scholarly journals Plastic Crushing Failure of Bio-Inspired Cellular Hierarchical Topological Sandwich Core

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5040
Author(s):  
Yuwu Zhang ◽  
Yuliang Lin ◽  
Xiangcheng Li
Keyword(s):  
Elastic Modulus ◽  
Relative Density ◽  
Small Deformation ◽  
Hierarchical Order ◽  
Compressive Response ◽  
Constituent Material ◽  
Unit Cells ◽  
316L Steel ◽  
Order Increase ◽  
Crushing Behavior

Bio-inspired self-similar hierarchical honeycombs are multifunctional cellular topologies used for resisting various loadings. However, the crushing behavior under large plastic deformation is still unknown. This paper investigates the in-plane compressive response of selective laser melting (SLM) fabricated hierarchical honeycombs. The effects of hierarchical order, relative density as well as constituent material are evaluated. The results show that at small deformation, the AlSi10Mg alloy hierarchical honeycombs show great advantages over the elastic modulus and compressive strength than 316L steel hierarchical honeycombs. As the relative density and hierarchical order increase, the failure mechanism of AlSi10Mg alloy honeycombs gradually changes from a bending-dominated mode to a fracture-dominated mode; whereas all the 316L steel honeycombs fail due to the distortion of original unit cells. At large deformation, the AlSi10Mg alloy honeycombs behave with brittle responses, while the 316L steel honeycombs exhibit ductile responses, showing a negative Poisson’s ratio behavior and gradient deformation of hierarchical unit cells. The addition of unit cell refinements improves the elastic modulus of AlSi10Mg alloy honeycombs and advances the densification of 316L steel honeycombs. In addition, the effect of constituent material on the compressive response of hierarchical honeycombs has been discussed. This study facilitates the development and future potential application of multifunctional ultra-light sandwich structures.

Material Behavior of 2D Steel Lattices with Different Unit-Cell Patterns

2021 ◽  
Vol 1046 ◽  
pp. 15-21
Author(s):  
Paiboon Limpitipanich ◽  
Pana Suttakul ◽  
Yuttana Mona ◽  
Thongchai Fongsamootr
Keyword(s):  
Elastic Modulus ◽  
Experimental Studies ◽  
Base Material ◽  
Unit Cell ◽  
Material Behavior ◽  
Closed Form Solutions ◽  
The Past ◽  
Weight Density ◽  
Unit Cells ◽  
Cell Patterns

Over the past years, two-dimensional lattices have attracted the attention of several researchers because they are lightweight compared with their full-solid counterparts, which can be used in various engineering applications. Nevertheless, since lattices are manufactured by reducing the base material, their stiffnesses then become lower. This study presents the weight efficiency of the lattices defined by relations between the elastic modulus and the weight density of the lattices. In this study, the mechanical behavior of 2D lattices is described by the in-plane elastic modulus. Experimental studies on the elastic modulus of the 2D lattices made of steel are performed. Three lattices having different unit cells, including square, body-centered, and triangular unit cells, are considered. The elastic modulus of each lattice is investigated by tensile testing. All specimens of the lattices are made of steel and manufactured by waterjet cutting. The experimental results of the elastic modulus of the lattices with the considered unit-cell patterns are validated with those obtained from finite element simulations. The results obtained in this study are also compared with the closed-form solutions founded in the literature. Moreover, the unit-cell pattern yielding the best elastic modulus for the lattice is discussed through weight efficiency.

Hierarchical Design of Phononic Materials and Structures

2005 ◽  
Author(s):  
Mahmoud I. Hussein ◽  
Gregory M. Hulbert ◽  
Richard A. Scott
Keyword(s):  
Wave Scattering ◽  
Design Methodology ◽  
Periodic Structures ◽  
Building Blocks ◽  
Hierarchical Design ◽  
Material Interfaces ◽  
Dynamical Characteristics ◽  
Constituent Material ◽  
Unit Cells ◽  
Damping Materials

Within periodically heterogeneous materials and structures, wave scattering and dispersion occur across constituent material interfaces leading to a banded frequency response. A novel multiscale dispersive design methodology is presented by which periodic unit cells are designed for desired frequency band structures, and are used as building blocks for forming fully or partially periodic structures, typically at larger length scales. Structures resulting from this hierarchical design approach are tailored to desired dynamical characteristics without the necessity for altering the overall geometric shape of the structure nor employing dissipative damping materials. Case studies are presented for shock isolation and frequency sensing.

The Effect of Surface Self-Nanocrystallization on Low-Temperature Gas Carburization for AISI 316L Steel

2019 ◽  
Vol 795 ◽  
pp. 137-144
Author(s):  
Zhe Liu ◽  
Ya Wei Peng ◽  
Jian Ming Gong ◽  
Chao Ming Chen
Keyword(s):  
Stainless Steel ◽  
Elastic Modulus ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Surface Hardness ◽  
Electron Probe Micro Analyzer ◽  
Gas Carburizing ◽  
316L Steel ◽  
Negative Effect ◽  
Effect Of Surface

In this work, the effect of surface self-nanocrystallization on low-temperature gas carburizing for AISI316L austenitic stainless steel has been studied. The surface ultrasonic rolling processing (SURP) was used to prepare nanostructured surface layers, and then the un-SURP and SURP samples were treated by LTGC at 470 °C for 10 h, 20 h and 30 h. In order to analyze the effect of surface self-nanocrystallization on low-temperature gas carburizing, optical microscopy (OM), atomic force microscope (AFM), scanning electron probe micro-analyzer (EPMA) and nano-indentation analyzer were used. The results show depth of SURP-induced plastic deformation layer was about 330 μm. Meanwhile, the surface hardness and elastic modulus were increased but the surface roughness decreased obviously after SURP. After low-temperature gas carburizing, according to the results of the thickness, carbon concentration, nano-hardness and elastic modulus of the carburized layer, the conclusion is that surface self-nanocrystallization carried by SURP has a negative effect on the low-temperature gas carburizing for AISI316L austenitic stainless steel and with the increase of carburizing time, the greater the adverse effect on carburizing.

Structure, Process, and Material Influences for 3D Printed Lattices Designed With Mixed Unit Cells

2020 ◽  
Author(s):  
Gabriel Briguiet ◽  
Paul F. Egan
Keyword(s):  
Elastic Modulus ◽  
Mechanical Testing ◽  
Mechanical Response ◽  
Cell Types ◽  
Unit Cell ◽  
Ultraviolet Curing ◽  
Mechanical Responses ◽  
Lattice Design ◽  
Unit Cells ◽  
3D Printed

Abstract Emerging 3D printing technologies are enabling the design and fabrication of novel architected structures with advantageous mechanical responses. Designing complex structures, such as lattices, with a targeted response is challenging because build materials, fabrication process, and topological design have unique influences on the structure’s mechanical response. Changing any factor may have unanticipated consequences, even for simpler lattice structures. Here, we conduct mechanical compression experiments to investigate varied lattice design, fabrication, and material combinations using stereolithography printing with a biocompatible polymer. Mechanical testing demonstrates that a higher ultraviolet curing time increases elastic modulus. Material testing demonstrated that anisotropy does not strongly influence lattice mechanics. Designs were altered by comparing homogenous lattices of single unit cell types and heterogeneous lattices that combine two types of unit cells. Unit cells for heterogeneous structures include a Cube design for a high elastic modulus and Cross design for improved shear response. Mechanical testing of three heterogeneous layouts demonstrated how unit cell organization influences mechanical outcomes, therefore enabling the tuning of an elastic modulus that surpasses the law of averages designed for application-dependent mechanical needs. These findings provide a foundation for linking design, process, and material for engineering 3D printed structures with preferred properties, while also facilitating new directions in design automation and optimization.

scholarly journals Corrosion and tribological behaviour in a 3.5% NaCl solution of vacuum arc deposited ZrCN and Zr–Cr–Si–C–N coatings

2018 ◽  
Vol 233 (1) ◽  
pp. 158-169 ◽  
Author(s):  
Lidia R Constantin ◽  
Anca C Parau ◽  
Mihai Balaceanu ◽  
Mihaela Dinu ◽  
Alina Vladescu
Keyword(s):  
Corrosion Resistance ◽  
Elastic Modulus ◽  
Tribological Performance ◽  
Vacuum Arc ◽  
Nacl Solution ◽  
Tribological Behaviour ◽  
Mechanical And Tribological Properties ◽  
316L Steel ◽  
Steel Substrates ◽  
Si Addition

ZrCN and Zr–Cr–Si–C–N coatings were deposited on Si (100) and 316L stainless steel substrates using the cathodic vacuum arc technique in a mixed atmosphere of C2H2 and N2. The coatings were grown keeping almost constant the ratio of the C2H2 and N2 mass flow rates, substrate bias and deposition temperature at ∼0.81, −200 V and 320 ℃, respectively. The investigation carried out aimed to determine the corrosion and tribological performance of the novel Zr–Cr–Si–C–N coating obtained by Cr and Si addition to the ZrCN reference coating. The films were characterized in terms of elemental and phase composition, crystalline structure, hardness, reduced elastic modulus and adhesion. Particular attention was devoted to the investigation of coatings' corrosion resistance and tribological performance carried out in a 3.5% NaCl solution. Cr and Si addition to ZrCN coating leads to reduction in film crystallinity, finer microstructure, enhanced corrosion resistance and better tribological performance under corrosive testing conditions. In this paper, we discuss the measured mechanical and tribological properties of the two coatings in terms of various ratios of hardness and reduced elastic modulus. The coated samples exhibited high corrosion protection efficiency, reaching 97.8% for the Zr–Cr–Si–C–N coating. Both coatings improved the tribological performance of 316L steel in the saline solution. Specifically, the addition of Cr and Si into ZrCN coating results in a decrease of the wear rate of about 60%.

Experimental studies of the deformation and breakup of a synthetic capsule in steady and unsteady simple shear flow

1993 ◽  
Vol 250 ◽  
pp. 609-633 ◽  
Author(s):  
K. S. Chang ◽  
W. L. Olbricht
Keyword(s):  
Elastic Modulus ◽  
Couette Flow ◽  
Membrane Surface ◽  
Experimental Studies ◽  
Small Deformation ◽  
Local Deformation ◽  
Polymeric Membrane ◽  
Simple Shear Flow ◽  
Freely Suspended ◽  
Theory Yield

An experimental study is reported of the motion, deformation, and breakup of a synthetic capsule that is freely suspended in Couette flow. The capsule is a liquid drop surrounded by a thin polymeric membrane. The shape and orientation of the capsule are measured in steady flow and following the start-up of Couette flow. Results are compared with predictions of the small-deformation theory of Barthes-Biesel and co-workers. The data suggest that the capsule membrane is viscoelastic, and comparisons with theory yield values of the membrane elastic modulus and the membrane viscosity. The values of the elastic modulus of the capsule membrane deduced from the flow data are compared with independent measurements for the same capsule.When the flow-induced deformation becomes sufficiently large, the capsules break. Breakup begins at points on the membrane surface near the principal strain axis of the undisturbed flow. By examining the local deformation within the membrane, it is shown that breakup is correlated with local thinning of the membrane and is initiated at points where the thickness is a minimum.

Elastic Properties of Rhombus Dodecahedron Open-Cell Cellular Materials

2013 ◽  
Vol 706-708 ◽  
pp. 99-102
Author(s):  
Hong Zhu ◽  
Li Gang Zhang ◽  
Xiang Dong Qi
Keyword(s):  
Elastic Modulus ◽  
Finite Elements ◽  
Relative Density ◽  
Pore Formation ◽  
Geometrical Model ◽  
Cellular Materials ◽  
Curvature Radius ◽  
Open Cell ◽  
Cell Shapes ◽  
Transitional Junction

Based on the principle of pore formation, geometrical model to describe open-cell cellular materials was constructed. The model is rhombus dodecahedron cell shapes with circle-strut and transitional-junction. The dependence of relative density on the microstructure of the model was analyzed; by finite elements method, the relative elastic modulus of the model was calculated, the influence of microstructure and relative density on the elastic modulus was also obtained. The results show that circle-strut radius and transitional-junction curvature radius are the primary factors on relative density increment; nonlinearity of relative density on relative elastic modulus is similar to that of circle-strut radius on relative elastic modulus, is obviously greater than that of transitional-junction curvature radius on relative elastic modulus.

scholarly journals Dual Graded Lattice Structures: Generation Framework and Mechanical Properties Characterization

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1528
Author(s):  
Khaled G. Mostafa ◽  
Guilherme A. Momesso ◽  
Xiuhui Li ◽  
David S. Nobes ◽  
Ahmed J. Qureshi
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Lattice Structure ◽  
Cell Types ◽  
Functionally Graded ◽  
Unit Cell ◽  
Lattice Structures ◽  
Unit Cells ◽  
Mechanical Properties Characterization ◽  
Graded Lattice

Additive manufacturing (AM) enables the production of complex structured parts with tailored properties. Instead of manufacturing parts as fully solid, they can be infilled with lattice structures to optimize mechanical, thermal, and other functional properties. A lattice structure is formed by the repetition of a particular unit cell based on a defined pattern. The unit cell’s geometry, relative density, and size dictate the lattice structure’s properties. Where certain domains of the part require denser infill compared to other domains, the functionally graded lattice structure allows for further part optimization. This manuscript consists of two main sections. In the first section, we discussed the dual graded lattice structure (DGLS) generation framework. This framework can grade both the size and the relative density or porosity of standard and custom unit cells simultaneously as a function of the structure spatial coordinates. Popular benchmark parts from different fields were used to test the framework’s efficiency against different unit cell types and grading equations. In the second part, we investigated the effect of lattice structure dual grading on mechanical properties. It was found that combining both relative density and size grading fine-tunes the compressive strength, modulus of elasticity, absorbed energy, and fracture behavior of the lattice structure.

Band Gaps in Bravais Lattices Inspired Periodic Cellular Materials and the Effect of Relative Density and Strain Fields

2014 ◽  
Author(s):  
Sumantu Iyer ◽  
Maen Alkhader ◽  
T. A. Venkatesh
Keyword(s):  
Relative Density ◽  
Volume Fraction ◽  
Hexagonal Lattice ◽  
Wave Dispersion ◽  
Phononic Crystals ◽  
Band Gaps ◽  
Acoustic Properties ◽  
Strain Fields ◽  
Lattice Materials ◽  
Constituent Material

Periodic cellular (lattice) materials, by virtue of their periodic structures and associated geometric impedance mismatch, exhibit wave dispersion, frequency dependent transmissibility, and directional characteristics that are inherently dependent on their constituent material and mesoscale microstructural features. These characteristics render lattice materials as potential candidates to perform as low frequency phononic crystals and metamaterials for radar, sonar, wave guiding, wave modulation and isolation applications. Accelerating the wide-spread implementation of lattice materials as phononic crystals hinges on establishing the ability to engineer them to exhibit application-tailored properties and tunable behavior (e.g. to activate/deactivate band gaps). Achieving tunability and application-oriented tailorablity requires, first, establishing an understating of phononic, acoustic, wave dispersion and directional properties of the lattices and how they are affected by lattices’ inherent features. Accordingly, using Bloch’s theorem in conjunction with finite element analysis, this work investigates the relationships between inherent microstructural features (such as lattice symmetry, relative density (i.e. volume fraction) and constituent material) and the acoustic properties (such as wave dispersion, band gaps, and acoustic anisotropy) of architectured lattice materials. The coupling between microstructural features and band gaps is investigated in a hexagonal lattice geometry which is inspired by the two dimensional Bravais family of lattices. Results illustrate that band structure and phononic properties are highly sensitive to relative density and can scale non-uniformly with it as eigenmodes are associated with relative density dependent deformation mechanisms. Moreover, results show that band gaps can potentially be activated and deactivated using macroscopic strain fields. The latter opens horizons for realizing cellular based phononic crystals with tunable properties.

Multiobjective optimization of a newly developed additively manufactured functionally graded anisotropic porous lattice structure

2020 ◽  
Vol 234 (11) ◽  
pp. 2233-2255
Author(s):  
Mahshid Mahbod ◽  
Masoud Asgari
Keyword(s):  
Elastic Modulus ◽  
Analytical Solution ◽  
Multiobjective Optimization ◽  
Relative Density ◽  
Elastic Moduli ◽  
Lattice Structure ◽  
Functionally Graded ◽  
Elastic Behavior ◽  
Average Error ◽  
Lattice Structures

In this paper, the elastic behavior of uniform and functionally graded porous lattice structures made by a double pyramid dodecahedron unit cell is investigated. Analytical solutions are derived in order to estimate the elastic moduli of the proposed structures in two directions. The analytical solution is validated by finite element simulations and experimental tests while the results show good agreement in general. The average difference between the numerical and analytical values of elastic modulus is under 14.44%, while the average error of experimental test and analytical solution is 15.69%. A comprehensive optimization is performed by considering elastic moduli in two different directions as objective functions. Various uniform lattice structures with different relative densities are optimized using NSGA-II algorithm as well as lattice structures with graded distribution of porosity. A variety of optimal designs are achieved by multiobjective optimization algorithm and the best point of the Pareto front is selected by the TOPSIS method. Furthermore, the functionally graded lattice structures are optimized by considering desirable relative densities in each layer and applying constructive constraints. Different distribution patterns of relative density are considered in layers in order to present the flexible design capability of the developed structure. The obtained results show that the elastic modulus is significantly dependent on the relative density of each layer as well as cell configuration. Also, different lattice structures could be achieved by applying desirable prescribed distribution of properties. A comparison between optimized and base model indicated that elastic moduli was considerably improved in optimized models. In optimization of uniform models, [Formula: see text] was increased by 115%, 89%, and 69% in optimized structures for relative densities of 10%, 30%, and 50%, respectively. Moreover, [Formula: see text] was improved in optimized models by 27%, 24%, and 18% for relative densities of 10%, 30%, and 50%, respectively.

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