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  • 1
    Online-Ressource
    Online-Ressource
    Wiley ; 2019
    In:  Fatigue & Fracture of Engineering Materials & Structures Vol. 42, No. 1 ( 2019-01), p. 352-362
    In: Fatigue & Fracture of Engineering Materials & Structures, Wiley, Vol. 42, No. 1 ( 2019-01), p. 352-362
    Kurzfassung: The main purpose of the present research paper is to investigate applicability of a new energy‐based failure prediction model, called EMC‐J criterion, to predict the critical loads of U‐notched polymeric samples having a ductile behaviour and loaded under symmetric 3‐point bending. The evaluated polymeric single edge notch bending samples containing U‐notches failed by considerable plastic deformations around the notch border, making it inappropriate to directly use classic linear elastic‐based formulations. Due to the elastic‐plastic behaviour of the tested polymeric material, EMC‐J criterion is applied to avoid using complex and extremely time‐consuming nonlinear analysis for failure load predictions. Finally, it is shown that EMC‐J criterion can provide a good consistency between the experimental and theoretical results with an average discrepancy of about 10%.
    Materialart: Online-Ressource
    ISSN: 8756-758X , 1460-2695
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2019
    ZDB Id: 2014746-6
    ZDB Id: 50922-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 23 ( 2020-11-26), p. 8445-
    In: Applied Sciences, MDPI AG, Vol. 10, No. 23 ( 2020-11-26), p. 8445-
    Kurzfassung: This paper analyzes the notch effect on the fracture behavior of two biomaterials (a brittle bone cement and a ductile dental material) under mode I loading. U-notched Brazilian disk (UNBD) specimens of both materials were tested under remote compression, determining the corresponding fracture loads and load-displacement curves. Additionally, cracked rectangular and semicircular bend (SCB) specimens were tested under symmetric three-point bending in order to determine the fracture toughness of the two materials. Then, fracture loads were derived theoretically by applying the maximum tangential stress (MTS) and the mean stress (MS) criteria. Due to the brittle linear elastic behavior of the bone cement material, the MTS and MS criteria were directly applied to this material; however, given the significant nonlinear behavior of the dental material, the two fracture criteria were combined with the Equivalent Material Concept (EMC) for the fracture analyses of the dental material specimens. The results reveal a very good accuracy of both the MTS and the MS criteria for the fracture analysis of bone cement notched specimens. In the case of the dental material, very good results are also obtained when combining the MTS and the MS criteria with the EMC. The proposed approach can be useful for the fracture analysis of a wide range of biopolymers, from brittle to ductile behavior.
    Materialart: Online-Ressource
    ISSN: 2076-3417
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2704225-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Wiley ; 2021
    In:  Fatigue & Fracture of Engineering Materials & Structures Vol. 44, No. 2 ( 2021-02), p. 488-504
    In: Fatigue & Fracture of Engineering Materials & Structures, Wiley, Vol. 44, No. 2 ( 2021-02), p. 488-504
    Kurzfassung: This paper examines the fracture of AA6061‐T6 specimens with ductile behavior having notches with keyhole geometry under combined loading of tension/torsion. The investigation is performed by theoretical and experimental methods. New fracture tests are performed using a loading fixture on the samples made of AA6061‐T6 weakened by keyhole notches with different notch tip radii. For theoretically estimating the onset of fracture in the tested notched specimens, a concept called “Fictitious Material Concept (FMC)” is used to equate the ductile material with a fictitious brittle material. Therefore, use of this concept allows use of the linear elastic brittle fracture criteria for ductile materials. The brittle fracture criteria utilized are the “mean stress (MS)” and “maximum tangential stress (MTS)” criteria. The small difference between the theoretical and experimental results confirms that use of the combination of FMC with the two criteria is successful in predicting failure of the keyhole notched AA6061‐T6 samples.
    Materialart: Online-Ressource
    ISSN: 8756-758X , 1460-2695
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2021
    ZDB Id: 2014746-6
    ZDB Id: 50922-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 10 ( 2022-05-20), p. 3661-
    In: Materials, MDPI AG, Vol. 15, No. 10 ( 2022-05-20), p. 3661-
    Kurzfassung: Spruce wood (Picea Mariana) is a highly orthotropic material whose fracture behavior in the presence of U-shaped notches and under combined tensile-tearing loading (so-called mixed-mode I/III loading) is analyzed in this work. Thus, several tests are carried out on U-notched samples with different notch tip radii (1 mm, 2 mm, and 4 mm) under various combinations of loading modes I and III (pure mode I, pure mode III, and three mixed-mode I/III loadings), from which both the experimental fracture loads and the fracture angles of the specimens are obtained. Because of the linear elastic behavior of the spruce wood, the point stress (PS) and mean stress (MS) methods, both being stress-based criteria, are used in combination with the Virtual Isotropic Material Concept (VIMC) for predicting the fracture loads and the fracture angles. By employing the VIMC, the spruce wood as an orthotropic material is modeled as a homogeneous and isotropic material with linear elastic behavior. The stress components required for calculating the experimental values of notch stress intensity factors are obtained by finite element (FE) analyses of the test configuration using commercial FE software from the fracture loads obtained experimentally. The discrepancies between the experimental and theoretical results of the critical notch stress intensity factors are obtained between −12.1% and −15% for the PS criterion and between −5.9% and −14.6% for the MS criterion, respectively. The discrepancies related to fracture initiation angle range from −1.0% to +12.1% for the PS criterion and from +1.5% to +12.2% for the MS criterion, respectively. Thus, both the PS and MS models have good accuracy when compared with the experimental data. It is also found that both failure criteria underestimate the fracture resistance of spruce wood under mixed-mode I/III loading.
    Materialart: Online-Ressource
    ISSN: 1996-1944
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2487261-1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Polymers, MDPI AG, Vol. 13, No. 7 ( 2021-03-27), p. 1057-
    Kurzfassung: This paper attempts to validate the application of the Virtual Isotropic Material Concept (VIMC) in combination with the average strain energy density (ASED) criterion to predict the critical load in notched laminated composites. This methodology was applied to E/glass–epoxy-laminated composites containing U-notches. For this purpose, a series of fracture test data recently published in the literature on specimens with different notch tip radii, lay-up configurations, and a number of plies were employed. It was shown that the VIMC–ASED combined approach provided satisfactory predictions of the last-ply failure (LPF) loads (i.e., critical loads).
    Materialart: Online-Ressource
    ISSN: 2073-4360
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2021
    ZDB Id: 2527146-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Hindawi Limited ; 2020
    In:  Material Design & Processing Communications Vol. 2, No. 2 ( 2020-04)
    In: Material Design & Processing Communications, Hindawi Limited, Vol. 2, No. 2 ( 2020-04)
    Materialart: Online-Ressource
    ISSN: 2577-6576 , 2577-6576
    URL: Issue
    Sprache: Englisch
    Verlag: Hindawi Limited
    Publikationsdatum: 2020
    ZDB Id: 2947562-4
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: Polymers, MDPI AG, Vol. 14, No. 16 ( 2022-08-09), p. 3246-
    Kurzfassung: This paper evaluates the fracture of notched epoxy matrix composites using the Brazilian disk (BD) test from both numerical and experimental points of view. The study began with a comprehensive experimental program covering three different composite lay-ups (quasi-isotropic, unidirectional, and cross-ply) and various geometries of U and V notches. Specifically, the BD samples combined the three layouts, four different notch angles, and three notch radii with three specimens per combination, leading to an overall number of 108 fracture tests. The experiments showed the appropriateness of the BD test for the study of the fracture behavior of composite materials and provided a good pool of data for further investigations. Subsequently, the virtual isotropic material concept (VIMC) was applied in combination with two fracture criteria to theoretically predict the experimentally acquired fracture loads. This study demonstrated that using the VIMC approach can provide robust predictions while incurring much lower computational costs compared to the conventional approaches found in the literature.
    Materialart: Online-Ressource
    ISSN: 2073-4360
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2527146-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    In: Applied Sciences, MDPI AG, Vol. 11, No. 5 ( 2021-02-27), p. 2104-
    Kurzfassung: In this paper, the fracture of notched polymeric specimens under compressive stresses was investigated both experimentally and theoretically. In the experimental section, to determine the load-carrying capacity (LCC) of U-notched specimens made of general-purpose polystyrene (GPPS) and polymethyl-methacrylate (PMMA) polymers, tests were performed on notched square samples under compression, i.e., negative mode I loading. In the observation of the nonlinear behavior of the two polymers in the standard compressive tests, for the first time, the equivalent material concept (EMC) was used under compressive loading to theoretically estimate the critical stresses of the two polymers, which were shown to be significantly different from the ultimate strengths obtained from the standard compression tests. By linking the EMC to the maximum tangential stress (MTS) and mean stress (MS) criteria, the LCC of the notched specimens was predicted. The outcomes are twofold: First, MTS, MS, EMC–MTS, and EMC–MS criteria provide accurate predictions of the experimental critical loads observed in the U-notched polymeric specimens; second, the combination of the EMC with the MTS and MS criteria, allow such predictions to be obtained without any need for experimental calibration.
    Materialart: Online-Ressource
    ISSN: 2076-3417
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2021
    ZDB Id: 2704225-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    In: Materials, MDPI AG, Vol. 16, No. 5 ( 2023-02-21), p. 1757-
    Kurzfassung: The purpose of this study is to predict the load-bearing capacity (LBC) of fracture specimens containing V-notched friction-stir welded (FSWed) joints of AA7075-Cu and AA7075-AA6061 materials and subjected to mode I loading conditions. Due to the resulting elastic-plastic behavior and the corresponding development of significant plastic deformations, the fracture analysis of the FSWed alloys requires elastic-plastic fracture criteria, which are complex and time-consuming. Thus, in this study, the equivalent material concept (EMC) is applied, equating the actual AA7075-AA6061 and AA7075-Cu materials to equivalent virtual brittle materials. Then, two brittle fracture criteria, the maximum tangential stress (MTS) and mean stress (MS), are utilized to estimate the LBC of the V-notched FSWed parts. The comparison between the experimental results and the theoretical predictions reveals that both fracture criteria, in combination with EMC, can accurately predict the LBC in the analyzed components.
    Materialart: Online-Ressource
    ISSN: 1996-1944
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2023
    ZDB Id: 2487261-1
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Online-Ressource
    Online-Ressource
    SAGE Publications ; 2022
    In:  Journal of Vibration and Control Vol. 28, No. 19-20 ( 2022-10), p. 2732-2745
    In: Journal of Vibration and Control, SAGE Publications, Vol. 28, No. 19-20 ( 2022-10), p. 2732-2745
    Kurzfassung: This article deals with the investigation of delamination effects on the flutter behavior of a composite wing subjected to unsteady aerodynamic loads by providing an integrated procedure using exact methods. For this purpose, an undamaged wing structure is modeled as a cantilevered Bernoulli–Euler beam with coupled bending–torsion and delaminated wing structure is modeled as three interconnected intact beams. The modal analysis of the intact and delaminated beams is performed and mode shapes are obtained based on the development of the dynamic stiffness matrix, a computer code and an iterative method. The fundamental modes of the intact and delaminated beam derived from the free vibration analysis are used in Galerkin’s method and the flutter and divergence speeds are obtained with aerodynamic forces applied. In fact, modified shape functions were developed to reflect the delamination effect in the aeroelastic analysis. Also, for the unsteady aeroelastic analysis, an iterative algorithm is developed. It was found that the delamination location and its length can have a positive or a negative influence on the flutter behavior of the wing which depends on the fiber angle.
    Materialart: Online-Ressource
    ISSN: 1077-5463 , 1741-2986
    Sprache: Englisch
    Verlag: SAGE Publications
    Publikationsdatum: 2022
    ZDB Id: 2070247-4
    Standort Signatur Einschränkungen Verfügbarkeit
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