A numerical approach to study the post-yield softening in cellular solids: role of microstructural ordering and cell size distribution

Hosseinabadi, Hossein Goodarzi; Bagheri, Reza; Altstädt, Volker

doi:10.1007/s00707-017-1802-y

Cited by 8 publications

(5 citation statements)

References 19 publications

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“…Mitigating the PYS can further improve this ability. Thus, many efforts have been made in this regard, including the introduction of irregular ( 7 ), heterogeneous ( 8 ), or hybrid structures ( 9 ) in stretching-dominated lattices. These measures are effective in reducing the PYS to some extent, but often at the expense of yield strength.…”

Section: Introductionmentioning

confidence: 99%

Post-yield softening of bending-dominated metal metamaterials

Zhong

Das

et al. 2023

PNAS Nexus

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Post-yield softening (PYS) plays an important role in guiding the design of high-performance energy-absorbing lattice materials. PYS is usually restricted to lattice materials that are stretching-dominated according to the Gibson-Ashby model. Contrary to this long-held assumption, this work shows that PYS can also occur in various bending-dominated Ti-6Al-4V lattices with increasing relative density. The underlying mechanism for this unusual property is elucidated using the Timoshenko-beam theory. It is attributed to the increase in stretching and shear deformation with increasing relative density, thereby increasing the tendency towards PYS. The finding of this work extends perspectives on PYS for the design of high-performance energy-absorbing lattice materials.

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Section: Introductionmentioning

confidence: 99%

Post-yield softening of bending-dominated metal metamaterials

Zhong

Das

et al. 2023

PNAS Nexus

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“…Metamaterials are designer materials that exhibit properties not usually found in nature [ 18 ]. Recent advances in additive manufacturing have made it possible to have control over the micro- and macro-structural design features of porous structures [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] and manufacture several types of mechanical metamaterials such as Pentamodes [ 23 , 27 , 28 , 29 ], auxetics [ 30 , 31 ], and materials with negative compressibility [ 32 ]. One of the most commonly known mechanical metamaterials is auxetics that show negative Poisson’s ratio behaviours [ 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

Femur Auxetic Meta-Implants with Tuned Micromotion Distribution

2020

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Stress shielding and micromotions are the most significant problems occurring at the bone-implants interface due to a mismatch of their mechanical properties. Mechanical 3D metamaterials, with their exceptional behaviour and characteristics, can provide an opportunity to solve the mismatch of mechanical properties between the bone and implant. In this study, a new porous femoral hip meta-implant with graded Poisson’s ratio distribution was introduced and its results were compared to three other femoral hip implants (one solid implant, and two porous meta-implants, one with positive and the other with a negative distribution of Poisson’s ratio) in terms of stress and micromotion distributions. For this aim, first, a well-known auxetic 3D re-entrant structure was studied analytically, and precise closed-form analytical relationships for its elastic modulus and Poisson’s ratio were derived. The results of the analytical solution for mechanical properties of the 3D re-entrant structure presented great improvements in comparison to previous analytical studies on the structure. Moreover, the implementation of the re-entrant structure in the hip implant provided very smooth results for stress and strain distributions in the lattice meta-implants and could solve the stress shielding problem which occurred in the solid implant. The lattice meta-implant based on the graded unit cell distribution presented smoother stress-strain distribution in comparison with the other lattice meta-implants. Moreover, the graded lattice meta-implant gave minimum areas of local stress and local strain concentration at the contact region of the implants with the internal bone surfaces. Among all the cases, the graded meta-implant also gave micromotion levels which are the closest to values reported to be desirable for bone growth (40 µm).

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“…Recent advances in additive manufacturing has made it possible to have control over the micro-and macro-structural design features of porous structures [19][20][21][22][23][24][25], and manufacture several types of mechanical metamaterials such as Pentamodes [23,[26][27][28], auxetics [29,30], and materials with negative compressibility [31]. One of the most commonly known mechanical metamaterials are auxetics that show negative Poisson's ratio behaviors [32,33].…”

Section: Introductionmentioning

confidence: 99%

Auxetic femur meta-implants with tuned micromotion distribution

Ghavidelnia¹,

Bodaghi²,

Hedayati³

2020

Preprint

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Stress shielding and micromotions are the most significant problems occurring at the bone-implants interface due to mismatch of their mechanical properties. Mechanical metamaterials with their exceptional behavior and characteristics, can provide an opportunity to solve the mismatch of mechanical properties between the bone and implant. In this study, four types of human femoral hip implants (one solid implant and three lattice-structured meta-implants) have been considered for stress and micromotion analysis. For this aim, at the first stage, a well-known auxetic 3D re-entrant structure was studied analytically, and precise closed-form analytical relationships for elastic modulus and Poisson’s ratio of the unit cell were obtained. The analytical solution was validated with the numerical solution based on beam elements. At the second stage, three lattice meta-implants made of 3D re-entrant unit cells with positive, negative, and graded distribution of Poisson’s ratio were analyzed and the stress and strain distributions in implant and the micromotion at the bone-implant interface were studied. The results of analytical solution for mechanical properties of the 3D re-entrant structure presented great improvements in comparison with previous analytical studies on this structure. Moreover, the implementation of the re-entrant structure in the hip implant provided very smooth results for stress and strain distributions in the lattice meta-implants and could solve the stress shielding problem which occurred in the solid implant. The lattice meta-implant based on the graded unit cell distribution presented smoother stress-strain distribution in comparison with the other lattice meta-implants. Moreover, the graded lattice meta-implant gave minimum areas of local stress and local strain concentration at the contact region of the implants with the internal bone surfaces. Among all the cases, the graded meta-implant also gave micromotion levels which are the closest to values reported to be desirable for bone growth (40 µm).

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A numerical approach to study the post-yield softening in cellular solids: role of microstructural ordering and cell size distribution

Cited by 8 publications

References 19 publications

Post-yield softening of bending-dominated metal metamaterials

Post-yield softening of bending-dominated metal metamaterials

Femur Auxetic Meta-Implants with Tuned Micromotion Distribution

Auxetic femur meta-implants with tuned micromotion distribution

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