Elasto-Plastic Impact on Auxetic/Metal Foams

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
N. Kumar ◽  
S. N. Khaderi ◽  
K. Tirumala Rao
Keyword(s):  
Energy Dissipation ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Metal Foam ◽  
Coefficient Of Restitution ◽  
Peak Force ◽  
Poisson's Ratio ◽  
Rigid Sphere ◽  
Yield Strain ◽  
Maximum Displacement

Abstract We investigate the normal impact of a rigid sphere on a half-space of elasto-plastic auxetic/metal foam using the finite element method. The dependence of the coefficient of restitution, peak force, maximum displacement, and contact duration on the yield strain, impact velocity, and elastic and plastic Poisson’s ratio is analyzed. For a given elastic Poisson’s ratio, the coefficient of restitution generally decreases with an increase in the plastic Poisson’s ratio and impact velocity. When the plastic Poisson’s is maintained constant, the coefficient of restitution increases with an increase of the elastic Poisson’s ratio. These trends are explained using plastic energy dissipation. The energy dissipation trends are further investigated by decomposing it into deviatoric and hydrostatic parts. For a given impact velocity, the peak force is relatively insensitive to most of the elastic and plastic Poisson’s ratio combinations. We also show that for the cases where the elastic and plastic Poisson’s ratios are equal, the coefficient of restitution is relatively insensitive to their actual values. These findings can guide researchers to identify the right elastic and plastic Poisson’s ratio combinations so that lattice materials with exceptional energy absorbing capacity can be designed using topology optimization.

Multi-Parameter Optimization to Improve the Erosion Resistance of Coating by Fe Simulation

2021 ◽  
Author(s):  
Fang Li ◽  
Liuxi Cai ◽  
Shun-sen Wang ◽  
Zhenping Feng
Keyword(s):  
Tensile Stress ◽  
Young’S Modulus ◽  
Impact Velocity ◽  
Coating Thickness ◽  
Poisson’S Ratio ◽  
Erosion Resistance ◽  
Young's Modulus ◽  
Tio2 Coating ◽  
Poisson's Ratio ◽  
Stress Peak

Abstract Finite element method (FEM) was used to study the stress peak of stress S11 (Radial stress component in X-axis) on the steam turbine blade surface of four typical erosion-resistant coatings (Fe2B, CrN, Cr3C2-NiCr and Al2O3-13%TiO2). The effect of four parameters, such as impact velocity, coating thickness, Young's modulus and Poisson's ratio on the stress peak of stress S11 were analyzed. Results show that: the position of tensile stress peak and compressive stress peak of stress S11 are far away from the impact center point with the increase of impact velocity. When coating thickness is equal to or greater than 10μm, the magnitude of tensile stress peak of stress S11 on the four coating surfaces does not change with the coating thickness at different impact velocities. When coating thickness is equal to or greater than 2μm, the magnitude of tensile stress peak of stress S11 of four coatings show a trend of increasing first and then decreasing with the increase of Young's modulus. Meanwhile, the larger the Poisson's ratio, the smaller the tensile stress peak of stress S11. After optimization, When coating thickness is 2μm, Poisson's ratio is 0.35 and Young's modulus is 800 GPa, the Fe2B coating has the strongest erosion resistance under the same impact conditions, followed by Cr3C2-NiCr, CrN, and the Al2O3- 13%TiO2 coating, Al2O3-13%TiO2 coating has the worst erosion resistance.

Elasto-Plastic Indentation of Auxetic and Metal Foams

2019 ◽  
Vol 87 (1) ◽  
Author(s):  
N. Kumar ◽  
S. N. Khaderi ◽  
K. Tirumala Rao
Keyword(s):  
Poisson’S Ratio ◽  
Strain Energy ◽  
Metal Foams ◽  
Poisson's Ratio ◽  
Indentation Hardness ◽  
The Finite Element Method ◽  
Yield Strain ◽  
Plastic Dissipation ◽  
Auxetic Materials ◽  
Plastic Indentation

Abstract The elasto-plastic indentation of auxetic and metal foams is investigated using the finite element method. The contributions of yield strain, elastic, and plastic Poisson’s ratio on the indentation hardness are identified. For a given yield strain, when the plastic Poisson’s ratio is reduced from 0.5, the indentation hardness decreases first and then increases. This trend was found to be valid for a wide of yield strains. For yield strains less than 0.08, the hardness of auxetic materials is much larger when compared with materials having positive plastic Poisson’s ratio. As the plastic Poisson’s ratio approaches −1, the elastic deformations dominate over the plastic deformations. The plastic dissipation, when compared with the elastic work, is lower for materials with negative Poisson’s ratio. There is no effect of elastic Poisson’s ratio on the indentation hardness when the plastic Poisson’s ratio is more than −0.8. When the plastic Poisson’s ratio is less than −0.8, the hardness increases with a decrease of elastic Poisson’s ratio. The plastic dissipation per unit strain energy is maximum for materials with vanishing plastic Poisson’s ratio.

From Peak Force Quantitative Nanomechanical Mapping Measurements to Triaxial Testing: A Comparative Study of Geomechanical Properties of Clay-Rich Carbonates

2020 ◽  
Author(s):  
Kim S. Mews ◽  
Mustafa M. Alhubail ◽  
Luka Hansen ◽  
Hem B. Motra ◽  
Frank Wuttke ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Peak Force ◽  
Poisson's Ratio ◽  
Triaxial Testing ◽  
Hydraulic Fractures ◽  
True Triaxial ◽  
Geomechanical Properties ◽  
Drill Cutting

Abstract The assessment of geomechanical properties of unconventional reservoirs is significant as they assist in placement as well as understanding of the geometry and properties of multi-stage hydraulic fractures in horizontal wells. Severe heterogeneities at micro-scale in addition to possibility of having non-intact samples provide opportunities for using micro-mechanics techniques on drill cutting size samples. This will lead to not only have a continuous log of geomechanical properties on heterogeneous formations but also be able to measure the mechanical properties of non-intact samples accurately. This study presents a multi-scale comparison of the elastic properties such as Young’s modulus and Poisson’s ratio on the Eagle Ford Formation. Peak Force Quantitative Nano-mechanical (PF-QNM) AFM-based technique has been performed and compared with true triaxial testing. A new model for AFM evaluation that corrects Young’s modulus in dependency of Poisson’s ratio has been developed. The results indicate that the distribution of Young’s modulus is separated into two regions, one dominated by brittle minerals indicating higher values and one dominated by ductile rock components resulting in lower values. The findings are significant as PF-QNM testing can be performed where only drill cutting-size samples are available, as it shows strong agreement with the triaxial testing result.

scholarly journals Effects of backfill soil on pipeline’s mechanical response subjected to perilous rock impact

2020 ◽  
Vol 40 (1) ◽  
pp. 25-31
Author(s):  
Jie Zhang ◽  
Wei Guo ◽  
Haiyang Li
Keyword(s):  
Elastic Modulus ◽  
Plastic Strain ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Low Velocity Impact ◽  
Soil Parameters ◽  
Buried Pipeline ◽  
Velocity Impact ◽  
Backfill Soil

Perilous rock impact is one of the most serious geological disasters that threats to buried pipeline security. Mechanical behavior of buried pipeline in rock stratum impacted by perilous rock was simulated in this paper. And effects of impact velocity and backfill soil parameters on stress and strain of pipeline were discussed. The resluts show that cross section shape of pipeline is oval when impact velocity is small. Impact dent appears on pipeline with the increasing of impact velocity, buckling is more serious and plastic stain increases. Under low velocity impact, stress and plastic strain decrease with the increasing of soil's elastic modulus. Plastic strain increases first and then decreases with the increasing of soil's Poisson's ratio. With the increasing of soil's cohesion, plastic strain increases, but stress first increases and then decreases. Under high velocity impact, deformation and plastic strain increase with the decreasing of elastic modulus and Poisson's ratio. But cohesion has a small effect on buckling behavior of pipeline.

Compliant Cellular Materials With Elliptical Holes for Extremely High Positive and Negative Poisson's Ratios

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Jaehong Lee ◽  
Kwangwon Kim ◽  
Jaehyung Ju ◽  
Doo-Man Kim
Keyword(s):  
Poisson’S Ratio ◽  
Longitudinal Direction ◽  
Materials Design ◽  
Cellular Materials ◽  
Poisson's Ratio ◽  
Yield Strain ◽  
Large Rotation ◽  
Elliptical Holes ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Cellular materials' two important properties—structure and mechanism—can be selectively used for materials design; in particular, they are used to determine the modulus and yield strain. The objective of this study is to gain a better understanding of these two properties and to explore the synthesis of compliant cellular materials (CCMs) with compliant porous structures (CPSs) generated from modified hexagonal honeycombs. An in-plane constitutive CCM model with CPSs of elliptical holes is constructed using the strain energy method, which uses the deformation of hinges around holes and the rotation of links. A finite element (FE) based simulation is conducted to validate the analytical model. The moduli and yield strains of the CCMs with an aluminum alloy are about 4.42 GPa and 0.57% in one direction and about 2.14 MPa and 20.9% in the other direction. CCMs have extremely high positive and negative Poisson's ratios (NPRs) (νxy* ∼ ±40) due to the large rotation of the link member in the transverse direction caused by an input displacement in the longitudinal direction. A parametric study of CCMs with varying flexure hinge geometries using different porous shapes shows that the hinge shape can control the yield strength and strain but does not affect Poisson's ratio which is mainly influenced by rotation of the link members. The synthesized CPSs can also be used to design a new CCM with a Poisson's ratio of zero using a puzzle-piece CPS assembly. This paper demonstrates that compliant mesostructures can be used for next generation materials design in tailoring mechanical properties such as moduli, strength, strain, and Poisson's ratios.

scholarly journals The 3D-Printed Honeycomb Metamaterials Tubes with Tunable Negative Poisson’s Ratio for High-Performance Static and Dynamic Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1353
Author(s):  
Chunxia Guo ◽  
Dong Zhao ◽  
Zhanli Liu ◽  
Qian Ding ◽  
Haoqiang Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Poisson’S Ratio ◽  
Dynamic Compression ◽  
Equal Mass ◽  
Peak Force ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
3D Printed

The synthesized understanding of the mechanical properties of negative Poisson’s ratio (NPR) convex–concave honeycomb tubes (CCHTs) under quasi-static and dynamic compression loads is of great significance for their multifunctional applications in mechanical, aerospace, aircraft, and biomedical fields. In this paper, the quasi-static and dynamic compression tests of three kinds of 3D-printed NPR convex–concave honeycomb tubes are carried out. The sinusoidal honeycomb wall with equal mass is used to replace the cell wall structure of the conventional square honeycomb tube (CSHT). The influence of geometric morphology on the elastic modulus, peak force, energy absorption, and damage mode of the tube was discussed. The experimental results show that the NPR, peak force, failure mode, and energy absorption of CCHTs can be adjusted by changing the geometric topology of the sinusoidal element. Through the reasonable design of NPR, compared with the equal mass CSHTs, CCHTs could have the comprehensive advantages of relatively high stiffness and strength, enhanced energy absorption, and damage resistance. The results of this paper are expected to be meaningful for the optimization design of tubular structures widely used in mechanical, aerospace, vehicle, biomedical engineering, etc.

scholarly journals Energy dissipation in microfluidic beam resonators: Effect of Poisson's ratio

2011 ◽  
Vol 84 (2) ◽  
Author(s):  
John E. Sader ◽  
Thomas P. Burg ◽  
Jungchul Lee ◽  
Scott R. Manalis
Keyword(s):  
Energy Dissipation ◽  
Poisson’S Ratio ◽  
Poisson's Ratio

scholarly journals In-plane Dynamic Crushing of a Novel Bio-inspired Re-entrant Honeycomb With Negative Poisson's Ratio 

2021 ◽  
Author(s):  
Yonghui Wang ◽  
Qiang He ◽  
Yu Chen ◽  
Hang Gu ◽  
Honggen Zhou
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Dynamic Compression ◽  
Absorption Capacity ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Energy Absorption Capacity ◽  
Plateau Stress ◽  
Negative Poisson's Ratio

Abstract In order to seek higher crashworthiness and energy absorption capacity, based on biological inspiration, a novel bio-inspired re-entrant honeycomb (BRH) structure with negative Poisson's ratio is designed by selecting lotus leaf vein as biological prototype. The numerical simulation model is established by the nonlinear dynamics software ABAQUS and further compared with the available reference results to verify the feasibility. The dynamic compression behavior and energy absorption capacity of two types of BRH (BRH-Ⅰ and BRH-Ⅱ) are firstly compared with conventional re-entrant honeycomb (RH). The simulation results show that BRH have better mechanical properties and energy absorption characteristics. Then, the crushing behavior of BRH-Ⅱ under different impact velocities are systematically studied. Three typical deformation modes of BRH-Ⅱ are observed through the analysis of deformation profile. The quasi-static plateau stress is closely related to the cellular structure. Based on one-dimensional shock theory, the empirical equations of dynamic plateau stress for BRH-Ⅱ with different relative densities are given by using least-square fitting. In addition, the effects of impact velocity and relative density on plateau stress and energy absorption behavior are also studied. The results show that the energy absorption capacity of BRH-Ⅱ is increased nearly six times compared with RH at the same impact velocity.

Axial Compression and Collapse Properties of 3D Re-Entrant Hexagonal Auxetic Structures

2020 ◽  
Author(s):  
Pu Li ◽  
Jingxia Yue ◽  
Xiaobin Li ◽  
Wenchao Wan
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Impact Load ◽  
Principal Direction ◽  
Honeycomb Structure ◽  
Poisson's Ratio ◽  
Beam Model ◽  
Deformation State ◽  
The Impact

Abstract A three-dimension (3D) re-entrant honeycomb structure which exhibits negative Poisson’s ratio in all three principal directions is modeled from a classical two-dimension (2D) auxetic material. In this work, on the basis of the Castigliano’s second theorem and Timoshenko beam model, the shear deformation and axial deformation of this structure are investigated. And the analytical formulas of the effective modulus and Poisson’s ratio in each principal direction of the honeycomb structure are derived. By comparing the analytical results with the finite element analysis results, the rationality of the formula is verified. Then, the collapse characteristics of honeycomb structures with different mechanical properties under variation impact velocities are studied. The results show that, the deformation of honeycomb structure can be divided into three patterns, “quasi-static” deformation, “transitional” deformation and “local” deformation varied with impact velocities. And due to inertial effect, with the increase of impact velocity, the load-bearing capacity and energy absorption of the structure also increased. In addition to the impact velocity, the cells’ configuration is also a non-negligible factor, and its turns out that the decrease of angle accelerates the deformation state of the honeycomb structure and strengthen the energy-absorption capability after being subjected to impact load.

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