Optimisation of the Capriccio Method to Couple Particle- and Continuum-Based Simulations of Polymers

Pfaller, Sebastian; Kergaßner, Andreas; Steinmann, Paul

doi:10.1007/s42493-019-00028-y

Cited by 19 publications

(44 citation statements)

References 20 publications

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“…Figure 22 compares the force histories of the MD-simulation and an optimized FE-model containing a single Maxwell element. The resulting material parameters are reasonable and add up to an instantaneous stiffness of c0=E+c1=809.80.166667emMPa, which is close to the values we have determined elsewhere [10,28,42]. All error values er stated below to quantify the quality of the calibration are computed as the Euclidean norm of the difference between the MD goal and FE optimum vectors, divided by the number of data points in the goal, e.g., er=1377∥FxMD−FxFE∥2.…”

Section: Exemplary Calibration Of Continuum Mechanical Constitutivsupporting

confidence: 72%

“…As mentioned in the introduction, such material laws are particularly needed in partitioned-domain multiscale techniques, like the Capriccio method introduced by Pfaller et al [9,28,42], but are also a necessity to correlate findings from MD simulations with those obtained from continuum mechanical computations and experimental evidence. Beyond this, developing and adjusting MD models focusing on their capability to reproduce mechanical material properties require a tool as presented here.…”

Section: Conclusion and Outlookmentioning

confidence: 99%

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Extensive CGMD Simulations of Atactic PS Providing Pseudo Experimental Data to Calibrate Nonlinear Inelastic Continuum Mechanical Constitutive Laws

et al. 2019

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In this contribution, we present a characterization methodology to obtain pseudo experimental deformation data from CG MD simulations of polymers as an inevitable prerequisite to choose and calibrate continuum mechanical constitutive laws. Without restriction of generality, we employ a well established CG model of atactic polystyrene as exemplary model system and simulate its mechanical behavior under various uniaxial tension and compression load cases. To demonstrate the applicability of the obtained data, we exemplarily calibrate a viscoelastic continuum mechanical constitutive law. We conclude our contribution by a thorough discussion of the findings obtained in the numerical pseudo experiments and give an outline of subsequent research activities. Thus, this work contributes to the field of multiscale simulation methods and adds a specific application to the body of knowledge of CG MD simulations.

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Section: Exemplary Calibration Of Continuum Mechanical Constitutivsupporting

confidence: 72%

Section: Conclusion and Outlookmentioning

confidence: 99%

Extensive CGMD Simulations of Atactic PS Providing Pseudo Experimental Data to Calibrate Nonlinear Inelastic Continuum Mechanical Constitutive Laws

et al. 2019

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“…A thorough overview of these atomistic-to-continuum coupling strategies can be found in [51]. Based on the preceding methods, Pfaller et al introduced the CAPRICCIO method [61,62,63,64,65,66,67] for the treatment of amorphous polymers, which we discuss in more detail in Section 2.1.…”

Section: Numerical Studiesmentioning

confidence: 99%

A coupled MD-FE methodology to characterize mechanical interphases in polymeric nanocomposites

Ries

Possart

Steinmann

et al. 2021

International Journal of Mechanical Sciences

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This contribution introduces an unconventional procedure to characterize spatial profiles of elastic and inelastic properties inside polymer interphases around nanoparticles. Interphases denote those regions in the polymer matrix whose mechanical properties are influenced by the filler surfaces and thus deviate from the bulk properties. They are of particular relevance in case of nano-sized filler particles with a comparatively large surface-to-volume ratio and hence can explain the frequent observation that the overall properties of polymer nanocomposites cannot be determined by classical mixing rules, which only consider the behavior of the individual constituents. Interphase characterization for nanocomposites poses hardly solvable challenges to the experimenter and is still an unsolved problem in many cases. Instead of real experiments, we perform pseudo experiments using our recently developed Capriccio method, which is an MD-FE domain-decomposition tool specifically designed for amorphous polymers. These pseudo-experimental data then serve as input for a typical inverse parameter identification. With this procedure, spatially varying mechanical properties inside the polymer are, for the first time, translated into intuitively understandable profiles of continuum mechanical parameters. As a model material, we employ silica-enforced polystyrene, for which our procedure reveals exponential saturation profiles for Young's modulus and the yield stress inside the interphase, where the former takes about seven times the bulk value at the particle surface and the latter roughly triples. Interestingly, hardening coefficient and Poisson's ratio of the polymer remain nearly constant inside the interphase. Besides gaining insight into the constitutive influence of filler particles, these unexpected and intriguing results also offer interesting explanatory options for the failure behavior of polymer nanocomposites.

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“…Therefore we combine the advantages of particle-based and continuum methods in a concurrent multiscale approach called the Capriccio method, which is specifically designed to model and investigate amorphous polymers and nanocomposites. The method was introduced by Pfaller et al [1,2,3] and has been optimized and extended since then [4,5]. The Capriccio method has been successfully employed to gain insights into mechanical interphases in polymeric nanocomposites [6,7].…”

Section: Introductionmentioning

confidence: 99%

Multiscale FE-MD Coupling: Influence of the Chain Length on the Mechanical Behavior of Coarse-Grained Polystyrene

Ries¹,

Weber²,

Striegel³

et al. 2021

14th WCCM-ECCOMAS Congress

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Polymers have become increasingly essential to cope with modern engineering challenges. To better understand their microstructure's influence, multi-scale approaches that couple molecular dynamics and continuum mechanics are emerging progressively. However, these simulation techniques require detailed knowledge of the material behavior, which is commonly derived from molecular dynamics simulations. Reducing the degrees of freedom by coarse graining enables the investigation of sufficiently large samples and thus we focus on coarse-grained (CG) polystyrene as a model material. The goal of this contribution is twofold: Firstly, we identify the minimum sample size necessary to analyze the mechanical properties. Secondly, we quantify the influence of chain length on the material behavior of polystyrene. To this end, we investigate density, end-to-end distance, stress-strain behavior, Young's modulus, and Poisson's ratio. In conclusion, we were able to verify that we can use significantly smaller samples for our investigations without affecting their structure or mechanical behavior. The chain length has a drastic influence on the mechanical properties, with a loss of stiffness in the range of 15 % for very short-chain specimens.

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Optimisation of the Capriccio Method to Couple Particle- and Continuum-Based Simulations of Polymers

Cited by 19 publications

References 20 publications

Extensive CGMD Simulations of Atactic PS Providing Pseudo Experimental Data to Calibrate Nonlinear Inelastic Continuum Mechanical Constitutive Laws

Extensive CGMD Simulations of Atactic PS Providing Pseudo Experimental Data to Calibrate Nonlinear Inelastic Continuum Mechanical Constitutive Laws

A coupled MD-FE methodology to characterize mechanical interphases in polymeric nanocomposites

Multiscale FE-MD Coupling: Influence of the Chain Length on the Mechanical Behavior of Coarse-Grained Polystyrene

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