Georgios V. Seretis, Ioannis D. Theodorakopoulos, Dimitrios E. Manolakos and Christopher G. Provatidis
Para-aramid fabrics see service in a great variety of applications, such as heavy weight lifting applications, penetration protective multilayer panels, etc. It is, therefore…
Abstract
Purpose
Para-aramid fabrics see service in a great variety of applications, such as heavy weight lifting applications, penetration protective multilayer panels, etc. It is, therefore, increasingly important to understand the strain rate range at which the fabric has optimum mechanical properties. Although this is a field that has not been studied before, it is of great significance since it allows for the determination of the fabric’s layer location within the multilayered structure which offers maximum overall performance. The paper aims to discuss this issue.
Design/methodology/approach
Rectangular strips of PARAX 300 S8 woven para-aramid fabric underwent uniaxial tensile tests at various extension rates. The angle between two fibers at the center of each specimen was measured after the fabrics were elongated at different tensile extensions. This recovery angle was determined by visual analysis of the test video recordings after specimen unloading. Based on this, the recovery of the weaving form after unloading was also estimated for each tensile extension. A recovery degree based deformation characterization of the sections of a typical load/extension curve has been introduced.
Findings
The fabric does not appear to be strain rate sensitive for a strain rate range of 0.03 s-1 to 0.53 s-1, and its load/extension characteristics are generally not affected by the extension rate. However, break load and maximum elongation values appear reduced at actuator velocity of 2,400 mm/min and enhanced at 3,600 mm/min. Finally, the effect of extension rate on the different deformation zones of the material is reported and discussed.
Originality/value
The current research work offers a novel approach for the investigation of non-standard response of woven para-aramid fabrics when subjected to tensile loading under various strain rates. Additionally, a new approach is introduced to explain in detail the deformation zones based on the recovery degree of the fiber orientation angle after unloading.
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Savvas G. Vassiliadis and Christopher G. Provatidis
The surface of the textile fabrics is not absolutely flat and smooth. Its geometrical roughness within certain extents is considerable. The surface roughness influences the fabric…
Abstract
The surface of the textile fabrics is not absolutely flat and smooth. Its geometrical roughness within certain extents is considerable. The surface roughness influences the fabric hand and it plays a significant role in the end use of the fabric. In parallel, the periodic variations of the fabric surface level due to the regular interlaced patterns of the yarns cause a respective variation of the geometrical roughness measurement. Thus, the fabric roughness data measured using the Kawabata Evaluation System for Fabrics and imposed to a certain process of numerical calculations result into the retrieval of the structural parameters of the fabric. The principle of the method has a non‐destructive character and can be applied to woven or knitted fabrics.
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Christopher G. Provatidis and Savvas G. Vassiliadis
The computer aided engineering and the respective computer aided design tools compose a modern mechanical modelling environment for the textile materials. The numerical mechanical…
Abstract
The computer aided engineering and the respective computer aided design tools compose a modern mechanical modelling environment for the textile materials. The numerical mechanical models of the textile structures are a strong tool for the in‐depth study of the mechanical properties and the behaviour of the textiles. The precision of these models in terms of their accuracy in representing the exact geometry of the real textile structures is the fundamental factor affecting the overall success of the idealisation. This paper discusses older traditional analytical models (Peirce, Saw‐tooth, Kemp) as well as some variations of these fundamental models. Their numerical solutions are successfully compared to the experimental measurements of the yarn longitudinal deformation parameters using microscopic and digital image processing techniques. The results of the analytical models are compared with the actual measurements and the more precise models are indicated.
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Christopher G. Provatidis, Savvas G. Vassiliadis and Eleni A. Anastasiadou
This paper proposes a simplified two‐dimensional representation of the unit cell of the fabric that involves three bodies in contact.
Abstract
Purpose
This paper proposes a simplified two‐dimensional representation of the unit cell of the fabric that involves three bodies in contact.
Design/methodology/approach
The fabrics are not simple homogenous structures. They have a discrete structural character and this is essential for their complex mechanical behaviour. Low stress micro‐mechanics is mainly used for the prediction of the fabric hand. Modelling of the fabric microstructure is a powerful tool for the in‐depth study of their performance. Based on the geometrical models of the fabrics, finite element analysis (FEA) is a very useful method for the mechanical analysis of their complex shape structures. Especially FEA can be applied on a system of bodies in contact by taking into account the interactions between the individual bodies. The parametric FEA analysis of the unit cell of the fabric provides interesting results about its mechanical behaviour.
Findings
The present work states that the use of the finite element method is a friendly and convenient method for an in‐depth study of the contact phenomena, which are dominating on the total mechanical behaviour of the fabrics.
Originality/value
This paper provides a simplified two‐dimensional representation of a unit cell of a fabric that involves three bodies in contact. The parametric FEA analysis of the unit cell of the fabric provides interesting results.
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Savvas G. Vassiliadis, Argyro E. Kallivretaki and Christopher G. Provatidis
The present work aims to focus on the simulation of tensile, shear and bending deformation of the plain‐weft knitted fabrics in an analogous manner to the tests performed on the…
Abstract
Purpose
The present work aims to focus on the simulation of tensile, shear and bending deformation of the plain‐weft knitted fabrics in an analogous manner to the tests performed on the Kawabata Evaluation System for Fabrics.
Design/methodology/approach
The simulation of the tests is based on the modelling of the fabric microstructure and the application of the boundary conditions and the equivalent loading that correspond to each mechanical test, with a respect to the contact phenomena. A three‐dimensional model consisting of three bodies in contact represents the unit cell of the fabric microstructure. Finite element analysis is used for the prediction of fabric performance since the complexity of the structure, the anisotropic properties of the yarns and the interaction phenomena between the yarns at the contact areas preclude the use of analytical methods.
Findings
The proper definition of the boundary conditions and the appropriate load is of great significance for the realistic simulation of the mechanical tests under examination. The results of the simulated deformations compared to the respective measurements of the laboratory tests are correlated very well and this enables the consideration of the computational analysis as a powerful textile design tool.
Originality/value
The prediction of the mechanical properties of the knitted fabrics based on the computational modelling supports the estimation of the fabric hand during the design stage and before its manufacturing.
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Examines the eleventh published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…
Abstract
Examines the eleventh published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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Savvas Vassiliadis, Argyro Kallivretaki, Paraskevas Frantzeskakis and Christopher Provatidis
The purpose of this paper is to focus on the development of a thorough method for the macromechanical analysis of fabrics.
Abstract
Purpose
The purpose of this paper is to focus on the development of a thorough method for the macromechanical analysis of fabrics.
Design/methodology/approach
The homogenization method was implemented for the generation of continuum equivalent model for the plain woven structure. Keystone of the method is the mesomechanical analysis of the textile unit cell for the evaluation of the apparent properties and the generation of an equivalent macromechanical model supporting the mechanical performance of the structure. The finite element method (FEM) using beam elements was applied for the mechanical analysis of the discrete model of the unit cell and the FEM using shell elements was applied for the analysis of the continuum macromechanical model.
Findings
The tensile, shear and bending test of the unit cell were simulated. The constitutive equations of the continuum model were formed considering equivalent performance with the discrete model.
Originality/value
The reliability of the equivalent model in tensile, shear (in‐plane) and bending (out‐of‐plane) deformation was achieved even for asymmetric woven structures. The low computational power demanded for the meso‐ and macro‐mechanical modelling and analysis is a beneficial feature of the proposed method.
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Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…
Abstract
Examines the fifthteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…
Abstract
Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.
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Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects…
Abstract
Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.