scholarly journals Effect of Subsurface Microstructures on Adhesion of Highly Confined Elastic Films

2020 ◽  
Vol 88 (3) ◽  
Author(s):  
Manar Samri ◽  
Attila Kossa ◽  
René Hensel
Keyword(s):  
Poisson’S Ratio ◽  
Contact Stiffness ◽  
Three Dimensional ◽  
Adhesive Layer ◽  
Interfacial Stress ◽  
Poisson's Ratio ◽  
Stress Distributions ◽  
Elastic Film ◽  
Polymer Adhesive ◽  
The Impact

Abstract Polymer adhesive films sandwiched between two rigid solids are a common bonding strategy. The mechanics and consequently the adhesion of such geometrically confined films depend mainly on their thickness, Young's modulus, and the Poisson's ratio of the material. In this work, we explore the effect of a micropatterned subsurface embedded into the adhesive layer. We compare experiments with three-dimensional numerical simulations to evaluate the impact of the microstructure on the contact stiffness and effective modulus. The results are used to extend a previously proposed size scaling argument on adhesion from incompressible to slightly compressible films to account for the silicone used in our study with a Poisson's ratio of 0.495. In addition, interfacial stress distributions between the elastic film and the glass disc are obtained from plane strain simulations to evaluate characteristic adhesion failures such as edge cracks and cavitation. Overall, the micropatterned subsurface has a large impact on the contact stiffness, the interfacial stress distribution, and the detachment behavior; however, the adhesion performance is only slightly improved in comparison to a non-patterned subsurface.

Three-Dimensional Finite Element Analysis of Single-Lap Joints: Effect of Adhesive Thickness and Poisson's Ratio

2013 ◽  
Vol 577-578 ◽  
pp. 393-396
Author(s):  
R. Afshar ◽  
Filippo Berto ◽  
Paolo Lazzarin
Keyword(s):  
Finite Element ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Lap Joints ◽  
Poisson's Ratio ◽  
Stress Distributions ◽  
Coupled Modes ◽  
Single Lap Joints ◽  
Out Of Plane ◽  
Adhesive Thickness

Three-dimensional (3D) elastic stress distributions in the vicinity of overlap corners of single-lap joints are investigated. A detailed 3D finite element (FE) model is carried out to study the intensity of the in-plane and out-of-plane stress distributions along the plate width direction. The effects of adhesive thickness and Poisson's ratio are also studied. The FE results show the presence of coupled modes at the overlap corners of the joint. In particular, sharp increment of out-of-plane fracture mode very near the lateral free surface of the joint is worth noting.

scholarly journals Sandwich panel with in-plane honeycombs in different Poisson's ratio under low to medium impact loads

2021 ◽  
Vol 60 (1) ◽  
pp. 145-157
Author(s):  
Yi Luo ◽  
Ke Yuan ◽  
Lumin Shen ◽  
Jiefu Liu
Keyword(s):  
Poisson’S Ratio ◽  
Sandwich Panel ◽  
Impact Force ◽  
Impact Resistance ◽  
Poisson's Ratio ◽  
Compression Performance ◽  
Post Impact ◽  
Local Impact ◽  
Collapse Behavior ◽  
The Impact

Abstract In this study, a series of in-plane hexagonal honeycombs with different Poisson's ratio induced by topological diversity are studied, considering re-entrant, semi-re-entrant and convex cells, respectively. The crushing strength of honeycomb in terms of Poisson's ratio is firstly presented. In the previous research, we have studied the compression performance of honeycomb with different negative Poisson's ratio. In this study, a comparative study on the local impact resistance of different sandwich panels is conducted by considering a spherical projectile with low to medium impact speed. Some critical criteria (i.e. local indentation profile, global deflection, impact force and energy absorption) are adopted to analyze the impact resistance. Finally, an influential mechanism of Poisson's ratio on the local impact resistance of sandwich panel is studied by considering the variation of core strength and post-impact collapse behavior.

scholarly journals The Multidirectional Auxeticity and Negative Linear Compressibility of a 3D Mechanical Metamaterial

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2193 ◽  
Author(s):  
Krzysztof K. Dudek ◽  
Daphne Attard ◽  
Ruben Gatt ◽  
James N. Grima-Cornish ◽  
Joseph N. Grima
Keyword(s):  
Theoretical Model ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Structural Units ◽  
Loading Direction ◽  
Arbitrary Loading ◽  
Negative Poisson's Ratio ◽  
Linear Compressibility

In this work, through the use of a theoretical model, we analyse the potential of a specific three-dimensional mechanical metamaterial composed of arrowhead-like structural units to exhibit a negative Poisson’s ratio for an arbitrary loading direction. Said analysis allows us to assess its suitability for use in applications where materials must be able to respond in a desired manner to a stimulus applied in multiple directions. As a result of our studies, we show that the analysed system is capable of exhibiting auxetic behaviour for a broad range of loading directions, with isotropic behaviour being shown in some planes. In addition to that, we show that there are also certain loading directions in which the system manifests negative linear compressibility. This enhances its versatility and suitability for a number of applications where materials exhibiting auxetic behaviour or negative linear compressibility are normally implemented.

Three-dimensional porous borocarbonitride BC2N with negative Poisson's ratio

2020 ◽  
Vol 8 (44) ◽  
pp. 15771-15777
Author(s):  
Kashif Hussain ◽  
Umer Younis ◽  
Imran Muhammad ◽  
Yu Qie ◽  
Yaguang Guo ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Negative Poisson's Ratio ◽  
Recent Synthesis

Motivated by the recent synthesis of three-dimensional (3D) porous borocarbonitride (Angew. Chem., Int. Ed., 2019, 58, 6033–6037), we propose a porous 3D-BC2N structure composed of BC2N nanoribbons.

Auxetic deformation of the weft-knitted Miura-ori fold

2019 ◽  
Vol 90 (5-6) ◽  
pp. 617-630
Author(s):  
Kun Luan ◽  
Andre West ◽  
Emiel DenHartog ◽  
Marian McCord
Keyword(s):  
Deformation Mechanism ◽  
Poisson’S Ratio ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Dimensional Structure ◽  
Damping Capacity ◽  
Analysis Model ◽  
Element Analysis ◽  
Specific Direction ◽  
Application Fields

Negative Poisson’s ratio (NPR) material with unique geometry is rare in nature and has an auxetic response under strain in a specific direction. With this unique property, this type of material is significantly promising in many specific application fields. The curling structure commonly exists in knitted products due to the unbalanced force inside a knit loop. Thus, knitted fabric is an ideal candidate to mimic natural NPR materials, since it possesses such an inherent curly configuration and the flexibility to design and process. In this work, a weft-knitted Miura-ori fold (WMF) fabric was produced that creates a self-folding three-dimensional structure with NPR performance. Also, a finite element analysis model was developed to simulate the structural auxetic response to understand the deformation mechanism of hierarchical thread-based auxetic fabrics. The simulated strain–force curves of four WMF fabrics quantitatively agree with our experimental results. The auxetic morphologies, Poisson’s ratio and damping capacity were discussed, revealing the deformation mechanism of the WMF fabrics. This study thus provides a fundamental framework for mechanical-stimulating textiles. The developed NPR knitted fabrics have a high potential to be employed in areas of tissue engineering, such as artificial blood vessels and artificial folding mucosa.

scholarly journals 4D Printing of NiTi Auxetic Structure with Improved Ballistic Performance

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 745
Author(s):  
Hany Hassanin ◽  
Alessandro Abena ◽  
Mahmoud Ahmed Elsayed ◽  
Khamis Essa
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Analytical Model ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
4D Printing ◽  
Auxetic Structures ◽  
Negative Poisson's Ratio ◽  
The Impact ◽  
Auxetic Structure

Auxetic structures have attracted attention in energy absorption applications owing to their improved shear modulus and enhanced resistance to indentation. On the other hand, four-dimensional (4D) printing is an emerging technology that is capable of 3D printing smart materials with additional functionality. This paper introduces the development of a NiTi negative-Poisson’s-ratio structure with superelasticity/shape memory capabilities for improved ballistic applications. An analytical model was initially used to optimize the geometrical parameters of a re-entrant auxetic structure. It was found that the re-entrant auxetic structure with a cell angle of −30° produced the highest Poisson’s ratio of −2.089. The 4D printing process using a powder bed fusion system was used to fabricate the optimized NiTi auxetic structure. The measured negative Poisson’s ratio of the fabricated auxetic structure was found in agreement with both the analytical model and the finite element simulation. A finite element model was developed to simulate the dynamic response of the optimized auxetic NiTi structure subjected to different projectile speeds. Three stages of the impact process describing the penetration of the top plate, auxetic structure, and bottom plate have been identified. The results show that the optimized auxetic structures affect the dynamic response of the projectile by getting denser toward the impact location. This helped to improve the energy absorbed per unit mass of the NiTi auxetic structure to about two times higher than that of the solid NiTi plate and five times higher than that of the solid conventional steel plate.

Effective properties of composite materials containing voids

1993 ◽  
Vol 440 (1909) ◽  
pp. 461-473 ◽  
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Effective Properties ◽  
Young's Modulus ◽  
Matrix Material ◽  
Practical Importance ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Two Dimensional ◽  
Isotropic Composite

Recent results of theoretical and practical importance prove that the two-dimensional (in-plane) effective (average) Young’s modulus for an isotropic elastic material containing voids is independent of the Poisson’s ratio of the matrix material. This result is true regardless of the shape and morphology of the voids so long as isotropy is maintained. The present work uses this proof to obtain explicit analytical forms for the effective Young’s modulus property, forms which simplify greatly because of this characteristic. In some cases, the optimal morphology for the voids can be identified, giving the shapes of the voids, at fixed volume, that maximize the effective Young’s modulus in the two-dimensional situation. Recognizing that two-dimensional isotropy is a subset of three-dimensional transversely isotropic media, it is shown in this more general case that three of the five properties are independent of Poisson’s ratio, leaving only two that depend upon it. For three-dimensionally isotropic composite media containing voids, it is shown that a somewhat comparable situation exists whereby the three-dimensional Young’s modulus is insensitive to variations in Poisson’s ratio, v m , over the range 0 ≤ v m ≤ ½, although the same is not true for negative values of v m . This further extends the practical usefulness of the two-dimensional result to three-dimensional conditions for realistic values of v m .

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