The sub-micron scale energy dissipative deformation mechanisms of Kevlar fibrils

McAllister, Quinn P.; Gillespie, John W.; VanLandingham, Mark R.

doi:10.1007/s10853-013-7422-6

Cited by 12 publications

(26 citation statements)

References 34 publications

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“…The result is a high aspect ratio split resembling a cat's eye. This type of deformation was first discussed in the indentation work of McAllister et al, which studied the fibrillar deformation of Kevlar fibers. Knowledge of our probe geometry reveals that the axial split dimension is typically larger than probe dimension at a given depth along the same axis.…”

Section: Resultsmentioning

confidence: 93%

Nanoscale interfibrillar adhesion in UHMWPE fibers

McDaniel

Strawhecker

Deitzel

et al. 2017

J Polym Sci B Polym Phys

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The goal of this research is to quantify the fibrillar adhesive energy in ultra-high molecular weight polyethylene fibers, characteristic of nanoscale fibril interactions. Quantification of these energies is vital to the understanding of fibrillar deformation mechanisms that have been shown to play an important role in fiber performance. This is achieved through the development and implementation of a nanosplitting technique developed through the use of AFM-enabled nanoindentation. This technique allows the quantification of nanoscale adhesive energies through careful monitoring of load and unload curves as well as examination of the residual split through high-resolution AFM images. Results indicate that the average nanoscale fibril adhesive energy is over 3 times larger than the energy expected from van der Waals interactions alone. This indicates that a significant degree of physical interactions exist between fibrils, beyond van der Waals interactions, in the form of tie-molecules, fibrillar network junctions, and bridging lamellar crystals.

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Section: Resultsmentioning

confidence: 93%

Nanoscale interfibrillar adhesion in UHMWPE fibers

McDaniel

Strawhecker

Deitzel

et al. 2017

J Polym Sci B Polym Phys

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“…Using similar nano-indentation techniques Cole and Strawhecker 123 reported local mechanical properties for four fibers including KM2Plus, Twaron, AuTx, and Dyneema. The nanoindentation and nanoscratch 124,125 studies are also important to understand the energy absorbing mechanisms in particle impregnated fabrics using shear thickening fluid 126 , silica nanoparticles 56,127 and carbon nanotubes (CNTs) 128 among others to improve the impact performance. These studies use probes that effectively mimic the contact in particle-fiber and reveal the effects of fundamental particle-fiber interactions on the energy dissipative mechanisms such as friction and particle gouging.…”

Section: Ballistic Fibrilsmentioning

confidence: 99%

Recent advances in modeling and experiments of Kevlar ballistic fibrils, fibers, yarns and flexible woven textile fabrics – a review

Sockalingam

Chowdhury

Gillespie

et al. 2016

Textile Research Journal

112

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Ballistic impact onto flexible woven textile fabrics is a complicated multi-scale problem given the structural hierarchy of the materials, anisotropic material behavior, projectile geometry-fabric interactions, impact velocity and boundary conditions. Although this subject has been an active area of research for decades, the fundamental mechanisms such as material failure, dynamic response, multi-axial loading occurring at the lower length scales during impact are not well understood. This paper reviews the recent advances in modeling and experiments of Kevlar ballistic fibrils, fibers, yarns and flexible woven textile fabrics pertinent to the deformation modes occurring during impact and serves to identify topics worthy of further investigation that will advance the basic understanding of the phenomena governing transverse impact. This review also explores on aspects such as homogeneous versus heterogeneous behavior of yarns consisting of individual fibers and the inelastic transverse behavior of the fiber which is not considered in the previous review papers on this topic.

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“…Examination of the public-domain literature carried out as part of the present work identified the following four recent papers which specifically deal with the nano-indentation/nano-scratch testing of Kevlar Õ fibers, all coauthored by Gillespie and co-workers. 4,[9][10][11] In 2012, McAllister et al 4 utilized AFM and instrumented nano-indentation testing to determine the local mechanical properties on the lengthscale of single fibers. The results obtained clearly established: (a) the absence of a well-defined shell section in the case of Kevlar Õ 49; (b) the presence of a well-defined, reduced-stiffness, ca.…”

Section: Review Of Prior Nano-indentation/nano-scratch Work On Kevlarmentioning

confidence: 99%

“…In their subsequent work in 2013, McAllister et al 10 extended the previous nano-indentation/ nano-scratch testing of Kevlar Õ 49 and Kevlar Õ KM2 single fibers to quantify the associated energies and correlate them with the attendant deformation modes. The results obtained established that:…”

Section: Review Of Prior Nano-indentation/nano-scratch Work On Kevlarmentioning

confidence: 99%

“…The findings (a)-(e) pertaining to the operation of different deformation mechanisms and the topology of the indentation are in very good agreement with their experimental counterparts reported in literature. [9][10][11] Examples of the corresponding results, but for the case of the indentation depth of 200 nm, are depicted in Figure 6(a) to (e). Examination of the results depicted in Figure 6(a) to (e), and their comparison with the corresponding results shown in Figure 5 and (e) a slightly elliptical shape of the plastic deformation zone associated with the largest extent of the equivalent plastic strain.…”

Section: Nano-indentation/nano-scratch Deformation/failure Mechanismsmentioning

confidence: 99%

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Multi-scale computational analysis of the nano-indentation and nano-scratch testing of Kevlar® 49 single fibers

Grujičić

Snipes

Ramaswami

2016

Proceedings of the Institution of Mechanical Engineers, Part L:

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Original ArticleMulti-scale computational analysis of the nano-indentation and nano-scratch testing of Kevlar Õ 49 single fibers M Grujicic, JS Snipes and S Ramaswami Abstract To carry out virtual nano-indentation and nano-scratch Kevlar Õ 49 single-fiber tests, a multi-scale computational framework has been developed and employed. Such tests are generally conducted to determine fiber local properties, as well as to provide some insight into the interaction of hard nano-particles with the fibers. The Kevlar Õ fabric-based soft armor is infused with these nano-particles for improved ballistic resistance, and tip geometry of the nano-indentation/-scratch probes is selected to match nano-particle size and geometry. Due to the fact that Kevlar Õ 49 fibers (typical diameter 12 mm) are effectively assemblies of parallel fibrils (typical diameter 100-300 nm), while atomic bond length in Kevlar Õ fibers is of the order of 0.2 nm, a continuum-level finite-element framework has been developed. However, to more accurately account for some of the key aspects of the fiber-material constitutive behavior, e.g. inter-fibril cohesion, the continuum-level computational analysis has been supplemented with atomic-level molecular-statics/-dynamics calculations. In good agreement with their experimental counterparts, the results obtained revealed that the extent of participation of different fibril-deformation modes (e.g. transverse compression, inter-fibril shear, axial tension, axial tensile fracture, fibrillation, axial compression, buckling and pile-up formation ahead of the nano-scratch probe, etc.) is a function of the indentation/scratch depth. Also, a relatively good agreement was obtained between the computed and experimentally measured nano-indentation forces/energies for both shallow and deep indentations, and for the nanoscratch forces/energies, but only for shorter scratch lengths. At longer scratch lengths, the ''short-fiber'' effects cause the computation/experiment agreement to worsen.

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The sub-micron scale energy dissipative deformation mechanisms of Kevlar fibrils

Cited by 12 publications

References 34 publications

Nanoscale interfibrillar adhesion in UHMWPE fibers

Nanoscale interfibrillar adhesion in UHMWPE fibers

Recent advances in modeling and experiments of Kevlar ballistic fibrils, fibers, yarns and flexible woven textile fabrics – a review

Multi-scale computational analysis of the nano-indentation and nano-scratch testing of Kevlar® 49 single fibers

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