Multi-length scale modeling and analysis of microstructure evolution and mechanical properties in polyurea

Grujičić, M.; Pandurangan, B.; King, A. E.; Runt, James; Tarter, J.; Dillon, Gregory P.

doi:10.1007/s10853-010-4998-y

Cited by 61 publications

(44 citation statements)

References 13 publications

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“…In other words, a vast body of experimental studies pertaining to the blast/ballistic-protection performance of various polyurea bearing protective structures was not the subject of the present investigation. An overview of the latter investigations can be found in our prior work (Ref [16][17][18][19][20][21].…”

Section: Overview Of the Prior Experimental Investigationsmentioning

confidence: 99%

Experimental Characterization and Material-Model Development for Microphase-Segregated Polyurea: An Overview

Grujičić

Pandurangan

et al. 2011

J. of Materi Eng and Perform

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Numerous experimental investigations reported in the open literature over the past decade have clearly demonstrated that the use of polyurea external coatings and/or inner layers can substantially enhance both the blast resistance (the ability to withstand shock loading) and the ballistic performance (the ability to defeat various high-velocity projectiles such as bullets, fragments, shrapnel, etc. without penetration, excessive deflection or spalling) of buildings, vehicles, combat-helmets, etc. It is also well established that the observed high-performance of polyurea is closely related to its highly complex submicron scale phasesegregated microstructure and the associated microscale phenomena and processes (e.g., viscous energy dissipation at the internal phase boundaries). As higher and higher demands are placed on blast/ballistic survivability of the foregoing structures, a need for the use of the appropriate transient nonlinear dynamics computational analyses and the corresponding design-optimization methods has become ever apparent. A critical aspect of the tools used in these analyses and methods is the availability of an appropriate physically based, high-fidelity material model for polyurea. There are presently several public domain and highly diverse material models for polyurea. In the present work, an attempt is made to critically assess these models as well as the experimental methods and results used in the process of their formulation. Since these models are developed for use in the high-rate loading regime, they are employed in the present work, to generate the appropriate shock-Hugoniot relations. These relations are subsequently compared with their experimental counterparts in order to assess the fidelity of these models.

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Section: Overview Of the Prior Experimental Investigationsmentioning

confidence: 99%

Experimental Characterization and Material-Model Development for Microphase-Segregated Polyurea: An Overview

Grujičić

Pandurangan

et al. 2011

J. of Materi Eng and Perform

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“…Intra-sheet hydrogen-bond term: Following our prior work on polyurea [21][22][23], the potential energy associated with intra-sheet inter-chain hydrogen bonding is expressed using the 18-9 Lennard-Jones type of function as…”

Section: Coarse-grained Force-field Functionsmentioning

confidence: 99%

“…In these cases (a) following uniaxial compression/ tension and the formation of deformation-induced defects such as kink bands or fibrillation, the unit cell is subjected to longitudinal-tensile deformation while allowing for the operation of the Poisson's effects in the transverse directions; and (b) the trajectory data had to be post-processed to extract and quantify the effect of preludial loading. During tensile reloading, the procedure described in our recent work [21] was utilized to compute the normal axial stress and its rate of change with an increase in the axial tensile strain. The longitudinal-tensile strength of the single PPTA fibril is then set equal to the value of the corresponding normal stress at which the rate of stress increases with increase in strain begins to decline ''appreciably'' (denoting the onset of inelastic-deformation and/or damage-initiation processes).…”

Section: Post-processing Data-reduction Analysismentioning

confidence: 99%

The effect of plain-weaving on the mechanical properties of warp and weft p-phenylene terephthalamide (PPTA) fibers/yarns

et al. 2014

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Coarse-grained molecular statics/dynamics methods are first used to investigate degradation in the PPTA fiber/yarn tensile strength, as a result of the prior compressive or tensile loading. PPTA fibers/yarns experience this type of loading in the course of a plain-weaving process, the process which is used in the fabrication of ballistic fabric and flexible armor. The more common allatom molecular simulations were not used to assess strength degradation for two reasons: (a) the size of the associated computational domain rendering reasonable run-times would be too small and (b) modeling of the mechanical response of multi-fibril PPTA fibers could not be carried out (again due to the limited size of the computational domain). However, all-atom simulations were used to (a) define the coarse-grained particles (referred to as ''beads'') and (b) parameterize various components of the bead/bead force-field functions. In the second portion of the work, a simplified finite-element analysis of the plain-weaving process is carried out in order to assess the extent of tensile-strength degradation in warp and weft yarns during the weaving process. In this analysis, a new material model is used for the PPTA fibers/yarns. Specifically, PPTA is considered to be a linearly elastic, transversely isotropic material with degradable longitudinal-tensile strength and the longitudinal Young's modulus. Equations governing damage and strength/stiffness degradation in this material model are derived and parameterized using the coarse-grained simulation results. Lastly, the finite-element results are compared with their experimental counterparts, yielding a decent agreement.

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“…2(b) represents a completely mixed state of this material. As discussed in our prior work [1], within the atomic scale computational methods used, micro-phase separation processes cannot be generally investigated. The main reasons for this are as follows:…”

Section: Computational Modelmentioning

confidence: 99%

“…Due to its resulting high direct and indirect economic costs to society at large (through lost earning potential of the affected and the burden of care imposed on their families), TBI has become an important societal problem. This has led to an urgent need for the development of novel head protection strategies requiring in-depth understanding of relationships between the morphology/structure (at different length scales) of the constituent materials and the activation/effectiveness of different blast-energy dissipation/dispersion mechanisms [1]. Once such knowledge is gained, new material systems with superior blast-energy dissipation/dispersion capabilities can be designed, synthesized, and their high shock-mitigation potential validated through the use of test coupons [2].…”

Section: Introductionmentioning

confidence: 99%

Molecular-level simulations of shock generation and propagation in polyurea

Grujičić

Pandurangan

Bell

et al. 2011

Materials Science and Engineering: A

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Multi-length scale modeling and analysis of microstructure evolution and mechanical properties in polyurea

Cited by 61 publications

References 13 publications

Experimental Characterization and Material-Model Development for Microphase-Segregated Polyurea: An Overview

Experimental Characterization and Material-Model Development for Microphase-Segregated Polyurea: An Overview

The effect of plain-weaving on the mechanical properties of warp and weft p-phenylene terephthalamide (PPTA) fibers/yarns

Molecular-level simulations of shock generation and propagation in polyurea

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