| 1. |
- Alfredsson, Svante, et al.
(författare)
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Flexure of beams with an interlayer : symmetric beams with orthotropic adherends
- 2008
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959 .- 2157-5428. ; 3:1, s. 45-62
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of the three-point flexure loading of a symmetric beam configurationconsisting of two identical adherends joined by a flexible layer is presented. Aclosed-form solution is presented in the form of a layer-wise approach, andshows excellent agreement with finite element results. Particular emphasis isgiven to the global beam compliance. The results show that a thin, sheardeformable layer may effectively decouple the responses of the two beams.Furthermore, in contrast to ordinary beams, the presence of an overhangreduces the beam compliance. These effects are quantified and discussed.Experiments on aluminum adherends joined by a rubber layer were conductedover a range of overhang lengths in a three-point flexure fixture, and verygood agreement between measured and predicted beam compliance was noted.
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| 2. |
- Jelagin, Denis, et al.
(författare)
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On Indenter Boundary Effects at Elastic Contact
- 2012
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959 .- 2157-5428. ; 7:2, s. 165-182
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Tidskriftsartikel (refereegranskat)abstract
- Axisymmetric contact problems at finite Coulomb friction and rounded profiles are examined for linear elastic solids. In previous analytical/numerical approaches to this problem often incremental procedures have been developed resulting in a reduced incremental problem corresponding to a rigid flat indentation of an elastic half-space. The reduced problem, being independent of loading and contact region, can be solved by a finite element method based on a stationary contact contour and characterized by high accuracy. Subsequently, with cumulative superposition procedures it is then possible to resolve the original problem in order to determine global and local field values. Such a procedure, when applied to for example to flat and conical profiles with rounded edges and apices, is exact save for the influence from boundaries close to the contact region. This influence could be exemplified by the indenter boundaries of a flat deformable profile with rounded edges indenting a linear elastic half-space. In the present analysis such effects are investigated qualitatively and quantitatively. In doing so, the results derived using previously discussed analytical/numerical approaches are compared with corresponding ones from full-field finite element calculations. Both local as well as global quantities are included in the comparison in order to arrive at a complete understanding of the boundary effects at elastic contact.
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| 3. |
- Karlsson, Lennart, et al.
(författare)
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Mechanics of materials and structures: a simulation-driven design approach
- 2011
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Ingår i: Journal of Mechanics of Materials and Structures. - Berkeley, USA : Mathematical Sciences Publishers. - 1559-3959 .- 2157-5428. ; 6:1-4, s. 277-301
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Tidskriftsartikel (refereegranskat)abstract
- Engineering product development has developed considerably over the past decade. In order for industry to keep up with continuously changing requirements, it is necessary to develop new and innovative simulation methods. However, few tools and methods for simulation-driven design have been applied in industrial settings and proven to actually drive the development and selection of the ideal solution. Such tools, based on fundamental equations, are the focus of this paper. In this paper the work is based on two cases of mechanics of materials and structures: welding and rotor dynamical simulations. These two examples of simulation-driven design indicate that a larger design space can be explored and that more possible solutions can be evaluated. Therefore, the approach improves the probability of innovations and finding optimal solutions. A calibrated block dumping approach can be used to increase the efficiency of welding simulations when many simulations are required.
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| 4. |
- Kroon, Martin, Professor, 1974-, et al.
(författare)
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A simple scalar directional hardening model for the Bauschinger effect compared with a tensorial model
- 2020
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959 .- 2157-5428. ; 15:4, s. 511-537
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Tidskriftsartikel (refereegranskat)abstract
- Modeling the Bauschinger effect is usually accomplished by introducing a second-order back-stress or directional hardening tensor. The objective of this paper is to propose a simpler scalar model of the Bauschinger effect based on a scalar directional hardening parameter that is determined by integration of an evolution equation. The behavior of this scalar model is compared to a tensorial model for a number of load cases. Strongly objective numerical algorithms are developed for integrating the evolution equations for both the tensorial and scalar models. Also, a consistent tangent is developed for both models. Obviously, the numerical implementation of the scalar model is significantly less complicated than for the tensorial model. Examples show that the tensorial and scalar models predict the same results for cyclic proportional triaxial extension and triaxial compression loadings. In contrast, the tensorial model predicts a Bauschinger effect for cyclic proportional pure torsion loading which is not predicted by the scalar model. More complicated examples with nonproportional loading paths and inhomogeneous deformations indicate that, relative to the tensorial model, the scalar model accounts for directional hardening fairly well and the simplicity of the model makes it an attractive option to add to isotropic hardening models.
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| 5. |
- Boström, Anders E, 1951, et al.
(författare)
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Elastic SH wave propagation in a layered anisotropic plate with periodic interface cracks: exact versus spring boundary conditions
- 2010
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 5:1, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- The propagating antiplane (SH) modes in a symmetrically three-layered, anisotropic, thick plate with a periodic array of interface cracks are investigated. The exact dispersion relation can be derived with the help of a hypersingular integral equation approach and Floquet's theorem. The interface cracks can be a model for interface damage, but a much simpler model is a recently developed spring boundary condition. This boundary condition is used both for the thick plate and in the derivation of plate equations with the help of power series expansions in the thickness coordinate. For low frequencies (cracks small compared to the wavelength) the three models are shown to give the same results and this is a confirmation that the spring boundary condition is a valid approximation at low frequencies.
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| 6. |
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| 7. |
- Kazemahvazi, Sohrab, 1981-, et al.
(författare)
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Dynamic failure of clamped circular plates subjected to an underwater shock
- 2007
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 2:10, s. 2007-2023
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Tidskriftsartikel (refereegranskat)abstract
- Clamped circular copper plates have been subjected to exponentially decaying underwater blast waves with peak pressures in the range 10MPa to 300MPa and decay constants varying between 0.05ms to 1.1 ms. The deformation and failure modes were observed by high-speed photography. For the thin plates considered in this study, the failure modes were primarily governed by the peak pressures and were reasonably independent of the blast wave decay constant. Three modes of deformation and failure were identified. At low pressures, the plates undergo bending and stretching without rupture (mode I). At intermediate pressures a range of tensile tearing modes were observed, from petalling failures to tearing at the supports with increasing blast pressures. These tearing modes are referred to as mode II failures. At the highest pressures investigated here, the plate tears at the supports in a manner that is reminiscent of a shear-off failure. This failure is labeled as mode III. Scanning electron micrographs of the failure surfaces showed that in all cases, the local failure mechanism was tensile necking. Finite element (FE) simulations employing a local shear failure criterion are used to model the rupture of the material. Appropriately calibrated FE models capture all failure modes with sufficient fidelity.
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| 8. |
- Poznic, Milan, et al.
(författare)
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So… is this a surface-breaking crack?
- 2006
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 1:4, s. 743-762
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Tidskriftsartikel (refereegranskat)abstract
- An inspection technique used to assess the structural integrity of critical components in a nuclear power plant must be able to discern surface-breaking cracks from subsurface cracks. This work proposes an ultrasonic method to provide that information and presents a theoretical investigation into it. The main assumption of the model is that water carried by pressurized pipes infiltrates and fills a surface-breaking crack, while a subsurface crack is dry. The model simulates an inspection in which the modulation technique is employed and the surface hosting the crack is not accessible. A ratio, R, constructed with signals recorded in backscattering configuration during a modulation cycle, is examined and shown to provide a clear criterion allowing subsurface cracks to be distinguished from surface-breaking cracks when a shear vertical wave at 45 degree incidence is employed as a probe.
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| 9. |
- Shao, Xinyuan, 1997, et al.
(författare)
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The closest isotropic, cubic and transversely isotropic stiffness and compliance tensor to an arbitrary anisotropic material
- 2021
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 16:4, s. 451-470
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to provide, in the framework of Green elasticity, the closest or nearest fourthorder isotropic, cubic and transversely isotropic elasticity tensors with higher symmetries for a general anisotropic elasticity tensor or any other tensors with lower symmetry. Using a gauge parameter, the procedure is done on a dimensionless form based on different generalized Euclidean distances, namely conventional, log-, and power-Euclidean distance functions. In the case of power-Euclidean distance functions, results are presented for powers of 0.5, 1 and 2. Except for the conventional distance function, the different generalized distance functions adopted in this paper preserve the property of invariance by inversion, meaning that the results for the closest stiffness tensor are also valid for the compliance tensor. Explicit formulations are given for determining the closest isotropic and cubic tensors, where the multiplication tables of the bases are diagonal. More involved coupled equations are given for the coefficients of the closest transversely isotropic elasticity tensors, which can be solved numerically. Two different material cases are studied in the numerical examples, which i llustrate the material coefficients and error measures based on the present methods, including the influence from the gauge parameter.
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| 10. |
- Wredenberg, Fredrik, et al.
(författare)
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Delamination of thin coatings at scratching : Experiments and numerics
- 2009
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 4:6, s. 1041-1062
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Tidskriftsartikel (refereegranskat)abstract
- Scratching of thin coatings on hard substrates is studied experimentally and numerically, in the latter case by use of the finite element method. In particular the delamination behaviour at scratching, by increasing the normal load up to failure, is of interest. The adhesion of the coating to the substrate is modelled as a cohesive zone where relevant model parameters are determined experimentally using the double cantilever beam test with uneven bending moments (DCB-UBM). Good correlation between experimental and numerical results were achieved and the most important finding confirms the fact that the delamination behaviour was very much dependent on the critical energy release rate of the film/substrate interface. The results achieved are directly relevant for thin film polymer coatings but can also be applied in more general situations as a comprehensive parameter study is performed using the finite element method.
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| 11. |
- Wredenberg, Fredrik, et al.
(författare)
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On the numerics and correlation of scratch testing
- 2007
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Ingår i: Journal of Mechanics of Materials and Structures. - : Mathematical Sciences Publishers. - 1559-3959. ; 2:3, s. 573-594
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Tidskriftsartikel (refereegranskat)abstract
- A numerical strategy based on the finite element method and intended for an accurate analysis of the scratch test is presented. For simplicity, but not out of necessity, the material was described by classical von Mises elastoplasticity utilizing large deformation theory. Based on this strategy numerous results are presented and correlation of scratch properties is discussed within the framework of theory for indentation testing. Furthermore, the existence of a representative plastic strain in the spirit of Tabor was studied. The investigation also concerns details regarding frictional effects, normal vs. tangential scratch hardness, similarities and differences between indentation and scratch test characteristics as well as details regarding the behavior of local field variables at scratching.
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