Weave and Fiber Volume Effects in a PIP CMC Material System

2012 ◽  
pp. 207-217 ◽  
Author(s):  
G. Ojard ◽  
E. Prevost ◽  
U. Santhosh ◽  
R. Naik ◽  
D. C. Jarmon
Keyword(s):  
Material System ◽  
Fiber Volume ◽  
Volume Effects

Micromechanics of a Smart Composite Actuator Embedded With Hollow Piezoelectric Fibers

2011 ◽  
Author(s):  
Sontipee Aimmanee ◽  
Supharoek Trakarnkulchai ◽  
Pakinee Aimmanee
Keyword(s):  
Volume Fraction ◽  
Transversely Isotropic ◽  
Material System ◽  
Smart Composite ◽  
Concentric Cylinder ◽  
Fiber Volume ◽  
Reinforced Composite ◽  
Concentric Cylinders ◽  
Matrix Volume ◽  
Composite Actuator

This paper presents a development of mathematical models for predicting the effective elastic and piezoelectric properties of a Smart Composite Actuator (SCA) reinforced with transversely isotropic piezoelectric hollow fibers. The models are established based on micromechanics of representative volume element of concentric cylinders or so-called concentric cylinder model (CCM). Five elastic constants and two piezoelectric coefficients are predicted as a function of fiber volume fraction, matrix volume fraction, and their constituents’ properties in the SCA. Numerical results of a chosen material system are obtained and discussed. The models can be found useful for developing a SCA or a novel hollow fiber-reinforced composite with the desired properties.

Experimental investigation of the crush performance of prepreg platelet molding compound tubes

2020 ◽  
Vol 54 (27) ◽  
pp. 4311-4324 ◽  
Author(s):  
Rebecca A Cutting ◽  
Federico Rios-Tascon ◽  
Johnathan E Goodsell
Keyword(s):  
Volume Fraction ◽  
Short Fiber ◽  
Material System ◽  
Structural Members ◽  
Continuous Fiber ◽  
Fiber Volume ◽  
Molding Compound ◽  
Cylindrical Tubes ◽  
Failure Morphology ◽  
Complex Structural

This work presents an experimental study characterizing the crush performance of hollow cylindrical tubes made with prepreg platelet molding compound (PPMC). PPMC is a composite material system that uses platelets from chopped and slit unidirectional prepreg as the basis for a molding compound. This material system has a higher fiber volume fraction and better mechanical properties than traditional short fiber systems and can be molded into complex geometries unlike continuous fiber systems. As such, this material system shows promise for use with complex structural members in vehicles. The failure morphology and specific energy absorption of the material are evaluated with different thickness-to-diameter geometries and test speeds. In addition, this work investigates how PPMC components compare to traditional continuous fiber components and finds that PPMC performs as well as continuous fiber layups with similar effective laminate stiffnesses.

Ion thinning of integrated circuit transverse specimens for transmission electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1426-1427
Author(s):  
F. Shaapur
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Integrated Circuit ◽  
Substrate Surface ◽  
Homogeneous Material ◽  
Material System ◽  
Ion Milling ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Motion Profile

Non-uniform ion-thinning of heterogenous material structures has constituted a fundamental difficulty in preparation of specimens for transmission electron microscopy (TEM). A variety of corrective procedures have been developed and reported for reducing or eliminating the effect. Some of these techniques are applicable to any non-homogeneous material system and others only to unidirectionalfy heterogeneous samples. Recently, a procedure of the latter type has been developed which is mainly based on a new motion profile for the specimen rotation during ion-milling. This motion profile consists of reversing partial revolutions (RPR) within a fixed sector which is centered around a direction perpendicular to the specimen heterogeneity axis. The ion-milling results obtained through this technique, as studied on a number of thin film cross-sectional TEM (XTEM) specimens, have proved to be superior to those produced via other procedures.XTEM specimens from integrated circuit (IC) devices essentially form a complex unidirectional nonhomogeneous structure. The presence of a variety of mostly lateral features at different levels along the substrate surface (consisting of conductors, semiconductors, and insulators) generally cause non-uniform results if ion-thinned conventionally.

Cross-sectional TEM specimen preparation from magneto-optical disk by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 236-237
Author(s):  
F. Shaapur ◽  
M.J. Kim ◽  
Seh Kwang Lee ◽  
Soon Gwang Kim
Keyword(s):  
System Development ◽  
Thin Foil ◽  
Specimen Preparation ◽  
Material System ◽  
Cross Sectional ◽  
Protective Layers ◽  
New Material ◽  
Diamond Saw ◽  
Original Production ◽  
Thick Medium

TEM characterization and microanalysis of the recording media is crucial and complementary to new material system development as well as quality control applications. Due to the type of material generally used for supporting the medium, i.e., a polymer, conventional macro- and microthinning procedures for thin foil preparation are not applicable. Ultramicrotorny (UM) is a viable option and has been employed in previous similar studies. In this work UM has been used for preparation of XTEM samples from a magneto-optical (MO) recording medium in its original production format.The as-received material system consisted of a 4-layer, 2100 Å thick medium including a 300 Å TbFeCo layer enveloped by silicon nitride protective layers supported on a 1.2 mm thick × 135 mm (5.25 in.) diameter polycarbonate disk. Recording tracks had an approximate pitch of 1.6 μm separated by 800 Å deep peripheral grooves. Using a Buehler Isomet low-speed diamond saw, 1 mm wide and 20 mm long strips were cut out of the disk along the recording tracks.

CBED study of low-temperature InP grown by gas source MBE

1993 ◽  
Vol 51 ◽  
pp. 810-811
Author(s):  
R. Rajesh ◽  
M.J. Kim ◽  
J.S. Bow ◽  
R.W. Carpenter ◽  
G.N. Maracas
Keyword(s):  
Low Temperature ◽  
Second Phase ◽  
Material System ◽  
Ion Milling ◽  
Electrical Measurements ◽  
Gas Source ◽  
Structural And Electrical Properties ◽  
The One ◽  
Lt Inp ◽  
Gas Source Mbe

In our previous work on MBE grown low temperature (LT) InP, attempts had been made to understand the relationships between the structural and electrical properties of this material system. Electrical measurements had established an enhancement of the resistivity of the phosphorus-rich LT InP layers with annealing under a P2 flux, which was directly correlated with the presence of second-phase particles. Further investigations, however, have revealed the presence of two fundamentally different types of precipitates. The first type are the surface particles, essentially an artefact of argon ion milling and containing mostly pure indium. The second type and the one more important to the study are the dense precipitates in the bulk of the annealed layers. These are phosphorus-rich and are believed to contribute to the improvement in the resistivity of the material.The observation of metallic indium islands solely in the annealed LT layers warranted further study in order to better understand the exact reasons for their formation.

Arrangement Of Monomeric Units In Fibrin

1979 ◽  
Author(s):  
Jan Hermans
Keyword(s):  
Fiber Axis ◽  
High Symmetry ◽  
Linear Polymers ◽  
Fiber Volume ◽  
High Fiber ◽  
Rotation Axes ◽  
Small Set ◽  
Helical Turn ◽  
The One ◽  
Kinetics Of

Measurements of light scattering have given much information about formation and properties of fibrin. These studies have determined mass-length ratio of linear polymers (protofibrils) and of fibers, kinetics of polymerization and of lateral association and volume-mass ratio of thick fibers. This ratio is 5 to 1. On the one hand, this high value suggests that the fiber contains channels that allow the diffusion of enzymes such as Factor XHIa and plasmin; on the other hand, the high value appears paradoxical for a stiff fiber made up of elongated units (fibrin monomers) arranged in parallel. Such a high fiber volume is a property of only a small set out of many high-symmetry models of fibrin, which may be constructed from overlapping three-domain monomers which are arranged into strands, are aligned nearly parallel to the fiber axis and make adequate longitudinal and lateral contacts. These models contain helical protofibrils related to each other by rotation axes parallel to the fiber axis. The protofibrils may contain 2, 3 or 4 monomers per helical turn and there are four possible symmetries. A large specific volume is achieved if the ends of each monomer are slightly displaced from the protofibril axis, either by a shift or by a tilt of the monomer. The fiber containing tilted monomers is more highly interconnected; the two ends of a tilted monomer form lateral contacts with different adjacent protofibrils, whereas the two ends of a non-tilted monomer contact the same adjacent protofibril(s).

STAGES OF HIGHER MATHEMATICS TEACHING FOR FUTURE CIVIL PROTECTION SPECIALISTS

2018 ◽  
pp. 168-172
Author(s):  
M. Kusiy
Keyword(s):  
Information Search ◽  
Cognitive Activity ◽  
Civil Defense ◽  
Educational Material ◽  
Material System ◽  
Civil Protection ◽  
Intellectual Activity ◽  
Innovative Teaching ◽  
The Future ◽  
Selection Of

Introduction.  During the training of emergency specialists, the development of a clear, structured thinking is important.  And the mathematical disciplines themselves are aimed at activating the intellectual activity of cadets and students, the ability to think logically, consistently, and reasonably.  However, cadets and students consider mathematics to be a complex, inaccessible and not very necessary science.  Therefore, there is a need for continuous, continuous development of methods, technologies of forms of training that would increase interest, accessibility to mathematical disciplines and at the same time, were aimed at improving the quality of training of future rescuers. Purpose.  Identify the main stages of teaching higher mathematics for future civil defense specialists and substantiate their peculiarities. Methods.  The article used methods of scientific knowledge (general), methods used in the empirical and theoretical levels of research (transition from abstract to specific).  Results.  The basic stages of teaching higher mathematics for future specialists of civil defense are determined: motivation, research, assimilation, application.  The proposed stages are analyzed in detail.  The regularities that contribute to the increase of motivation (selection of educational material, system approach, creative approach, a variety of forms and methods of teaching, taking into account the specifics of the future profession, the use of innovative teaching technologies) are highlighted.  There are three phases of knowledge (curiosity, curiosity, theoretical knowledge).  It is determined that for the acquisition of knowledge it is possible to use the information - search type of classes with its microstructure.  Planning the microstructure of occupations in the first place should put the level of cognitive activity, awareness and independence in the performance of educational tasks.  It is noted that the process of assimilation is the process of internalization of knowledge, putting it into the inner plan of man, and the application is to extraorise knowledge, make it to the outline of human activity.  It was investigated that the stage of application of knowledge is divided into two parts (the first is the application of knowledge, skills in standard terms, the second - the transfer of knowledge, skills, skills in new, changed conditions).  Examples of applied tasks that can be solved in higher mathematics classes are given.  It is substantiated that only in combination of all stages is formed the need for knowledge acquisition and their application. Conclusion.  Stages of teaching higher mathematics - a cyclical process that requires constant improvement, hard work of the teacher.  Stages of motivation and application combine the same laws (selection of educational material, creative approach, taking into account the specifics of the future profession, the use of innovative teaching technologies).  And only in a logical, thought-out combination of these stages can one form the future need for civil protection specialists to expand the knowledge and apply it to practical application.

Changing the face of short fiber –a review of the eucalyptus revolution

TAPPI Journal ◽  
2015 ◽  
Vol 14 (6) ◽  
pp. 353-359 ◽  
Author(s):  
PETER W. HART ◽  
RICARDO B. SANTOS
Keyword(s):  
Fossil Fuels ◽  
Wood Quality ◽  
Short Fiber ◽  
Fiber Volume ◽  
Private Industry ◽  
High Productivity ◽  
Paper Manufacturing ◽  
Short Rotation ◽  
Eucalypt Plantations ◽  
Eucalyptus Plantations

Eucalyptus plantations have been used as a source of short fiber for papermaking for more than 40 years. The development in genetic improvement and clonal programs has produced improved density plantations that have resulted in fast growing, increased fiber volume eucalypts becoming the most widely used source of short fibers in the world. High productivity and short rotation times, along with the uniformity and improved wood quality of clonal plantations have attracted private industry investment in eucalypt plantations. Currently, only a handful of species or hybrids are used in plantation efforts. Many more species are being evaluated to either enhance fiber properties or expand the range of eucalypt plantations. Eucalyptus plantations are frequently planted on nonforested land and may be used, in part, as a means of conserving native forests while allowing the production of high quality fiber for economic uses. Finally, eucalypt plantations can provide significant carbon sinks, which may be used to help offset the carbon released from burning fossil fuels. The development and expansion of eucalypt plantations represents a substantial revolution in pulp and paper manufacturing.

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