A model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations. Two contributions existing in the literature have been integrated into the enhanced model. The first is the model of Gologanu-Leblond-Devaux, extending the Gurson model to void shape effects. The second is the approach of Thomason for the onset of void coalescence. Each of these has been extended heuristically to account for strain hardening. In addition, a micromechanically-based simple constitutive model for the void coalescence stage is proposed to supplement the criterion for the onset of coalescence. The fully enhanced Gurson model depends on the flow properties of the material and the dimensional ratios of the void-cell representative volume element. Phenomenological parameters such as critical porosities are not employed in the enhanced model. It incorporates the effect of void shape, relative void spacing, strain hardening, and porosity. The effect of the relative void spacing on void coalescence, which has not yet been carefully addressed in the literature. has received special attention. Using cell model computations, accurate predictions through final fracture have been obtained for a wide range of porosity, void spacing, initial void shape, strain hardening, and stress triaxiality. These predictions have been used to assess the enhanced model. (C) 2000 Elsevier Science Ltd. All rights reserved.

An extended model for void growth and coalescence - application to anisotropic ductile fracture

With the increasing application of orthopedic scaffolds, a dramatically increasing number of requirements for scaffolds are precise The porous structure has been a fundamental design in the bone tissue engineering or orthopedic clinics because of its low Young's modulus, high compressive strength, and abundant cell accommodation space The porous structure manufactured by additive manufacturing (AM) technology has controllable pore size, pore shape, and porosity The single unit can be designed and arrayed with AM, which brings controllable pore characteristics and mechanical properties This paper presents the current status of porous designs in AM technology The porous structures are stated from the cellular structure and the whole structure In the aspect of the cellular structure, non-parametric design and parametric design are discussed here according to whether the algorithm generates the structure or not The non-parametric design comprises the diamond, the body-centered cubic, and the polyhedral structure, etc The Voronoi, the Triply Periodic Minimal Surface, and other parametric designs are mainly discussed in parametric design In the discussion of cellular structures, we emphasize the design, and the resulting biomechanical and biological effects caused by designs In the aspect of the whole structure, the recent experimental researches are reviewed on uniform design, layered gradient design, and layered gradient design based on topological optimization, etc These parts are summarized because of the development of technology and the demand for mechanics or bone growth Finally, the challenges faced by the porous designs and prospects of porous structure in orthopedics are proposed in this paper

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Porous Scaffold Design for Additive Manufacturing in Orthopedics: A Review.

Processing and design methodologies for advanced and novel thermal barrier coatings for engineering applications

Degradation behavior, cytotoxicity, hemolysis, and antibacterial properties of electro-deposited Zn-Cu metal foams as potential biodegradable bone implants.

Practical application of roller compaction process modeling

Effect of annealing on the dynamic Young׳s modulus E of ultrafine-grained (UFG) and microcrystalline (MC) copper obtained by combined severe plastic deformation (SPD) including repeated hydrostatic extrusion and drawing (UFG copper) or only repeated drawing (MC copper) is investigated. It is established that the Young׳s modulus in the SPD-prepared UFG and MC samples exceeds that in the coarse-grained fully annealed (CGFA) samples by 10% to 20%. Subsequent isothermal annealing at elevated temperatures between 90 and 470 °С leads to a sharp decrease of the Young׳s modulus for annealing temperatures above 210 °С. After annealing at 410 °С, the value of E reaches its minimal value that is 35% lower than E in CGFA samples (total change in E is about 50% of the initial value). Further annealing at higher temperatures leads to some increase in the Young׳s modulus. It is shown that the unusual behavior of the Young׳s modulus is caused by the formation of the 〈111〉 axial drawing texture in the SPD-treated samples which is replaced by the 〈001〉 annealing texture during the post-SPD heat treatments.

Unusual Young׳s modulus behavior in ultrafine-grained and microcrystalline copper wires caused by texture changes during processing and annealing

Cinematics and volume deformations during roll-press briquetting

The structure and texture of a pipe from steel AMg6 produced by the method of hot pressing (extrusion) are studied. The important role of special (special and “half-special”) boundaries in the process of dynamic recrystallization is described.

Interrelation of Crystallographic Orientations of Grains in Aluminum Alloy AMg6 Under Hot Deformation and Recrystallization

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Annealing Characteristics and Strain Resistance of 99.93 wt.% Platinum

It has been found by textural analysis methods that, in the course of annealing with heating and cooling at a rate of 100 K/s, the textured state of an oxygen-containing copper wire of grade M00 deformed by drawing to 97% reduction changes, retaining the zonal structure. In the central zone, at a relative current radius from 0 to 0.3, the 〈111〉 orientation dominates to a temperature of 300°C. At the higher temperatures, the 〈100〉 orientation becomes dominant and remains up to 500°C. At relative current radii of 0.6–1.0 (peripheral zone) and 0.3–0.6 (intermediate zone), the dominant 〈100〉 orientation is retained to 300°C; at the higher temperatures, the dominance of the 〈100〉 orientation levels off. As the annealing temperature increases, the intermediate zone wedges out at the expense of growth of the central and peripheral zones. On the whole, the annealing at high temperatures (above 400°C) leads to the predominance of the 〈100〉 orientation; it is highly dominant for relative radii of 0–0.5.

Yu. N. Loginov

Papers

Unusual Young׳s modulus behavior in ultrafine-grained and microcrystalline copper wires caused by texture changes during processing and annealing

Cinematics and volume deformations during roll-press briquetting

Interrelation of Crystallographic Orientations of Grains in Aluminum Alloy AMg6 Under Hot Deformation and Recrystallization

Annealing Characteristics and Strain Resistance of 99.93 wt.% Platinum

Effect of annealing temperature on the texture of copper wire