Compressive Strain at the Onset of Densification of Cellular Solids

Li, Qingming; Magkiriadis, I; Harrigan, Jane

doi:10.1177/0021955x06063519

Cited by 536 publications

(199 citation statements)

References 9 publications

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“…The determined values of the parameters discussed above are provided in tables 3 and 5. ε D were determined using the energy efficiency method outlined by Miltz and Ramon 25 and Li et al 26 The BCC z lattices, with their additional cellular reinforcing struts in the z direction, provided higher modulus and plastic collapse strength than the BCC lattices. Their modulus and plastic collapse strength were around 220% and 41% larger, respectively, than those of the BCC lattice when the compressive load was applied in the z direction.…”

Section: Resultsmentioning

confidence: 99%

An investigation into reinforced and functionally graded lattice structures

Maskery

Hussey

Panesar

et al. 2016

Journal of Cellular Plastics

246

108

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Lattice structures are regarded as excellent candidates for use in lightweight energy absorbing applications, such as crash protection. In this paper we investigate the crushing behaviour, mechanical properties and energy absorption of lattices made by an additive manufacturing (AM) process. Two types of lattice were examined; body-centred-cubic (BCC) and a reinforced variant called BCC z . The lattices were subject to compressive loads in two orthogonal directions, allowing an assessment of their mechanical anisotropy to be made. We also examined functionally graded versions of these lattices, which featured a density gradient along one direction. The graded structures exhibited distinct crushing behaviour, with a sequential collapse of cellular layers preceding full densification. For the BCC z lattice, the graded structures were able to absorb around 114% more energy per unit volume than their non-graded counterparts before full densification, 1371 ± 9 kJ/m 3 vs. 640 ± 10 kJ/m 3 . This highlights the strong potential for functionally graded lattices to be used in energy absorbing applications. Finally, we determined several of the Gibson-Ashby coefficients relating the mechanical properties of lattice structures to their density; these are crucial in establishing the constitutive models required for effective lattice design. These results improve the current understanding of AM lattices, and will enable the design of sophisticated, functional, lightweight components in the future.

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Section: Resultsmentioning

confidence: 99%

An investigation into reinforced and functionally graded lattice structures

Maskery

Hussey

Panesar

et al. 2016

Journal of Cellular Plastics

246

108

View full text Add to dashboard Cite

show abstract

“…When the impact velocity is close to or exceeds the critical impact velocity V = √2 ys / * , it will tend to a constant. Based on the concept of energy absorption efficiency method [31][32][33], the densification strain can be determined as where is the energy efficiency parameter of cellular solids, and it can be defined as the ratio of the absorbed energy up to a given nominal strain divided by the corresponding stress value, as follows:…”

Section: Finite Element Methods Simulationmentioning

confidence: 99%

Numerical Investigation on Dynamic Crushing Behavior of Auxetic Honeycombs with Various Cell-Wall Angles

Zhang

Ding

et al. 2014

Advances in Mechanical Engineering

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Auxetic honeycombs have proven to be an attractive advantage in actual engineering applications owing to their unique mechanical characteristic and better energy absorption ability. The in-plane dynamic crushing behaviors of the honeycombs with various cellwall angles are studied by means of explicit dynamic finite element simulation. The influences of the cell-wall angle, the impact velocity, and the edge thickness on the macro/microdeformation behaviors, the plateau stresses, and the specific energy absorption of auxetic honeycombs are discussed in detail. Numerical results show, that except for the impact velocity and the edge thickness, the in-plane dynamic performances of auxetic honeycombs also rely on the cell-wall angle. The "> <"-mode local deformation bands form under low-or moderate-velocity impacting, which results in lateral compression shrinkage and shows negative Poisson's ratio during the crushing. For the given impact velocity, the plateau stress at the proximal end and the energy-absorbed ability can be improved by increasing the negative cell angle, the relative density, the impact velocity, and the matrix material strength. When the microcell parameters are the constant, the plateau stresses are proportional to the square of impact velocity.

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“…Therefore, it was essential to determine these two parameters precisely and make the defined process clear. In this paper, an energy efficiency-based approach was adopted to calculate the plateau stress and densification strain (Li et al, 2006). Energy absorption efficiency ( ) a   was defined as the energy absorbed up to a given nominal strain a  normalized by the corresponding stress value ( ) c   , to remove the recoverable energy at the elastic stage and reflect the nature of energy absorption efficiency, it was in the following form…”

Section: Shock Wave Theorymentioning

confidence: 99%

Dynamic crushing of uniform and density graded cellular structures based on the circle arc model

Zhang

Wei

Wang

et al. 2015

Lat. Am. j. solids struct.

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A new circle-arc model was established to present the cellular structure. Dynamic response of models with density gradients under constant velocities is investigated by employing Ls-dyna 971. Compared with the uniform models, the quasi-static plateau stress of different layers seems a significant parameter correlated with the deformation mode except for inertia effect when the density gradient is introduced. The impact velocity becomes much more vital on the deformation of the unit cell than the density gradient. The stress at both the impact and stationary sides is investigated in details. Furthermore, the stress-strain curve is compared with the modified shock wave theory. The density gradient does have some remarkable influence on the energy absorption capability, and a certain density gradient is not always beneficial to the energy absorption. Irrespective of the impact velocity, there seems always a critical strain where the energy absorbed by all these specimens could approximate to nearly the same value. So the critical strain-velocity curve is plotted and gives the beneficial area for energy absorption pertinent to density gradients and impact velocity.

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Compressive Strain at the Onset of Densification of Cellular Solids

Cited by 536 publications

References 9 publications

An investigation into reinforced and functionally graded lattice structures

An investigation into reinforced and functionally graded lattice structures

Numerical Investigation on Dynamic Crushing Behavior of Auxetic Honeycombs with Various Cell-Wall Angles

Dynamic crushing of uniform and density graded cellular structures based on the circle arc model

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