Temat: microcracking - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Application of Acoustic Emission Method to Determine Critical Stress in Fibre Reinforced Mortar Beams
Autorzy:: Ranachowski, Z.
Jóźwiak-Niedźwiedzka, D.
Brandt, A. M.
Dębowski, T.
Powiązania:: https://bibliotekanauki.pl/articles/176697.pdf
Data publikacji:: 2012
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: critical stress
acoustic emission
microcracking
self-healing
concrete microstructure
fly ash
Opis:: The objective of this investigation was to test the effectiveness of the Acoustic Emission (AE) mea- surements in determining the critical stresses during four-point bending of mortar beams. Within the measuring procedure the parameter σcr/σ300 was calculated and analysed. Additionally, the influence of cement replacement by high calcium fly ash (HCFA) on the process of crack healing was discussed. Mortar beams with different content of HCFA and reinforced by steel microfibres were prepared for tests. After curing in standard conditions the beams were subjected to four-point bending test in order to introduce the pre-cracking. Thereafter the beams were cured in the lime water and loaded after 56 and 112 days in the same way as for the first time. Additionally the microstructure of mortars was studied in a stereo optical microscope as well in an electron scanning microscope including the Energy Dispersive X-ray analysis (EDX). The results of microstructural characterization of mortar containing HCFA from lignite combustion are presented. The applied load level slightly exceeded the critical stress, producing intense crack growth processes however did not significant affected the load capacity of the beams. During the consecutive loading the decreasing tendency of σcr/σ300 ratio was noted. The obtained results confirm that the latter parameter can be applied as a measure of the composite degradation level for the elements carrying the repeated loads of amplitude close to the critical stress of the structure and also that the cement replacement with HCFA influences the process of crack healing.
Źródło:: Archives of Acoustics; 2012, 37, 3; 261-268
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A surface engineering approach applicable to concrete repair engineering
Autorzy:: Garbacz, A.
Courard, L.
Bissonnette, B.
Powiązania:: https://bibliotekanauki.pl/articles/202018.pdf
Data publikacji:: 2013
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: durability of concrete structure
repair
adhesion
surface roughness
microcracking
surface engineering
Opis:: The objective of the paper is to analyze the effect of substrate roughness and superficial microcraking upon adhesion of repair systems using concrete surface engineering approach. The results presented in this paper have been obtained within the framework of research projects performed to develop a better understanding of the factors affecting the adhesion of repair materials through a surface engineering approach. Based on the results of investigations, the authors showed that the durability and quality of concrete repairs depend to a large degree on the characteristics of the substrate. Mechanical preparation and profiling of the concrete surface to be repaired has to be balanced with potential co-lateral effects such as superficial cracking, too often induced as a result of inappropriate concrete removal method selection, and the loss of benefits due to better mechanical anchorage. The results obtained confirm also that Concrete Surface Engineering, as a scientific concept, will definitely contribute to shed more light on how to optimize repair bond, taking into account interactions between the materials at different observation scales.
Źródło:: Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 1; 73-84
0239-7528
Pojawia się w:: Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Ultrasound monitoring for evaluation of damage in reinforced concrete
Autorzy:: Rucka, M.
Wilde, K.
Powiązania:: https://bibliotekanauki.pl/articles/201306.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: concrete
degradation
microcracking
non-destructive evaluation
ultrasonic waves
beton
degradacja
mikropęknięcia
fale ultradźwiękowe
Opis:: The paper deals with automated monitoring of damage evolution in concrete elements subjected to three-point bending tests. The monitoring is based on the nonlinear interactions of traveling ultrasonic waves with micro-crack zones inside the concrete specimens and surface-breaking cracks. The developed procedure assumes semi-continuous ultrasonic testing during the element full loading cycle and generation of the power spectral density maps for the on-line assessment of the degradation process. Two damage indicators are introduced to evaluate micro- and macro-damage. The preliminary experimental results show that the proposed automated monitoring system provides an effective method for the evaluation of progressive damage in concrete.
Źródło:: Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 1; 65-75
0239-7528
Pojawia się w:: Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Damage modelling framework for viscoelastic particulate composites via a scale transition approach
Modelowanie uszkodzenia w granulowanych kompozytach lepkosprężystych przy pomocy podejścia wieloskalowego
Autorzy:: Nadot, C.
Dragon, A.
Trumel, H.
Fanget, A.
Powiązania:: https://bibliotekanauki.pl/articles/280933.pdf
Data publikacji:: 2006
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: mikroszczeliny
kompozyty lepkosprężyste
modelowanie uszkodzeń
micro-macro transition
heterogeneous materials
morphology
viscoelasticity
anisotropic damage
microcracking
Opis:: The aim of this paper is to pursue, in the wake of the work by Nadot-Martin et al. (2003), a non-classical micromechanical study and scale transition for highly filled particulate composites with viscoelastic matrices. The present extension of a morphology-based approach due to Christoffersen (1983), carried forward to the viscoelastic small strain context by Nadot-Martin et al. (2003), consists here in introducing a supplementary mechanism, namely damage by grain/matrix debonding. Displacement discontinuities (microcracks) on grain/matrix interfaces are first incorporated in a compatible way within geometric and kinematic hypotheses regarding the grains-and-layers assembly of Christoffersen. Then, local field expressions as well as homogenized stresses are established and discussed for a given state of damage (i.e. for a given actual number of open and closed microcracks) and using the hypothesis of no sliding on closed crack lips. A comparison with the results obtained for the sound viscoelastic composite by Nadot-Martin et al. (2003) allows to quantify the damage influence on local and global levels. At last, the basic formulation of the model obtained by scale transition is completed by the second stage leading to a thermodynamically consistent formulation eliminating some superfluous damaged-induced strain-like variables related to open cracks. This second stage is presented here for a simplified system where delayed (viscoelastic) effects are (tentatively) neglected. It appears as a preliminary and crucial step for further generalization in viscoelasticity.
Celem tej publikacji jest sformułowanie wieloskalowego modelu mikromechanicznego dla granulowanych kompozytów o wysokim stopniu upakowania inkluzji w osnowie lepkosprężystej. Przedstawiony model, będący rozwinięciem morfologicznego podejścia Christoffersena (1983) i Nadot-Martin i in. (2003) w zakresie małych odkształceń lepkosprężystych, polega na wprowadzeniu do analizy dodatkowego mechanizmu uszkodzenia - mikropękania na granicy inkluzji i osnowy. Mikroszczeliny na granicy inkluzji i osnowy uwzględniono w hipotezie geometrycznej i kinematycznej metody Christoffersena. Następnie, wyznaczono lokalne oraz uśrednione pola naprężenia dla zadanego stanu uszkodzenia (tzn. dla zadanej liczby otwartych i zamkniętych mikroszczelin przy pominięciu poślizgów na powierzchniach mikroszczelin zamkniętych). Porównanie z wynikami uzyskanymi przez Nadot-Martin i in. (2003) dla nieuszkodzonego kompozytu lepkosprężystego pozwoliło na określenie wpływu uszkodzenia na poziomie lokalnym i globalnym. Na koniec, podstawowy model wieloskalowy uzupełniono o drugą część sformułowania, która pozwoliła usunąć pewne nadmiarowe odkształcenia związane z mikroszczelinami otwartymi, czyniąc cały model termodynamicznie spójnym. Ta druga część modelu wieloskalowego jest przeprowadzona przy założeniu upraszczającym, polegającym na (tymczasowym) pominięciu efektów lepkosprężystych.
Źródło:: Journal of Theoretical and Applied Mechanics; 2006, 44, 3; 553-583
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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