Topic
Fracture toughness
About: Fracture toughness is a research topic. Over the lifetime, 39642 publications have been published within this topic receiving 854338 citations.
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TL;DR: In this paper, three Al2O3-ZrO2 composite series, containing 0, 2 and 7.5 mol % Y2O 3, were fabricated for fracture toughness determinations.
Abstract: Three Al2O3-ZrO2 composite series, containing 0, 2 and 7.5 mol % Y2O3, were fabricated for fracture toughness determinations. Without Y2O3 additions, tetragonal-phase ZrO2 could only be retained up to approximately 10 vol % ZrO2; additions of 2 mol % Y2O3 allowed full retention of the tetragonal phase up to 60 vol % ZrO2. Cubic ZrO2 was produced with additions of 7.5 mol % Y2O3. Significant toughening and strengthening was achieved when tetragonal ZrO2 was present.
276 citations
TL;DR: In this paper, the fracture toughness of a single-phase commercial lead zirconate titanate (PZT) ceramic was measured using the single edge notched beam method above and below the Curie temperature.
Abstract: Fracture toughness, KIC, of a single-phase commercial lead zirconate titanate (PZT) ceramic (Zr/Ti=0.54/0.46) of tetragonal structure (c/a=1.019) was measured using the single edge notched beam method above and below the Curie temperature. Domain switching (poling) under electrical and mechanical loading was examined using X-ray diffraction. Surface grinding, electrical poling, and mechanical poling caused crystallographic texture. Similar texture, indicative of domain switching, was also observed on fracture surfaces of some saples fractured at room temperature. At room temperature, the highest KIC measured was 1.85 MPa·m1/2, while above the Curie temperature it was about 1.0 MPa·m1/2. Cracks emanating from Vickers indents in poled samples were different in the poling and the transverse directions. The difference in crack sizes is explained on the basis of domain switching during crack growth. These results indicate that ferroelastic domain switching (twinning) is a viable toughening mechanism in the PZT materials tested.
276 citations
TL;DR: In this paper, a general model for normal/shear cracking in quasi-brittle materials is presented, which is defined in terms of the normal and shear stresses on the average plane of the crack and the corresponding relative displacements, and implemented in two ways: directly as the constitutive law of an interface element in the context of discrete crack analysis, or as the law of a generic cracking plane in a multicrack formulation.
Abstract: A simple but general model for normal/shear cracking in quasi-brittle materials is presented. It is defined in terms of the normal and shear stresses on the average plane of the crack and the corresponding normal and shear relative displacements. A crack surface in stress space determines crack initiation under pure tension, shear-tension, or shear-compression loading. Two independent fracture energy parameters are used: the classical Mode I fracture energy GfI, and the asymptotic Mode II fracture energy GfIIa under very high shear-compression and no dilatancy. The cracking model proposed can be implemented in two ways: directly as the constitutive law of an interface element in the context of discrete crack analysis, or as the law of a generic cracking plane in a multicrack formulation in the context of smeared crack analysis. In this paper, the first approach is presented and examples are given of numerical constitutive testing and verification with experimental data.
275 citations
TL;DR: In this paper, the concept of hierarchical design is applied to conventional compounds such as alumina and poly(methyl methacrylate) (PMMA) to make bulk hybrid materials that display exceptional toughness that can be nearly 300 times higher than either of their constituents.
275 citations
21 Apr 2016
TL;DR: In this article, a review of published data on the mechanical properties of additively manufactured metallic materials can be found, including powder bed fusion and directed energy deposition, and the effects of test orientation/build direction on properties, along with discussion of the potential source(s) of anisotropy in properties.
Abstract: : This article reviews published data on the mechanical properties of additively manufactured metallic materials. The additive manufacturing techniques utilized to generate samples covered in this review include powder bed fusion (e.g., EBM, SLM, DMLS) and directed energy deposition (e.g., LENS, EBF3). Although only a limited number of metallic alloy systems are currently available for additive manufacturing (e.g., Ti-6Al-4V, TiAl, stainless steel, Inconel 625/718, and Al-Si-10Mg), the bulk of the published mechanical properties information has been generated on Ti-6Al-4V. However, summary tables for published mechanical properties and/or key figures are included for each of the alloys listed above, grouped by the additive technique used to generate the data. Published values for mechanical properties obtained from hardness, tension/compression, fracture toughness, fatigue crack growth, and high cycle fatigue are included for as-built, heat-treated, and/or HIP conditions, when available. The effects of test orientation/build direction on properties, when available, are also provided, along with discussion of the potential source(s) (e.g., texture, microstructure changes, defects) of anisotropy in properties. Recommendations for additional work are also provided.
273 citations