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    Wyświetlanie 1-5 z 5
    Tytuł:
    The elastic undrained modulus Eu50 for stiff consolidated clays related to the concept of stress history and normalized soil properties
    Autorzy:
    Stróżyk, J.
    Tankiewicz, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/178538.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    consolidated clays
    stress history
    normalised elastic modulus
    triaxial test
    Opis:
    The paper presents the results of a triaxial test conducted on stiff, consolidated clays. The standard TXCIU procedure (isotropic consolidation and undrained shearing) was applied in the laboratory soil tests. The undrained elastic modulus Eu50 was de- termined from each test. The Eu50 values were determined for soil samples cut out from different depths and tested under different confining pressures. There was a significant scatter of values with depth, and no relationships between Eu50 modules or other geotechnical parameters (e.g., cu) were observed. This work presents the concept of normalization of Eu50 modulus values using modified normalization SHANSEP (Stress History And Normalized Soil Engineering Properties). This method was first proposed for estimating the value of the undrained shear strength cu normalizing the parameter relative to the in situ effective vertical stress σ vo and loading history (overconsolidation stress σ p and overconsolidation ratio OCR) of the soil. The study demonstrated that the concept of normalization of soil properties can also be used for testing elastic modulus Eu50 of con- solidated natural clays and normalized values of geotechnical parameters taking into account the state of stress and load history can be correlated with the value of the overburden pressure.
    Źródło:
    Studia Geotechnica et Mechanica; 2016, 38, 3; 67-72
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elastic modulus for long-term evaluation of the tensile properties of polypropylene meshes in an in vivo rat model
    Autorzy:
    Przydacz, M.
    Mahfouz, W.
    Loutochin, O.
    Ghezzi, Ch. E.
    Carmel, M.
    Corcos, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/306894.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    wytrzymałość
    stała sprężystości
    I-STOP
    TVT-O
    tensile properties
    elastic modulus
    mid-urethral slings
    Opis:
    Mid-urethral slings have become the gold standard treatment of stress urinary incontinence in women. Their tensile properties should be evaluated to measure how they wear off with time. Our objective was long-term assessment of the tensile properties of 2 synthetic tapes (TVT-O and I-STOP) after in vivo implantation in rats in terms of elastic modulus. Methods: Strips from both meshes were implanted in the abdominal wall of 30 rats, which were sacrificed at 5 time intervals. Their fibers were untangled to single components. Ultimate tensile strength (UTS), strain at UTS and the elastic modulus of each fiber type were measured. Results: I-STOP maintained UTS and strain over time, while TVT-O UTS and strain were significantly reduced. However, the elastic modulus of both tapes remained constant. Conclusions: Both meshes maintained their stiffness and elasticity with time. Elastic modulus could be an appropriate factor to predict long-term implantation outcomes. The clinical significance of such findings remains to be demonstrated by long-term analysis.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2017, 19, 4; 153-160
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On prediction of the compressive strength and failure patterns of human vertebrae using a quasi-brittle continuum damage finite element model
    Autorzy:
    Nakhli, Zahira
    Hatira, Fafa Ben
    Pithioux, Martine
    Chabrand, Patrick
    Saanouni, Khemais
    Powiązania:
    https://bibliotekanauki.pl/articles/307420.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    element końcowy
    moduł sprężystości
    złamanie kręgów
    model uszkodzenia
    finite element
    elastic modulus
    vertebrae fracture
    quasi-brittle damage model
    mesh sensitivity
    Opis:
    Damage of bone structures is mainly conditioned by bone quality related to the bone strength. The purpose of this work was to present a simple and reliable numerical treatment of a quasi-brittle damage constitutive model coupled with two different elastic modulus and to compare the numerical results with the experimental ones. Methods: To achieve this goal, a QCT based finite element model was developed within the framework of CDM (Continuum Damage Mechanics) and implemented in the FE code (ABAQUS). It described the propagation of brittle cracks which will help to predict the ultimate load fracture of a human vertebra by reproducing the experimental failure under quasi-static compressive loading paths of nineteen cadaveric lumbar vertebral bodies. Results: The numerical computations delivered by the proposed method showed a better agreement with the available experimental results when bone volume fraction related Young’s modulus (E(BV/TV)) is used instead of density related Young’s modulus (E(ρ)). Also, the study showed that the maximum relative error (%) in failure was 8.47% when E(BV/TV) was used, whereas the highest relative error (%) was 68.56% when E(ρ) was adopted. Finally, a mesh sensitivity analysis revealed that the element size has a weak incidence on the computed load magnitude. Conclusions: The numerical results provided by the proposed quasi-brittle damage model combined with E(BV/TV) are a reliable tool for the vertebrae fracture prediction.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 2; 143-151
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effect of trabecular bone storage method on its elastic properties
    Autorzy:
    Mazurkiewicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307220.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    analiza statystyczna
    moduł sprężystości
    kość beleczkowa
    zamrażanie-odmrażanie cykliczne
    statistical analysis
    elastic modulus
    trabecular bone
    freeze-thaw cycle
    storage method
    Opis:
    Purpose: The purpose of the study was to evaluate the effects of different methods of trabecular bone storage on changes in its elastic properties. Methods: 186 porcine trabecular bone samples were divided into 6 groups, approximately 30 samples each. Five groups were stored using the following methods: in buffered 10% formalin solution at room temperature, frozen at –21 C, in the open air at room temperature, in 96% alcohol solution and in 50% alcohol solution at room temperature. The samples were subjected to compression test to measure the elastic modulus. The samples after the first measurement were subjected to further measurements for 14 weeks, every 2 weeks. The sixth group was used to determine the effects of 10 freeze-thaw cycles on changes in the elastic modulus. A Kolmogorov–Smirnov test at significance level p = 0.05 was used to determine the significance of changes in time. Results: The changes in elastic properties caused by the different storage methods were statistically insignificant, except for the group of samples stored in the open air. The changes in elastic modulus after 10 freeze-thaw cycles were also statistically insignificant. Conclusions: Except for the storage method in the open air, other storage methods did not significantly affect changes in elastic properties of the trabecular bones after 14 weeks. No effects of 10 freeze-thaw cycles on changes in elastic modulus were observed.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2018, 20, 1; 21-27
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    O występowaniu i wpływie na trwałość konstrukcji drewnianych, zmiennego w czasie modułu sztywności poprzecznej G
    On the occurrence of the time-dependent shear modulus G and its effect on the durability of wooden structures
    Autorzy:
    Misztal, Barbara
    Powiązania:
    https://bibliotekanauki.pl/chapters/2194752.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    moduł sztywności poprzecznej
    włókno drzewne
    lepkosprężysta matryca
    siła poprzeczna
    shear modulus
    wooden fibre
    visco-elastic matrix
    shear force
    Opis:
    W opracowaniu omówiono historyczne rozwiązania konstrukcji stosowane w celu zmniejszenia wpływu sił poprzecznych. Zaprezentowano model drewna jako naturalnego kompozytu włóknistego, zbudowanego z włókien umieszczonych w lepkosprężystej matrycy. Opisano badania na modelach wspornikowych z drewna, w celu pokazania trendu zmian ugięć i zmniejszenia wartości modułów sprężystości podłużnej E i poprzecznej G zaobserwowaną w czasie 72 godzin. Wskazuje to na osłabienie zamocowania włókien w lepko sprężystej matrycy po długim czasie eksploatacji konstrukcji i powoduje wzrost przemieszczenia poprzecznego.
    The paper discusses some historical solutions of wooden structures used in order to reduce the impact of shear forces. A model of wood as a natural fibrous composite, built of fibres located in a visco-elastic matrix, was presented. The testing on support models made of wood was described in order to show the trend of variations of deflections and that of the reduction in the value of moduli of longitudinal elasticity E and shear moduli G surveyed during 72 hours. The trend demonstrated evidences a weakening of the fastening of fibres in the visco-elastic matrix during the operation of the wooden structure, also an increase in shear forces leading to the reduction in the global load capacity of an element or a system made of wood.
    Źródło:
    Dziedzictwo architektoniczne. Ochrona i badania obiektów zabytkowych; 17-25
    9788374931519
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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