On the Compression Mechanism of the Composite Lattice Structures

2015 ◽  
Vol 24 (5) ◽  
pp. 096369351502400
Author(s):  
Yunpeng Jiang
Keyword(s):  
Porous Material ◽  
Analytical Model ◽  
Phenomenological Model ◽  
Volume Fraction ◽  
Lattice Structure ◽  
Void Volume Fraction ◽  
Lattice Structures ◽  
Compression Mechanism ◽  
Composite Lattice ◽  
Comparison With Experiments

The composite lattice structure is regarded as a porous material in the present work, and then the corresponding compression mechanism is clearly interpreted by a simple but reasonable phenomenological model, which containing a damage element to account for the micro-buckling progression and a reinforcement element for the reduction of void volume fraction. Moreover, a micromechanics model is developed to quantitatively characterize the stiffness degradation induced by the micro-buckling deformation. The accuracy of the analytical model is verified by the comparison with experiments.

scholarly journals Design of Variable-Density Structures for Additive Manufacturing Using Gyroid Lattices

2017 ◽  
Author(s):  
Botao Zhang ◽  
Kunal Mhapsekar ◽  
Sam Anand
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Volume Fraction ◽  
Complex Geometry ◽  
Lattice Structure ◽  
Variable Density ◽  
Light Weight ◽  
Lattice Structures ◽  
Density Mapping ◽  
Usage Cost

Additive manufacturing (AM) processes enable the creation of lattice structures having complex geometry which offer great potential for designing light weight parts. The combination of AM and cellular lattice structures provide promising design solutions in terms of material usage, cost and part weight. However, the geometric complexity of the structures calls for a robust methodology to incorporate the lattices in parts designs and create optimum light weight designs. This paper proposes a novel method for designing light weight variable-density lattice structures using gyroids. The parametric 3D implicit function of gyroids has been used to control the shape and volume fraction of the lattice. The proposed method is then combined with the density distribution information from topology optimization algorithm. A density mapping and interpolation approach is proposed to map the output of topology optimization into the parametric gyroids structures which results in an optimum lightweight lattice structure with uniformly varying densities across the design space. The proposed methodology has been validated with two test cases.

scholarly journals Improved Mechanical Properties and Energy Absorption of BCC Lattice Structures with Triply Periodic Minimal Surfaces Fabricated by SLM

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2411 ◽  
Author(s):  
Miao Zhao ◽  
Fei Liu ◽  
Guang Fu ◽  
David Zhang ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Computer Aided Design ◽  
Volume Fraction ◽  
Lattice Structure ◽  
The Body ◽  
Lattice Structures ◽  
Volume Fractions ◽  
Lattice Design ◽  
Bcc Lattice ◽  
Triply Periodic

The triply periodic minimal surface (TPMS) method is a novel approach for lattice design in a range of fields, such as impact protection and structural lightweighting. In this paper, we used the TPMS formula to rapidly and accurately generate the most common lattice structure, named the body centered cubic (BCC) structure, with certain volume fractions. TPMS-based and computer aided design (CAD) based BCC lattice structures with volume fractions in the range of 10–30% were fabricated by selective laser melting (SLM) technology with Ti–6Al–4V and subjected to compressive tests. The results demonstrated that local geometric features changed the volume and stress distributions, revealing that the TPMS-based samples were superior to the CAD-based ones, with elastic modulus, yield strength and compression strength increasing in the ranges of 18.9–42.2%, 19.2–29.5%, and 2–36.6%, respectively. The failure mechanism of the TPMS-based samples with a high volume fraction changed to brittle failure observed by scanning electron microscope (SEM), as their struts were more affected by the axial force and fractured on struts. It was also found that the TPMS-based samples have a favorable capacity to absorb energy, particularly with a 30% volume fraction, the energy absorbed up to 50% strain was approximately three times higher than that of the CAD-based sample with an equal volume fraction. Furthermore, the theoretic Gibson–Ashby mode was established in order to predict and design the mechanical properties of the lattice structures. In summary, these results can be used to rapidly create BCC lattice structures with superior compressive properties for engineering applications.

Analysis of the compression behaviour of different composite lattice designs

2017 ◽  
Vol 52 (6) ◽  
pp. 715-729 ◽  
Author(s):  
R Umer ◽  
Z Barsoum ◽  
HZ Jishi ◽  
K Ushijima ◽  
WJ Cantwell
Keyword(s):  
Lattice Structure ◽  
Numerical Models ◽  
Fibre Volume ◽  
Lattice Structures ◽  
Compression Tests ◽  
Static Compression ◽  
Bcc Lattice ◽  
Compression Behaviour ◽  
Composite Lattice ◽  
Quasi Static Compression

Four all-composite lattice designs were produced using a lost-mould procedure that involved inserting carbon fibre tows through holes in a core. Following resin infusion and curing, samples were heated to melt the core, leaving well-defined lattice structures based on what are termed BCC, BCCz, FCC and F2BCC designs. Analytical and numerical models for predicting the mechanical properties of the four designs are presented and these results are compared with the experimental data from the quasi-static compression tests. Compression tests on the four lattice structures indicated that the F2BCC lattice offered the highest compression strength, although when normalized by relative density, the BCCz lattice structure out-performed other structures. Similarly, the specific compression strengths were found to be superior to those of more traditional core materials. A number of failure mechanisms were also highlighted, including strut buckling, fracture at the strut-skin joints and debonding of reinforcing members at the central nodes. Finally, it is believed that the properties of these lattices can be further increased using higher fibre volume fractions.

The Design of Optimal Lattice Structures Manufactured by Maypole Braiding

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Austin Gurley ◽  
David Beale ◽  
Royall Broughton ◽  
David Branscomb
Keyword(s):  
Carbon Fiber ◽  
Full Advantage ◽  
Cross Sections ◽  
Design Methodology ◽  
Lattice Structure ◽  
Axial Stiffness ◽  
Lattice Structures ◽  
Braided Composite ◽  
Composite Lattice ◽  
Round Cross

Beginning with the maypole braiding process and its inherent constraints, we develop a design methodology for the realization of optimal braided composite lattice structures. This process requires novel geometric, mechanical, and optimization procedures for comprehensive design-ability, while taking full advantage of the capabilities of maypole braiding. The composite lattice structures are braided using yarns comprised of multiple prepreg carbon fiber (CF) tows that are themselves consolidated in a thin braided jacket to maintain round cross sections. Results show that optimal lattice-structure tubes provide significant improvement over smooth-walled CF tubes and nonoptimal lattices in torsion and bending, while maintaining comparable axial stiffness (AE).

scholarly journals Topology optimized thermoelectric generator: a parametric study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
John Mativo ◽  
Kevin Hallinan ◽  
Uduak George ◽  
Greg Reich ◽  
Robin Steininger
Keyword(s):  
Topology Optimization ◽  
Thermoelectric Generator ◽  
Volume Fraction ◽  
Power Conversion ◽  
Power Production ◽  
Power Reduction ◽  
Void Volume Fraction ◽  
Thermoelectric Generators ◽  
Maximal Power ◽  
Design Yield

Abstract Typical thermoelectric generator legs are brittle which limits their application in vibratory and shear environments. Research is conducted to develop compliant thermoelectric generators (TEGs) capable of converting thermal loads to power, while also supporting shear and vibratory loads. Mathematical structural, thermal, and power conversion models are developed. Topology optimization is employed to tailor the TEG design yield maximal power production while sustaining the applied shear and vibratory loads. As a specific example, results are presented for optimized TEG legs with a void volume fraction of 0.2 that achieve compliance shear displacement of 0.0636 (from a range of 0.0504 to 0.6079). In order to achieve the necessary compliance to support the load, the power reduction is reduced by 20% relative to similarly sized void free TEG legs.

scholarly journals Forming Limit Stress Diagram Prediction of Pure Titanium Sheet Based on GTN Model

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1783 ◽  
Author(s):  
Tao Huang ◽  
Mei Zhan ◽  
Kun Wang ◽  
Fuxiao Chen ◽  
Junqing Guo ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Pure Titanium ◽  
Void Volume Fraction ◽  
Void Volume ◽  
Forming Limit ◽  
Stress And Strain ◽  
Gtn Model ◽  
Stress Diagram ◽  
Limit Stress ◽  
Hemispherical Punch

In this paper, the initial values of damage parameters in the Gurson–Tvergaard–Needleman (GTN) model are determined by a microscopic test combined with empirical formulas, and the final accurate values are determined by finite element reverse calibration. The original void volume fraction (f0), the volume fraction of potential nucleated voids (fN), the critical void volume fraction (fc), the void volume fraction at the final failure (fF) of material are assigned as 0.006, 0.001, 0.03, 0.06 according to the simulation results, respectively. The hemispherical punch stretching test of commercially pure titanium (TA1) sheet is simulated by a plastic constitutive formula derived from the GTN model. The stress and strain are obtained at the last loading step before crack. The forming limit diagram (FLD) and the forming limit stress diagram (FLSD) of the TA1 sheet under plastic forming conditions are plotted, which are in good agreement with the FLD obtained by the hemispherical punch stretching test and the FLSD obtained by the conversion between stress and strain during the sheet forming process. The results show that the GTN model determined by the finite element reverse calibration method can be used to predict the forming limit of the TA1 sheet metal.

A Phenomenological Model for Vortex-Induced Motions of the Monocolumn Platform and Comparison With Experiments

2009 ◽  
Author(s):  
Guilherme F. Rosetti ◽  
Rodolfo T. Gonc¸alves ◽  
Andre´ L. C. Fujarra ◽  
Kazuo Nishimoto ◽  
Marcos D. Ferreira
Keyword(s):  
Time Domain ◽  
Phenomenological Model ◽  
Structural Model ◽  
Design Phase ◽  
Van Der Pol ◽  
Floating Structures ◽  
Towing Tank ◽  
Wake Oscillator ◽  
Two Degree Of Freedom ◽  
Comparison With Experiments

Vortex-Induced Motions (VIM) of floating structures is a very relevant subject for the design of mooring and riser systems. In the design phase, Spar VIM behavior as well as Semi Submersible and Tension Leg Platform (TLP) flow-induced motions are studied and evaluated. This paper discusses flow-induced behavior on the Monocolumn concept by presenting a phenomenological model and comparing its results with a set of experiments that took place in the IPT Towing Tank - Brazil (September 2008). The experimental results have shown some fundamental differences from previous VIM tests on other units such as Spars. This numerical model attempts to identify these disparities in order to better understand the mechanics of this phenomenon. The model is based on a time-domain, two degree-of-freedom structural model coupled with a van der Pol type wake oscillator. The comparison was performed in order to calibrate the model, to study and better understand the tests results, and finally to identify important aspects to investigate in further experiments.

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