A computational study of elongated pore interactions in a low density porous copper

Kee, A.; Matic, Peter; Wolla, Jeffrey M.

doi:10.1016/s0921-5093(97)80110-4

Cited by 6 publications

(4 citation statements)

References 9 publications

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“…5. [19][20][21][22][23][24] Importantly, the cross section for perpendicular loading hardly changes, despite the occurrence of a large tensile deformation exceeding 20% strain. The average and standard deviation of porosity and tensile properties among the specimens used for the cross-section measurements are shown in Table I.…”

Section: Anisotropy Of Change In Cross Section Of Specimen and Appmentioning

confidence: 99%

“…Importantly, the specific strength parallel to the pore direction is independent of porosity and, thus, much greater than that of metal foams, as is the case with the tensile elongation. [19][20][21][22][23][24] However, almost all these previous studies focused only on the anisotropy associated with the stress field around pores as a cause of the anisotropic tensile properties; stress concentration rarely occurs around the pores for loads parallel to the pore direction, while large stress concentration occurs in the case of loads perpendicular to the pore direction. 14 The unique anisotropic porous structure of lotus metals have prompted researchers to elucidate the deformation mechanism both experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

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Tensile deformation of anisotropic porous copper with directional pores

2010

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The tensile deformation of anisotropic porous copper with unidirectionally oriented cylindrical pores was investigated by an acoustic emission method. In the loadings parallel and perpendicular to the orientation direction of the pores, many cracks are formed after yielding and they strongly affect the deformation. The formed cracks rapidly grow and connect with each other near the peak stress of the stress-strain curve, thereby leading to final fracture. Crack formation is easier under perpendicular loading than under parallel loading, because high stress concentration and stress triaxiality occurs around the pores. As a result, the strength and elongation for perpendicular loading are much smaller than those for parallel loading. Furthermore, in the case of perpendicular loading, the localized deformation around pores drastically decreases the plastic Poisson's ratio. These results indicate that a porous copper macroscopically behaves as a semibrittle material under perpendicular loading, while the porous copper exhibits ductility under parallel loading.

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Section: Anisotropy Of Change In Cross Section Of Specimen and Appmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tensile deformation of anisotropic porous copper with directional pores

2010

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“…Kee and coworkers 54 have reported an investigation of gasar copper, 21 . 5% pore volume fraction, under tension deformation based on finite element modelling.…”

Section: Physical Phenomena In Gasar Structure Formation Processmentioning

confidence: 99%

“…A number of authors have applied mathematical models to study some aspects of the unusual mechanical behaviour of gasars. Kee and coworkers 54 have reported an investigation of gasar copper, 21 . 5% pore volume fraction, under tension deformation based on finite element modelling.…”

Section: Physical Phenomena In Gasar Structure Formation Processmentioning

confidence: 99%

Gasars: A class of metallic materials with ordered porosity

Drenchev¹,

Sobczak²,

Malinov³

et al. 2006

Materials Science and Technology

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High porosity metallic materials are designed for special properties, which can be used in many industrial applications. The development of new porous structures is a challenge for materials scientists. This paper discusses general characteristics, structure, properties and some manufacturing practices of a class of relatively new metallic materials named gasars, ordered porosity materials, or lotus type porous materials. An overview of the metals and alloys used and mechanical properties studied is presented. Some relations between structure characteristics and mechanical properties are discussed. Basic relations between processing parameters and structure characteristics are analysed. Special attention is paid to the complex physical phenomena in ordered porosity structure formation. Conditions for production of high porosity ingot are discussed. List of symbolsA, A9 constants in Sievert's law, K B, B9 constants in Sievert's law, mol m 23 Pa 21/2 C E eutectic concentration, mol m 23 C L gas concentration in liquid, mol m 23 C S gas concentration in solid, mol m 23 C 0 initial gas concentration in melt, mol m 23 C * maximum gas concentration in melt at solid/ liquid interface, mol m 23 F 1 empirical parameter, dimensionless g acceleration of gravity (9.81), m s 22 k distribution coefficient (k5C S /C L ), dimensionless K L , K S coefficients, mol m 23 Pa 21/2 p porosity, dimensionless p eff effective pressure (p eff 5F 2 1 P H ), Pa p M partial gas pressure, Pa Dp b driving force (Dp b 5p M 2p eff ), Pa P pressure in gas bubble, Pa P 1 , P 2 pressures, Pa P Ar partial gas (Ar) pressure in surrounding atmosphere, Pa P hyd hydrostatic pressure in melt (P hyd 5rgh), Pa P H partial gas (H 2 ) pressure in surrounding atmosphere, Pa P tot total pressure in melt (P tot 5P H zP Ar zP hyd ), Pa DP pressure drop across curved meniscus in equilibrium (DP5P 2 2P 1 ), Pa Q constant (P Ar /P H ), dimensionless R radius of curvature, m R b radius of bubble, m R P radius of conical pit at the level of meniscus, m R 0 critical radius, m S l relative part of bubble surface contacting with liquid, dimensionless S s relative part of bubble surface contacting with solid, dimensionless T temperature, K T m melting point of metal, K n b velocity of bubble movement, m s 21 v cr solidification front velocity, m s 21 g melt viscosity, Pa s r melt density, kg m 23 r g gas density, kg m 23 r s solid copper density, kg m 23 r * gasar ingot density, kg m 23 s surface energy, J m 22 s gl surface tension for gas/liquid interfaces, J m 22 s gs surface tension for gas/solid interfaces, J m 22 s y yield strength, MPa s UTS ultimate tensile strength, MPa h C half angle of conical pit, u h W contact angle of melt on solid inclusion, u

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