bluuebunny/crossref_metadata_2025_split huggingface dataset:
On corner singularities in Reissner‐Mindlin's theory of elastic plates
Authors: Felger Julian , Becker Wilfried 
Published: October 2015

AbstractIn the framework of linear elasticity, singularities occur in domains with non‐smooth boundaries. Particularly in Fracture Mechanics, the local stress field near stress concentrations is of interest. In this work, singularities at re‐entrant corners or sharp notches in Reissner‐Mindlin plates are studied. Therefore, an asymptotic solution of the governing system of partial differential equations is obtained by using a complex potential approach which allows for an efficient calculation of the singularity exponent λ. The effect of the notch opening angle and the boundary conditions on the singularity exponent is discussed. The results show, that it can be distinguished between singularities for symmetric and antisymmetric loading and between singularities of the bending moments and the transverse shear forces. Also, stronger singularities than the classical crack tip singularity with free crack faces are observed. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element method for the vibration of cracked beams with varying cross section
Authors: Haskul Mehmet , Kısa Murat 
Published: October 2015

AbstractVibration analysis of cracked beams having linearly varying cross‐sections both in thickness and width was investigated. A computer program using the finite element method has been written to find the dynamical characteristics (natural frequencies and mode shapes) of the cracked beam. The cracked section in the beam has been modeled by a massless spring whose flexibility depens on the local flexibility induced by the crack. The stiffness of spring has been derived from the linear elastic fracture mechanics theory as the inverse of the compliance matrix calculated using stress intensity factors and strain energy release rate expression. Some examples have been given to explain the proposed method and investigate the effects of the depth and location of cracks on the natural frequencies and mode shapes. The results of current study and those in the literature are compared and good agreements have been found. Consequently it is showed that proposed method is reliable and simple. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fatigue mechanisms of cord–rubber composites
Authors: Jha Niraj Kumar , Nackenhorst Udo 
Published: October 2015

AbstractThis article presents a continuum damage mechanics approach to characterize fatigue mechanisms of cord‐rubber composites. An airspring bellow which consists of layers of rubber and reinforcing cords is considered for this work. The phenomenological material model for rubber is formulated for the purpose of analyzing the rate dependent behavior under cyclic loading. The rate dependency and hysteretic behavior are characterized by using the concept of internal variables [1]. The implementation of the constitutive formulation for rubber material is done in ABAQUS via UMAT.A fatigue failure mechanisms of cord‐reinforced airspring is for example interfacial debonding. Within the framework of finite element cohesive zone modeling, a user element is developed to study the cord‐rubber interfacial debonding. Furthermore, the developed methodology can be easily extended to understand the long‐term effects of e.g. temperature, frequency, loading rates, amplitudes etc. on the fatigue life of airsprings. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stabilizing the XFEM for static and dynamic crack simulations
Authors: Loehnert Stefan 
Published: October 2015

AbstractFor many crack geometries the standard XFEM may lead to badly conditioned equation systems. Recently a number of remedies to that problem have been published. In this contribution the stabilization technique presented in [1] is extended to dynamic and possibly nonlinear fracture mechanics and additionally combined with the SGFEM / SXFEM [2]. The performance of the different strategies is demonstrated in a linear elastic 3D mode 1 crack problem for which the analytical solution exists. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A three‐dimensional progressive damage model for fiber reinforced composites with an implicit‐explicit integration scheme
Authors: Maass Grischa , Gruttmann Friedrich 
Published: October 2015

AbstractThis contribution proposes a fully three dimensional “continuum damage model” (CDM) to describe the interlaminar and intralaminar failure mechanisms of transversely isotropic elastic‐brittle materials under static loading. The constitutive model is derived from an energy function with independent damage variables for each damage mode. The evolution law is based on energy dissipation within the damage process, taking into account the critical energy release rate to weaken the effect of mesh dependent outcome. The onset of damage can be predicted with Cuntze's failure mode concept [1] as well as with Hashin's failure criteria. In this model linear stress decreasing is assumed. In addition, an implicit‐explicit integration scheme, first proposed by Oliver [3] for isotropic damage models, is adapted to increase the stability and robustness of numerical simulations and to decrease the computational cost of material failure analyses. By comparing the results from implicit‐explicit integration schemes and standard implicit integration schemes, a high level of agreement is found. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crack propagation at bi‐material interfaces
Authors: Alam Mahabub , Parmigiani John P. 
Published: October 2015

AbstractThere is currently a gap in the understanding of how crack propagation by intergranular versus transgranular fracture varies with changes in material properties and grain size. Much of the prior work in this area has been in terms of LEFM and criterion based on toughness alone. More recent work has shown that a toughness‐and‐strength approach is required. In this study a strength‐and‐energy approach is applied to intergranular‐versus‐transgranular fracture through a cohesive‐zone approach implemented in a finite element model. Results show that intergranular fracture becomes more likely, and has an increasing shear component, as grain toughness increases and grain stiffness and grain size decrease. These results can help guide material development. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Macroscopic damage modeling for silicon nitride
Authors: Ruck Johannes , Othmani Yamen , Lube Tanja , Khader Iyas , Kailer Andreas , Böhlke Thomas 
Published: October 2015

AbstractModeling the damage of brittle materials is of great importance considering a variety of structural components. Prominent examples are high strength engineering ceramics. The present work is concerned with silicon nitride, a material with increasing relevance in industrial applications. In the sense of a hierarchical model structure, effective properties of micromechanical simulations were applied to macroscopic, phenomenological damage models for monotonous and cyclic loading. In the following, both models are introduced and the application of the cyclic damage model to a four point bending test is discussed. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A regularization approach for damage models based on a displacement gradient
Authors: Schwarz Stephan , Junker Philipp , Hackl Klaus 
Published: October 2015

AbstractCommon material models that take into account softening effects due to damage encounter the problem of ill‐posed boundary value problems if no regularization is applied. This condition leads to a non‐unique solution for the resulting algebraic system and a strong mesh dependence of the numerical results. A possible solution approach to prevent this problem is to apply regularization techniques that take into account the non‐local behavior of the damage [1]. For this purpose a field function is used to couple the local damage parameter to a non‐local level, in which differences between the local and non‐local parameter as well as the gradient of the non‐local parameter can be penalized.In contrast, we present a novel approach to regularization in which no field function is needed [2]. Hereto, the regularization is carried out by means of the divergence of the displacements and no additional quantity is necessary since the displacements are already defined on a non‐local level. The idea is that with an increasing value of the damage the element's volume will increase as well. This is a result of the softening due to the occurring damage. The increasing volume can be measured by the divergence of the displacements which can be penalized by an additional energy part. The lack of any field function and the regularization by the use of the divergence of the displacements entails several numerical advantages: the computational effort is considerably reduced and the convergence behavior is improved as well. Naturally, the numerical results are mesh independent due to the regularization. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical properties of cold sprayed Titanium and Nickel based coatings
Authors: Silvello A. , Cavaliere P. 
Published: October 2015

AbstractCold spray is an innovative coating technology. Very fine particles are accelerated, then sprayed on a substrate in condition very far from material melting. The unique mechanical properties experienced by the sprayed material are due to the severe plastic deformation acting during particle impact. In the present paper, the microstructural and mechanical behavior of Ti‐ and Ni‐based nanocomposites coatings produced via cold spray are presented. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of a circular defect size and position on the damage progression in hybrid laminates under compressive loading
Authors: Tala‐Ighil Nacer , Mokhtari Ahcene , Brick Chaouche Amine 
Published: October 2015

AbstractThe effects of a circular defect size and position on the post‐damage response of the FMLs laminates under compressive loading has been studied. Compression tests are performed on composite plates comprising a hole having different diameters (8 mm, 12 mm and 16 mm) and located at different positions (25%, 50% and 75%) in the loading direction. A numerical analysis using the finite element method FEM has permits the identification of the initiation zones and the description of the damage evolution in these laminates. The results of the numerical simulation are in good agreement with the experimental results. The FEM has well predicted the critical damage zones. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase‐Field Modeling of Fracture in Anisotropic Media
Authors: Teichtmeister Stephan , Miehe Christian 
Published: October 2015

AbstractIn the recent years phase‐field modeling of fracture has become a promising tool to describe complex crack patterns in all kinds of solid materials. Many of the models assume an isotropic material behavior, which of course is not a meaningful assumption for e.g. biological tissues such as arterial walls. Since the phase‐field approach introduces an additional (smeared) phase describing the evolution of the crack, this method is well suited to be extended to anisotropic materials without thinking about an adaption of the discretization technique. Anisotropy can be incorporated in several ways, like by an extension of the surface energy, i.e. by making the energy release rate orientation dependent, as considered in [1]. Our ansatz is based on a pure geometrical approach, namely on an anisotropic formulation of the crack surface itself. Here, we will focus on transversely isotropic and cubically anisotropic solids, where the latter one makes the incorporation of the second gradient of the crack phase field necessary. At the end one numerical example is shown, which conceptually shows the influence of the anisotropy on the crack path. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical methods for crack loading analyses in quasicrystals
Authors: Wang Zhibin , Ricoeur Andreas 
Published: October 2015

AbstractSince the first discovery of quasicrystals in a man made Al‐Mn alloy about thirty years ago, people made great effort to investigate this kind of outstanding material. The materials scientists are constantly trying to produce stable quasicrystalline particles or even a complete single quasicrystalline specimen. On the other hand, the fracture behaviour of quasicrystals is started to be investigated because the coupling effect between phonon and phason fields can rebuild the conventional fracture criteria. This work develops a numerical tool for simulating in‐plane problems of 1D QC and extends the fracture quantities i.e. stress intensity factors (SIF) and strain energy release rate to phason fields. Finally, numerical results are given to reveal what difference the phason field can bring into conventional fracture quantities. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crack initiation in elliptically notched plates
Authors: Weißgraeber Philipp , Felger Julian , Becker Wilfried 
Published: October 2015

AbstractIn this work, crack initiation in elliptically notched plates under uniaxial tension is studied by means of a Finite Fracture Mechanics analysis. The stress concentration factor changes with the aspect ratio of the half axes: from unity for slender ellipses in loading direction to infinity for crack‐like ellipses normal to the loading. The closed‐form solutions of the stress field and an approximate formulae of the stress intensity factor of mode I cracks allows for an efficient Finite Fracture Mechanics analysis of plates with elliptical notches with arbitrary aspect ratios. The results show that the transition from vanishing stress concentration to infinite (crack‐like) stress concentration is rendered continuously by the present approach. A transition from strength of materials to Linear Elastic Fracture Mechanics is obtained that shows distinct size effects. A comparison to experimental results on size effects of notched plates shows good agreement. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Anisotropic Damage Theories based on 2nd Order Damage Tensors
Authors: Wulfinghoff Stephan , Reese Stefanie 
Published: October 2015

AbstractIsotropic and anisotropic damage theories are shortly reviewed concerning different aspects like thermodynamical consistency, effective undamaged configurations, crack‐closure effects and the interpretation of the damage variable. A recently proposed damage growth criterion for second order damage tensors is discussed in integral as well as incremental form. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the discontinuous Galerkin finite element method in small deformation regimes
Authors: Bayat Hamid Reza , Wulfinghoff Stephan , Reese Stefanie 
Published: October 2015

AbstractIn this paper, a finite element formulation is defined in the framework of the discontinuous Galerkin method. Discontinuous Galerkin (dG) methods are classically used in fluid mechanics, however recently their application in solid mechanics has become more vivid among scientists. Of special interest is their application in elliptic problems with constraints such as incompressibility which leads to volumetric locking phenomenon and also in some structural models of shells, plates and beams with compatibility constraints, which brings about shear locking [1]. While classical standard Galerkin methods must be continuous, dG methods can be applied for discontinuities across element boundaries, where a jump of a value (displacement) can be observed. In the present work, a dG method is applied to a linear elastic bar, where a weak discontinuity is allowed in the bar. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of a Constitutive Friction Law Using an Elastic‐Plastic Half‐Space Model
Authors: Beyer Florian , Willner Kai 
Published: October 2015

AbstractFriction influences metal forming processes both in economic and technical terms. A precise understanding of friction is inevitable as friction restricts the potential of the product design. Friction depends on the occurring contact loads which is especially true for sheet‐bulk metal forming (SBMF) as the incorporated contact loads appear in a very broad range. Numerical simulations, which are verified experimentally, are carried out to analyse contact interactions which typically appear in SBMF. On the one hand the multi‐scale character of rough surfaces requires a very fine resolution of the contact area, on the other hand a large contact area is necessary to be representative. A half‐space model is chosen for the contact analysis, because it only depends on the two‐dimensional surface boundary which consumes less computing capacity than the finite element method (FEM) with its three‐dimensional volume approach for the same surface resolution and area. The outcome is a constitutive friction law (CFL) consisting of two equations. The law is implemented into the framework of FEM to see the impact in a typical SBMF‐process which aims to form metal sheet into cups with integrated gearing teeth. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Corotational flat triangular elements for the nonlinear analysis of thin shell structures
Authors: Caselli Federica , Bisegna Paolo 
Published: October 2015

AbstractThis contribution shows the effectiveness and versatility of the corotational formulation in the development of shell finite elements for geometric and material nonlinear analysis of thin structures. In particular, flat triangular elements especially suited to shell structures made of shape memory alloys (SMA) or soft biological tissues are dealt with. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear Stochastic Finite Element
Authors: Caylak Ismail , Dridger Alex , Mahnken Rolf 
Published: October 2015

AbstractThis paper investigates the uncertainty of physically non‐linear problems by modeling the elastic random material parameters as stochastic fields. For its stochastic discretization a polynomial chaos (PC) is used to expand the coefficients into deterministic and stochastic parts. Then, from experimental data for an adhesive material the distribution of the random variables, i.e. Young's modulus E(θ), the static yield point Y0 and the nonlinear hardening parameters q and b, are known. In the numerical example the distribution of the stresses obtained by the PC based SFEM and Monte Carlo simulation is compared. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a Mathematical Problem of Cusped Double‐Layered Plates
Authors: Chinchaladze Natalia 
Published: October 2015

AbstractThe present paper is devoted to the system of degenerate partial differential equations arise from the investigation of elastic two layered prismatic shells. Harmonic vibration of cusped double‐layered plates is consider. The weak setting of the BVPs in the case of the zero approximation of hierarchical models is considered. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An efficient and robust Reissner–Mindlin shell formulation for isogeometric analysis
Authors: Dornisch Wolfgang , Müller Ralf , Klinkel Sven 
Published: October 2015

AbstractThe novel idea of isogeometric analysis is to use the basis functions of the geometry description of the design model also for the analysis. Thus, the geometry is represented exactly on element level. A closer integration of design and analysis is fostered by the usage of one common geometry model for design and analysis. A prevalent choice for the geometry description in isogeometric shell analysis are Non‐Uniform Rational B‐spline (NURBS) surfaces, which are commonly used in industrial design software to model thin structures. In order to directly compute structures defined by NURBS surfaces, an efficient isogeometric shell formulation is required. In this contribution an isogeometric Reissner–Mindlin shell formulation derived from the continuum theory is presented. The shell body is described by a shell reference surface, which is defined by NURBS surfaces, and a director vector. The director vector in the current configuration is computed by an orthogonal rotation using Rodrigues' tensor in every integration point. The axial vector of the rotation is interpolated. A multiplicative update formulation for the rotations accounts for finite rotations. A benchmark example shows the superior accuracy of the presented shell formulation for nonlinear computations. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical Analysis of Metallic SLM‐Lattices on Small Scales: Finite Element Simulations versus Experiments
Authors: Didam S. , Eidel B. , Ohrndorf A. , Christ H.‐J. 
Published: October 2015

AbstractThe present contribution deals with the mechanics of metallic microlattices from selective laser melting (SLM). Finite element analyses with elasto‐plastic material parameters identified in experiments investigate the structural load bearing behavior of different unit cell topologies. Typical failure modes like local buckling as well as global localization in shear bands are analyzed in simulations and experiments for compression tests. Ashby diagrams for the scaling behavior of stiffness and strength at various densities are determined for both bending‐ and stretch‐dominated lattice types. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Mechanics of Ultralight Hollow Microlattices
Authors: Eidel B. 
Published: October 2015

AbstractThe objective of the present work is a thorough understanding of the mechanics of microlattices by finite element analysis. A thin‐shell model for a unit‐cell along with an isotropic material law of elasto‐plasticity captures for compression experiments (i) significant deformation characteristics in terms of stress‐strain curves, (ii) the interplay of inelasticity with shell geometrical features and (iii) the scaling behavior of stiffness and strength for various densities. The octet cell in comparison to the bcc cell shows an increase in elastic stiffness and strength by 1‐2 orders of magnitude, thus making a step towards ultralight and ultratight properties of structural materials. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of non‐stationary vibration signals based on the modified Kronecker sequences
Authors: Girip Iulian , Munteanu Ligia 
Published: October 2015

AbstractThe paper establishes a representation model for non‐stationary random vibration signals based on the modified Kronecker sequences. The modified Kronecker sequence constructed via generalizing golden ratio is one of the special types of low discrepancy sequences which have better dimensional projections [1]. The actual modeling and simulation of non‐stationary random data is more suitable for seismological signals and not for the vehicle vibrations [2, 3]. Under these circumstances, this paper presents a new algorithm for finding the modified Kronecker sequences in order to generate non‐stationary vehicle vibration signals which mostly withhold the amplitude‐frequency‐time distribution of the sample signal. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A model reduction approach for hyperelastic materials based on Proper Orthogonal Decomposition
Authors: Hürkamp André , Kaliske Michael 
Published: October 2015

AbstractIn this contribution, we present a model reduction approach for hyperelastic materials based on Proper Orthogonal Decomposition. A separation of the solution into time and space dependent functions is performed, which allows to compute reduced solutions within real time. The functionality of the method is demonstrated by a tensile test and is further applied to a stochastic analysis and a multi‐parametric analysis involving non‐linear material behaviour and large deformations. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)