Scaling of structural failure

Bažant, Zdeněk P.; Chen, Er-Ping

doi:10.2172/420364

Cited by 34 publications

(43 citation statements)

References 45 publications

(74 reference statements)

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“…Bazant and Chen, 1997) that energy release for crack extension in real (granular) materials is related to the scale (and configuration) of intensified strain energy density due to heterogeneities. For most practical cases in cast A356-T6 alloy, cracks form in the matrix phase and hence the enclave of local cyclic plastic strain defines the length scale of the initiated crack.…”

Section: -16mentioning

confidence: 99%

Microstructure-Property Relations in Fatigue of a Cast A356-T6 Aluminum Alloy

Horstemeyer¹

2001

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The work in this report was a five year effort to foster fundamental advances in microstructureproperty fatigue relations of a cast A356-T6 aluminum alloy. We identified and quantified microstructure-property relations and then developed a mathematical tool for fatigue analysis of a cast A356-T6 aluminum alloy that is used in automotive structural components. We focused on three main areas of research: a wide variety of cyclic experiments in which specimens were examined with scanning electron microscopic imaging, finite element micromechanical modeling, and the development of a macroscale microstructure-property model for fatigue. Collaborations with Lawrence Livermore National Laboratory (LLNL) and Oak Ridge National Laboratory (ORNL) were important to this work. LLNL provided quantitative data for casting pore size, distribution, volume fraction, and nearest neighbor distance using nondestructive methods. ORNL performed solidification modeling of the casting process and provided insight into the silicon particle size, distribution, and volume fraction; the pore size, distribution, volume fraction, and nearest neighbor distance; and the dendrite cell size. EXECUTIVE SUMMARYThe work in this report, performed by Sandia National Laboratories (SNL) in collaboration with Georgia Institute of Technology, was a five year effort to foster fundamental advances in microstructure-property fatigue relations of a cast A356-T6 aluminum alloy. The goal was to identify and quantify microstructure-property relations and then develop mathematical tools for fatigue analysis of a cast A356-T6 aluminum alloy that is used in automotive structural components. This comprehensive experimental-computational fatigue study was conducted in parallel with developing microstructure-property relations for monotonic loading conditions, covered in a companion report (Microstructure-Property Relations for a Cast A356 Aluminum Alloy). We focused on three main areas of research: a wide variety of cyclic experiments in which specimens were examined with scanning electron microscopic imaging, finite element micromechanical modeling, and the development of a macroscale microstructure-property model for fatigue. Collaborations with Lawrence Livermore National Laboratory (LLNL) and Oak Ridge National Laboratory (ORNL) were important to this work. LLNL provided quantitative data for casting pore size, distribution, volume fraction, and nearest neighbor distance using nondestructive methods. ORNL performed solidification modeling of the casting process and provided insight into the silicon particle size, distribution, and volume fraction; the pore size, distribution, volume fraction, and nearest neighbor distance; and the dendrite cell size.The mechanical, physical, and casting properties of this A356 aluminum alloy make it attractive for use in cheaper and lighter engineering components. However, to successfully use cast A356 in long life components, it is necessary to understand its resistance to fatigue. The standard method in determining fa...

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Section: -16mentioning

confidence: 99%

Microstructure-Property Relations in Fatigue of a Cast A356-T6 Aluminum Alloy

Horstemeyer¹

2001

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“…The microstructures (grain boundaries, lattice defects, and intergranular pores) and mesostructures (size, shape, distribution characteristics, and microcracks of 2 Advances in Materials Science and Engineering mineral grains) inside rock minerals are the root cause of the various macromechanical properties in a rock body [2]. However, the existing strength and deformation theories have not effectively correlated the atomic scale, mesoscale, lab scale, and engineering scale for geomaterials.…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Simulation Method and Its Application to Determine the Mechanical Behavior of Heterogeneous Geomaterials

Xie

Zhang

et al. 2017

Advances in Materials Science and Engineering

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To study the micro/mesomechanical behaviors of heterogeneous geomaterials, a multiscale simulation method that combines molecular simulation at the microscale, a mesoscale analysis of polished slices, and finite element numerical simulation is proposed. By processing the mesostructure images obtained from analyzing the polished slices of heterogeneous geomaterials and mapping them onto finite element meshes, a numerical model that more accurately reflects the mesostructures of heterogeneous geomaterials was established by combining the results with the microscale mechanical properties of geomaterials obtained from the molecular simulation. This model was then used to analyze the mechanical behaviors of heterogeneous materials. Because kernstone is a typical heterogeneous material that comprises many types of mineral crystals, it was used for the micro/mesoscale mechanical behavior analysis in this paper using the proposed method. The results suggest that the proposed method can be used to accurately and effectively study the mechanical behaviors of heterogeneous geomaterials at the micro/mesoscales.

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“…Shear-and torsion-critical members, deep beams, slabs, fastenings and splices should be recalled among the structural cases, which have been more thoroughly investigated (Bazant and Chen, 1997;Ozbolt and Eligehausen, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Central to this transition is the energy dissipated at the fracture front, in the "fracture process zone", which is typical of cracking in heterogeneous, quasi brittle materials and structures (Shah and Ouyang, 1994;Bazant and Chen, 1997) and is the source of their softening behavior (and size effect).…”

Section: Introductionmentioning

confidence: 99%

“…As observed by Bazant and Chen (1997), "scaling is the most important aspect of every physical theory", and as such concerns also bar-concrete bond, even more since the bond stress-slip law of a smooth bar exhibits a strong softening. In such a case, however, the barconcrete interface should be considered as a sort of preorientated crack ("interfacial crack", length "a", Fig.2 see also Stang et al, 1990), provided that "cracking" and "fracture process zone" are replaced with "debonding" and "transitional zone", the latter meaning that "hazy" part of the bonded interface, which is at the onset of the frictional slip and where bond is increasingly damaged, but still fairly efficient.…”

Section: Introductionmentioning

confidence: 99%

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Smooth Anchored Bars in NSC and HPC: a Study on Size Effect

Bamonte¹,

Coronelli

Gambarova

2003

ACT

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The bonding of moderately-long anchorages to ordinary and high-performance silica-fume concrete is studied here with reference to size effect. To this purpose, 24 anchorages (L/d b = 10), consisting of a quasi-smooth, micro-roughened bar embedded in a concrete cylinder, were cast and tested up to the pull-out of the bars, which had 4 different diameters (d b = 5, 12, 18 and 26 mm). For each of the 8 cases examined here (4 diameters ¥ 2 mixes), 3 nominally-identical specimens were tested. Though the primary objective of this study is to investigate whether a general-type size-effect law applies to bond in high-performance concrete, the modeling of an anchorage by means of a local elastic-fracturingfrictional bond-slip law is also carried out, and two approaches are adopted for the description of size dependency, the first based on a stress criterion for the debonding, and the second on an energy criterion. The former approach leads to a size-dependent formulation of the local bond strength, while the second approach makes it possible to evaluate the debonding energy, which is size independent. In both approaches the values of the fundamental parameters of the model are identified by means of a bidimensional or mono-dimensional, least-square regression procedure. The results confirm that size effect in bond should be taken into consideration directly in the codes, and pave the way to the study of size effect in high-bond bars.

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Scaling of structural failure

Cited by 34 publications

References 45 publications

Microstructure-Property Relations in Fatigue of a Cast A356-T6 Aluminum Alloy

Microstructure-Property Relations in Fatigue of a Cast A356-T6 Aluminum Alloy

A Multiscale Simulation Method and Its Application to Determine the Mechanical Behavior of Heterogeneous Geomaterials

Smooth Anchored Bars in NSC and HPC: a Study on Size Effect

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