Mapping the structure, composition and mechanical properties of bamboo

2006 ◽  
Vol 21 (8) ◽  
pp. 1969-1976 ◽  
Author(s):  
I.M. Low ◽  
Z.Y. Che ◽  
B.A. Latella
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Damage Zone ◽  
Elastic Stiffness ◽  
Indentation Creep ◽  
Interfacial Damage ◽  
Depth Profiles ◽  
High Toughness ◽  
Synchrotron Radiation Diffraction

The structure, composition, and mechanical response of Australian bamboo were investigated. The graded structure, composition, and mechanical properties were confirmed by depth profiles obtained using synchrotron radiation diffraction and Vickers indentation. The mechanical performance of bamboo was strongly dependent on age. Results indicated that young bamboo has a higher strength, elastic stiffness, and fracture toughness than its older counterpart does. In addition, the hardness of bamboo is both load dependent and time dependent as a result of an expanding interfacial damage zone and indentation creep, respectively. In addition to fiber debonding, crack deflection and crack-bridging are the major energy dissipative processes for imparting a high toughness in bamboo.

Mechanical and Fracture Properties of Bamboo

2006 ◽  
Vol 312 ◽  
pp. 15-20 ◽  
Author(s):  
It Meng Low ◽  
Z.Y. Che ◽  
Bruno A. Latella ◽  
K.S. Sim
Keyword(s):  
Fracture Toughness ◽  
Mechanical Performance ◽  
Elastic Stiffness ◽  
Crack Deflection ◽  
Vickers Indentation ◽  
Fracture Properties ◽  
Depth Profiles ◽  
High Toughness ◽  
Synchrotron Radiation Diffraction ◽  
Mechanical And Fracture Properties

The microstructure, mechanical, impact and fracture properties of Australian bamboo have been investigated. The graded composition and property has been confirmed by depth-profiles obtained by synchrotron radiation diffraction and Vickers indentation. The mechanical performance of bamboo is stronly dependent on age. Results showed that young bamboo has higher strength, elastic stiffness and fracture toughness than its old counterpart. Both crack-deflection and crackbridging are the major energy dissipative processes for imparting a high toughness in bamboo.

Mechanical Properties of Additively Manufactured Periodic Cellular Structures and Design Variations

2021 ◽  
pp. 1-48
Author(s):  
Derek G. Spear ◽  
Anthony N. Palazotto ◽  
Ryan A. Kemnitz
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Material Selection ◽  
Cellular Structures ◽  
New Approach ◽  
Triply Periodic ◽  
Superior Mechanical Properties ◽  
Manufacturing Technologies ◽  
Surface Thickness

Abstract Advances in manufacturing technologies have led to the development of a new approach to material selection, in that architectured designs can be created to achieve a specific mechanical objective. Cellular lattice structures have been at the forefront of this movement due to the ability to tailor their mechanical response through tuning of the topology, surface thickness, cell size, and cell density. In this work, the mechanical properties of additively manufactured periodic cellular lattices are evaluated and compared, primarily through the topology and surface thickness parameters. The evaluated lattices were based upon triply periodic minimal surfaces (TPMS), including novel variations on the base TPMS designs, which have not been tested previously. These lattices were fabricated out of Inconel 718 (IN718) through the selective laser melting (SLM) process. Specimens were tested under uniaxial compression, and the resultant mechanical properties were determined. Further discussion of the fabrication quality and deformation behavior of the lattices are provided. Results of this work indicate that the Diamond TPMS lattice has superior mechanical properties to the other lattices tested. Additionally, with the exception of the Primitive TPMS lattice, the base TPMS designs exhibited superior mechanical performance to their derivative lattice designs.

Computational Mechanics Routes to Explore the Origin of Mechanical Properties in a Biological Nanocomposite: Nacre

2004 ◽  
Vol 844 ◽  
Author(s):  
Dinesh Katti ◽  
Kalpana Katti
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Computational Mechanics ◽  
Critical Role ◽  
Physical Restraint ◽  
Model System ◽  
Tensile Failure ◽  
Organic Layer ◽  
High Toughness ◽  
Free Relative

ABSTRACTNacre, the inner layer of seashells, is a laminated nanocomposite consisting of micron sized pseudo hexagonal aragonitic calcium carbonate platelets with about 20 nanometer thick organic layer sandwiched between the platelets. This nanocomposite has been studied extensively as a model system for the design of new biomimetic nanocomposites. The nano and micro architecture of nacre has many features and nuances, which have been attributed as possible reasons for the exceptional mechanical properties. In our work, we have used computational mechanics routes to model and simulate observed macro response, to quantitatively evaluate the contribution of various components of the nano and micro architecture of nacre to the mechanical properties. We also describe our discovery of platelet interlocks and their impact on the mechanical response of nacre. Our experiments on tensile failure and scanning electron microscopy of nacre specimens, and simulations using finite element modeling, indicate that the interlocks function as a physical restraint against free relative movement of platelets. Hence, these interlocking features need to yield/break before the complete transfer of load can occur to an intervening organic. The observed interlocks play a critical role in the mechanical response of nacre. During failure the features observed in the microstructure of nacre, such as relative rotation between platelet layers, platelet penetration, and other geometrical abnormalities such as an elongated side etc., appear not to be accidents of nature; they seem to exist for a purpose. These abnormalities lead to high toughness and strength, which is necessary for protecting the organism within the seashell.

ENGINEERING ORIENTATION IN BLOCK COPOLYMERS FOR APPLICATION TO PROSTHETIC HEART VALVES

2010 ◽  
Vol 03 (04) ◽  
pp. 249-252 ◽  
Author(s):  
JOANNA STASIAK ◽  
GEOFF D. MOGGRIDGE ◽  
ADRIANO ZAFFORA ◽  
ANNA PANDOLFI ◽  
MARIA L. COSTANTINO
Keyword(s):  
Mechanical Properties ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Long Range ◽  
Heart Valves ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Prosthetic Heart Valves ◽  
Anisotropic Mechanical Properties ◽  
Butadiene Styrene

This study demonstrates how the mechanical performance of polymeric material can be enhanced by morphology and phase orientation of block copolymers to achieve desired anisotropic mechanical properties. The material used was a new Kraton block copolymer consisting of styrene-isoprene-butadiene-styrene blocks having cylindrical morphology. We report a method of achieving long range uniaxial as well as biaxial orientation of block copolymer. Each microstructural organization results in a specific mechanical performance, which depends on the direction of the applied deformation. The method of tailoring mechanical properties by engineering microstructure may be successfully utilized to applications requiring anisotropic mechanical response, such as prosthetic heart valves.

Tough Hydrogels Based on Macromicelles as Crosslinkers with pH and Ion Sensitive Properties

2019 ◽  
Vol 944 ◽  
pp. 537-542
Author(s):  
Rui Jia Yan ◽  
Yan Zi Yan ◽  
Jing Hong Ma ◽  
Jing Hua Gong
Keyword(s):  
Mechanical Properties ◽  
Fracture Stress ◽  
Mechanical Performance ◽  
High Strength ◽  
Radical Copolymerization ◽  
Pluronic F127 ◽  
Free Radical Copolymerization ◽  
Elongation At Break ◽  
High Toughness ◽  
Stimuli Sensitive

Stimuli-sensitive hydrogels crosslinked by macromolecular micelles usually present good mechanical properties. In this paper, a novel kind of pH and ion sensitive hydrogels with high toughness and strength were prepared using Pluronic F127 diacrylate (F127DA) as crosslinking centers for the free radical copolymerization of acrylamide (AM) and methacrylate (MA) monomers. These hydrogels showed high strength and tensibility with elongation at break of 1208%, fracture stress of 328 kPa and toughness of 1.80 MJ/m-3. The hydrogels not only exhibited enhancement of mechanical performance, but also achieved sensitive response to changes of pH and ionic strength, making an approach for the development of applications in drug delivery and sensors.

Weldability - Behavior of Welded Reinforcement

2019 ◽  
Vol 70 (10) ◽  
pp. 3469-3472
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Current Work ◽  
Carbon Equivalent ◽  
Work Process ◽  
Ultimate Limit

Weldability involves two aspects: welding behavior of components and safety in operation. The two aspects will be reduced to the mechanical characteristics of the elements and to the chemical composition. In the case of steel reinforcing rebar’s, it is reduces to the percentage of Cech(carbon equivalent) and to the mechanical characteristics: the yielding limit, the ultimate limit, and the elongations which after that represent the ductility class in which the re-bars is framed. The paper will present some types of steel reinforcing rebar’s with its mechanical characteristics and the welding behavior of those elements. In the current work, process-related behavior of welded reinforcement, joint local and global mechanical properties, and their correlation with behavior of normal reinforcement and also the mechanical performance resulted in this type of joints. Keywords: welding behavior, ultimate limit, reinforcing rebar’s

scholarly journals Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1124
Author(s):  
Zhifang Liang ◽  
Hongwu Wu ◽  
Ruipu Liu ◽  
Caiquan Wu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Mechanical Performance ◽  
Tensile Elongation ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
The Matrix ◽  
Blending Process ◽  
Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

scholarly journals Tribological and Mechanical Properties of Multicomponent CrVTiNbZr(N) Coatings

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 41
Author(s):  
Yin-Yu Chang ◽  
Cheng-Hsi Chung
Keyword(s):  
Mechanical Properties ◽  
Nitrogen Content ◽  
Adhesion Strength ◽  
Mechanical Performance ◽  
Bulk Material ◽  
High Entropy Alloy ◽  
Composition Gradient ◽  
Multilayered Structures ◽  
High Entropy ◽  
Alloy Target

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance.

Experimental investigation of the mechanical behavior of glass fiber/high fluidity polyamide-based composites for automotive market

2021 ◽  
pp. 073168442110140
Author(s):  
Hossein Ramezani-Dana ◽  
Moussa Gomina ◽  
Joël Bréard ◽  
Gilles Orange
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Mechanical Performance ◽  
Physical And Mechanical Properties ◽  
Ultimate Strain ◽  
Uniaxial Tensile ◽  
Compression Tests ◽  
Automotive Market ◽  
Glass Fiber Reinforced ◽  
Glass Fiber Reinforcement

In this work, we examine the relationships between the microstructure and the mechanical properties of glass fiber–reinforced polyamide 6,6 composite materials ( V f = 54%). These materials made by thermocompression incorporate different grades of high fluidity polyamide-based polymers and two types of quasi-UD glass fiber reinforcement. One is a classic commercial fabric, while the other specially designed and manufactured incorporates weaker tex glass yarns (the spacer) to increase the planar permeability of the preform. The effects of the viscosity of the polymers and their composition on the wettability of the reinforcements were analyzed by scanning electron microscopy observations of the microstructure. The respective influences of the polymers and the spacer on the mechanical performance were determined by uniaxial tensile and compression tests in the directions parallel and transverse to the warp yarns. Not only does the spacer enhance permeability but it also improves physical and mechanical properties: tensile longitudinal Young’s modulus increased from 38.2 GPa to 42.9 GPa (13% growth), tensile strength increased from 618.9 MPa to 697 MPa (3% growth), and decrease in ultimate strain from 1.8% to 1.7% (5% reduction). The correlation of these results with the damage observed post mortem confirms those acquired from analyses of the microstructure of composites and the rheological behaviors of polymers.

scholarly journals Effects of a Twin-Screw Extruder Equipped with a Molten Resin Reservoir on the Mechanical Properties and Microstructure of Recycled Waste Plastic Polyethylene Pellet Moldings

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1058
Author(s):  
Hikaru Okubo ◽  
Haruka Kaneyasu ◽  
Tetsuya Kimura ◽  
Patchiya Phanthong ◽  
Shigeru Yao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Value Added ◽  
Industrial Applications ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Polymer Properties ◽  
Wide Range ◽  
Twin Screw ◽  
Recycled Plastics

Each year, increasing amounts of plastic waste are generated, causing environmental pollution and resource loss. Recycling is a solution, but recycled plastics often have inferior mechanical properties to virgin plastics. However, studies have shown that holding polymers in the melt state before extrusion can restore the mechanical properties; thus, we propose a twin-screw extruder with a molten resin reservoir (MSR), a cavity between the screw zone and twin-screw extruder discharge, which retains molten polymer after mixing in the twin-screw zone, thus influencing the polymer properties. Re-extruded recycled polyethylene (RPE) pellets were produced, and the tensile properties and microstructure of virgin polyethylene (PE), unextruded RPE, and re-extruded RPE moldings prepared with and without the MSR were evaluated. Crucially, the elongation at break of the MSR-extruded RPE molding was seven times higher than that of the original RPE molding, and the Young’s modulus of the MSR-extruded RPE molding was comparable to that of the virgin PE molding. Both the MSR-extruded RPE and virgin PE moldings contained similar striped lamellae. Thus, MSR re-extrusion improved the mechanical performance of recycled polymers by optimizing the microstructure. The use of MSRs will facilitate the reuse of waste plastics as value-added materials having a wide range of industrial applications.

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