficult to measure the loop length in the knitted fabrics. Therefore, it is required to find an equation, through which the value of loop length can be easily calculated from the measured values of courses and wales per unit length at any state after the knitting process. In this work estimated equations to calculate the knitted loop length for open to normal structure and for normal to compact structure are developed. By comparing the value of the loop length predicted from this work with the other mentioned models, it was found that the calculated values are very near to the L value of the case study; so the developed equations are acceptable. The tightness factor and the porosity of single jersey fabrics were also calculated theoretically.
Alexandria Engineering Journal, 2014
This study shows the effect of fabric tightness and fabric material on the mechanical properties ... more This study shows the effect of fabric tightness and fabric material on the mechanical properties of fabric-cement composites. Six fabric designs from the same fabric material were used. These fabric designs are vary in the specific tightness. Also, three fabric materials with the same fabric design were used in this work. Different sets of specimens were made, after that these specimens were tested on tensile and bending testing machines. It was found that the mechanical properties of the composite materials were influenced by the length of the warp thread float, i.e. the longer is the yarns float in the fabric, the greater is the tensile strength properties of the reinforced fabric, its construction and the material of the reinforced fabric. Therefore, it is recommended to use fabric with yarns with higher tenacity in the direction of the application of load and with either long float or minimum number of intersections.
Journal of Industrial Textiles, 2014
Protective body armors, providing protection against stab threats, have long been in a focus of s... more Protective body armors, providing protection against stab threats, have long been in a focus of substantial interest. Lightweight fabric for flexible body armors that satisfy the customized fit, comfort, and protection should be considered. Sharp impact experiments were conducted on single and multilayer fabrics of Kevlar29, Vectran, and Polyester triaxial woven fabrics and compared with polyester woven and knitted fabrics. The experimental results evaluate the energy absorption of the different triaxial woven fabrics for stab resistance. An index was developed to evaluate the capability of fibers to absorb the impact energy which indicated that high fiber tenacity and Young’s modulus and low density lead to high rate of punching resistance force. The present work indicates that Vectran triaxial weave fabrics propose to improve the impact performance when used in developing multilayer fabrics for designing lightweight soft body armor with enhanced stab performance adding flexibility...
Journal of Composites, 2016
Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts... more Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts. Knit fabric can more easily deform or stretch by compressing or elongating the individual stitches that form the fabric. Cotton yarns, which are not elastomeric, do not have the ability of recovery to rearrange the stitches. As a consequence, single-knit fabrics may have permanent deformation. To improve the recovery performance of circular single-knit fabrics, it is now a common practice to knit a small amount of spandex fiber or yarn with companion cotton yarn. In this study the physical, dimensional, and mechanical properties of back plaited cotton/spandex single jersey knitted fabrics were investigated and the results are compared with knitted fabrics made from 100% cotton and the effect of spandex percentage was also studied. It was found that as the loop length increases, the wales density was not affected and specific fabric hand and extension increased, but bursting strength an...
Abstract Protective body armors, providing protection against stab threats, have long been in a f... more Abstract
Protective body armors, providing protection against stab threats, have long been in a
focus of substantial interest. Lightweight fabric for flexible body armors that satisfy the
customized fit, comfort, and protection should be considered. Sharp impact experiments
were conducted on single and multilayer fabrics of Kevlar29, Vectran, and
Polyester triaxial woven fabrics and compared with polyester woven and knitted fabrics.
The experimental results evaluate the energy absorption of the different triaxial woven
fabrics for stab resistance. An index was developed to evaluate the capability of fibers to
absorb the impact energy which indicated that high fiber tenacity and Young’s modulus
and low density lead to high rate of punching resistance force. The present work
indicates that Vectran triaxial weave fabrics propose to improve the impact performance
when used in developing multilayer fabrics for designing lightweight soft body
armor with enhanced stab performance adding flexibility and comfort.
After fabric relaxation, there is a reduction in wale and course density due to a reduction in lo... more After fabric relaxation, there is a reduction in wale and course density due to a reduction in loop length and this actually will affect the fabric properties. Then, it is useful to find a relation between loop length and courses and wales per unit length as well as the yarn thickness because wales and courses per unit length can be easily measured at any state while it is difficult to measure the loop length in the knitted fabrics. Therefore, it is required to find an equation, through which the value of loop length can be easily calculated from the measured values of courses and wales per unit length at any state after the knitting process. In this work estimated equations to calculate the knitted loop length for open to normal structure and for normal to compact structure are developed. By comparing the value of the loop length predicted from this work with the other mentioned models, it was found that the calculated values are very near to the L value of the case study; so the developed equations are acceptable. The tightness factor and the porosity of single jersey fabrics were also calculated theoretically.
This study shows the effect of fabric tightness and fabric material on the mechanical properties ... more This study shows the effect of fabric tightness and fabric material on the mechanical properties of fabric–cement composites. Six fabric designs from the same fabric material were used. These fabric designs are vary in the specific tightness. Also, three fabric materials with the same fabric design were used in this work. Different sets of specimens were made, after that these specimens were tested on tensile and bending testing machines. It was found that the mechanical properties of the composite materials were influenced by the length of the warp thread float, i.e. the longer is the yarns float in the fabric, the greater is the tensile strength properties of the reinforced fabric, its construction and the material of the reinforced fabric. Therefore, it is recommended to use fabric with yarns with higher tenacity in the direction of the application of load and with either long float or minimum number of intersections. ª 2014 Production and hosting by Elsevier B.V. on behalf
The paper deals with the application of triaxial fabric from different high tenacity fibers as so... more The paper deals with the application of triaxial fabric from different high tenacity fibers as soft body armor .