Finite Element Stress Analysis of a Push-Out Test Part II: Free Interface With Nonlinear Friction Properties

1992 ◽  
Vol 114 (2) ◽  
pp. 155-161 ◽  
Author(s):  
A. Shirazi-Adl ◽  
A. Forcione
Keyword(s):  
Boundary Conditions ◽  
Stress Analysis ◽  
Relative Difference ◽  
Shear Stresses ◽  
Free Interface ◽  
Frictional Properties ◽  
Press Fit ◽  
Pull Out ◽  
Push Out

In this second part of a two-part paper, nonlinear frictional properties measured at the bone/porous-surfaced metal interface are used to perform the stress analysis of a push-out test assuming free interface. In this case, the friction at the interface is the only mechanism to resist the externally applied load. Similar to the part I, the model is axisymmetric and consists of two cylinders in contact with each other through the interface. Various relative material properties and boundary conditions are simulated in order to examine their effects on the interface stresses and overall push-out resistance. The role of the force-fit and the load direction (push-out versus pull-out) on the results is also investigated. The computed radial and shear stresses are found to markedly vary both with location along the interface and with the testing configuration. The ultimate push-out resistance is also found to significantly alter as the material arrangement and boundary conditions change. The predicted push-out load augments with an increase in the force-fit and diminishes to nil in the absence of a press-fit. For the cases studied here, there is a relative difference of as large as 13 percent between the push-out response and the pull-out response so far as the interface stresses and the maximum resistance are concerned. Therefore, any comparison between the results of push-out (or pull-out) tests performed with different design configurations appears to be invalid.

Finite Element Stress Analysis of a Push-Out Test Part 1: Fixed Interface Using Stress Compatible Elements

1992 ◽  
Vol 114 (1) ◽  
pp. 111-118 ◽  
Author(s):  
A. Shirazi-Adl
Keyword(s):  
Boundary Conditions ◽  
Stress Analysis ◽  
Dissimilar Materials ◽  
Factors Affecting ◽  
Pull Out ◽  
Interface Bond Strength ◽  
Fixed Interface ◽  
Compatible Elements ◽  
Interface Bond ◽  
Push Out

In this first part of a two-part paper, interelement stress compatible finite elements are developed and used to perform the stress analysis of a push-out test with a fixed interface. In the formulation, the required continuity of some of the stresses along either a specific interface or all interelement interfaces is enforced by a penalty procedure. The model is axisymmetric and consists of two cylinders attached to each other through the interface. Various relative material properties and boundary conditions are simulated in order to examine their effects on the interface stresses. Both loadings of axial compression force and axial torque are considered. The predicted results exhibit identical interelement stresses and displacements even when highly dissimilar materials are used. They also exhibit a complex state of interface stresses which depend on the geometry, material arrangement, boundary conditions, and loading. The variation of the shear stress is often highly nonuniform and the radial normal stresses are likely to be large. The present results, therefore, disagree with the common assumptions made in the pull-out tests in the orthopaedic applications. Finally, stress analysis of a number of possible testing configurations could lead to the design of an optimal pull-out test which maximizes the usefulness of the measured results in terms of the interface bond strength and factors affecting it.

Determining preference for potential: The role of perceived economic mobility

2019 ◽  
Vol 47 (6) ◽  
pp. 1-8 ◽  
Author(s):  
Chen Yang ◽  
Shaochen Zhao
Keyword(s):  
Boundary Conditions ◽  
Economic Mobility ◽  
Individual Perceptions ◽  
Future Success ◽  
The Future

Although previous researchers have demonstrated that people often prefer potential rather than achievement when evaluating other people or products, few have focused on the boundary conditions on this effect. We proposed that the preference for potential would emerge when individuals’ perception of economic mobility was high, but the preference for achievement would emerge among individuals with low perceptions of economic mobility. Our results showed that people paid more attention to the future (vs. the present) when their perception of economic mobility was high; this, in turn, promoted more favorable reactions toward potential (vs. achievement). Thus, we suggested circumstances under which highlighting a person’s potential for future success is effective and those when it is not effective. Moreover, we revealed the important role of individual perceptions regarding economic mobility in driving this effect.

scholarly journals Charge algebra in Al(A)dSn spacetimes

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Adrien Fiorucci ◽  
Romain Ruzziconi
Keyword(s):  
Boundary Conditions ◽  
Dirichlet Boundary ◽  
Three Dimensional ◽  
Dirichlet Boundary Conditions ◽  
Boundary Structure ◽  
Asymptotic Symmetry ◽  
Renormalization Procedure ◽  
Field Dependent ◽  
Odd Dimensions

Abstract The gravitational charge algebra of generic asymptotically locally (A)dS spacetimes is derived in n dimensions. The analysis is performed in the Starobinsky/Fefferman-Graham gauge, without assuming any further boundary condition than the minimal falloffs for conformal compactification. In particular, the boundary structure is allowed to fluctuate and plays the role of source yielding some symplectic flux at the boundary. Using the holographic renormalization procedure, the divergences are removed from the symplectic structure, which leads to finite expressions. The charges associated with boundary diffeomorphisms are generically non-vanishing, non-integrable and not conserved, while those associated with boundary Weyl rescalings are non-vanishing only in odd dimensions due to the presence of Weyl anomalies in the dual theory. The charge algebra exhibits a field-dependent 2-cocycle in odd dimensions. When the general framework is restricted to three-dimensional asymptotically AdS spacetimes with Dirichlet boundary conditions, the 2-cocycle reduces to the Brown-Henneaux central extension. The analysis is also specified to leaky boundary conditions in asymptotically locally (A)dS spacetimes that lead to the Λ-BMS asymptotic symmetry group. In the flat limit, the latter contracts into the BMS group in n dimensions.

scholarly journals Mechanics of tubular helical assemblies: ensemble response to axial compression and extension

2021 ◽  
Author(s):  
Jacopo Quaglierini ◽  
Alessandro Lucantonio ◽  
Antonio DeSimone
Keyword(s):  
Boundary Conditions ◽  
Elastic Properties ◽  
Central Region ◽  
Mechanical Response ◽  
Different Boundary Conditions ◽  
Kirchhoff Rods ◽  
Model Versus ◽  
The Individual ◽  
Opposite Chirality

Abstract Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In this paper, we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints, both analytically and numerically. We first focus on compression and find that, whereas a single helical rod would buckle, the rods of the assembly deform coherently as stable helical shapes wound around a common axis. Moreover, we investigate the response of the assembly under different boundary conditions, highlighting the emergence of a central region where rods remain circular helices. Secondly, we study the effects of different hypotheses on the elastic properties of rods, i.e., stress-free rods when straight versus when circular helices, Kirchhoff’s rod model versus Sadowsky’s ribbon model. Summing up, our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods, as well as some interesting features, and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology. Graphic Abstract We study the mechanical response under compression/extension of an assembly composed of 8 helical rods, pin-jointed and arranged in pairs with opposite chirality. In compression we find that, whereas a single rod buckles (a), the rods of the assembly deform as stable helical shapes (b). We investigate the effect of different boundary conditions and elastic properties on the mechanical response, and find that the deformed geometries exhibit a common central region where rods remain circular helices. Our findings highlight the key role of mutual interactions in the ensemble response and shed some light on the reasons why tubular helical assemblies are so common and persistent.

A Discussion on natural strain and geological structure - Fold shapes as functions of progressive strain

1976 ◽  
Vol 283 (1312) ◽  
pp. 129-138 ◽  
Keyword(s):  
Boundary Conditions ◽  
Mechanical Behaviour ◽  
Finite Strain ◽  
Geological Structure ◽  
Stages Of Development ◽  
Rock System ◽  
Frictional Properties ◽  
Natural Strain ◽  
Progressive Strain ◽  
Strain Dependent

The folding of the components (layers or texture) of a rock system is viewed as an unstable strain-dependent process. The folds undergo successive stages of development, including initiation, amplification, propagation and decay. Fold shapes are functions of (i) initial morphology, (ii) mechanical behaviour of the rock, including stiffness contrasts and frictional properties of adjacent components, (in) overall finite strain. The folded components may or may not adopt periodic waveforms, depending on (i) the relative rates of propagation versus amplification of the folds and (n) the boundary conditions of the rock system.

scholarly journals A first intercomparison of the simulated LGM carbon results within PMIP-carbon: role of the ocean boundary conditions

2021 ◽  
Author(s):  
Fanny Lhardy ◽  
Nathaelle Bouttes ◽  
Didier M. Roche ◽  
Ayako Abe-Ouchi ◽  
Zanna Chase ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Ocean Boundary

Free Bending Vibrations of a Centrally Bonded Symmetric Double Lap Joint (or Symmetric Double Doubler Joint) With a Gap in Mindlin Plates or Panels

2007 ◽  
Author(s):  
U. Yuceoglu ◽  
O. Gu¨vendik ◽  
V. O¨zerciyes
Keyword(s):  
Boundary Conditions ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Shear Stresses ◽  
Lap Joint ◽  
Bending Vibrations ◽  
Joint System ◽  
Adhesive Layers ◽  
Bonded Joint ◽  
Free Bending

In this present study, the “Free Bending Vibrations of a Centrally Bonded Symmetric Double Lap Joint (or Symmetric Double Doubler Joint) with a Gap in Mindlin Plates or Panels” are theoretically analyzed and are numerically solved in some detail. The “plate adherends” and the upper and lower “doubler plates” of the “Bonded Joint” system are considered as dissimilar, orthotropic “Mindlin Plates” joined through the dissimilar upper and lower very thin adhesive layers. There is a symmetrically and centrally located “Gap” between the “plate adherends” of the joint system. In the “adherends” and the “doublers” of the “Bonded Joint” assembly, the transverse shear deformations and the transverse and rotary moments of inertia are included in the analysis. The relatively very thin adhesive layers are assumed to be linearly elastic continua with transverse normal and shear stresses. The “damping effects” in the entire “Bonded Joint” system are neglected. The sets of the dynamic “Mindlin Plate” equations of the “plate adherends”, the “double doubler plates” and the thin adhesive layers are combined together with the orthotropic stress resultant-displacement expressions in a “special form”. This system of equations, after some further manipulations, is eventually reduced to a set of the “Governing System of the First Order Ordinary Differential Equations” in terms of the “state vectors” of the problem. Hence, the final set of the aforementioned “Governing Systems of Equations” together with the “Continuity Conditions” and the “Boundary conditions” facilitate the present solution procedure. This is the “Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials). The present theoretical formulation and the method of solution are applied to a typical “Bonded Symmetric Double Lap Joint (or Symmetric Double Doubler Joint) with a Gap”. The effects of the relatively stiff (or “hard”) and the relatively flexible (or “soft”) adhesive properties, on the natural frequencies and mode shapes are considered in detail. The very interesting mode shapes with their dimensionless natural frequencies are presented for various sets of boundary conditions. Also, several parametric studies of the dimensionless natural frequencies of the entire system are graphically presented. From the numerical results obtained, some important conclusions are drawn for the “Bonded Joint System” studied here.

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