Mechanical properties of a balsa wood veneer structural sandwich core material

Having a unique microstructure, nonwoven fabrics possess distinct mechanical properties, dissimilar to those of woven fabrics and composites. This paper aims to introduce a methodology for simulating a dynamic response of core/sheath-type thermally bonded bicomponent fibre nonwovens. The simulated nonwoven fabric is treated as an assembly of two regions with distinct mechanical properties. One region - the fibre matrix – is composed of non-uniformly oriented core/sheath fibres acting as link between bond points. Non-uniform orientation of individual fibres is introduced into the model in terms of the orientation distribution function in order to calculate the structure’s anisotropy. Another region – bond points – is treated in simulations as a deformable bicomponent composite material, composed of the sheath material as its matrix and the core material as reinforcing fibres with random orientations. Time-dependent anisotropic mechanical properties of these regions are assessed based on fibre characteristics and manufacturing parameters such as the planar density, core/sheath ratio, fibre diameter etc. Having distinct anisotropic mechanical properties for two regions, dynamic response of the fabric is modelled in the finite element software with shell elements with thicknesses identical to those of the bond points and fibre matrix.

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Moisture Absorption Effects on the Mechanical Properties of Sandwich Biocomposites with Cork Core and Flax/PLA Face Sheets

Molecules ◽

10.3390/molecules26237295 ◽

2021 ◽

Vol 26 (23) ◽

pp. 7295

Author(s):

Hom Nath Dhakal ◽

Chulin Jiang ◽

Moumita Sit ◽

Zhongyi Zhang ◽

Moussa Khalfallah ◽

...

Keyword(s):

Mechanical Properties ◽

Failure Modes ◽

Moisture Absorption ◽

Mechanical Performance ◽

Core Sample ◽

Environmental Benefits ◽

Matrix Cracking ◽

Core Material ◽

Poly Lactic Acid ◽

The Core

The aim of this study was to evaluate the moisture absorption behaviour and its influence on the mechanical properties of newly developed sandwich biocomposites with flax fibre-reinforced poly-lactic acid (PLA) face sheets and soft cork as the core material. Three different types of sandwich biocomposite laminates comprised of different layup configurations, namely, non-woven flax/PLA (Sample A), non-woven flax/PLA and cork as core (Sample B) and non-woven flax/paper backing/PLA, cork as core (Sample C), were fabricated. In order to evaluate the influence of moisture ingress on the mechanical properties, the biocomposites were immersed in seawater for a period of 1200 h. The biocomposites (both dry and water immersed) were then subjected to tensile, flexural and low-velocity falling weight impact tests. It was observed from the experimental results that the moisture uptake significantly influenced the mechanical properties of the biocomposites. The presence of the cork and paper in sample C made it more susceptible to water absorption, reaching a value of 34.33%. The presence of cork in the core also has a considerable effect on the mechanical, as well as energy dissipation, behaviours. The results of sample A exhibited improved mechanical performance in both dry and wet conditions compared to samples B and C. Sample A exhibits 32.6% more tensile strength and 81.4% more flexural strength in dry conditions than that in sample C. The scanning electron microscopy (SEM) and X-ray micro-CT images revealed that the failure modes observed are a combination of matrix cracking, core crushing and face core debonding. The results from this study suggest that flax/PLA sandwich biocomposites can be used in various lightweight applications with improved environmental benefits.

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Development in mechanical and fatigue properties of AA6061/AL2O3 nanocomposites under stirring temperature (ST)

Eastern-European Journal of Enterprise Technologies ◽

10.15587/1729-4061.2021.238588 ◽

2021 ◽

Vol 4 (12(112)) ◽

pp. 47-52

Author(s):

Raad Mohammed Abed ◽

Ali Yousuf Khenyab ◽

Hussain Jasim M. Alalkawi

Keyword(s):

Mechanical Properties ◽

Cost Effective ◽

Fatigue Tests ◽

Core Material ◽

Fatigue Properties ◽

Uniform Distributions ◽

Al2o3 Composite ◽

Structural Applications ◽

The Matrix ◽

High Fatigue

Aluminum is expected to remain the core material for many critical applications such as aircraft and automobiles. This is due to the high resistance to different environmental conditions, desired and manageable mechanical properties, as well as high fatigue resistance. Aluminum nanocomposites such as AA6061/Al2O3 can be made in many ways using a liquid metallurgy method. The main challenges for this method in the production of nanocomposites are the difficulties of achieving a uniform distribution of reinforcing materials and possible chemical reactions between the reinforcing material and the matrix. For structural applications exclusive to aerospace sectors. The growing cost-effective nanocomposites mass production technology with essential operational and geometric flexibility is a big challenge all the time. Each method of preparing AA6061/Al2O3 nanocomposites can provide different mechanical properties. In the present study, nine nanocomposites were prepared at three stirring temperatures (800, 850, and 900 °C) with the level of Al2O3 addition of 0, 5, 7, and 9 wt %. The results of tensile, hardness and fatigue tests revealed that the composite including 9 wt % Al2O3 with 850 °C stirring temperatures has the best properties. It was also revealed that the 850 °C stirring temperature (ST) with 9 wt % Al2O3 composite provide an increase in tensile strength, VHN and reduction in ductility by 20 %, 16 % and 36.8 % respectively, compared to zero-nano. Also, the fatigue life at the 90 MPa stress level increased by 17.4 % in comparison with 9 wt % nanocomposite at 800 °C (ST). Uniform distributions were observed for all nine microstructure compositions.

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High-temperature mechanical properties and thermal recovery of balsa wood

Journal of Wood Science ◽

10.1007/s10086-010-1125-2 ◽

2010 ◽

Vol 56 (6) ◽

pp. 437-443 ◽

Cited By ~ 25

Author(s):

Thomas Goodrich ◽

Nadia Nawaz ◽

Stefanie Feih ◽

Brian Y. Lattimer ◽

Adrian P. Mouritz

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Thermal Recovery ◽

Balsa Wood ◽

High Temperature Mechanical Properties

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Effect of stacking sequence on mechanical properties neem wood veneer plastic composites

10.1063/1.5029605 ◽

2018 ◽

Cited By ~ 4

Author(s):

M. Nagamadhu ◽

G. C. Mohan Kumar ◽

P. Jeyaraj

Keyword(s):

Mechanical Properties ◽

Stacking Sequence ◽

Wood Veneer ◽

Plastic Composites

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Mechanical Properties and Mineralogical Composition of Potash Ore as a Factor in Selecting the Processing Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1022.17 ◽

2021 ◽

Vol 1022 ◽

pp. 17-26

Author(s):

Yana V. Kuskova ◽

Nikita A. Lipnitsky

Keyword(s):

Mechanical Properties ◽

Mining Industry ◽

Mineralogical Composition ◽

Core Material ◽

Correct Selection ◽

Dry Cleaning ◽

Size And Shape ◽

Natural Size ◽

Selection Of ◽

Intergranular Space

The correct selection of technology for processing potash ore depends on its mineralogical composition, the natural size and shape of grains, as well as on the amount and size of halite grains located in the intergranular space of sylvinites. The study of seams and mineralogical and petrographic studies of potash ore were carried out in order to determine the natural size of sylvinite grains, their shape, and the content of halite in the intergranular space.Moreover, the influence of these parameters on the beneficiation ability of the ore using dry cleaning process was determined. In addition, the data on laboratory studies using electric separation is provided in the paper. The results of the provided studies can be used by specialists of the mining industry when considering the influence of the mineral composition, size and shape of grains of potash ore in order to select the separation method at the early stages of development of potash deposits. The study of core material and mechanical properties, mineralogical and petrographic studies together with studies on beneficiation ability of ore presented in the article can be used, for example, in the preparation of a feasibility report.

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Polyurea With Hybrid Polymer Grafted Nanoparticles: A Parametric Study

Volume 8: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2012-88395 ◽

2012 ◽

Author(s):

Kristin Holzworth ◽

Gregory Williams ◽

Bedri Arman ◽

Zhibin Guan ◽

Gaurav Arya ◽

...

Keyword(s):

Mechanical Properties ◽

Computational Modeling ◽

Chain Length ◽

Polymer Chain ◽

Parametric Study ◽

Nano Particles ◽

Core Material ◽

Experimental Characterization ◽

Hybrid Polymer ◽

Grafted Nanoparticles

The basis of this research is to mitigate shock through material design. In this work, we seek to develop an understanding of parametric variations in polyurea-based nano-composite materials through experimental characterization and computational modeling. Blast-mitigating applications often utilize polyurea due to its excellent thermo-mechanical properties. Polyurea is a microphase-separated segmented block copolymer formed by the rapid reaction of an isocyanate component and an amine component. Block copolymers exhibit unique properties as a result of their phase-separated morphology, which restricts dissimilar block components to microscopic length scales. The soft segments form a continuous matrix reinforced by the hard segments that are randomly dispersed as microdomains. The physical properties of the separate phases influence the overall properties of the polyurea. While polyurea offers a useful starting point, control over crystallite size and morphology is limited. For compositing, the blending approach allows superb control of particle size, shape, and density; however, the hard/soft interface is typically weak for simple blends. Here, we overcome this issue by developing hybrid polymer grafted nanoparticles, which have adjustable exposed functionality to control both their spatial distribution and interface. These nano-particles have tethered polymer chains that can interact with their surrounding environment and provide a method to control well defined and enhanced nano-composites. This approach allows us to adjust a number of variables related to the hybrid polymer grafted nanoparticles including: core size and shape, core material, polymer chain length, polymer chain density, and monomer type. In this work, we embark on a parametric study focusing on the effect of silica nanoparticle size, polymer chain length, and polymer chain density. Preliminary results from experimental characterization and computational modeling indicate that the dynamic mechanical properties of the material can be significantly altered through such parametric modifications. These efforts are part of an ongoing initiative to develop elastomeric composites with optimally designed compositions and characteristics to manage blast-induced stress-wave energy.

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