Polymer Fibers

A special issue of Fibers (ISSN 2079-6439).

Deadline for manuscript submissions: closed (30 November 2016) | Viewed by 42710

Special Issue Editors


E-Mail Website
Guest Editor
Center for Composite Materials, Department of Materials Science and Engineering, Department of Civil and Environmental, Engineering Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
Interests: composites; fibers; interphases; processing; multi-scale modeling

E-Mail Website
Guest Editor
Center for Composite Materials, Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA
Interests: composites; ballistic impact; computational mechanics; materials

Special Issue Information

Dear Colleagues,

High performance fibers such as carbon, glass, Kevlar, Spectra and Dyneema are used in fiber reinforced composites in the form of flexible textile fabrics and laminates for applications including aerospace, automotive and personenel protection ballistic impact among others. These fibers have superior specific strength and specific stiffness. From an application standpoint, structural performance of these materials is a complicated multiscale problem due to the hierarchical multiscale architecture, anisotropic material behavior, statistical fiber failure and others. The objective of this special issue is to focus on the fiber properties, microstructure, processing, deformation, failure and energy absorption mechanisms of these materials at different length scales pertinent to the application. Original research papers are invited for this special issue.

Prof. Dr. John W. Gillespie
Dr. Subramani Sockalingam
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fibers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aerospace
  • Ballistic impact
  • Polymer fibers
  • Failure mechanisms
  • Strength
  • Stiffness
  • Multiscale
  • Energy absorption

Published Papers (5 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

15917 KiB  
Article
Exploration of Wave Development during Yarn Transverse Impact
by Matthew Hudspeth, Emily Jewell, Suzanne Horner, James Zheng and Weinong Chen
Fibers 2017, 5(2), 17; https://doi.org/10.3390/fib5020017 - 16 May 2017
Cited by 4 | Viewed by 7202
Abstract
Single yarns have been impacted in a transverse fashion so as to probe the characteristics of resulting wave development. Longitudinal wave speeds were tracked in efforts to directly measure the yarn tensile stiffness, resulting in a slight increase in the modulus of Kevlar [...] Read more.
Single yarns have been impacted in a transverse fashion so as to probe the characteristics of resulting wave development. Longitudinal wave speeds were tracked in efforts to directly measure the yarn tensile stiffness, resulting in a slight increase in the modulus of Kevlar® KM2 and Dyneema® SK76. Additionally, the load developed in AuTx® and Kevlar® KM2 yarns behind the longitudinal wave front has been recorded, providing additional verification for the Smith relations. Further effort to bolster the Smith equations has been successfully performed via tracking transverse wave speeds in AuTx® yarns over a range of impacting velocities. Additional emphasis has been placed at understanding the transverse wave development around the yarn critical velocity, demonstrating that there is a velocity zone where partial yarn failure is detected. Above the critical velocity, measurement of early time transverse wave speeds also agrees with the Smith solution, though the wave speed quickly reduces in value due to the drop in tensile stresses resulting from filament rupture. Finally, the Smith equations have been simplified and are compared to the Cunniff equation, which bear a striking resemblance. Due to such a resemblance, it is suggested that yarn critical velocity experiments can be performed on trial yarn material, and the effect of modifying yarn mechanical properties is discussed. Full article
(This article belongs to the Special Issue Polymer Fibers)
Show Figures

Figure 1

5323 KiB  
Article
Verification and Validation of a Three-Dimensional Orthotropic Plasticity Constitutive Model Using a Unidirectional Composite
by Canio Hoffarth, Bilal Khaled, Loukham Shyamsunder, Subramaniam Rajan, Robert Goldberg, Kelly S. Carney, Paul DuBois and Gunther Blankenhorn
Fibers 2017, 5(1), 12; https://doi.org/10.3390/fib5010012 - 4 Mar 2017
Cited by 15 | Viewed by 7259
Abstract
A three-dimensional constitutive model has been developed for modeling orthotropic composites subject to impact loads. It has three distinct components—a deformation model involving elastic and plastic deformations; a damage model; and a failure model. The model is driven by tabular data that is [...] Read more.
A three-dimensional constitutive model has been developed for modeling orthotropic composites subject to impact loads. It has three distinct components—a deformation model involving elastic and plastic deformations; a damage model; and a failure model. The model is driven by tabular data that is generated either using laboratory tests or via virtual testing. A unidirectional composite—T800/F3900, commonly used in the aerospace industry, is used in the verification and validation tests. While the failure model is under development, these tests indicate that the implementation of the deformation and damage models in a commercial finite element program, LS-DYNA, is efficient, robust and accurate. Full article
(This article belongs to the Special Issue Polymer Fibers)
Show Figures

Figure 1

6017 KiB  
Article
Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles
by Stuart Leigh Phoenix, Ulrich Heisserer, Harm Van der Werff and Marjolein Van der Jagt-Deutekom
Fibers 2017, 5(1), 8; https://doi.org/10.3390/fib5010008 - 2 Mar 2017
Cited by 24 | Viewed by 8642
Abstract
Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to [...] Read more.
Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i) a reverse-fired, fragment simulating projectile (FSP) where the flat rear face impacted the yarn rather than the beveled nose; and (ii) a ‘saddle-nosed projectile’ having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young’s modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre-tension stress resulted in apparent yarn strengths much lower than 3.4 GPa from quasi-static tension tests, although a plot of critical velocity versus initial tension did project to 3.4 GPa at zero velocity. This strength reduction (occurring also in aramid fibers) suggested that transverse fiber distortion and yarn compaction from a compressive shock wave under the projectile results in fiber-on-fiber interference in the emerging transverse wave front, causing a gradient in fiber tensile strains with depth, and strain concentration in fibers nearest the projectile face. A model was developed to illustrate the phenomenon. Full article
(This article belongs to the Special Issue Polymer Fibers)
Show Figures

Figure 1

6840 KiB  
Article
Role of Inelastic Transverse Compressive Behavior and Multiaxial Loading on the Transverse Impact of Kevlar KM2 Single Fiber
by Subramani Sockalingam, John W., Gillespie and Michael Keefe
Fibers 2017, 5(1), 9; https://doi.org/10.3390/fib5010009 - 22 Feb 2017
Cited by 13 | Viewed by 7767
Abstract
High-velocity transverse impact of ballistic fabrics and yarns by projectiles subject individual fibers to multi-axial dynamic loading. Single-fiber transverse impact experiments with the current state-of-the-art experimental capabilities are challenging due to the associated micron length-scale. Kevlar® KM2 fibers exhibit a nonlinear inelastic [...] Read more.
High-velocity transverse impact of ballistic fabrics and yarns by projectiles subject individual fibers to multi-axial dynamic loading. Single-fiber transverse impact experiments with the current state-of-the-art experimental capabilities are challenging due to the associated micron length-scale. Kevlar® KM2 fibers exhibit a nonlinear inelastic behavior in transverse compression with an elastic limit less than 1.5% strain. The effect of this transverse behavior on a single KM2 fiber subjected to a cylindrical and a fragment-simulating projectile (FSP) transverse impact is studied with a 3D finite element model. The inelastic behavior results in a significant reduction of fiber bounce velocity and projectile-fiber contact forces up to 38% compared to an elastic impact response. The multiaxial stress states during impact including transverse compression, axial tension, axial compression and interlaminar shear are presented at the location of failure. In addition, the models show a strain concentration over a small length in the fiber under the projectile-fiber contact. A failure criterion, based on maximum axial tensile strain accounting for the gage length, strain rate and multiaxial loading degradation effects are applied to predict the single-fiber breaking speed. Results are compared to the elastic response to assess the importance of inelastic material behavior on failure during a transverse impact. Full article
(This article belongs to the Special Issue Polymer Fibers)
Show Figures

Figure 1

10687 KiB  
Article
Molecular Dynamics Modeling of the Effect of Axial and Transverse Compression on the Residual Tensile Properties of Ballistic Fiber
by Sanjib C. Chowdhury, Subramani Sockalingam and John W. Gillespie
Fibers 2017, 5(1), 7; https://doi.org/10.3390/fib5010007 - 14 Feb 2017
Cited by 29 | Viewed by 11265
Abstract
Ballistic impact induces multiaxial loading on Kevlar® and polyethylene fibers used in protective armor systems. The influence of multiaxial loading on fiber failure is not well understood. Experiments show reduction in the tensile strength of these fibers after axial and transverse compression. [...] Read more.
Ballistic impact induces multiaxial loading on Kevlar® and polyethylene fibers used in protective armor systems. The influence of multiaxial loading on fiber failure is not well understood. Experiments show reduction in the tensile strength of these fibers after axial and transverse compression. In this paper, we use molecular dynamics (MD) simulations to explain and develop a fundamental understanding of this experimental observation since the property reduction mechanism evolves from the atomistic level. An all-atom MD method is used where bonded and non-bonded atomic interactions are described through a state-of-the-art reactive force field. Monotonic tension simulations in three principal directions of the models are conducted to determine the anisotropic elastic and strength properties. Then the models are subjected to multi-axial loads—axial compression, followed by axial tension and transverse compression, followed by axial tension. MD simulation results indicate that pre-compression distorts the crystal structure, inducing preloading of the covalent bonds and resulting in lower tensile properties. Full article
(This article belongs to the Special Issue Polymer Fibers)
Show Figures

Figure 1

Back to TopTop