Energy absorption in lattice structures in dynamics: Nonlinear FE simulations

Özdemir, Zuhal; Tyas, A.; Goodall, Russell; Askes, Harm

doi:10.1016/j.ijimpeng.2016.11.016

Cited by 74 publications

(33 citation statements)

References 31 publications

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“…This assumption is supported by a study [2] that shows very low effect of intrinsic strain rate sensitivity and large inertia effect. Furthermore, the work done in [3] shows a limited influence of strain rate on octet truss lattice structures: the flow stress is increased by around 10 to 20% between the quasi-static (10 -3 s -1 ) and the dynamic regime (10 3 s -1 ).…”

Section: Numerical Model and Firing Test Design 41 Penetrator Finitementioning

confidence: 64%

Additively manufactured penetrating warheads

Limido¹,

Deconinck²,

Beaucamp³

et al. 2018

EPJ Web Conf.

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Penetrating warheads have to both defeat thick and high strength targets and have high blast effects. Lattice structures could help to enhance blast effect and reduce the weight of the penetrators. Additive manufacture provides a method to produce this concept. This paper details a programme to evaluate the perforation performance of such a penetrator. This study implemented an approach based on the integration of virtual and physical tests. A mesoscale numerical approach based on explicit high order finite element (HOFEM) was first developed to optimize the lattice pattern. The dynamic behaviour of this material was then determined using the Split Hopkinson Pressure Bar (SHPB) technique and this was then used to fit a constitutive model in Impetus Afea Solver®. The modelling of the concrete penetration of small scale warhead was based on the advanced meshless approach coupled with HOFEM. The models developed enabled the determination, simultaneously, of the homogenised behaviour of the lattice material and also the global behaviour of the penetrators during and after the penetration. Seven ballistic tests against concrete targets were performed at Thiot Ingenierie to investigate the penetration capabilities of the additively manufactured penetrating warhead concept and especially when using a lattice pattern.

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Section: Numerical Model and Firing Test Design 41 Penetrator Finitementioning

confidence: 64%

Additively manufactured penetrating warheads

Limido¹,

Deconinck²,

Beaucamp³

et al. 2018

EPJ Web Conf.

View full text Add to dashboard Cite

show abstract

“…Finite element analysis could be one way of further analyzing this effect, though this is likely to be affected by underlying anisotropy of material response, such as that which could arise in titanium alloys where the microstructure has a preferential orientation, and may require specific definitions of the properties of different struts (Rashed et al, 2016). Such modeling may also be rendered more complex by the uneven surface shown by real additively manufactured lattices, which has been suggested previously to be responsible for real lattices not achieving the same level of strength as predicted by FE simulations (Ozdemir et al, 2017), though there has been recent work toward developing advanced FE approaches to incorporate these kinds of structural variations (Lozanovski et al, 2019).…”

Section: Effect Of Missing Strut Defectsmentioning

confidence: 99%

The Effects of Defects and Damage in the Mechanical Behavior of Ti6Al4V Lattices

et al. 2019

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With recent advances in manufacturing methods for metals with defined, complex shapes, the investigation of metallic lattice materials (metals containing significant porosity with a regular arrangement of the solid, frequently in the form of thin structural members or struts) has become more common. These materials show many interesting properties, and may have the capacity to be more highly engineered and optimized for a given application than the random structures of other microcellular metals, such as metallic foams and sponges, permit. However, the novel structure brings new structure-properties correlations to bear on the mechanical behavior of the materials. This paper examines one type of lattice, made from titanium alloy (Ti6Al4V) and fabricated by Electron Beam Melting (EBM), a material which typically shows only limited plasticity on deformation. The overall mechanical response is governed by the cooperative deformation of a very large number of individual struts that make up the lattice, and thus there is great potential for significant impact from damage arising due to defects in individual struts in the assembly. We explore the effect of simulated processing defects (missing struts) on the lattice properties, and how deformation and failure is distributed across the lattice after the onset of failure. To gain knowledge of how lattices deform, samples of various geometries, designed to probe compression, indentation-compression and tension (in the form of bending) are produced and tested under Digital Image Correlation (DIC) mapping. The understanding gained here will be of great use in designing new metallic lattice structures with greater damage tolerance and resistance to failure.

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“…Note that the univariate functions cðρ,μj j ¼ω j Þ are independent since the random variables are independent, and therefore Eqs. (10) and (11) can be approximated as follows [46]:…”

Section: Calculation Of Statistical Momentsmentioning

confidence: 99%

“…At the microscale, for example, lattice metamaterials have been designed for negative Poisson's ratio [1][2][3], acoustic manipulation [4,5] and energy absorption [6]. Mesoscale lattice structures have also been embedded into global structures to achieve multifunctional heat exchangers [7,8], and parts with high energy absorption [9][10][11][12] and low weight [13,14]. In particular, lattice structures are exceptionally popular in the biomedical field due to their porosity, which allows biocompability with organic tissue, high performance-toweight ratio, and ease of customization [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Robust topology optimization of multi-material lattice structures under material and load uncertainties

2019

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Enabled by advancements in multi-material additive manufacturing, lightweight lattice structures consisting of networks of periodic unit cells have gained popularity due to their extraordinary performance and wide array of functions. This work proposes a density-based robust topology optimization method for meso-or macroscale multi-material lattice structures under any combination of material and load uncertainties. The method utilizes a new generalized material interpolation scheme for an arbitrary number of materials, and employs univariate dimension reduction and Gauss-type quadrature to quantify and propagate uncertainty. By formulating the objective function as a weighted sum of the mean and standard deviation of compliance, the tradeoff between optimality and robustness can be studied and controlled. Examples of a cantilever beam lattice structure under various material and load uncertainty cases exhibit the efficiency and flexibility of the approach. The accuracy of univariate dimension reduction is validated by comparing the results to the Monte Carlo approach.

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Energy absorption in lattice structures in dynamics: Nonlinear FE simulations

Cited by 74 publications

References 31 publications

Additively manufactured penetrating warheads

Additively manufactured penetrating warheads

The Effects of Defects and Damage in the Mechanical Behavior of Ti6Al4V Lattices

Robust topology optimization of multi-material lattice structures under material and load uncertainties

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