Kriging-assisted design of functionally graded cellular structures with smoothly-varying lattice unit cells

2022 ◽  
Vol 390 ◽  
pp. 114466
Author(s):  
Xiliang Liu ◽  
Liang Gao ◽  
Mi Xiao ◽  
Yan Zhang
Keyword(s):  
Functionally Graded ◽  
Cellular Structures ◽  
Unit Cells ◽  
Lattice Unit

scholarly journals Buckling of regular, chiral and hierarchical honeycombs under a general macroscopic stress state

2014 ◽  
Vol 470 (2167) ◽  
pp. 20130856 ◽  
Author(s):  
Babak Haghpanah ◽  
Jim Papadopoulos ◽  
Davood Mousanezhad ◽  
Hamid Nayeb-Hashemi ◽  
Ashkan Vaziri
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Closed Form ◽  
Plane Stress ◽  
Plane Stress State ◽  
Cellular Structures ◽  
Two Dimensional ◽  
Buckling Strength ◽  
Macroscopic Stress ◽  
Unit Cells

An approach to obtain analytical closed-form expressions for the macroscopic ‘buckling strength’ of various two-dimensional cellular structures is presented. The method is based on classical beam-column end-moment behaviour expressed in a matrix form. It is applied to sample honeycombs with square, triangular and hexagonal unit cells to determine their buckling strength under a general macroscopic in-plane stress state. The results were verified using finite-element Eigenvalue analysis.

Mechanical behavior of regular open-cell porous biomaterials made of diamond lattice unit cells

2014 ◽  
Vol 34 ◽  
pp. 106-115 ◽  
Author(s):  
S.M. Ahmadi ◽  
G. Campoli ◽  
S. Amin Yavari ◽  
B. Sajadi ◽  
R. Wauthle ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Diamond Lattice ◽  
Open Cell ◽  
Unit Cells ◽  
Lattice Unit ◽  
Regular Open ◽  
Porous Biomaterials

Impact Resistance and Energy Absorption of Functionally Graded Cellular Structures

2011 ◽  
Vol 69 ◽  
pp. 73-78 ◽  
Author(s):  
Xiao Kai Wang ◽  
Zhi Jun Zheng ◽  
Ji Lin Yu ◽  
Chang Feng Wang
Keyword(s):  
Energy Absorption ◽  
Impact Resistance ◽  
Functionally Graded ◽  
Cellular Structures ◽  
Stress Wave Propagation ◽  
Initial Kinetic Energy ◽  
Gradual Change ◽  
Two Dimensional ◽  
The One ◽  
The Impact

The dynamic response of functionally graded cellular structures subjected to impact of a finite mass was investigated in this paper. Compared to a cellular structure with a uniform cell size, the one with gradually changing cell sizes may improve many properties. Based on the two-dimensional random Voronoi technique, a two-dimensional topological configuration of cellular structures with a linear density-gradient in one direction was constructed by changing the cell sizes. The finite element method using ABAQUS/Explicit code was employed to investigate the energy absorption and the influence of gradient on stress wave propagation. Results show that functionally graded cellular structures studied are superior in energy absorption to the equivalent uniform cellular structures under low initial kinetic energy impacts, and the performance of such structures can be significantly improved when the density difference is enlarged. The stress levels at the impact and support ends may be reduced by introducing a gradual change of density in cellular structures when the initial impact velocity is low.

A Preliminary Study on the Effect of Strut Waviness on the Mechanical Properties of BCC Lattice Unit Cells

2021 ◽  
pp. 431-441
Author(s):  
Davide Tumino ◽  
Andrea Alaimo ◽  
Calogero Orlando ◽  
Stefano Valvano
Keyword(s):  
Mechanical Properties ◽  
Bcc Lattice ◽  
Unit Cells ◽  
Lattice Unit ◽  
Preliminary Study

scholarly journals Mechanical Performance of Additively Manufactured Fiber-Reinforced Functionally Graded Lattices

JOM ◽  
2019 ◽  
Vol 72 (3) ◽  
pp. 1292-1298 ◽  
Author(s):  
János Plocher ◽  
Ajit Panesar
Keyword(s):  
Energy Absorption ◽  
Mechanical Performance ◽  
Weight Ratio ◽  
Short Fiber ◽  
Functionally Graded ◽  
Fused Deposition Modelling ◽  
Valuable Insight ◽  
Fiber Reinforced ◽  
Fused Deposition ◽  
Unit Cells

AbstractLatticing has become a common design practice in additive manufacturing (AM) and represents a key lightweighting strategy to date. Functional graded lattices (FGLs) have recently gained immense traction in the AM community, offering a unique way of tailoring the structural performance. This paper constitutes the first ever investigation on the combination of graded strut- and surface-based lattices with fiber-reinforced AM to further increase the performance-to-weight ratio. The energy absorption behavior of cubic lattice specimens composed of body-centered cubic and Schwarz-P unit cells with different severities of grading but the same mass, considered for uniaxial compression testing and printed by fused deposition modelling of short fiber-reinforced nylon, were investigated. The results elucidate that grading affects the energy absorption capability and deformation behavior of these lattice types differently. These findings can provide engineers with valuable insight into the properties of FGLs, aiding targeted rather than expertise-driven utilization of lattices in design for AM.

Multiphase Thermomechanical Topology Optimization of Functionally Graded Lattice Injection Molds

2016 ◽  
Author(s):  
Tong Wu ◽  
Kai Liu ◽  
Andres Tovar
Keyword(s):  
Topology Optimization ◽  
Heat Conduction ◽  
Mechanical Performance ◽  
Lattice Structure ◽  
Functionally Graded ◽  
Unit Cell ◽  
Design Approach ◽  
Stiffness Reduction ◽  
Lattice Unit ◽  
Graded Lattice

This work presents a design methodology of lightweight, thermally efficient injection molds with functionally graded lattice structure using multiphase thermomechanical topology optimization. The aim of this methodology is to increase or maintain thermal and mechanical performance as well as to lower the cost of thermomechanical components such as injection molds when these are fabricated using additive manufacturing technologies. The proposed design approach makes use of thermal and mechanical finite element analyses to evaluate the components stiffness and heat conduction in two length scales: mesoscale and macroscale. The mesoscale contains the structural features of the lattice unit cell. Mesoscale homogenized properties are implemented in the macroscale model, which contains the components boundary conditions including the external mechanical loads as well as the heat sources and heat sinks. The macroscale design problem addressed in this work is to find the optimal distribution of given number of lattice unit cell phases within the component so its mass is minimized, while satisfying stiffness and heat conduction constraints of the overall component and the specific regions. This problem is solved through two steps: conceptual design generation and multiphase material distribution. In the first step, the mass is minimized subject to constraints of mechanical compliance and thermal cost function. In the second step, a given number of lattice material are optimally distributed subjected to nonlinear thermal and mechanical constraints, e.g., maximum nodal temperature, maximum nodal displacement. The proposed design approach is demonstrated through 2D and 3D examples including the optimal design of the core of an injection mold. The results demonstrate that a small reduction in mechanical and thermal performance allows for significant mass savings: the second example shows that 3.5% heat conduction reduction and 8.7% stiffness reduction results in 30.3% mass reduction.

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.

scholarly journals Design of Kinematic Connectors for Microstructured Materials Produced by Additive Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1500
Author(s):  
Miguel R. Silva ◽  
João A. Dias-de-Oliveira ◽  
António M. Pereira ◽  
Nuno M. Alves ◽  
Álvaro M. Sampaio ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Functionally Graded Materials ◽  
Cellular Structure ◽  
Young's Modulus ◽  
Functionally Graded ◽  
Graded Materials ◽  
Mean Values ◽  
Shear Moduli ◽  
Young’S Moduli ◽  
Unit Cells

The main characteristic of materials with a functional gradient is the progressive composition or the structure variation across its geometry. This results in the properties variation in one or more specific directions, according to the functional application requirements. Cellular structure flexibility in tailoring properties is employed frequently to design functionally-graded materials. Topology optimisation methods are powerful tools to functionally graded materials design with cellular structure geometry, although continuity between adjacent unit-cells in gradient directions remains a restriction. It is mandatory to attain a manufacturable part to guarantee the connectedness between adjoining microstructures, namely by ensuring that the solid regions on the microstructure’s borders i.e., kinematic connectors) match the neighboring cells that share the same boundary. This study assesses the kinematic connectors generated by imposing local density restrictions in the initial design domain (i.e., nucleation) between topologically optimised representative unit-cells. Several kinematic connector examples are presented for two representatives unit-cells topology optimised for maximum bulk and shear moduli with different volume fractions restrictions and graduated Young’s modulus. Experimental mechanical tests (compression) were performed, and comparison studies were carried out between experimental and numerical Young’s modulus. The results for the single maximum bulk for the mean values for experimental compressive Young’s modulus (Ex¯) with 60%Vf show a deviation of 9.15%. The single maximum shear for the experimental compressive Young’s modulus mean values (Ex¯) with 60%Vf, exhibit a deviation of 11.73%. For graded structures, the experimental mean values of compressive Young’s moduli (Ex¯), compared with predicted total Young’s moduli (ESe), show a deviation of 6.96 for the bulk graded structure. The main results show that the single type representative unit-cell experimental Young’s modulus with higher volume fraction presents a minor deviation compared with homogenized data. Both (i.e., bulk and shear moduli) graded microstructures show continuity between adjacent cells. The proposed method proved to be suitable for generating kinematic connections for the design of shear and bulk graduated microstructured materials.

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