Modeling the Large Deformation and Microstructure Evolution of Nonwoven Polymer Fiber Networks

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Mang Zhang ◽  
Yuli Chen ◽  
Fu-pen Chiang ◽  
Pelagia Irene Gouma ◽  
Lifeng Wang
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Mechanical Behavior ◽  
Large Deformation ◽  
Biological Tissues ◽  
High Porosity ◽  
Polymer Fiber ◽  
Fiber Networks ◽  
Fiber Aspect Ratio ◽  
Network Microstructure

The electrospinning process enables the fabrication of randomly distributed nonwoven polymer fiber networks with high surface area and high porosity, making them ideal candidates for multifunctional materials. The mechanics of nonwoven networks has been well established for elastic deformations. However, the mechanical properties of the polymer fibrous networks with large deformation are largely unexplored, while understanding their elastic and plastic mechanical properties at different fiber volume fractions, fiber aspect ratio, and constituent material properties is essential in the design of various polymer fibrous networks. In this paper, a representative volume element (RVE) based finite element model with long fibers is developed to emulate the randomly distributed nonwoven fibrous network microstructure, enabling us to systematically investigate the mechanics and large deformation behavior of random nonwoven networks. The results show that the network volume fraction, the fiber aspect ratio, and the fiber curliness have significant influences on the effective stiffness, effective yield strength, and the postyield behavior of the resulting fiber mats under both tension and shear loads. This study reveals the relation between the macroscopic mechanical behavior and the local randomly distributed network microstructure deformation mechanism of the nonwoven fiber network. The model presented here can also be applied to capture the mechanical behavior of other complex nonwoven network systems, like carbon nanotube networks, biological tissues, and artificial engineering networks.

scholarly journals Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2350 ◽  
Author(s):  
Jun Peng ◽  
Sheng-Qi Yang
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Damage ◽  
Strain Curve ◽  
Treatment Temperature ◽  
P Wave ◽  
High Temperature Treatment ◽  
High Porosity ◽  
Compression Tests

High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

Mechanical Properties of Electrospun Carbon Nano Fiber (ECNF)/Epoxy Nanocomposites

2007 ◽  
Author(s):  
Darunee Aussawasathien ◽  
Erol Sancaktar
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Carbon Nanofiber ◽  
Mechanical Analysis ◽  
Short Fiber ◽  
Neat Epoxy ◽  
Epoxy Nanocomposites ◽  
Cure Reaction ◽  
Fiber Aspect Ratio

Electrospun polyacrylonitrile (PAN) fiber precursor based Carbon Nanofiber (CNF) mats were produced and impregnated with epoxy resin. The mechanical properties of as-prepared nanofibers in the mat and short fiber filled epoxy nanocomposite forms were determined to demonstrate the effect of fiber aspect ratio and interconnecting network on those properties. Our experimental results reveal that epoxy nanocomposites containing Electrospun Carbon Nano Fibers (ECNF) with high fiber aspect ratio and high interconnecting network in the non-woven mat form yield better mechanical properties than those filled with short ECNFs. The ECNF mat in epoxy nanocomposites provides better homogeneity, more interlocking network, and easier preparation than short ECNFs. Mechanical properties of ECNF mat-epoxy nanocomposites, which we obtained using tensile and flexural tests, such as stiffness and modulus increased, while toughness and flexural strength decreased, compared to the neat epoxy resin. Dynamic Mechanical Analysis (DMA) results showed, higher modulus for ECNF mat-epoxy nanocomposites, compared to those for neat epoxy resin and short ECNF-epoxy nanocomposites. The epoxy nanocomposites had high modulus, even though the glass transition temperature, Tg values dropped at some extents of ECNF mat contents when compared with the neat epoxy resin. The cure reaction was retarded since the amount of epoxy and hardener decreased at high ECNF contents together with the hindering effect of the ECNF mat to the diffusion of epoxy resin and curing agent, leading to low crosslinking efficiency.

Modelling the Mechanical Behavior of Polymer-Based Nanocomposites

2012 ◽  
Vol 730-732 ◽  
pp. 543-548
Author(s):  
Alexandre Correia ◽  
S. Mohsen Valashani ◽  
Francisco Pires ◽  
Ricardo Simões
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Aspect Ratio ◽  
Mechanical Behavior ◽  
Molecular Dynamics Simulations ◽  
Initial Orientation ◽  
Fiber Concentration ◽  
Experimental Knowledge ◽  
Dynamics Simulations ◽  
Two Parameters

Molecular dynamics simulations were employed to analyze the mechanical properties of polymer-based nanocomposites with varying nanofiber network parameters. The study was focused on nanofiber aspect ratio, concentration and initial orientation. The reinforcing phase affects the behavior of the polymeric nanocomposite. Simulations have shown that the fiber concentration has a significant effect on the properties, with higher loadings resulting in higher stress levels and higher stiffness, matching the general behavior from experimental knowledge in this field. The results also indicate that, within the studied range, the observed effect of the aspect ratio and initial orientation is smaller than that of the concentration, and that these two parameters are interrelated.

Research of Mechanical Behavior for Rounded and Rectangular Clinched Joint

2014 ◽  
Vol 1035 ◽  
pp. 144-148 ◽  
Author(s):  
Lun Zhao ◽  
Xiao Cong He ◽  
Yi Lu
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Aspect Ratio ◽  
Mechanical Behavior ◽  
Failure Mode ◽  
Cross Section ◽  
Minimum Thickness ◽  
Neck Fracture ◽  
Joining Process

Joining process and mechanical properties of clinched joints in Al5052 aluminum alloy sheets had been studied in this study. The clinched joints were classified to round one and rectangle one. Results of cross-section showed that the minimum thickness of the rectangle joints were lower than the round joints, and the aspect ratio of undercut section corresponding was larger. The strength of rectangular joint was 1.7 times of round one. Failure mode of rounded joint was the upper sheet fractures at the neck having a minimum thickness, but failure mode was the mix of neck-fracture and pulled-out for rectangular joint.

scholarly journals Preparation of open-porous stereocomplex PLA/PBAT scaffolds and correlation between their morphology, mechanical behavior, and cell compatibility

RSC Advances ◽  
2018 ◽  
Vol 8 (23) ◽  
pp. 12933-12943 ◽  
Author(s):  
Yuan Kang ◽  
Peng Chen ◽  
Xuetao Shi ◽  
Guangcheng Zhang ◽  
Chaoli Wang
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Mechanical Behavior ◽  
High Porosity ◽  
Engineering Applications ◽  
Cell Compatibility ◽  
Biodegradable Scaffolds ◽  
Good Biocompatibility

For tissue engineering applications, it is essential that biodegradable scaffolds have accessible mechanical properties, high porosity, and good biocompatibility to support the formation of new tissues.

The Effect of Glass Fiber Aspect Ratio on Mechanical and Thermal Properties of PU/GF Foam Composites

2010 ◽  
Vol 93-94 ◽  
pp. 210-213
Author(s):  
Bongkot Hararak ◽  
Natcha Prakymoramas ◽  
Wuttipong Rungseesantivanon ◽  
Dumrong Thamumjitr
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Aspect Ratio ◽  
Impact Strength ◽  
Glass Fiber ◽  
Flexural Modulus ◽  
Strength Increase ◽  
Mechanical And Thermal Properties ◽  
Fiber Aspect Ratio ◽  
Heat Distortion Temperature

In this study Polyurethane (PU)/glass fiber (GF) foam composites have been produced. The PU matrix consisted of Polyol and Diphenylmethane Diisocyanate (MDI). A long glass fiber (GF) at different aspect ratio (L/D ratio) was used to study the effect of reinforcement content on their properties such as; mechanical properties (flexural modulus, stress and strain at break, hardness, impact strength) and thermal properties (heat distortion temperature, HDT). It is found that the mechanical properties such as the flexural properties (strength, strain, and modulus) and impact strength increase as increasing GF aspect ratio and optimum at aspect ratio = 7.05. However, GF aspect ratio has a slight effect on the composites hardness due to GF contents and PU densities of PU/GF foam composites are not different, significantly. And the heat distortion temperature slightly increases as GF aspect ratio.

Fabrication of High-Porosity Silicon Nitride Ceramics with Excellent Mechanical Properties

2011 ◽  
Vol 284-286 ◽  
pp. 1339-1342
Author(s):  
Shao Yun Shan ◽  
Qing Ming Jia ◽  
Ya Ming Wang ◽  
Jin Hui Peng
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Strength ◽  
High Porosity ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics ◽  
Sintering Conditions

High-porosity silicon nitride ceramics with excellent mechanical properties were fabricated by the carbothermal reduction of SiO2. The influences of sintering conditions on microstructure and mechanical properties were studied. The results showed that microstructure and mechanical properties of porous silicon nitride ceramics were dependent mostly on the sintering conditions. The sintered porous silicon nitride ceramics exhibited the formation of fibrous microstructure with submicrometer-sized, high-aspect ratio b-Si3N4 grains, and uniform pore structure. Porous Si3N4 ceramics with a porosity of about 70%, and a flexural strength of about 70 MPa were obtained by sintering at 1750°C, with lower rate of temperature rise and no retaining time. The high strength was attributed to fine, high-aspect ratio b-Si3N4 grains and uniform pores between grains.

scholarly journals Impedance of tissue-mimicking phantom material under compression

2019 ◽  
Vol 4 (1) ◽  
pp. 2-12 ◽  
Author(s):  
Barry Belmont ◽  
Robert E. Dodde ◽  
Albert J. Shih
Keyword(s):  
Mechanical Properties ◽  
Electrical Properties ◽  
Soft Tissue ◽  
Porous Structure ◽  
Mechanical Behavior ◽  
Biological Tissues ◽  
Stress And Strain ◽  
The Relationship ◽  
Passive Electrical Properties ◽  
Phantom Material

Abstract The bioimpedance of tissues under compression is a field in need of study. While biological tissues can become compressed in a myriad of ways, very few experiments have been conducted to describe the relationship between the passive electrical properties of a material (impedance/admittance) and its underlying mechanical properties (stress and strain) during deformation. Of the investigations that have been conducted, the exodus of fluid from samples under compression has been thought to be the cause of changes in impedance, though until now was not measured directly. Using a soft tissue-mimicking phantom material (tofu) whose passive electrical properties are a function of the conducting fluid held within its porous structure, we have shown that the mechanical behavior of a sample under compression can be measured through bioimpedance techniques.

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