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Fatigue Failure Criteria
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
In the rotating-beam test, the machine applies a pure bending moment to the highly polished, so-called “mirror finish” specimen of a circular cross-section (Figure 7.4b). As the specimen rotates at a point on its outer surface, the bending stress varies continuously from maximum tension to maximum compression. This fully or completely reversed bending stress can be represented on the stress S-cycles N axes by the curves of Figure 7.4c. It is obvious that the highest level of stress is at the center, where the smallest diameter is about 0.3 in. The large radius of curvature avoids stress concentration. Various standard types of fatigue specimens are used, including those for axial, torsion, and bending stresses described in the ASTM manual on fatigue testing.
Fundamental concepts
Published in Bernard S. Massey, John Ward-Smith, Mechanics of Fluids, 2018
Bernard S. Massey, John Ward-Smith
Surface tension becomes important when solid boundaries of a liquid surface are close together or when the surface separating two immiscible fluids has a very small radius of curvature. The forces due to surface tension then become comparable to other forces and so may appreciably affect the behaviour of the liquid. Such conditions may occur, for example, in small-scale models of rivers or harbours. The surface tension forces may be relatively much more significant in the model than in the full-size structure; consequently a simple scaling-up of measurements made on the model may not yield results accurately corresponding to the full-size situation.
Fatigue Failure Criteria
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, MECHANICAL DESIGN of Machine Components, 2018
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
In the rotating-beam test, the machine applies a pure bending moment to the highly polished, so-called mirror finish, specimen of circular cross section (Figure 7.4b). As the specimen rotates at a point on its outer surface, the bending stress varies continuously from maximum tension to maximum compression. This fully or completely reversed bending stress can be represented on the stress S-cycles N axes by the curves of Figure 7.4c. It is obvious that the highest level of stress is at the center, where the smallest diameter is about 7.5 mm. The large radius of curvature avoids stress concentration. Various standard types of fatigue specimens are used, including those for axial, torsion, and bending stresses described in the ASTM manual on fatigue testing.
Entropy generation on MHD flow of Williamson hybrid nanofluid over a permeable curved stretching/shrinking sheet with various radiations
Published in Numerical Heat Transfer, Part B: Fundamentals, 2023
K. Sakkaravarthi, Bala Anki Reddy P
Consider a steady, two-dimensional, incompressible Williamson hybrid nanofluid with blood as the primary fluid, permeability flow, and hybrid nanoparticles of aluminum oxide (Al2O3) and silver (Ag) across a curved shrinking or stretching sheet. The boundary layer of a hybrid nanofluid traveling across an extended curved surface of radius R has been estimated. Applying two equal and opposing pressures along the s axis while keeping the origin constant and the velocity uw = as (a > 0), where a is the stretching constant. The stretchable surface is subjected to a continuous magnetic force (B0). The radius of curvature is the measure of the value of the surface’s shape, as illustrated in Figure 1. The effects of MHD, porous media, nonlinear thermal radiation, and Joule heating are all being examined. The governing equations are [28]: boundary conditions are as flows [29]:
Elastic and elastic-perfectly plastic analysis of an axisymmetric sinusoidal surface asperity contact
Published in Tribology - Materials, Surfaces & Interfaces, 2020
Swarna Saha, Robert L. Jackson
The Greenwood and Williamson [1] model (GW model) is one of the earliest and most applied rough surface contact models. In the GW model, (1) the rough surface is modelled as a dispersion of asperities with tips having a common radius of curvature. Obviously, the radius of curvature of each asperity is not actually constant. In addition, depending on the geometry, boundary conditions and applied load, the asperity radius of curvature changes continuously during loading which has been clearly shown and formulated in [19]. (2) In the GW model, the heights of the asperity vary and the distribution of heights is often idealized using a Gaussian or exponential distribution. (3) The GW model does not consider the interaction with adjacent asperities and the bulk materials below the asperities, although Greenwood and Tripp [20] soon alleviated this assumption. Modelling of rough surfaces using isolated asperities works well when deformation is limited to the tips of the asperities. However, when the applied load is higher or the radius of the curvature of the asperities is smaller, the amount of asperity interaction becomes very important. This has clearly been shown in the paper of Yastrebov et al. [15] by comparing the deterministic model with and without asperity interactions. Gao et al. [21] have also showed the importance of asperity interaction in their model.
Experimental study on steam side vacuum capillary concentrated ethylene glycol aqueous solution
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Liangwei Hao, Hao Wu, Hong Xu, Jun Cao
where γ is the surface tension of the liquid and r is the radius of curvature of the liquid surface. The pressure difference decreases with the increase of pore radius of the capillary wick. As excessive negative pressure or excessive flow rate can easily lead to leakage and lead to experimental failure. Therefore, a capillary with a smaller pore diameter should be used in the experiment. At the same time, the vacuum and the inlet flow of the working medium should not be too large.