Progressive Damage of Unidirectional Composite Panels

Laš, Vladislav; Zemčík, Robert

doi:10.1177/0021998307086187

Cited by 35 publications

(14 citation statements)

References 44 publications

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“…Modal analysis was performed using finite element method and the resulting eigenfrequencies were compared to the experimental data. The cracks in the damaged beam were simulated by stiffness degradation approach [4]. The summary of frequencies calculated by modal analysis and corresponding values from experiments are shown in Table 1 for the four lowest modes.…”

Section: Experimental Setup Methods and Numerical Modelmentioning

confidence: 99%

Structural health monitoring of hybrid composite structure with piezoelectric patches

Zemčík

Kroupa

Bartošek

2011

Proc Appl Math and Mech

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Structural health monitoring is performed on a hybrid structure specially designed for simple assembly and disassembly or replacement of components. The net‐like structure is composed of composite beams connected with aluminum pads and it is fixed to a frame in selected locations. Modal analysis is performed both experimentally and numerically. The experiment is carried out using impact hammer, accelerometer and spectrum analyzer and the frequency and damping characteristics are thus obtained. The numerical model using finite element method is validated by comparison of the calculated and measured eigenfrequencies and eigenshapes. Furthermore, piezoelectric patches are applied on selected beam. The modal analysis is carried out again using the piezoelectric patches and with some of the composite beams replaced by damaged beam. The variation in modal characteristics between original and damaged configurations is analyzed both experimentally and numerically. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Experimental Setup Methods and Numerical Modelmentioning

confidence: 99%

Structural health monitoring of hybrid composite structure with piezoelectric patches

Zemčík

Kroupa

Bartošek

2011

Proc Appl Math and Mech

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“…The elasto-plastic decomposition of the axial strain e is also considered: 6,7 e e e = + E P (8) where e P is the plastic strain. The function of plasticity decides whether the plastic flow will be present.…”

Section: Materials Modelmentioning

confidence: 99%

One-dimensional elasto-plastic material model with damage for a quick identification of the material properties

Kroupa¹,

Srbová²,

Klesa³

2017

Mater. tehnol.

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Material parameters for elastic, plastic and damage behavior of low-molecular-weight epoxy resin CHS-EPOXY 520 hardened with CHS-P 11 are identified in the paper. Uniaxial cyclic static tests were performed on specimens in line with the ASTM standard D638 -10 using a Zwick Roell/Z050 test machine with a BTC-Exaclbi.001 clip-on biaxial extensometer. Poisson's ratio and tensile strength were calculated directly from the test results. Other parameters were identified using a combination of a one-dimensional material model, which assumes the infinitesimal strain theory and takes into account elastic, plastic and damage behavior and the optimization method. The model is coded in Python and the values of the material parameters are identified using the optiSLang optimization software. The optimization process uses simple design improvement and gradient-based algorithms with the goal to minimize the difference between the force-elongation curves recorded during the tests and those calculated with the proposed model. Keywords: epoxy, identification, optimization, elasticity, plasticity, damage V~lanku so opredeljeni parametri epoksi smole z majhno molekulsko maso CHS-EPOXY 520, utrjeno z CHS-p 11, pri elasti~nem, plasti~nem obna{anju in pri po{kodbi. Enoosni stati~ni cikli~ni preizkusi so bili izvedeni na vzorcih, ki ustrezajo ASTM standardu D638-10, z uporabo Zwick Roell/Z050 preizkusnega stroja z name{~enim dvoosnim ekstenziometrom BTC-Exaclbi.001. Poissonov koli~nik in natezna trdnost sta bili izra~unani neposredno iz rezultatov preizkusov. Drugi parametri so ugotovljeni s kombinacijo enodimenzijskega modela materiala, ki predpostavlja infinitezimalno teorijo napetosti in ki upo{teva obna{anje v elasti~nem, plasti~nem in ob po{kodbi ter metodo optimizacije. Model je kodiran v Pythonu in vrednosti parametrov materiala so ugotovljene z uporabo optiSLang programske opreme za optimizacijo. Proces optimizacije uporablja enostavno izbolj{anje oblike in algoritme, ki temeljijo na gradientu, s ciljem po zmanj{anju razlike med krivuljo silaraztezek zabele`ene med preizkusom in izra~unane z uporabo predlaganega modela.

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“…The transformation from system O (1,2,3) to system O(x,h,z) is performed using deformation gradient: …”

Section: Specimensmentioning

confidence: 99%

“…(Figure 2). The transformation from system O(x,y,z) to system O (1,2,3) is performed using the rotation about axes z º e 3 by angle q. The strains are transformed using relation e 12 = T r e xy 1,2 and the stresses are transformed using relation s 12 = T r -T s xy 3 where the transformation matrix has the following form: …”

Section: Introductionmentioning

confidence: 99%

Non-linear finite-element simulations of the tensile tests of textile composites

Kroupa¹,

Kunc²,

Zemčík³

2015

Mater. Tehnol.

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The main aim of this paper is to find if it is possible to identify material parameters using only three force-displacement dependencies, each for a different angle between the loading force and the principal material directions. The tested materials are textiles made of epoxy resin and fibers in the form of a glass plain weave, a glass quasi-unidirectional weave, a carbon plain weave, a carbon quasi-unidirectional weave, an aramid plain weave and an aramid quasi-unidirectional weave. The plain weave has theoretically 50 % of the fibers in the first and 50 % in the second principal material direction. The quasi-unidirectional weave has theoretically 90 % of the fibers in the first and 10 % in the second principal material direction. Seven types of specimens for each material were subjected to experimental tests. The first principal material direction of each material forms an angle between 0°and 90°with a step of 15°with the applied loading force. The results show that it is possible to identify the material parameters with sufficient accuracy using only three force-displacement dependencies for five out of six materials. Keywords: textile composite, cyclic tensile test, material parameters, plasticity, weave locking, identification, optimization Namen~lanka je preiskava mo`nosti ugotavljanja parametrov materiala z uporabo samo treh odvisnosti sila-raztezek pri razli~nem kotu med silo obremenjevanja in glavno smerjo materiala. Preiskovani materiali so tekstil, izdelan iz epoksi smole in vlaken v obliki platnene vezave, kvazi usmerjene vezave, ogljikove platnene vezave, ogljikove kvazi usmerjene vezave, aramidne platnene vezave in aramidne kvazi usmerjene vezave. Platnena vezava ima teoreti~no 50 % vlaken v prvi in 50 % v drugi prednostni smeri usmerjenosti materiala. Kvazi usmerjena vezava ima teoreti~no 90 % v prvi in 10 % v drugi prednostni smeri usmerjenosti materiala. Sedem vrst vzorcev vsakega materiala je bilo preverjeno s preizkusi. Prva glavna usmerjenost pri vseh materialih je bila pod kotom med 0°in 90°s koraki po 15°glede na delovanje sile. Rezultati ka`ejo, da je bilo mogo~e dovolj zanesljivo ugotoviti parametre materiala samo z uporabo treh odvisnosti sila-raztezek pri petih od {estih uporabljenih materialih.

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Progressive Damage of Unidirectional Composite Panels

Cited by 35 publications

References 44 publications

Structural health monitoring of hybrid composite structure with piezoelectric patches

Structural health monitoring of hybrid composite structure with piezoelectric patches

One-dimensional elasto-plastic material model with damage for a quick identification of the material properties

Non-linear finite-element simulations of the tensile tests of textile composites

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