scholarly journals Hierarchical Interfaces as Fracture Propagation Traps in Natural Layered Composites

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6855
Author(s):  
Hanoch Daniel Wagner
Keyword(s):  
Architectural Design ◽  
Layered Structures ◽  
Layered Composite ◽  
Simultaneous Occurrence ◽  
Layered Composites ◽  
Powerful Approach ◽  
Different Types ◽  
Alternative Designs ◽  
Structural Levels ◽  
Overall Reliability

Compared with their monolithic version, layered structures are known to be beneficial in the design of materials, especially ceramics, providing enhanced fracture toughness, mechanical strength, and overall reliability. This was proposed in recent decades and extensively studied in the engineering literature. The source of the property enhancement is the ability of layered structures to deflect and often arrest propagating cracks along internal interfaces between layers. Similar crack-stopping abilities are found in nature for a broad range of fibrillary layered biological structures. Such abilities are largely governed by complex architectural design solutions and geometries, which all appear to involve the presence of various types of internal interfaces at different structural levels. The simultaneous occurrence at several scales of different types of interfaces, designated here as hierarchical interfaces, within judiciously designed layered composite materials, is a powerful approach that constrains cracks to bifurcate and stop. This is concisely described here using selected biological examples, potentially serving as inspiration for alternative designs of engineering composites.

Determination of the transverse shear stress in layered composites

2020 ◽  
Vol 86 (2) ◽  
pp. 44-53
Author(s):  
Yu. I. Dudarkov ◽  
M. V. Limonin
Keyword(s):  
Shear Stress ◽  
Transverse Shear ◽  
Composite Beam ◽  
Layered Composite ◽  
Equivalent Model ◽  
Shear Stresses ◽  
Transverse Shear Stress ◽  
Layered Composites ◽  
Laminate Composites ◽  
Transverse Shear Stresses

An engineering approach to estimation of the transverse shear stresses in layered composites is developed. The technique is based on the well-known D. I. Zhuravsky equation for shear stresses in an isotropic beam upon transverse bending. In general, application of this equation to a composite beam is incorrect due to the heterogeneity of the composite structure. According to the proposed method, at the first stage of its implementation, a transition to the equivalent model of a homogeneous beam is made, for which the Zhuravsky formula is valid. The transition is carried out by changing the shape of the cross section of the beam, provided that the bending stiffness and generalized elastic modulus remain the same. The calculated shear stresses in the equivalent beam are then converted to the stress values in the original composite beam from the equilibrium condition. The main equations and definitions of the method as well as the analytical equation for estimation of the transverse shear stress in a composite beam are presented. The method is verified by comparing the analytical solution and the results of the numerical solution of the problem by finite element method (FEM). It is shown that laminate stacking sequence has a significant impact both on the character and on the value of the transverse shear stress distribution. The limits of the applicability of the developed technique attributed to the conditions of the validity of the hypothesis of straight normal are considered. It is noted that under this hypothesis the shear stresses do not depend on the layer shear modulus, which explains the absence of this parameter in the obtained equation. The classical theory of laminate composites is based on the similar assumptions, which gives ground to use this equation for an approximate estimation of the transverse shear stresses in in a layered composite package.

scholarly journals Preparation and Properties of Layered SiC-Graphene Composites for EDM

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2916
Author(s):  
Ondrej Hanzel ◽  
Zoltán Lenčéš ◽  
Peter Tatarko ◽  
Richard Sedlák ◽  
Ivo Dlouhý ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Surface Layer ◽  
Positive Influence ◽  
Layered Composite ◽  
Layered Composites ◽  
Good Adhesion ◽  
Electric Discharge Machining ◽  
Layer Sequence ◽  
The Individual ◽  
Scratch Tests

Three and five-layered silicon carbide-based composites containing 0, 5, and 15 wt.% of graphene nanoplatelets (GNPs) were prepared with the aim to obtain a sufficiently high electrical conductivity in the surface layer suitable for electric discharge machining (EDM). The layer sequence in the asymmetric three-layered composites was SiC/SiC-5GNPs/SiC-15GNPs, while in the symmetric five-layered composite, the order of layers was SiC-15GNPs/SiC-5GNPs/SiC/SiC-5GNPs/SiC-15GNPs. The layered samples were prepared by rapid hot-pressing (RHP) applying various pressures, and it was shown that for the preparation of dense 3- or 5-layered SiC/GNPs composites, at least 30 MPa of the applied load was required during sintering. The electrical conductivity of 3-layered and 5-layered composites increased significantly with increasing sintering pressure when measured on the SiC surface layer containing 15 wt.% of GNPs. The increasing GNPs content had a positive influence on the electrical conductivity of individual layers, while their instrumented hardness and elastic modulus decreased. The scratch tests confirmed that the materials consisted of well-defined layers with straight interfaces without any delamination, which suggests good adhesion between the individual layers.

scholarly journals Application of Biomimetics to Architectural and Urban Design: A Review across Scales

2020 ◽  
Vol 12 (23) ◽  
pp. 9813 ◽  
Author(s):  
Yuta Uchiyama ◽  
Eduardo Blanco ◽  
Ryo Kohsaka
Keyword(s):  
Urban Design ◽  
Architectural Design ◽  
Evolutionary Process ◽  
Future Research ◽  
Conceptual Level ◽  
Sustainable Society ◽  
Types Of Knowledge ◽  
The Social ◽  
Different Types ◽  
Shed Light

Application of biomimetics has expanded progressively to other fields in recent years, including urban and architectural design, scaling up from materials to a larger scale. Besides its contribution to design and functionality through a long evolutionary process, the philosophy of biomimetics contributes to a sustainable society at the conceptual level. The aim of this review is to shed light on trends in the application of biomimetics to architectural and urban design, in order to identify potential issues and successes resulting from implementation. In the application of biomimetics to architectural design, parts of individual “organisms”, including their form and surface structure, are frequently mimicked, whereas in urban design, on a larger scale, biomimetics is applied to mimic whole ecosystems. The overall trends of the reviewed research indicate future research necessity in the field of on biomimetic application in architectural and urban design, including Biophilia and Material. As for the scale of the applications, the urban-scale research is limited and it is a promising research which can facilitate the social implementation of biomimetics. As for facilitating methods of applications, it is instrumental to utilize different types of knowledge, such as traditional knowledge, and providing scientific clarification of functions and systems based on reviews. Thus, interdisciplinary research is required additionally to reach such goals.

scholarly journals The architectural design of networks of protein domain architectures

2013 ◽  
Vol 9 (4) ◽  
pp. 20130268 ◽  
Author(s):  
Chia-Hsin Hsu ◽  
Chien-Kuo Chen ◽  
Ming-Jing Hwang
Keyword(s):  
Architectural Design ◽  
Molecular Form ◽  
Protein Domains ◽  
Single Domain ◽  
Protein Domain ◽  
Protein Architecture ◽  
Different Types ◽  
Protein Functions ◽  
Shed Light ◽  
Multiple Domain

Protein domain architectures (PDAs), in which single domains are linked to form multiple-domain proteins, are a major molecular form used by evolution for the diversification of protein functions. However, the design principles of PDAs remain largely uninvestigated. In this study, we constructed networks to connect domain architectures that had grown out from the same single domain for every single domain in the Pfam-A database and found that there are three main distinctive types of these networks, which suggests that evolution can exploit PDAs in three different ways. Further analysis showed that these three different types of PDA networks are each adopted by different types of protein domains, although many networks exhibit the characteristics of more than one of the three types. Our results shed light on nature's blueprint for protein architecture and provide a framework for understanding architectural design from a network perspective.

Ballistic Performance of TiC-TiB2 Composite Armour under the Impact of Long-Rod Tungsten Alloy Projectiles of 1.4 km · s-1

2013 ◽  
Vol 544 ◽  
pp. 310-315
Author(s):  
Xue Gang Huang ◽  
Zhong Min Zhao ◽  
Long Zhang
Keyword(s):  
Layered Composite ◽  
Tungsten Alloy ◽  
Ti Alloy ◽  
Impact Point ◽  
Layered Composites ◽  
Micro Hardness ◽  
Ballistic Performance ◽  
Long Rod ◽  
High Gravity Field ◽  
The Impact

Based on using combustion synthesis in high-gravity field to prepare the solidified TiC-TiB2 composites, the layered composites of the ceramic to Ti-6Al-4V at graded composition were achieved by fusion joint and atomic inter-diffusion between liquid TiC-TiB2 and Ti-6Al-4V substrate. The mechanical properties showed that the relative density, micro-hardness and fracture toughness of TiC-TiB2 ceramic layer measured 98.5%, 21.5 GPa and 13.5 ± 2.5 MPa • m0.5, respectively, and the shear strength at joint of TiC-TiB2 to Ti-6Al-4V measured 450 ± 25 MPa. By conducting DOP test to evaluate ballistic performance of the ceramic and layered-composite targets against long-rod KE projectiles at impact velocity of 1.4 km • s-1, it was obtained the mass efficiency 3.28 of the solidified TiC-TiB2 was achieved as the impact point of the projectile was nearby the centre of the target, whereas the mass efficiency 3.18 of the layered composite with the solidified ceramic to Ti-6Al-4V was also achieved even if the impact point of the projectile was at the edge of the target. By combining penetration damage of the targets with the dynamic behavior of the ceramic, it was obtained that the layered composite achieved by the joint of the solidified ceramic to Ti-6Al-4V not only improve ballistic performance of the ceramic, but also weaken the sensitivity of the ceramic target against the impact point of KE projectile by tearing the joint of the ceramic with Ti alloy to restrain formation and propagation of conical crack and fracture cone in the ceramic.

Under Construction: Alternative Spaces of Discourse at the National Library of Israel (Critical Essay)

2019 ◽  
Vol 53 (01) ◽  
pp. 59-82 ◽  
Author(s):  
Jeremy Kargon
Keyword(s):  
Digital Media ◽  
Architectural Design ◽  
Public Discourse ◽  
Jewish People ◽  
Institutional Transformation ◽  
Functional Requirements ◽  
National Library ◽  
Alternative Spaces ◽  
Under Construction ◽  
Alternative Designs

AbstractA new building for the National Library of Israel (NLI), scheduled for completion in 2021, is the culmination of a two-decade process of institutional transformation. Formerly known as the Jewish National and University Library, the NLI has historically served simultaneously as Israel's official state repository, as the Hebrew University's central library, and as a “library of the Jewish people.” Like other national libraries around the world, including elsewhere in the Middle East, the National Library of Israel has had to grapple with accelerated changes in management of library collections due to the proliferation of digital media. More fundamental, however, have been changes in the cultural expectations about how libraries should function. Since 1998, the NLI has sought to expand its mission to promote not only scholarship but also cultural “discourse” among Israel's diverse constituencies. The architectural design of NLI's new edifice was intended, therefore, to do more than house the functional requirements of a modern library. It was commissioned to express through its design the significance of the transformed institution for the Israeli public. Towards that goal, a highly publicized competition for the NLI's design was held in 2012. The original two-stage competition ended in controversy after the architect endorsed by the jurors was dismissed. Yet a review of designs submitted by four Israeli architects in that first competition shows how public spaces, affiliated with public institutions, are expected to foster public discourse in Israel. Whether that discourse is cultural or political, contentious or contradictory, these alternative designs for the NLI illustrate common themes based upon specific environmental tropes, familiar across a broad spectrum of Israeli society.

Two deep-ultraviolet nonlinear optical alkaline-earth metal borates based on different types of oxoboron clusters

2017 ◽  
Vol 46 (24) ◽  
pp. 7911-7916 ◽  
Author(s):  
Qi Wei ◽  
Li Sun ◽  
Jie Zhang ◽  
Guo-Yu Yang
Keyword(s):  
Nonlinear Optical ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Layered Structures ◽  
Alkaline Earth Metal ◽  
Different Types ◽  
Nlo Materials ◽  
Deep Ultraviolet ◽  
Deep Uv

Two non-centrosymmetric alkaline-earth metal borates were synthesized, showing the layered structures constructed from different oxoboron clusters and potentially new candidates for deep-UV NLO materials.

Clause-final negation

2003 ◽  
Vol 9 (2) ◽  
pp. 239-268 ◽  
Author(s):  
Ger P. Reesink
Keyword(s):  
Final Position ◽  
Different Types ◽  
Structural Levels ◽  
Sentential Operator ◽  
Negative Adverb

Negation in a number of Austronesian and Papuan languages with SVO order is expressed by a rather rigid clause-final position of the negative adverb. Some typological generalizations for negation are reviewed and the distribution of this trait in languages of different stocks is discussed, arguing that it most likely originates in Papuan languages. Some proposals for different types of negation, such as whether it is a verbal (or VP) operator, a constituent operator or a sentential operator are considered. The problem of determining the scope of negation is discussed, with the conclusion that hard and fast semantic meanings for NEG at different structural levels cannot be posited, suggesting that perhaps a solution can be found in the application of some universal pragmatic principles.

Fabrication, Structure and Properties of Aluminum-Aluminide Layered Composites

1996 ◽  
Vol 434 ◽  
Author(s):  
D. E. Alman
Keyword(s):  
Layered Structure ◽  
Hot Pressing ◽  
Tensile Tests ◽  
Layered Composite ◽  
Structure And Properties ◽  
Layered Composites ◽  
Heat Treated

AbstractThe fabrication of aluminum-aluminide layered composites by reactive bonding of elemental Al and Ni foils was investigated. It was observed that after hot-pressing, thin Ni foils were converted to NiAl. The as-processed Al-NiAl layered structure could be heat-treated to produce an equilibrium Al-Al3Ni layered composite. Tensile tests revealed that composites could be produced that failed in a “tough” manner and were stronger and stiffer than aluminum.

scholarly journals Torsion Dynamic Behaviour of the Ship Hull Made out of Layered Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Ionel Chirica
Keyword(s):  
Composite Plates ◽  
Past Research ◽  
Layered Composite ◽  
Ship Hull ◽  
Scale Model ◽  
Behavioral Characteristics ◽  
Container Ship ◽  
Layered Composites ◽  
Dynamic Torsion ◽  
Software Code

This paper addresses the dynamic torsion behaviour of the ship hull with very large open decks. A short overview of the past research is presented, and several key findings and behavioral characteristics are discussed. In the paper, the author is focusing on the dynamic part of a new macroelement model used for torsion dynamic analysis of the ship hull made of composite materials. The numerical analysis (using two methods, one of them being a new proposed method) and experiments are developed on a simplified typical hull of a container ship. The torsion analysis is performed on a scale model of a container ship, made of layered composite plates, and the first 5 natural frequencies are determined. The results obtained with the proposed numerical method (software code TORS, made by the author) are compared with the results obtained with FE analysis and with the experiments done on the physical model.

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