scholarly journals Experimental and Numerical Analysis of 3D Printed Polymer Tetra-Petal Auxetic Structures under Compression

2021 ◽  
Vol 11 (21) ◽  
pp. 10362
Author(s):  
Demetris Photiou ◽  
Stelios Avraam ◽  
Francesco Sillani ◽  
Fabrizio Verga ◽  
Olivier Jay ◽  
...  
Keyword(s):  
Finite Element ◽  
3D Printing ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Poisson Ratio ◽  
Impact Resistance ◽  
Experimental Tests ◽  
Polymer Materials ◽  
Compression Tests ◽  
Auxetic Structures

Auxetic structures possess a negative Poisson ratio (ν < 0) as a result of their geometrical configuration, which exhibits enhanced indentation resistance, fracture toughness, and impact resistance, as well as exceptional mechanical response advantages for applications in defense, biomedical, automotive, aerospace, sports, consumer goods, and personal protective equipment sectors. With the advent of additive manufacturing, it has become possible to produce complex shapes with auxetic properties, which could not have been possible with traditional manufacturing. Three-dimensional printing enables easy and precise control of the geometry and material composition of the creation of desirable shapes, providing the opportunity to explore different geometric aspects of auxetic structures with a variety of different materials. This study investigated the geometrical and material combinations that can be jointly tailored to optimize the auxetic effects of 2D and 3D complex structures by integrating design, modelling approaches, 3D printing, and mechanical testing. The simulation-driven design methodology allowed for the identification and creation of optimum auxetic prototype samples manufactured by 3D printing with different polymer materials. Compression tests were performed to characterize the auxetic behavior of the different system configurations. The experimental investigation demonstrated a Poisson’s ration reaching a value of ν = −0.6 for certain shape and material combinations, thus providing support for preliminary finite element studies on unit cells. Finally, based on the experimental tests, 3D finite element models with elastic material formulations were generated to replicate the mechanical performance of the auxetic structures by means of simulations. The findings showed a coherent deformation behavior with experimental measurements and image analysis.

Experimental and finite element analysis of the effect of geometrical parameters on the mechanical behavior of auxetic cellular structure under static load

2020 ◽  
pp. 030932472095757
Author(s):  
MJ Khoshgoftar ◽  
H Abbaszadeh
Keyword(s):  
Finite Element ◽  
Poisson Ratio ◽  
High Strength ◽  
Experimental Tests ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Cell Structures ◽  
Cell Components ◽  
Auxetic Structures ◽  
Unit Cell Dimensions

The auxetic structures are structures with negative Poisson ratio that behave under tension or compression as opposed to ordinary materials. Due to the unique mechanical properties, such as increasing the resistance against collision and different formation capability, extensive research is ongoing. In this research, using finite element modeling, simulation of various geometrical parameters of auxetic cell structures have been studied. Verification of the results is done by experimental tests of the model made by 3D printing technology. By introducing different measurement methods such as image processing, the modeling results are compared with experimental tests that show high accuracy results. In this analysis, the effect of the angle between the cell components, unit cell dimensions, thickness, and density of cells are investigated. In addition, new designs to improve the performance of the auxetic structure such as the use of different thicknesses are studied. Auxetic structures are part of advanced structures such as composites and biomaterials with diverse properties and applications in various fields such as military, medical, textile, and aerospace industries. Auxetic applications are excellent in absorbing impact force as bulletproof vests and similar equipment, high strength to weight in lightweight sandwich panels, and in tissue engineering like stent application.

scholarly journals Developing polymer composite-based leaf spring systems for automotive industry

2018 ◽  
Vol 25 (6) ◽  
pp. 1167-1176 ◽  
Author(s):  
Nahit Oztoprak ◽  
Mehmet Deniz Gunes ◽  
Metin Tanoglu ◽  
Engin Aktas ◽  
Oguz Ozgur Egilmez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Mechanical Performance ◽  
Experimental Tests ◽  
Polymer Materials ◽  
Leaf Spring ◽  
Element Analysis ◽  
Reinforced Polymer ◽  
Light Commercial Vehicle ◽  
The Finite Element Analysis

AbstractComposite-based mono-leaf spring systems were designed and manufactured to replace existing mono-leaf metal leaf spring in a light commercial vehicle. In this study, experimentally obtained mechanical properties of different fiber-reinforced polymer materials are presented first, followed by the description of the finite element analytical model created in Abaqus 6.12-1 (Dassault Systemes Simulia Corp., RI, US) using the obtained properties. The results from the finite element analysis are presented next and compared with actual size experimental tests conducted on manufactured prototypes. The results demonstrated that the reinforcement type and orientation dramatically influenced the spring rate. The prototypes showed significant weight reduction of about 80% with improved mechanical properties. The hybrid composite systems can be utilized for composite-based leaf springs with considerable mechanical performance.

scholarly journals Determination of energy absorption in different cellular auxetic structures

2019 ◽  
Vol 20 (3) ◽  
pp. 302 ◽  
Author(s):  
M. Shokri Rad ◽  
Hossein Hatami ◽  
R. Alipouri ◽  
A. Farokhi Nejad ◽  
F. Omidinasab
Keyword(s):  
Energy Absorption ◽  
Experimental Testing ◽  
Impact Resistance ◽  
Geometrical Parameters ◽  
Compression Tests ◽  
Fundamental Properties ◽  
Simulation Techniques ◽  
Auxetic Materials ◽  
Auxetic Structures ◽  
Energy Absorbers

This paper deals with the effect of unit cell configuration on the energy absorption response of different cellular auxetic structures subjected to quasi-static and dynamic loadings through the experimental and numerical methods. Among the various structures, a re-entrant structure was selected due to its fundamental properties underlying the main characteristics of an auxetic material. Computer simulation techniques using ABAQUS software validated by experimental testing were used to conduct the evaluation of such devices. Several re-entrant structures with different geometrical parameters were modeled and compared with the conventional ones. Standard compression tests were carried out on the different structures produced by the 3D printing machine to evaluate the influence of auxeticity phenomenon in the energy absorption capability. It is discovered that the auxetic structures are superior to non-auxetic structures in terms of all studied impact resistance and energy absorption indicators due to their ability to withstand quasi-static axial impact loads. The primary outcome of this research is to extract design information for the use of auxetic materials as energy absorbers where quasi-static loading is expected.

Mechanical Performance of Composite Laminate with Oblique Splicing Ply

2012 ◽  
Vol 476-478 ◽  
pp. 600-604 ◽  
Author(s):  
Ling Wang ◽  
Pu Rong Jia ◽  
Liang Li
Keyword(s):  
Finite Element ◽  
Composite Laminate ◽  
Mechanical Performance ◽  
Damage Model ◽  
Experimental Tests ◽  
Element Model ◽  
Linear Elastic ◽  
Polyurethane Composite ◽  
Element Simulation ◽  
Joint Gap

In order to determine the mechanical properties of the carbon/polyurethane composite laminate with splicing ply, the tensile testing were performed on laminate specimens which has been designed specially. The tensile elastic modulus and tensile strength were obtained from the experimental datum. The breakage happened in place of joint gap. The stiffness of the composite laminate was affected by the oblique splicing ply significantly, but the strength is mainly determined by the continuous layers. The laminate is failure in low load. The numerical analyses using linear elastic and progressive damage model were conducted with the commercial the finite element model (FEM) software ABAQUS. The linear elastic FEM is established to calculate the inter-laminar stress. The progressive model is used to predict the strength on the basis of numerical computation. There are three different criteria used here in the strength prediction. By combining the damage model with classical lamination theory, the behavior of laminates under plane stress loading is predicted. The results show that the experimental tests are in good agreement with the finite element simulation.

scholarly journals Mechanical Performance of Long-fibre Reinforced Polymer Composites by 3D Printing

2020 ◽  
Author(s):  
Francis Dantas ◽  
Greg Gibbons
Keyword(s):  
3D Printing ◽  
Polymer Composites ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Fibre Composite ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Base Material ◽  
Fibre Reinforcement ◽  
Number Of Layers

Abstract Additive Manufacturing (AM), also known as 3D Printing, has been around for more than 2 decades and has recently gained importance for use in direct manufacturing. The quantified physical properties of materials are required by design engineers to inform and validate their designs, and this is no less true for AM that it is for traditional manufacturing methods. Recent innovation in AM has seen the emergence of long-fibre composite AM technologies, such as the Mark Two (Markforged Inc, USA) system, enabling the manufacture of thermoplastic polymer composites with long-fibre reinforcement. To date though, the mechanical response of the materials with respect to build parameter variation is little understood. In this project, selected mechanical properties (ultimate tensile strength – UTS and flexural modulus) of samples processed using the Mark Two printer were studied. The effect of the reinforcement type (Carbon, Kevlar®, and HSHT glass), amount of reinforcement, reinforcement lay-up orientation, and the base matrix material (Onyx and polyamide) on these properties were assessed using accepted standard test methods. For Onyx, the UTS and Flexural Modulus was improved by a maximum of 244 ± 10 MPa (1228 ± 19%) and 14.2 ± 0.3 GPa (1114 ± 6%) (Carbon), by 143 ± 1 MPa (721 ± 18%) and 7.1 ± 0.3 GPa (560 ± 6%) (Kevlar®) and 209 ± 4 MPa (1049 ± 19%) and 6.0 ± 0.1 GPa (469 ± 6%) (HSHT glass). For Nylon the UTS and Flexural Modulus was improved by 235 ± 4 MPa (1431 ± 56%) and 14.1 ± 0.2 GPa (1924 ± 5%) (Carbon), 143 ± 3 MPa (867 ± 56%) and 6.79 ± 0.08 GPa (927 ± 5%) (Kevlar®) and 204 ± 2 MPa (1250 ± 55%) and 5.73 ± 0.09 GPa (782 ± 5%) (HSHT glass). A regression and ANOVA analysis for UTS indicated that the number of layers of reinforcement had the largest impact on UTS (F = 11,483 P < 0.005), with the second most important parameter being the type of reinforcement (F = 855 P < 0.005). The parameter effects for all four parameters were significant (P ≤ 0.05). For the Flexural Modulus, the number of layers of reinforcement was again the most significant parameter (F = 2733 P < 0.005), with the second most important parameter again being the type of reinforcement (F = 1339 P < 0.005). Again, the parameter effects for all four parameters were significant (P ≤ 0.05), although the influence of base material had much less significant effect on determining the Flexural Modulus than it did in controlling UTS.

scholarly journals Investigation of the Biocidal Performance of Multi-Functional Resin/Copper Nanocomposites with Superior Mechanical Response in SLA 3D Printing

Biomimetics ◽  
2022 ◽  
Vol 7 (1) ◽  
pp. 8
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Emmanuel Velidakis ◽  
Nikolaos Mountakis ◽  
Dimitris Tsikritzis ◽  
...  
Keyword(s):  
3D Printing ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Matrix Material ◽  
International Standards ◽  
Added Value ◽  
Diffusion Method ◽  
Host Defense Peptides ◽  
Antibacterial Performance ◽  
Biocidal Properties

Metals, such as silver, gold, and copper are known for their biocidal properties, mimicking the host defense peptides (HDPs) of the immune system. Developing materials with such properties has great importance in medicine, especially when combined with 3D printing technology, which is an additional asset for various applications. In this work, copper nanoparticles were used as filler in stereolithography (SLA) ultraviolet (UV) cured commercial resin to induce such biocidal properties in the material. The nanocomposites developed featured enhanced mechanical responses when compared with the neat material. The prepared nanocomposites were employed to manufacture specimens with the SLA process, to be tested for their mechanical response according to international standards. The process followed was evaluated with Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA). The antibacterial activity of the fabricated nanocomposites was evaluated using the agar-well diffusion method. Results showed enhanced mechanical performance of approximately 33.7% in the tensile tests for the nanocomposites filled with 1.0 wt.%. ratios, when compared to the neat matrix material, while this loading showed sufficient antibacterial performance when compared to lower filler loadings, providing an added value for the fabrication of effective nanocomposites in medical applications with the SLA process.

Molecular Dynamics Simulations of the Mechanical Response of Metallic glass/BCC Nanocomposite Materials

2006 ◽  
Vol 977 ◽  
Author(s):  
Yunfeng Shi ◽  
Michael L Falk
Keyword(s):  
Metallic Glass ◽  
Strain Hardening ◽  
Mechanical Response ◽  
Impact Resistance ◽  
Shear Bands ◽  
High Strength ◽  
Quasicrystalline Phase ◽  
Compression Tests ◽  
Body Center Cubic ◽  
Dynamics Simulations

AbstractBulk metallic glass (BMG) has been of intense interest recently because of its unique combination of excellent mechanical properties including high strength. One of the major drawbacks of monolithic BMG materials is the limited ductility due to strain localization. Except a few recent reports on monolithic ductile BMG, the most popular method to enhance the ductility of the BMG samples is to introduce a crystalline or quasicrystalline phase by precipitation or mixing. The composite material usually exhibits some degree of strain hardening along with significantly higher impact resistance and fracture toughness. However, the mechanism of this strain hardening is not well understood. We present simulated uniaxial compression tests on a monatomic model amorphous system embedded with body-center cubic (BCC) nanocrystals. The advantage of this model system is that intimate amorphous-crystal interfaces can be obtained. We observe that when comparing to monolithic glassy samples where a single shear band normally dominates, multiple shear bands appear in the BCC-amorphous composite samples. The plastic deformation initiates at the interfaces between nanocrystals and the glassy phase due to stress concentration. Furthermore, we demonstrate that shear along the bands results in growth of the nanocrystals.

scholarly journals Assessment of the Suitability of Elastomeric Bearings Modeling Using the Hyperelasticity and the Finite Element Method

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7665
Author(s):  
Marcin Daniel Gajewski ◽  
Mikołaj Miecznikowski
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Constitutive Relations ◽  
Experimental Tests ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Compression Tests ◽  
The Finite Element Method ◽  
Elastomeric Bearings ◽  
Element Method

The paper presents modeling of bridge elastomeric bearings using large deformation theory and hyperelastic constitutive relations. In this work, the simplest neo-Hookean model was compared with the Yeoh model. The parameters of the models were determined from the elastomer uniaxial tensile test and then verified with the results from experimental bearing compression tests. For verification, bearing compression tests were modeled and executed using the finite element method (FEM) in ABAQUS software. Additionally, the parameters of the constitutive models were determined using the inverse analysis method, for which the simulation results were as close as possible to those recorded during the experimental tests. The overall assessment of the suitability of elastomer bearings modeling with neo-Hookean and Yeoh hyperelasticity models is presented in detail.

scholarly journals Investigating the influence of the core material on the mechanical performance of a nitinol wire wrapped helical auxetic yarn

2021 ◽  
pp. 030932472110270
Author(s):  
Nadimul Haque Faisal ◽  
Andrew Fowlie ◽  
Joe Connell ◽  
Sean Mackenzie ◽  
Ryan Noble ◽  
...  
Keyword(s):  
Analytical Model ◽  
Mechanical Performance ◽  
Poisson Ratio ◽  
Axial Strain ◽  
Impact Resistance ◽  
Tensile Tests ◽  
Core Material ◽  
The Core ◽  
Nitinol Wire ◽  
Theoretical Predictions

Helical Auxetic Yarns (HAYs) can be used in a variety of applications from healthcare to blast and impact resistance. This work focuses on the effect of the use of different core materials (e.g. rubber, polyurethane, polytetrafluoroethylene/teflon, polypropylene, polyetheretherketone, polycarbonate, acetal) with a nitinol wire wrap component on the maximum Negative Poisson Ratio (NPR) produced and thus the auxetic performance of Helical Auxetic Yarns (HAYs). From the analytical model, it was found that an acetal core produced the largest NPR when compared to the other six materials. The trend obtained from the experimental tensile tests (validation) correlated closely with the theoretical predictions of the NPR as axial strain was increased. The experimental method presented a maximum NPR at an average axial strain of 0.148 which was close to the strain of 0.155 predicted by theory. However, the maximum experimental NPR was significantly lower than that predicted by the analytical model.

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