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This paper presents further development of a spring mechanical system, proposed by Guranlick et al, in (1) deriving equations for the determination of the mechanical system parameters in terms of material properties; (2) developin...
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This paper presents further development of a spring mechanical system, proposed by Guranlick et al, in (1) deriving equations for the determination of the mechanical system parameters in terms of material properties; (2) developing applications for deriving fatigue life relations with consideration for the ratio of the minimum to maximum stress; and (3) extending the model to incorporate the hysteresis behavior of steel under cycling loading. These applications are demonstrated in this paper with numerical illustrations.
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Fatigue crack propagation tests were conducted on the powder metallurgy nickel-base superbly KM4 at room temperature. Two different heat treatment were investigated, one which produced a reactively coarse grain size around 55 μm,...
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Fatigue crack propagation tests were conducted on the powder metallurgy nickel-base superbly KM4 at room temperature. Two different heat treatment were investigated, one which produced a reactively coarse grain size around 55 μm, and another which produced a very fine grain size around 6μm. Tests were conducted at 50 Hz and 1000 Hz in an advanced servo-hydriaulic testing machine at R-ratios between 0.4 and 0.7. There was no effect of frequency on the fatigue beaver at room temperature, which is expected in this type of alloy, and this result yields confidence in the reliability of the servohydraulic fatigue testing system. The threshed stress intensity for fatigue crack propagation decreased with decreasing grain size and with increasing R-ratio, again as expected.
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? 2021 “IISE”.Few studies have explored the similarities and differences between patients’ and care partners’ perspectives in terms of their ideal dialysis procedure and desired outcomes. As part of a project to improve the qu...
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? 2021 “IISE”.Few studies have explored the similarities and differences between patients’ and care partners’ perspectives in terms of their ideal dialysis procedure and desired outcomes. As part of a project to improve the quality of life of patients with end-stage renal disease, we elicited unbiased feedback from both patients and care partners regarding the design of a wearable dialysis device tailored to meet users’ clinical needs. We interviewed 24 hemodialysis patients and 12 hemodialysis care partners using a mixed-methods approach of open-ended and rank-order questions. Inductive content analysis showed that both patients and care partners preferred a wearable dialysis device that a patient could carry on their upper body, particularly on their back or shoulder, or wear as a vest. Analysis of responses to the rank-order questions showed a significant preference for a vest design. Operational simplicity and compactness were the attributes most frequently mentioned in response to the open-ended questions, while the accuracy of the device was ranked as significantly more important than ease of attachment, comfort, simplicity, size, or invisibility in response to the rank-order questions. The findings from this study will help to ensure that new wearable dialysis devices are designed in accordance with patients’ and care partners’ preferences.
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Basic approaches for assessment of Structural Durability are outlined in principle. Some of their limits in actual application fields and new solutions are shown. Multiaxial Fatigue remains as to be treated very carefully. The sup...
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Basic approaches for assessment of Structural Durability are outlined in principle. Some of their limits in actual application fields and new solutions are shown. Multiaxial Fatigue remains as to be treated very carefully. The superposition of damaging processes known as "Very High Cycle Fatigue" and "Corrosion Fatigue" might be a key for assessment of components at very high load cycles.
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Fretting fatigue is correlated with plain fatigue in order to develop a method to estimate fretting fatigue life from plain fatigue data. Fretting fatigue experiments as well as plain ones were conducted to obtain fatigue life dat...
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Fretting fatigue is correlated with plain fatigue in order to develop a method to estimate fretting fatigue life from plain fatigue data. Fretting fatigue experiments as well as plain ones were conducted to obtain fatigue life data at various conditions. Finite element analyses were conducted to evaluate the Smith-Watson-Topper (SWT) fatigue damage parameter around crack initiation location. It is revealed that the SWT in fretting fatigue decays exponentially away from the surface. Moreover, a correlation function exists that relates the gradient of normalized SWT at the surface to the maximum SWT ratio of plain fatigue to fretting fatigue at the same life. It is demonstrated that equivalent SWT for fretting fatigue, which is determined from the correlation function, can be compared directly with plain fatigue data for estimation of fretting fatigue life.
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This technical brief is intended to warn failure analysts against assuming that dimples indicate overload fracture. Dimples simply mean that microvoid processes were active; these processes can occur in cyclic as well as monotonic...
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This technical brief is intended to warn failure analysts against assuming that dimples indicate overload fracture. Dimples simply mean that microvoid processes were active; these processes can occur in cyclic as well as monotonic fractures. The failure analyst must examine the entire fracture, the macroscopic as well as the microscopic features, to be confident of the cracking mode.
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摘要 :
This technical brief is intended to warn failure analysts against assuming that dimples indicate overload fracture. Dimples simply mean that microvoid processes were active; these processes can occur in cyclic as well as monotonic...
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This technical brief is intended to warn failure analysts against assuming that dimples indicate overload fracture. Dimples simply mean that microvoid processes were active; these processes can occur in cyclic as well as monotonic fractures. The failure analyst must examine the entire fracture, the macroscopic as well as the microscopic features, to be confident of the cracking mode.
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A well-known method for determining the number of fatigue load cycles prior to failure is to perform a striation counting on the fractured surface. The primary objective of this study is to evaluate the accuracy of a striation cou...
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A well-known method for determining the number of fatigue load cycles prior to failure is to perform a striation counting on the fractured surface. The primary objective of this study is to evaluate the accuracy of a striation counting performed using a high-resolution scanning electron microscope. Fatigue experiments were conducted on two aluminum alloy AA-2024-T3 specimens and two low alloy steel AISI-4130-O specimens. We then performed a fractographical analysis of the fractured specimens and compared the results to the experimental data. The second objective of this study is to determine several guidelines regarding the method of striation counting process which will raise its accuracy. This study shows that high accuracy can be achieved by counting fatigue striation using a scanning electron microscope, but one must be aware of several problems and difficulties which can occur during the counting process. Several guidelines that will raise the accuracy were determined.
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Time domain approach with S-N approach and local strain approach were used for fatigue life estimation. But these days, using PSD (Power Spectral Density) method is highlighted, because of short amount of time in measurement and a...
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Time domain approach with S-N approach and local strain approach were used for fatigue life estimation. But these days, using PSD (Power Spectral Density) method is highlighted, because of short amount of time in measurement and analysis. Especially, PSD method is useful for analysis of fatigue failure which is caused by vibration damage, also FRF (Frequency Response Function) is useful for efficient prediction of fatigue life when the same product is employing different motor vehicle or test condition. In order to estimate fatigue life of compressor for air conditioning, time domain analysis and frequency domain analysis were performed and the results were compared. As a result, results of analysis in frequency domain and time domain were similar. With this, there is recognition of decreasing the period of measuring and analysis in PSD analysis. Moreover, in case of FRF pursued of a part, using FRF is applicable at fatigue life prediction in different testing condition. There was investigated an analysis method with curtailed analysis period by FRF.
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