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Yukitaka Murakami - One of the best experts on this subject based on the ideXlab platform.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by selective laser melting
International Journal of Fatigue, 2018Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV > 400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV = ∼470 manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The successful application of the area parameter model was confirmed. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence on Fatigue strength than an internal defect and has the effective larger size termed as area eff than the real size, area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the area parameter model is proposed.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by additive manufacturing
Procedia structural integrity, 2017Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV >400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV =~470 which was manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The √area parameter model was confirmed the successful application. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence and has the effective larger size termed as √ area eff than the real size, √ area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the √area parameter model is proposed.
Yoichi Yamashita - One of the best experts on this subject based on the ideXlab platform.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by selective laser melting
International Journal of Fatigue, 2018Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV > 400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV = ∼470 manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The successful application of the area parameter model was confirmed. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence on Fatigue strength than an internal defect and has the effective larger size termed as area eff than the real size, area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the area parameter model is proposed.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by additive manufacturing
Procedia structural integrity, 2017Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV >400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV =~470 which was manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The √area parameter model was confirmed the successful application. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence and has the effective larger size termed as √ area eff than the real size, √ area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the √area parameter model is proposed.
C M Sonsino - One of the best experts on this subject based on the ideXlab platform.
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a consideration of allowable equivalent stresses for Fatigue Design of welded joints according to the notch stress concept with the reference radii rref 1 00 and 0 05 mm
Welding in The World, 2009Co-Authors: C M SonsinoAbstract:In the literature, allowable stresses (FAT-values) for the Fatigue Design of welded joints are established according to the notch stress concept with the reference radii rref = 1.00 mm for thick connections (t ≥ 5 mm) and 0.05 mm for thin connections (t < 5 mm). However, it is not clear for which strength hypothesis they are valid. As local equivalent stresses may be calculated by the principal stress or von Mises hypotheses, it is necessary to distinguish between the applied hypotheses. The FAT-values according to the principal stress and von Mises hypotheses are compiled for steel, aluminium and magnesium for the reference radii rref = 1.00 and 0.05 mm. The allowable stresses are derived from normal as well as from shear stresses. However, the values derived from pure normal loading (axial or bending) and from pure torsion are not compatible when the principle stress or the von Mises hypotheses are applied. Therefore, in case of biaxial loading, the stated incompatibility between the values obtained from different loading modes should be overcome by the Gough-Pollard relationship.
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Fatigue Design of welded joints from the wrought magnesium alloy az31 by the local stress concept with the fictitious notch radii of rf 1 0 and 0 05 mm
International Journal of Fatigue, 2008Co-Authors: Ozler Karakas, C Morgenstern, C M SonsinoAbstract:Investigations were carried out with three different types of MIG- and TIG-welded joints of the magnesium alloy AZ31(ISO-MgAl3Zn1): fully or partially penetrated butt welds, transversal stiffeners. The evaluation of the results showed that the local stress concept using the fictitious notch radius of rf = 1.0 mm can be applied to magnesium welded joints from plates with thicknesses t ⩾ 5 mm independently of the weld geometries. Design curves are proposed for different stress ratios, i.e. R = −1 as well as 0 and 0.5, which allow the consideration of residual stresses as well as load induced mean-stresses. The results also permit the suggestion of Δσ = 28 MPa for rf = 1.0 mm as FAT-value in the IIW-Fatigue Design Recommendations. Further, the FAT-value Δσ = 73 MPa is also derived for the fictitious radius of rf = 0.05 mm to be applied to welded thin magnesium joints (t < 5 mm). These FAT-values are compared with data already known for steel and aluminium joints. A linear relationship between the FAT-values and the Young’s modulus is determined.
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Fatigue Design of aluminium welded joints by the local stress concept with the fictitious notch radius of rf 1 mm
International Journal of Fatigue, 2006Co-Authors: C Morgenstern, C M Sonsino, Adolf Hobbacher, Francesco SorboAbstract:Abstract The investigations were carried out with three different types of MIG-welded joints of the two aluminium alloys AlMg4.5Mn (AW-5083) and AlMgSi1 T6 (AW-6082 T6) under fully reversed and pulsating axial loading. The evaluation of the results showed that the local stress concept using the fictitious notch radius of r f =1.0 mm can be applied to aluminium welded joints from plates with thickness t ≥5 mm independently from the alloy and weld geometries (fully or partially penetrated butt welds, transversal stiffener). Master Design curves are proposed for different stress ratios, i.e. R =−1, 0 and 0.5, which allow the consideration of residual stresses as well as load induced mean stresses. The results permit also the suggestion of Δ σ =70 MPa as FAT-value for the IIW-Fatigue Design recommendations.
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principles of variable amplitude Fatigue Design and testing
Journal of Astm International, 2004Co-Authors: C M SonsinoAbstract:The proper consideration of variable amplitude loading by utilizing service spectra and appropriate Gassner-lines is essential for the Design of light-weight components and structures by allowing loads in significant excess of the Woehler-line (S-N curve). This permits higher stresses than under constant amplitude loading and renders reduced component dimensions. Reliable reconstitution and simulation methods for service load-time histories require not only the rainflow matrices, but also information about the order of the cycles described by Markovian matrices, the power spectral density and, for multiaxial applications, the cross-correlations between the particular load directions as well as the phase relations. A major problem in numerical Fatigue life assessment is still the Fatigue life calculations for spectrum loading, because of the scattering of the real damage sum D over a wide range, which is not entirely understood. These findings demonstrate the need for experimental spectrum tests, which are indispensable for ensuring the safety of parts. With regard to safety and liability requirements, the failure probability resulting from the probability of occurrence of the spectrum, from the scattering of the Fatigue strength and from the failure criterion (technical crack or propagation), must be taken into account.
Takao Murakami - One of the best experts on this subject based on the ideXlab platform.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by selective laser melting
International Journal of Fatigue, 2018Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV > 400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV = ∼470 manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The successful application of the area parameter model was confirmed. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence on Fatigue strength than an internal defect and has the effective larger size termed as area eff than the real size, area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the area parameter model is proposed.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by additive manufacturing
Procedia structural integrity, 2017Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV >400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV =~470 which was manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The √area parameter model was confirmed the successful application. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence and has the effective larger size termed as √ area eff than the real size, √ area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the √area parameter model is proposed.
Rei Mihara - One of the best experts on this subject based on the ideXlab platform.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by selective laser melting
International Journal of Fatigue, 2018Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV > 400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV = ∼470 manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The successful application of the area parameter model was confirmed. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence on Fatigue strength than an internal defect and has the effective larger size termed as area eff than the real size, area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the area parameter model is proposed.
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defect analysis and Fatigue Design basis for ni based superalloy 718 manufactured by additive manufacturing
Procedia structural integrity, 2017Co-Authors: Yoichi Yamashita, Takao Murakami, Rei Mihara, Masami Okada, Yukitaka MurakamiAbstract:Abstract It is well known that high strength metallic materials with Vickers hardness HV >400 are very sensitive to small defects. This paper discusses Fatigue properties of a Ni-based Superalloy 718 with HV =~470 which was manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The √area parameter model was confirmed the successful application. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence and has the effective larger size termed as √ area eff than the real size, √ area , of the defect from the viewpoint of fracture mechanics. The guide for the Fatigue Design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the √area parameter model is proposed.
