scholarly journals Dynamic Response of Thermally Bonded Bicomponent Fibre Nonwovens

2011 ◽  
Vol 70 ◽  
pp. 405-409 ◽  
Author(s):  
Emrah Demirci ◽  
Memiş Acar ◽  
Behnam Pourdeyhimi ◽  
Vadim V. Silberschmidt
Keyword(s):  
Mechanical Properties ◽  
Dynamic Response ◽  
Fibre Diameter ◽  
Orientation Distribution ◽  
Nonwoven Fabric ◽  
Woven Fabrics ◽  
Core Material ◽  
Finite Element Software ◽  
Anisotropic Mechanical Properties ◽  
Fibre Matrix

Having a unique microstructure, nonwoven fabrics possess distinct mechanical properties, dissimilar to those of woven fabrics and composites. This paper aims to introduce a methodology for simulating a dynamic response of core/sheath-type thermally bonded bicomponent fibre nonwovens. The simulated nonwoven fabric is treated as an assembly of two regions with distinct mechanical properties. One region - the fibre matrix – is composed of non-uniformly oriented core/sheath fibres acting as link between bond points. Non-uniform orientation of individual fibres is introduced into the model in terms of the orientation distribution function in order to calculate the structure’s anisotropy. Another region – bond points – is treated in simulations as a deformable bicomponent composite material, composed of the sheath material as its matrix and the core material as reinforcing fibres with random orientations. Time-dependent anisotropic mechanical properties of these regions are assessed based on fibre characteristics and manufacturing parameters such as the planar density, core/sheath ratio, fibre diameter etc. Having distinct anisotropic mechanical properties for two regions, dynamic response of the fabric is modelled in the finite element software with shell elements with thicknesses identical to those of the bond points and fibre matrix.

Anisotropic Elastic-Plastic Mechanical Properties of Thermally Bonded Bicomponent Fibre Nonwovens

2010 ◽  
Author(s):  
Emrah Demirci ◽  
Memis¸ Acar ◽  
Behnam Pourdeyhimi ◽  
Vadim V. Silberschmidt
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Core Material ◽  
Random Orientation ◽  
Elastic Plastic ◽  
Nonwoven Fabrics ◽  
Anisotropic Elastic ◽  
Manufacturing Parameters ◽  
Fibre Matrix

Having a unique structure, nonwoven fabrics possess distinct mechanical properties dissimilar to those of woven fabrics and composites. Anisotropic elastic-plastic mechanical properties of core/sheath type thermally bonded bicomponent fibre nonwoven textiles are computed based on manufacturing parameters and fibre properties. Initially, tensile tests are performed on nonwoven fabrics and their single fibres to assess their mechanical behaviour and obtain input parameters for the developed algorithms. Random orientation of individual fibres is introduced into the model in terms of the orientation distribution function (ODF). An algorithm, based on the Hough transform, is developed to determine the ODF and calculate the structure’s anisotropy. The nonwoven fabric is modelled as an assembly of two regions — bond points and a fibre matrix, having distinct mechanical properties. Bond points are treated as a deformable bicomponent composite material composed of the sheath material of fibres as matrix reinforced with the core material as fibres with random orientation of reinforcement. On the other hand, the fibre matrix is treated as a composite membrane structure having low stiffness in thickness direction. A second algorithm is developed to calculate anisotropic material properties of these regions based on fibre characteristics and manufacturing parameters; it can be used in numerical modelling as well as product development and optimization of nonwovens.

Numerical Modelling of Thermally Bonded Nonwovens: Continuous and Discontinuous Approaches

2012 ◽  
Vol 188 ◽  
pp. 164-169 ◽  
Author(s):  
Emrah Demirci ◽  
Xiao Nan Hou ◽  
Memiş Acar ◽  
Behnam Pourdeyhimi ◽  
Vadim V. Silberschmidt
Keyword(s):  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Orientation Distribution ◽  
Random Orientation ◽  
Shell Elements ◽  
Nonwoven Fabrics ◽  
Anisotropic Mechanical Properties ◽  
Composite Microstructure ◽  
Fibre Matrix ◽  
Modelling Approach

Nonwoven fabrics are web structures of randomly-oriented fibres, bonded by means of mechanical, thermal or chemical techniques. This paper focuses on nonwovens manufactured with polymer-based fibres and bonded thermally. During thermal bonding of such fibres, as a hot calender with an engraved pattern contacts the fibre web, bond spots are formed by melting of the polymer material. As a result of this bonding process, a pattern of bond points connected with randomly oriented polymer-based fibres form the nonwoven web. Due to their manufacturing-induced composite microstructure and random orientation of fibres, nonwovens demonstrate a complex mechanical behaviour. Two distinct modelling approaches were introduced to simulate the non-trivial mechanical response of thermally bonded nonwovens based on their planar density. The first modelling approach was developed to simulate the mechanical behaviour of high-density nonwovens, and the respective fabric was modelled with shell elements with thicknesses identical to those of the bond points and the fibre matrix having distinct anisotropic mechanical properties. Random orientation of individual fibres was introduced into the model in terms of the orientation distribution function in order to determine the material’s anisotropy. The second modelling approach was introduced to simulate low-density nonwovens, and it treated the nonwoven media as a structure composed of fibres acting as truss links between bond points.

Study of Electrospun Poly\acrylonitrile (PAN) and PAN/CNT Composite Nanofibrous Webs

2015 ◽  
Vol 19 (1) ◽  
pp. 36-45 ◽  
Author(s):  
M. K. Sinha ◽  
B. R. Das ◽  
A. Srivastava ◽  
A. K. Saxena
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Specific Conductivity ◽  
Research Work ◽  
Fibre Diameter ◽  
Nonwoven Fabric ◽  
Coating Process ◽  
Carbon Nano Tube ◽  
Conductive Properties ◽  
Poly Acrylonitrile

The electrospinng of PAN and PAN/CNT composite webs is carried out with the commercially available Nanospider machine. The webs are spun under similar processes and coated on Polypropylene spun bonded nonwoven fabric. This research work reports on the influence of multi-walled carbon nano tube (MWCNT) on the morphology, tensile properties, conductivity, thermal, chemical and crystalline structure of PAN and PAN/CNT composite nanofibrous webs. The morphological developments are explained on the basis of nanofibre diameter and web density as depicted by FESEM images. An addition of CNT greatly affects the morphology of webs, increases fibre diameter, decreases web density and leads to a roughened web surface. The mechanical properties of PAN /CNT composite webs are also found to be influenced by CNT concentration. The addition of MWCNT to PAN enhances the conductive properties of webs. The specific conductivity of PAN/CNT composite webs is found to be in order of 10-6 S/cm, which falls in the semiconducting regime and follows Ohm's law of conductivity. The TGA plots confirmed that the PAN/CNT composite web is more thermally stable than the PAN web. The presence of CNT in the polymer matrix is evidenced by D and G band, indicating a successful electrospun coating process.

scholarly journals A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

2021 ◽  
Vol 5 (5) ◽  
pp. 130
Author(s):  
Tan Ke Khieng ◽  
Sujan Debnath ◽  
Ernest Ting Chaw Liang ◽  
Mahmood Anwar ◽  
Alokesh Pramanik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Polymer Composites ◽  
Stress Transfer ◽  
Natural Fibre ◽  
Transfer Efficiency ◽  
Strain Rates ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Fibre Matrix

With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

Effect of fibre content on the mechanical properties of hemp fibre woven fabrics/polypropylene composite laminates

2021 ◽  
pp. 096739112110239
Author(s):  
Sheedev Antony ◽  
Abel Cherouat ◽  
Guillaume Montay
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Composite Laminates ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Woven Fabrics ◽  
Fibre Content ◽  
Viscoelastic Behaviour ◽  
Hemp Fibre

Nowadays natural fibre composites have gained great significance as reinforcements in polymer matrix composites. Composite material based on a polymer matrix reinforced with natural fibres is extensively used in industry due to their biodegradability, recyclability, low density and high specific properties. A study has been carried out here to investigate the fibre volume fraction effect of hemp fibre woven fabrics/PolyPropylene (PP) composite laminates on the tensile properties and impact hammer impact test. Initially, composite sheets were fabricated by the thermal-compression process with desired number of fabric layers to obtain composite laminates with different fibre volume fraction. Uniaxial, shear and biaxial tensile tests were performed and mechanical properties were calculated. Impact hammer test was also carried out to estimate the frequency and damping parameters of stratified composite plates. Scanning Electron Microscope (SEM) analysis was performed to observe the matrix and fibre constituent defects. Hemp fabrics/PP composite laminates exhibits viscoelastic behaviour and as the fibre volume fraction increases, the viscoelastic behaviour decreases to elastic behaviour. Due to this, the tensile strength increases as the fibre content increases. On the other hand, the natural frequency increases and damping ratio decrease as the fibre volume fraction increases.

Quasi-static mechanical properties of novel generalized Resch-pattern composite foldcores

2020 ◽  
pp. 095440622094000
Author(s):  
Antao Deng ◽  
Bin Ji ◽  
Xiang Zhou
Keyword(s):  
Mechanical Properties ◽  
Design Method ◽  
Absorption Capacity ◽  
Woven Fabrics ◽  
Geometric Design ◽  
Honeycomb Core ◽  
Reinforced Plastic ◽  
Static Mechanical ◽  
Laminate Thickness ◽  
Static Mechanical Properties

A new geometric design method for foldcores based on the generalized Resch patterns that allow face-to-face bonding interfaces between the core and the skins is proposed. Based on the geometric design method, a systematic numerical investigation on the quasi-static mechanical properties of the generalized Resch-based foldcores made of carbon fiber-reinforced plastic (CFRP) woven fabrics subjected to compression and shear loads is performed using the finite element method that is validated by experiments. The relationships between the mechanical properties and various geometric parameters as well as laminate thickness of the generalized Resch-based CFRP foldcores are revealed. Additionally, the mechanical properties of the generalized Resch-based CFRP foldcore are compared to those of the standard Resch-based, Miura-based foldcore, the honeycomb core, and the aluminum counterpart. It is found that the generalized Resch-based CFRP foldcore performs more stably than the honeycomb core under compression and has higher compressive and shear stiffnesses than the standard Resch-based and Miura-based foldcores and absorbs as nearly twice energy under compression as the Miura-based foldcore does. When compared with the aluminum counterpart, the CFRP model has higher weight-specific stiffness and strength but lower energy absorption capacity under shearing. The results presented in this paper can serve as the useful guideline for the design of the generalized Resch-based composite foldcore sandwich structures for various performance goals.

scholarly journals Anisotropic Mechanical Properties of Living Cells Revealed by Integrated Spinning Disk Confocal and Atomic Force Microscopy

2018 ◽  
Vol 114 (3) ◽  
pp. 513a
Author(s):  
Yuri M. Efremov ◽  
Mirian Velay-Lizancos ◽  
Daniel M. Suter ◽  
Pablo D. Zavattieri ◽  
Arvind Raman
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Living Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
Spinning Disk ◽  
Anisotropic Mechanical Properties
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