scholarly journals The Mechanical and Material Designs of Composite Ju|’hoansi Arrowheads

2020 ◽  
Vol 4 (3) ◽  
pp. 139
Author(s):  
Courtney Archer ◽  
Iain Campbell ◽  
Fraser Cheyne ◽  
Amos Lim Jun Meng ◽  
Csongor Senanszky ◽  
...  
Keyword(s):  
Physical Properties ◽  
Engineering Design ◽  
Mechanical And Physical Properties ◽  
Properties Of Materials ◽  
Design Skills ◽  
Composite Engineering ◽  
Materials Used ◽  
Composite Designs

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the design of arrowheads are intimately linked to their unique geometrical and composite designs. The Ju|’hoansi arrowheads have evolved to become complex engineered units with distinct function-specific purpose. We demonstrate herein that the geometrical designs of the arrowheads are optimised with respect to the material used. We furthermore verify the veracity of the Ju|’hoansi claim that their composite link-shafts are designed to break off leaving the arrowhead in the animal and the remaining parts of the arrow intact, reusable and easily retrievable.

scholarly journals Esterases affect the physical properties of materials used to seal the endodontic space

2019 ◽  
Vol 35 (8) ◽  
pp. 1065-1072
Author(s):  
M.Q. Marashdeh ◽  
S. Friedman ◽  
C. Lévesque ◽  
Y. Finer
Keyword(s):  
Physical Properties ◽  
Properties Of Materials ◽  
Materials Used

Analysis of Impact of Selected Structure Parameters of Reinforcing Preforms for Metal-Matrix Composites on their Saturation Process

2013 ◽  
Vol 334-335 ◽  
pp. 219-224
Author(s):  
Dorota Nagolska ◽  
Katarzyna Gawdzińska
Keyword(s):  
Physical Properties ◽  
Metal Matrix Composite ◽  
Metal Matrix Composites ◽  
Mathematical Description ◽  
Metal Matrix ◽  
Geometrical Structure ◽  
Structure Parameters ◽  
Matrix Composites ◽  
Properties Of Materials ◽  
Materials Used

The process of saturation of reinforcement preforms for metal-matrix composite castings is dependent on many different factors. One group of these factors is related to the process of manufacturing of metal-matrix composites with saturated reinforcement. Another group is related to the physical properties of materials used for manufacturing of such composites. The structure of reinforcement preforms is one of such factors. Due to its complexity, its mathematical description is difficult to perform. This structure can be examined and described using physical properties like porosity or permeability. During the conducted analysis presented in the paper, it was checked whether there is a relation between studied physical properties of reinforcement preforms and a degree of their saturation. It was also determined, which of the studied parameters is the best for description of an influence of the geometrical structure of reinforcement preforms on the process of their saturation and in consequence, on the porosity of the obtained composite castings.

Influence of Technological Media on the Mechanical and Physical Properties of Materials for Fuel Cells

2015 ◽  
Vol 51 (2) ◽  
pp. 149-157
Author(s):  
А. D. Ivasyshyn ◽  
O. P. Ostash ◽  
T. О. Prikhna ◽  
V. Ya. Podhurs’ka ◽  
T. V. Basyuk
Keyword(s):  
Fuel Cells ◽  
Physical Properties ◽  
Mechanical And Physical Properties ◽  
Properties Of Materials

The Physical Characteristics of Materials Used in the Manufacture of Orthoses for Patients with Diabetes

2007 ◽  
Vol 28 (10) ◽  
pp. 1057-1063 ◽  
Author(s):  
Joanne Paton ◽  
Ray B. Jones ◽  
Elizabeth Stenhouse ◽  
Graham Bruce
Keyword(s):  
Physical Properties ◽  
Diabetic Foot ◽  
Performance Indicator ◽  
Practical Method ◽  
Relevant Information ◽  
Foot Ulcers ◽  
Diabetic Foot Ulcers ◽  
Patients With Diabetes ◽  
Properties Of Materials ◽  
Materials Used

Background: Neuropathic diabetic foot ulceration may be prevented if the mechanical stress transmitted to the plantar tissues can be modified. Orthotic therapy is one practical method commonly used to maintain tissue integrity. Orthotic design must consider the materials chosen for use in fabrication and profile of the device because both aspects influence the performance and durability of the device. Published research evaluating the physical properties of materials commonly used in the manufacture of orthoses for patients with diabetes is limited. This study investigated the physical properties of materials used to fabricate orthoses designed for the prevention of neuropathic diabetic foot ulcers. Methods: Fifteen commonly used orthotic materials were selected for testing: four specifications of 6.4-mm Poron® (Rogers Corp., Gent, Belgium), 3.2-mm Poron®, three densities of 12-mm Ethylene Vinyl Acetate (EVA), 12-mm low-density plastazote, two depths (6.4-mm, 3.2-mm) of Cleron™ (Algeo Ltd., Liverpool, UK), Professional Protective Technology (PPT), and MaxaCane (Algeo Ltd, Liverpool, UK). The density, resilience, stiffness, static coefficient of friction, durability, and compression set of each material were tested, ranked, and allocated a performance indicator score. Results: The most clinically desirable dampening materials tested were Poron® 96 (6-mm) and Poron® 4000 (6-mm). High density EVA (Algeo Ltd., Liverpool, UK) and Lunacell Nora® EVA (Freudenberg, Weinhein, Germany) possessed the properties most suitable to achieve motion control. The data present a simple and useful comparison and classification of the selected materials. Conclusions: Although this information should not be used as a single indicator for assessing the suitability of an orthotic material, the results provide clinically relevant information relating to the physical properties of orthotic materials commonly used in the prevention of neuropathic diabetic foot ulcers.

scholarly journals Designing a Three-Dimensional Woven Fabric Structure as an Element of a Baby Stroller

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Bethalihem T. Samuel ◽  
Marcin Barburski ◽  
Tsegaye Sh. Lemmi
Keyword(s):  
Physical Properties ◽  
Three Dimensional ◽  
Woven Fabric ◽  
Double Layers ◽  
Fabric Structure ◽  
Mechanical And Physical Properties ◽  
Reinforcing Material ◽  
3D Composite ◽  
Materials Used ◽  
Composite Samples

AbstractA baby stroller allows the transportation of a child over long or short distances. The materials used to produce the stroller make it heavy for users, which creates difficulties when lifting the stroller. The goal of this project was to design and fabricate a three-dimensional (3D) fabric structure that can be used as part of a stroller seat to improve its mechanical and physical properties. The idea of implementing a woven 3D system allows the development of an egg-shaped or shell-like structure as part of a stroller seat. The combination of double-woven material and honeycomb polypropylene (as the reinforcing material) was used to create a 3D composite structure. Single and double layers of polypropylene honeycomb sandwiched within layers of linen flax fabric were used to prepare the composite samples. Subsequently, tests on mechanical and physical properties, such as density, flexural strength, and tensile strength, were carried out. Analysis of the results showed that the composite with one layer of honeycomb has half the density of polyvinyl chloride.

scholarly journals VIII. The constitution of the alloys of aluminium and zinc

1912 ◽  
Vol 211 (471-483) ◽  
pp. 315-343 ◽  
Keyword(s):  
Physical Properties ◽  
Equilibrium Diagram ◽  
Point Of View ◽  
Cooling Curves ◽  
Research Committee ◽  
Mechanical And Physical Properties ◽  
Materials Used ◽  
High Degree ◽  
John Brunner ◽  
Complete Investigation

The alloys of aluminium and zinc have been studied as regards their constitution by Heycock and Neville, Shepherd, and Ewen and Turner. The present authors having occasion to study these alloys from the point of view of their mechanical and physical properties in a research carried out under the auspices of The Alloys Research Committee of the Institution of Mechanical Engineers, began by accepting the equilibrium diagram in which Shepherd had expressed the results of his investigation. A few cooling-curves, however, which were taken in the first place with the object of confirming shepherd's results, immediately showed that the constitution of these alloys must be much more complex than had been supposed by Shepherd. It therefore seemed desirable to carry out a more complete investigation on the constitution of these alloys, and the results of that investigation are presented in the present paper. The materials used in the present investigation were : aluminium of a high degree of purity, kindly presented by the British Aluminium Company, and a very pure variety of zinc, kindly presented by Sir John Brunner. The analyses of these materials are as follows :— Aluminium— Silicon ..........................................0T7 percent. Iron ...............................................0'20 ,, Copper...................................Trace. Aluminium (diff.)......................99˙63 per cent. Zinc— The zinc used contained traces only of iron and silicon, and was of at least 99˙98 per cent, purity.

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