Simulation Of Fracture Behavior Research Articles

Analysis and simulation of fracture behavior in naturally occurring Bouligand structures

Through natural selection processes, refined biological materials could be created that adapt to various environments and exhibit specific functions. Such materials include typical Bouligand structures that can be widely observed in marine creatures that have hard shells. Consisting of a helicoidal arrangement of aligned fibrils, layered single-twisted Bouligand-type structures (SBS) display exceptional fracture and damage resistance. A much more primitive and rarer type of this formation, the double-twisted Bouligand-type structures (DBS), has been discovered in ancient fish scales, and this architecture could provide added rigidity and significantly contribute to toughness when facing fracture risk. In this work, we describe a computational modeling approach to investigating fracture behaviors and toughening mechanisms in Bouligand structures. To achieve qualitative insights into the fracture behaviors of DBS and SBS, we applied these two configurations, which were identified from corresponding biological materials, to analyze load-displacement responses during single edge notched (SEN) tensile testing; the toughening mechanism is also discussed further. The results clearly show that the arrangement of helix fibrils and interlaminar properties play a major role in the resulting fracture behaviors of Bouligand architectures. This is of interest for the future design of engineering materials and structures that require composites with enhanced toughness, and could deepen our understanding of the structure-property relationship of Bouligand-type structures in bionic design. Statement of significanceIn this work, a novel numerical modeling approach based on the extended finite element method (XFEM) has been established to evaluate the fracture behavior of a naturally-occurring Bouligand-type helicoidal structure subjected to the single edge notched (SEN) tensile loading. The roles of the biological features (i.e., layered arrangement of collagen fibrils and interbundle fibrils) on the fracture resistance and toughening mechanism of the Bouligand-type structures have been uncovered and analyzed quantitatively. This is of interest for future design of engineering materials and structures that require composites with enhanced toughness, and can deepen the understanding of the structure-property relationship of the Bouligand-type structure in bionic design.

Fracture mechanics test standards for fiber-reinforced polymer composites: Suggestions for adapting them to Industry 4.0 and the digital age

Fracture mechanics is expected to play an increasingly important role in design and development of components or structural elements made of fiber-reinforced polymer-matrix (FRP) composites, e.g., from carbon fiber epoxy. Test standard development in this sector has been slow. However, there are additional issues that impede implementation of the existing standards in Industry 4.0 and the digital age test facilities. Selected examples focus on recent developments in digital technologies, specifically imaging and image analysis and use of nondestructive test methods as well as handling of big data. Using these tools will reduce scatter (e.g., in determination of delamination lengths) and dependence on operator experience or qualification (i.e., the "human factor"). Further aspects discussed are automated data analysis and data fitting for evaluating materials properties, or for providing data for modelling and simulation of fracture behavior. It is argued that test set-ups with non-destructive delamination monitoring combined with automated analysis will efficiently provide reliable data for fracture mechanics based FRP structural design. Such data can also be compiled in data bases, e.g., for suppliers’ data sheets or for comparing different FRP composites for use in structural applications. This is expected to have effects on the quality of data and on the test requirements as well as the related cost.

Numerical Simulation of Fracture Behavior of Brittle Solids under I/III Loading

This study used numerical analysis to carry out a large number of numerical model calculations based on a new semicircular bend (SCB) model. Instead of existing numerical computation methods (J‐integral), the M‐integral method was used to calculate the mixed mode fracture parameters (KI, KII, and KIII), investigate the influence of the geometry and material parameters on the fracture behavior under mixed mode I/III loading, and predict the fracture path. The results revealed that the limitations in the scope of the mixity parameter Me in the previous studies can be overcome to a certain extent. The range of Me was established under different Poisson ratios and can be used as a reference for actual material testing. The simulation path is in good agreement with the experimentally obtained fracture path, and the proposed method can be used to simulate the fracture path under mixed mode I/III loading.

Analysis of the Versatility of Multi-Linear Softening Functions Applied in the Simulation of Fracture Behaviour of Fibre-Reinforced Cementitious Materials.

Fibre-reinforced cementitious materials (FRC) have become an attractive alternative for structural applications. Among such FRC, steel- and polyolefin fibre-reinforced concrete and glass fibre-reinforced concrete are the most used ones. However, in order to exploit the properties of such materials, structural designers need constitutive relations that accurately reproduce FRC fracture behaviour. This contribution analyses the suitability of multilinear softening functions combined with a cohesive crack approach for reproducing the fracture behaviour of the FRC mentioned earlier. The performed implementation accurately simulated fracture behaviour, while being versatile, robust, and efficient from a numerical point-of-view.

Computational simulation of fracture behaviour in auxetic cellular structure by multiaxial loading

A computational simulation of fracture behaviour in auxetic cellular structure, subjected to multiaxial loading is presented in this paper. A fracture behaviour of the 3D (three-dimensional) chiral auxetic structure under multiaxial loading conditions was studied. The computational models were used to study the geometry effect of the unit cell on the Poisson’s ratio and fracture behaviour of the analysed chiral auxetic structure. A 3D computational model was built using FEM-code LS DYNA. The discrete computational model of chiral auxetic structure was built using beam finite elements. The lattice model of the analysed auxetic structure was positioned between rigid plates and assembled in a way to simulate a hydro-compression loading conditions. Between the contacting surfaces interactions in normal (contact) and tangential direction (friction) with the node-to-surface approach were simulated. A developed computational model offers insight in the fracture behaviour of considered auxetic cellular structure and helps to better understanding their crushing behaviour under impact multiaxial loading.

Simulation of Fracture Behavior in the Microstructure of Ceramic Tool Materials

In the paper, the Voronoi tessellation model is used to represent the microstructure of ceramic tool materials. And a finite element model based on cohesive element method has been developed to investigate the fracture behavior of the microstructure. The influences of mesh densities and cohesive parameters on the cracking patterns have been discussed. It is found that the enhancement of the grain boundary strength is beneficial for raising the fracture resistance of single-phase ceramic tool materials.

Simulation of Fracture Behavior in the Microstructure of Ceramic Tool Materials

In the paper, the Voronoi tessellation model is used to represent the microstructure of ceramic tool materials. And a finite element model based on cohesive element method has been developed to investigate the fracture behavior of the microstructure. The influences of mesh densities and cohesive parameters on the cracking patterns have been discussed. It is found that the enhancement of the grain boundary strength is beneficial for raising the fracture resistance of single-phase ceramic tool materials.

Direct Numerical Simulation of Fracture Behaviour for Random Short Wood Fibres Reinforced Composites, Comparison with Digital Image Correlation Experiments

The work is to predict fracture behaviour of bio-composites from the tensile properties of its components. In this work, we have realized a direct numerical simulation of fracture behaviour for random short spruce fibers reinforced composites. For calculations, wood fibers have been considered as linear elastic bodies, polypropylene matrix as an elastic-plastic material. Then, numerical results have been compared with experimental results that have been obtained by digital image correlation. This comparison indicates that random fiber FE model of random short spruce fibers reinforced composites can be able to fairly reflect the influence of random fibers microstructure in the composite on its fracture behavior. The calculation of both random fiber and homogeneous FE model and their comparison with experiments show that the average values of J-integral in a region in the front of the crack tip from both numerical FE models are in good agreement with the average J value of DIC experiment in the same region when the numerical and experimental CT specimens of the short spruce fiber reinforced composite are subjected to the same extension at their loading point.

Three_Dimensional Simulation of Fracture Behavior of Elastic-Brittle Material with Initial Crack Pattern

Numerical simulation of mechanical behavior of heterogeneous materials under loading with an explicit consideration for their 3D mesoscale structure is given. A 3-D problem in the dynamic formulation is solved using the finite-difference method. As an example, a coal specimen under tension and compression is examined, with an initial crack pattern taken into account. It is been shown that the fracture criterion we used in the calculations provides adequate description of fracture behavior under tension and compression on both macro and mesoscale level.

On the change of fracture mechanism with test temperature

Three point bending (3PB) tests of precracked specimens were carried out for coarse grain C–Mn steel at three low temperatures. Details of fracture surfaces in the specimens were microscopically observed and cleavage initiation sites were located. Calculations of local critical parameters and simulations of fracture behavior were made using finite element method (FEM). The results reveal that at very low temperature (−196 °C), the critical event controlling cleavage fracture is the nucleation of crack at the precrack tip in ferrite. The critical event moves to the initiation and propagation of a second phase particle crack at moderately low temperature (−110 °C). At higher temperature (−30 °C), the critical event for cleavage fracture after a fibrous crack extends is the propagation of a grain-sized crack.

Finite element simulation of fracture behaviour for aged duplex stainless steels

In this paper, the local approach model developed by Gurson–Tvergaard has been applied to simulate both the crack initiation and the crack growth of aged duplex stainless steel. The parameters of the Gurson–Tvergaard model have been obtained, from axisymmetric notched specimen testing, as a function of the ageing time at 400°C, the ferrite content of the steel and the stress triaxiality. After that, to simulate the fracture of CT specimens, finite element (FE) calculations have been effected in order to obtain the stress triaxiality value at each point on the process zone ahead of the crack tip of these specimens. The adequate damage parameters concerning triaxiality are determined from the ones obtained at the notched specimens, in order to be used in FE simulations of fracture behaviour. With them, the corresponding J−Δa curves have been simulated as representative of both the crack initiation and crack propagation stages, and compared with experimental results in order to validate the methodology proposed.

Simulation of fracture behavior of unidirectional SiC/SiC composite exposed in air at 823–1673 K

It is known that SiC/SiC composite has high strength and toughness, but is degraded when exposed in air at high temperatures due to the propagation of the crack made by the premature fracture of the SiO2 layer. It is also known that the fracture morphology of this composite varies from fiber pull-out type to non pull-out type with progressing oxidation. The present work aimed to describe such a behavior with a computer-aided Monte Carlo shear lag simulation method. The experimentally measured variation of strength of the unidirectional composite as a function of thickness of the SiO2 layer and also as a function of exposure time and temperature, and the experimentally observed variation of fracture morphology with progressing oxidation, could be reproduced satisfactorily by this method.

Computational Simulation of Fracture Behavior Due to Mechanical and Constituent Properties of CFCCs

Continuous fiber reinforced ceramic matrix composites (CFCCs) are recently a subject of a lot of research interest due to advantages which are high specific stiffness and strength, high toughness and nonbrittle failure as compared to monolithic ceramics. The basic purpose of the present study is to describe graphically the fracture behavior of CFCCs according to a dependence on constituent properties. In CFCCs, following matrix cracking, intact fibers bridge effects impose closure tractions behind the crack tip that reduce the driving force for further cracking. Thus matrix cracking stress and bridging stress are important. Then the change of fiber volume fraction is given for the matrix cracking stress by the numerical simulation. Numerical simulation are carried out by using a finite element analysis code ANSYS. The double mesh concept is applied to account for fiber and matrix material properties.

OS08W0450 Numerical simulation of fracture behavior of brittle materials based on micro-crack formation

OS08W0450 Numerical simulation of fracture behavior of brittle materials based on micro-crack formation

OS8(2)-9(OS08W0450) Numerical Simulation of Fracture Behavior of Brittle Materials Based on Micro-Crack Formation

OS8(2)-9(OS08W0450) Numerical Simulation of Fracture Behavior of Brittle Materials Based on Micro-Crack Formation

543 ランダムき裂群の破壊挙動シミュレーション

543 ランダムき裂群の破壊挙動シミュレーション

939 DEM による合わせガラスの破壊挙動シミュレーション : ガラスと中間膜の接着強さの効果

939 DEM による合わせガラスの破壊挙動シミュレーション : ガラスと中間膜の接着強さの効果

Simulation of fracture behavior in particle-dispersed ceramic composites

A two-dimensional crack path is simulated in particle-dispersed ceramic composites along with the related variation of fracture resistance with crack extension. The direction of crack propagation is influenced by the geometrical crack shape and localized residual stresses due to the thermal expansion mismatch between particle and matrix. The simulation is conducted for both a SiC matrix composite dispersed with Al 2O 3 particles and an Al 2O 3 matrix composite dispersed with SiC particles, under an assumption of hard particles. In the SiCAl 2O 3 (p) composite, a crack propagating near the Al 2O 3 particles has a tendency to be repelled due to the residual tensile stress in the radial direction around the particles, and the entire fracture resistance shows a lower value than the matrix toughness. In the Al 2O 3SiC (p) composite, a crack is attracted by the SiC particles. Due to the residual compressive stress in the radial direction around the SiC particles, the fracture resistance increases up to five times the matrix toughness when the crack propagates along the interface. The apparent fracture resistance of the Al 2O 3SiC (p) composite shows a higher value than the matrix toughness, and an increasing R-curve behavior with crack extension is predicted. The approximately estimated two-dimensional fracture toughness of the Al 2O 3SiC (p) composite increases with the volume fraction of particles, while it decreases in the SiCAl 2O 3 (p) composite.

A Numerical Analysis of Fracture and High Temperature Creep Characteristics of Composites with Discontinuous Ductile Reinforcements

ABSTRACTThe role of the material parameters on the fracture and creep behavior of discontinuous ductile fiber reinforced brittle matrix composite system was numerically investigated. For simulation of fracture behavior, the ductile fibers were modeled using a constitutive relationship that accounts for strength degradation resulting from nucleation and growth of the voids. The matrix is assumed to be elastic and fails according to requirements of a stress criterion. Results indicate that the contribution of ductile reinforcement to the work of fracture value (toughness) of the composite increases with less exhaustion of its work hardening capacity before the onset of matrix failure. At creep regime, for rigidly bonded interfaces, the creep rate of the composite is not significantly influenced by the material properties of the ductile reinforcing phase due to development of large hydrostatic stress and constrained deformation in the reinforcement. Significant increases in room temperature fracture toughness can be achieved without extensively sacrificing the creep strength by ductile discontinuous reinforcements.