Shear mechanical properties of the core structure of biomimetic fully integrated honeycomb plates

2018 ◽  
Vol 22 (4) ◽  
pp. 1184-1198 ◽  
Author(s):  
Wanyong Tuo ◽  
Jinxiang Chen ◽  
Mengye Xu ◽  
Zhijie Zhang ◽  
Zhensheng Guo
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Shear Failure ◽  
Core Structure ◽  
Resin Matrix ◽  
Joint Interface ◽  
Shear Direction ◽  
Material Interface ◽  
Fully Integrated ◽  
The Core

In the present study, the shear failure mode and mechanical properties of the core structure of biomimetic fully integrated honeycomb plates with sealing edges were investigated experimentally and through the finite element method. The findings are as follows: (1) the failure mode of the sealing edges and honeycomb walls perpendicular to the shear direction is mainly debonding between the fiber and matrix, whereas fiber breakage, debonding between the fiber and matrix and exfoliation of the resin matrix occur in the sealing edges parallel to the shear direction. Meanwhile, the reasonableness and feasibility of the double shear testing apparatus designed in this study were verified, thus confirming the results of research are reliable and valid. (2) Shear failure of the core structure of fully integrated honeycomb plates is mainly fiber debonding appearing in the middle surface of the core structure, which is a failure of the material interface. Stripping failure in the joint interface of the core layer and upper and lower plates does not occur, which indicates that the biological structure possesses excellent integral mechanical properties. (3) The sealing edges parallel to the shear direction and the honeycomb walls that are oriented 30 degrees to the shear direction are the first to fail, followed by the sealing edges and honeycomb walls perpendicular to the shear direction, which is consistent with the microscopic failure phenomenon observed in both directions. To prevent failure at the material interface, the fully integrated honeycomb plates manufactured in this experiment require further improvements. Thus, countermeasures are proposed, such as pre-treating the fiber surface. These findings will specify future research directions to perfect fully integrated honeycomb plates and improve the shear mechanical properties of core structures.

scholarly journals Mechanical properties of the wood-based X-type lattice sandwich structure

BioResources ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 1927-1944 ◽  
Author(s):  
Tengteng Zheng ◽  
Yanpeng Cheng ◽  
Shuai Li ◽  
Yan Zhang ◽  
Yingcheng Hu
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Sandwich Structure ◽  
Shear Failure ◽  
Compressive Test ◽  
The Core ◽  
Short Beam ◽  
Out Of Plane ◽  
Beam Shear ◽  
Type Lattice

In this study, a wood-based X-type lattice sandwich structure was fabricated by an insertion glue method using medium density fiberboard (MDF) and plywood as panels. Birch was used for the core. The mechanical properties and failure modes of the wood-based X-type lattice sandwich structure were investigated by an out-of-plane compressive test, a short beam shear test, and their matching analytical models. The out-of-plane compressive test and the compression analytical model showed that the failure mode of the plywood and birch combination was mainly shear failure in the core. The cores were broken or had sliding surfaces, while the failure mode of the MDF and birch combination was mainly shear failure of the core at both ends. Although the compression properties of the MDF and birch combination were better, the specific strength and modulus of the plywood and birch combination was larger, which align with the characteristics of lightweight and strong strength. The failure mode of the plywood and birch combination was delamination at both ends of the panel or core breakage, which indicated that this combination had better short beam shear properties. The theoretical models of the compressive /short beam shear properties were in good agreement with experimental results obtained for the plywood and birch combination.

scholarly journals Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Aneta Krzyżak ◽  
Michał Mazur ◽  
Mateusz Gajewski ◽  
Kazimierz Drozd ◽  
Andrzej Komorek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Polymer Composites ◽  
Impact Load ◽  
Sandwich Panels ◽  
Adhesive Layer ◽  
Core Structure ◽  
Road Vehicles ◽  
The Core ◽  
Press Method

Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb) thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

scholarly journals Experimental Study on the Fracture Evolution Processof Rock-like Specimens Containing a Closed RoughJoint Based on 3D-Printing Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Jiawei Liu ◽  
Haijian Su ◽  
Hongwen Jing ◽  
Chengguo Hu ◽  
Qian Yin
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Failure Mode ◽  
Shear Failure ◽  
Rock Joints ◽  
Image Correlation ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Joint Inclination ◽  
Joint Length

In order to overcome the disadvantage of traditional joint fabrication method—inability to reproduce the rough surfaces of practical rock joints—3D-printing technology was applied to restructure five kinds of rough joint according to the failure surface formed by the triaxial prepeak unloading test in this study. And uniaxial compression test was carried out on the rock-like specimens containing closed 3D-printing rough joint to study the effects of joint inclination and joint length on the mechanical properties (peak strength, peak strain, elastic modulus, and secant modulus), cracking process, and failure modes. Besides, digital image correlation (DIC) method and acoustic emission (AE) system are used to investigate the whole evolution process of strain fields and crack propagation during loading. It is found that the mechanical parameters decrease first and then go up as the joint inclination increases, while presenting a continuous downward trend with the increase of joint length. Inclination of 45° and the larger joint length bring more extensive reduction to mechanical properties of specimens. Specimens exhibit typical brittle failure characteristics. The failure mode of specimens affected by different joint inclination is tension-shear failure. And the joint scale rises; the failure mode of specimens changes from tensile failure to shear failure. Larger joint scale results in the longer prepeak fluctuation phase on axial stress-strain curves and more dispersed distribution of high-value AE counts.

Experimental Investigation on Compressive Properties for 3D Four-Directional Braided Composites

2010 ◽  
Vol 160-162 ◽  
pp. 1744-1748 ◽  
Author(s):  
Bao Lai Wang ◽  
Zhen Qing Wang ◽  
Guo Dong Fang ◽  
Jun Liang ◽  
Li Min Zhou
Keyword(s):  
Experimental Investigation ◽  
Compressive Stress ◽  
Failure Mode ◽  
Epoxy Matrix ◽  
Failure Modes ◽  
Shear Failure ◽  
Shear Direction ◽  
Compressive Properties ◽  
Braided Composites ◽  
Stress Strain

Based on changing the braid angle and geometrical sizes, the compressive experiment of 3D braided four-directional Carbon/Epoxy braided composites is researched. It is found that failure of the braided composites exhibits compressive and shear failure mode. The failure crack propagates mainly in one or two 45º shear direction. Epoxy matrix among braid yarns of the braided composites is squeezed out to form epoxy band. The stress-strain relations of the braided composites with 45º and 30º braid angles all appear nonlinear apparently. Meanwhile the correlation of failure modes and constitutive relation with geometrical sizes of the braided composites is obtained. The compressive stress-strain relations of the braided composites are not great affected by the geometrical sizes. The compressive strengths with great discrete behaviors do not have obvious rules with height of the braided composites.

scholarly journals Exploring the Effect of Asperity Order on Mechanical Character of Joint Specimen from the Perspective of Damage

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Zhouhao Yuan ◽  
Yicheng Ye ◽  
Binyu Luo
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Normal Stress ◽  
Failure Mode ◽  
Shear Failure ◽  
Joint Surface ◽  
Normal Stresses ◽  
Joint Specimen ◽  
Waviness And Unevenness ◽  
Softening Stage

The joint morphology is multiscale. The effect of each asperity order on the mechanical properties of joints is different. The shear mechanical properties of joint specimens are related to its surface damage characteristics. At present, there are still few studies on the effect of roughness on the shearing mechanical properties of joint from the perspective of damage of each asperity order. In this paper, the standard roughness profile was chosen as initial morphology. The standard roughness profile was decomposed into waviness and unevenness by the method combine the ensemble empirical mode decomposition (EEMD) and the cut-off criterion. Then, the joint specimen which contains waviness and unevenness and the specimen which only contains waviness were prepared by the 3D engraving technology. The 40 sets of joint specimens with different asperity order were subjected to direct shear tests under different normal stresses. Based on the 3D scanning technology and ICP iterative method, the damaged area and the damage volume were calculated. Based on the damage volume data and the acoustic emission (AE) data, the effect of asperity order to the joint mechanical behaviour was studied. The results indicate that (1) under low normal stress, the unevenness plays a control role in the failure mode of the joint specimen. Under low normal stress, the joint surface containing only waviness exhibits slip failure, and the joint surface with unevenness exhibits shear failure. With the increase of the normal stress, the failure mode of the specimen containing only waviness changes from slip failure to shear failure; (2) the unevenness controls the damage degree of the joint specimen. The damaged area, damage volume, AE energy rate, and accumulative AE energy of the joint specimen with unevenness are larger than those of the specimen with only waviness, and this difference increases with the normal stress increase; (3) the difference between the joint specimen with unevenness and specimen with only waviness mainly exists in the prepeak nonlinear stage and the postpeak softening stage. The characteristic parameters of acoustic emission generated in the postpeak softening stage of the joint specimen with unevenness are greater than those of the specimen with only waviness. This phenomenon can be used to explain the stress drop difference at the postpeak softening stage; (4) the AE b value can be used to evaluate the damage of joint specimens. Analysing the damage difference of each asperity order under different normal stresses is of great significance to the analysis of the influence of the morphology of the joint surface on the mechanical properties of the joint.

Flexural Properties of Kenaf Sandwich Panel

2012 ◽  
Vol 567 ◽  
pp. 216-219
Author(s):  
Zahurin Halim ◽  
Siti Khadijah Abdul Rahman
Keyword(s):  
Mechanical Properties ◽  
Steel Sheet ◽  
Sandwich Panel ◽  
Core Structure ◽  
Main Element ◽  
Flexural Properties ◽  
Skin Thickness ◽  
The Core ◽  
Galvanised Steel

This study concerns on effect of varying skin thickness to flexural properties of sandwich panel. The main element of the core structure is kenaf and the skin used in this study is galvanised steel sheet. Skin thickness being used in this research is 1.0 mm and 1.2 mm. In this study, comparing sandwich of skin thickness 1.0 mm and 1.2 mm, result shows that 1.0 mm skin is sufficient as mechanical properties of sandwich decreases and density of sandwich increases as skin thickens.

Review of Resistance Spot Welding Sheets: Processes and Failure Mode

2016 ◽  
Vol 17 ◽  
pp. 31-57 ◽  
Author(s):  
A.M. Al-Mukhtar
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Shear Failure ◽  
Welding Process ◽  
Current Time ◽  
Resistance Spot ◽  
Weld Properties ◽  
Weld Area

The engineering parts joining by the spot welding require acceptable properties to survive the loading conditions XE "temperature". Several studies show that the welding variables have an effect on the properties of spot nugget XE "nugget" and on the future cracking. This review summarizes the resistance spot welding process (RSW). It introduces the basic spot welding principles, experiments XE"experiments" , limitation and defects XE "defects". The new concepts and awareness were presented. The results from the series of scientific works and literature are discussed. The metal’s weldability, XE "spotweldability" strength, XE"strength" and fracture are the main topics in several structural analysis. The welding variables effect on the mechanical properties and performance XE "mechanicalproperties" of the structures is the key analysis. In general, the increasing of the heat input by adjusting the current, time, and pressure producing higher weld area in turn enhance the toughness. However, by increasing the weld area, the defects and cracking tend to appear. Hence, a desired weld size with the mechanical properties is required. The nugget fracture mode is changing from plug or button tearing to shear failure mode depending on the weld properties. The crack grows either from the internal defects or around the nugget.

Indexicality of Grammar: The Case of Japanese Transgender Speakers

2019 ◽  
Author(s):  
Hideko Abe
Keyword(s):  
Gender Identity ◽  
Gender Identity Disorder ◽  
Grammatical Gender ◽  
Core Structure ◽  
Subject Positions ◽  
Transgender Identity ◽  
The Core ◽  
History Of ◽  
History Of Scholarship ◽  
Grammatical Structures

This article discusses how the intersection of grammatical gender and social gender, entwined in the core structure of language, can be analyzed to understand the dynamic status of selfhood. After reviewing a history of scholarship that demonstrates this claim, the discussion analyzes the language practices of transgender individuals in Japan, where transgender identity is currently understood in terms of sei-dōitsusei-shōgai (gender identity disorder). Based on fieldwork conducted between 2011 and 2017, the analysis reveals how individuals identifying with sei-dōitsusei-shōgai negotiate subject positions by manipulating the specific indexical meanings attached to grammatical structures.

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