Length-scale dependency of biomimetic hard-soft composites

Mirzaali, Mohammad J.; Edens, Maike; Nava, Alba Herranz de la; Janbaz, Shahram; Vena, Pasquale; Doubrovski, Eugeni L.; Zadpoor, Amir A.

doi:10.1038/s41598-018-30012-9

Cited by 28 publications

(22 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the case of mixed mode I/II loading scenario, both Equations (13) and (14) have specific non-zero values and the equivalent J-integral value J eq can be determined by:…”

Section: A Brief Review Of J-integral In U-notchesmentioning

confidence: 99%

“…The path ACB is considered as the contour path for J-integral calculation. Due to the traction-free surface on the contour path ACB, the second term of J-integral equations are equal to zero (Equations (13) and (14)).…”

Section: A Brief Review Of J-integral In U-notchesmentioning

confidence: 99%

“…In ductile materials, cracks that originate from surface imperfections or notches often grow slowly, accompanied by significant plastic deformation. However, the rate of crack growth accelerates with the progressively increasing applied stresses [14].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fracture Resistance Analysis of 3D-Printed Polymers

2020

View full text Add to dashboard Cite

Three-dimensional (3D)-printed parts are an essential subcategory of additive manufacturing with the recent proliferation of research in this area. However, 3D-printed parts fabricated by different techniques differ in terms of microstructure and material properties. Catastrophic failures often occur due to unstable crack propagations and therefore a study of fracture behavior of 3D-printed components is a vital component of engineering design. In this paper, experimental tests and numerical studies of fracture modes are presented. A series of experiments were performed on 3D-printed nylon samples made by fused deposition modeling (FDM) and multi-jet fusion (MJF) to determine the load-carrying capacity of U-notched plates fabricated by two different 3D printing techniques. The equivalent material concept (EMC) was used in conjunction with the J-integral failure criterion to investigate the failure of the notched samples. Numerical simulations indicated that when EMC was combined with the J-integral criterion the experimental results could be predicted successfully for the 3D-printed polymer samples.

show abstract

“…In the case of mixed mode I/II loading scenario, both Equations (13) and (14) have specific non-zero values and the equivalent J-integral value J eq can be determined by:…”

Section: A Brief Review Of J-integral In U-notchesmentioning

confidence: 99%

Section: A Brief Review Of J-integral In U-notchesmentioning

confidence: 99%

See 1 more Smart Citation

Fracture Resistance Analysis of 3D-Printed Polymers

2020

View full text Add to dashboard Cite

show abstract

“…, elastic modulus and Poisson’s ratio) of mechanical metamaterials remains elusive. Recent advances in multi-material additive manufacturing (also called 3D printing) techniques have enabled the fabrication of ‘multi-material’ mechanical metamaterials 40 – 42 whose unusual properties and advanced functionalities are as much dependent on the spatial distribution of multiple phases with different mechanical properties as they are on the small-scale geometrical design of the constituting unit cells. Essentially, the complex distributions of the multiple phases are alternative ways of creating non-affine deformations so as to expand the range of achievable macroscale properties 41 .…”

Section: Introductionmentioning

confidence: 99%

Non-affinity in multi-material mechanical metamaterials

Mirzaali

Pahlavani

Yarali

et al. 2020

Sci Rep

Self Cite

View full text Add to dashboard Cite

Non-affine deformations enable mechanical metamaterials to achieve their unusual properties while imposing implications for their structural integrity. The presence of multiple phases with different mechanical properties results in additional non-affinity of the deformations, a phenomenon that has never been studied before in the area of extremal mechanical metamaterials. Here, we studied the degree of non-affinity, Ŵ , resulting from the random substitution of a fraction of the struts,ρ h , that make up a lattice structure and are printed using a soft material (elastic modulus = E s) by those printed using a hard material (E h). Depending on the unit cell angle (i.e., θ = 60°, 90°, or 120°), the lattice structures exhibited negative, near-zero, or positive values of the Poisson's ratio, respectively. We found that the auxetic structures exhibit the highest levels of non-affinity, followed by the structures with positive and near-zero values of the Poisson's ratio. We also observed an increase in Ŵ with E h E s and ρ h until E h E s =10 4 and ρ h = 75%-90% after which Ŵ saturated. The dependency of Ŵ upon ρ h was therefore found to be highly asymmetric. The positive and negative values of the Poisson's ratio were strongly correlated with Ŵ. Interestingly, achieving extremely high or extremely low values of the Poisson's ratio required highly affine deformations. In conclusion, our results clearly show the importance of considering non-affinity when trying to achieve a specific set of mechanical properties and underscore the structural integrity implications in multi-material mechanical metamaterials. A simple mechanical load (e.g., uniaxial compression, tension, or shear) applied to a geometrically simple (e.g., square-shaped) piece of what is traditionally considered a material (e.g., metals, polymers) leads to a simple deformation that is highly predictable at large enough length scales and is homogeneously distributed within the material. Such a homogenous deformation is formally called an 'affine' deformation and can be fully described using an affine transformation (i.e., a linear transformation plus a rigid body translation) applied to the coordinates of the points constituting the material 1,2. All this simplicity, predictability, and homogeneity may be lost when a simple mechanical load is applied to an architected material. Architected materials 3 , which are sometimes referred to as mechanical metamaterials 4-6 , possess complex small-scale geometries that are engineered to give rise to unusual mechanical properties at the macroscale. In a way, the whole point of rationally designing 7 the small-scale geometry of architected materials, may be to break the affinity of the deformations in an exact way so as to achieve unusual macroscale properties. Non-affine deformations can, for example, be exploited to achieve negative values of the Poisson's ratio 8,9 , action-at-a-distance actuation behaviors 10 , and independent tailoring of the elastic properties 11. Some other functionalities of mechanical metamat...

show abstract

“…The research into both latter rational design approaches has just started, as the multimaterial 3D printing (¼ additive manufacturing) techniques required for achieving complex spatial distributions of mechanical properties and combining that with complex geometries are just emerging. A few recent studies on 3D lattices with high Poisson's ratio properties, 11 topology optimization of multi-material mechanical metamaterials with negative Poisson's ratio 12 or multifunctionality, 13 and controlling instabilities, 14 are examples of the applications of dual-phase materials 15,16 for achieving new ranges of properties and new types of functionalities in mechanical metamaterials.…”

mentioning

confidence: 99%

Multi-material 3D printed mechanical metamaterials: Rational design of elastic properties through spatial distribution of hard and soft phases

Mirzaali

Caracciolo

Pahlavani

et al. 2018

Applied Physics Letters

Self Cite

102

View full text Add to dashboard Cite

Up until recently, the rational design of mechanical metamaterials has usually involved devising geometrical arrangements of micro-architectures that deliver unusual properties on the macro-scale. A less explored route to rational design is spatially distributing materials with different properties within lattice structures to achieve the desired mechanical properties. Here, we used computational models and advanced multi-material 3D printing techniques to rationally design and additively manufacture multi-material cellular solids for which the elastic modulus and Poisson's ratio could be independently tailored in different (anisotropic) directions. The random assignment of a hard phase to originally soft cellular structures with an auxetic, zero Poisson's ratio, and conventional designs allowed us to cover broad regions of the elastic modulus-Poisson's ratio plane. Patterned designs of the hard phase were also used and were found to be effective in the independent tuning of the elastic properties. Close inspection of the strain distributions associated with the different types of material distributions suggests that locally deflected patterns of deformation flow and strain localizations are the main underlying mechanisms driving the above-mentioned adjustments in the mechanical properties.

show abstract

Length-scale dependency of biomimetic hard-soft composites

Cited by 28 publications

References 38 publications

Fracture Resistance Analysis of 3D-Printed Polymers

Fracture Resistance Analysis of 3D-Printed Polymers

Non-affinity in multi-material mechanical metamaterials

Multi-material 3D printed mechanical metamaterials: Rational design of elastic properties through spatial distribution of hard and soft phases

Contact Info

Product

Resources

About