Efficiency of visual strength grading of timber with respect to origin, species, cross section, and grading rules: a critical evaluation of the common standards

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 203-216 ◽  
Author(s):  
Peter Stapel ◽  
Jan-Willem G. van de Kuilen
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Critical Evaluation ◽  
International Standards ◽  
National Standards ◽  
Visual Grading ◽  
Source Areas ◽  
The Common ◽  
Machine Strength

Abstract Strength grading is essential for the efficient use of structural timber. Although international standards exist for machine strength grading, visual grading is still regulated based on national rules, which are expected to allow safe and economic grading results. Although there are large differences in the graded output because the species, the cross section, and the origin of the timber influence the results, some of these standards are considered to be applicable universally. The present article demonstrates how the chosen standards influence the grading results. Depending on the parameters, the yields or the mechanical properties are low compared with the declared values. The results also show the efficiency and applicability of different national standards for strength grading of timber from various origins. Furthermore, it is recommended to reconsider the existing limits for source areas and cross sections given in the standard EN 1912.

scholarly journals Assessment of Standards and Codes Dedicated to CFRP Confinement of RC Columns

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2390 ◽  
Author(s):  
Stefan Kaeseberg ◽  
Dennis Messerer ◽  
Klaus Holschemacher
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Rupture Strength ◽  
Axial Strain ◽  
Design Guidelines ◽  
International Standards ◽  
National Standards ◽  
Rc Columns ◽  
New Findings ◽  
Cfrp Confinement

Reinforced concrete (RC) columns are often placed under confinement to increase their strength and ductility. Carbon fiber reinforced polymer (CFRP) materials have recently been recognized as favorable confinement systems. At present, a number of national standards and codes dedicated to the design of concrete components strengthened with CFRP in general and CFRP confinement in particular are available. These sets of rules provide design equations for confined reinforced concrete columns with circular and rectangular cross sections. Most of the standards and codes exhibit significant differences, including the used predictive models, limitations, observed effects and covered loading conditions. In this paper, five international standards and design guidelines are introduced and discussed. The purpose is to present a constructive and critical assessment of the state-of-the-art design methodologies available for CFRP confined RC columns and to discuss effects not previously considered properly. Therefore, some recent research efforts and findings from the Leipzig University of Applied Sciences are also introduced. The obtained data is used for a comparative study of the guideline predictive equations. Furthermore, it is shown that some new findings concerning the rupture strength and the maximum strength plus accompanying axial strain of a CFRP confined column are suitable to improve the current guidelines.

The Brittleness of Ebonite

1937 ◽  
Vol 10 (4) ◽  
pp. 778-786
Author(s):  
R. Ariano
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Test Specimen ◽  
The State ◽  
The Other ◽  
Appreciable Effect ◽  
Considerable Influence ◽  
Minimum Depth ◽  
The Moment

Abstract The results of tests of the brittleness of ebonite are described. Resilience is influenced chiefly by the moment of inertia of the cross section of the test-specimen, but it seems also to be affected by the form of the specimen. The state of vulcanization has considerable influence on these mechanical properties within the undercured range, but with thorough vulcanization the state of cure plays no appreciable part. Notching of test-specimens is not of great importance. It diminishes the resilience, but when the tests are compared on a basis of equal moments of inertia of the resistant cross sections, this diminution becomes inappreciable in the case of brittle ebonites. On the other hand, the shape of the notch in ebonites containing no loading ingredients does influence the resilience. With V-shaped notches, the depth of the notch and its angle of aperture influence considerably the resilience of this latter type of ebonite, and notches of minimum depth are sufficient to have an appreciable effect.

The absolute photoionization cross sections of helium, neon, argon and krypton in the extreme vacuum ultraviolet region of the spectrum

1976 ◽  
Vol 349 (1658) ◽  
pp. 397-421 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Critical Evaluation ◽  
Inert Gases ◽  
Ultraviolet Region ◽  
Section Data ◽  
Wide Range ◽  
Helium Neon

An experiment has been set up at the Daresbury Synchrotron Radiation Facility to make absolute absorption cross section measurements over a wide range of photon energies. New data are reported for helium, neon, argon and krypton over the range 340-40 Å which are believed to be reliable to ± 5%. A critical evaluation of published cross section data has been carried out to produce best value data from the ionization thresholds throughout the vacuum ultraviolet and X-ray region. Agreement with theoretical calculations on helium is demonstrated to be within ± 2-3% from threshold down to the double ionization threshold at 79 eV. Comparison with recent calculations of photoionization cross sections has shown that the effect of electron correlations is significant for the heavier inert gases. Contrary to previous claims, the position of the M shell maximum in krypton is located at 184 + 10 eV in good agreement with r. p. a. e. calculations. Oscillator strength sum rules have been examined and their moments calculated. Discrepancies developing towards the heavier inert gases suggests a decrease in polarizabilities and other atomic factors from those predicted by Hartree-Fock calculations.

scholarly journals Assessment of Standards and Codes Dedicated to CFRP Confinement of RC Columns

2019 ◽  
Author(s):  
Stefan Kaeseberg ◽  
Dennis Messerer ◽  
Klaus Holschemacher
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Rupture Strength ◽  
Axial Strain ◽  
Design Guidelines ◽  
International Standards ◽  
National Standards ◽  
Rc Columns ◽  
New Findings ◽  
Cfrp Confinement

Reinforced concrete (RC) columns are often placed under confinement to increase their strength and ductility. Carbon fiber reinforced polymer (CFRP) materials have recently been recognized as favorable confinement systems. At present, a number of national standards and codes dedicated to the design of concrete components strengthened with CFRP in general and CFRP confinement in particular are available. These sets of rules provide design equations for confined reinforced concrete columns with circular and rectangular cross sections. Most of the standards and codes exhibit significant differences, including the used predictive models limitations, observed effects, and covered loading conditions. In this paper, five international standards and design guidelines are introduced and discussed. The purpose is to present a constructive and critical assessment of the state-of-the-art design methodologies available for CFRP confined RC columns and to discuss effects not previously considered properly. Therefore, some recent research efforts and findings from the Leipzig University of Applied Sciences are also introduced. The obtained data is used for a comparative study of the guideline predictive equations. Furthermore, it is shown that some new findings concerning the rupture strength and the maximum strength plus accompanying axial strain of a CFRP confined column are suitable to improve the current guidelines.

Directional-Tribological Investigation of Magnesium Alloys Under As-Cast and Hot Extrusion Conditions

2015 ◽  
Author(s):  
Paul McGhee ◽  
Devdas Pai ◽  
Sergey Yarmolenko ◽  
Jagannathan Sankar ◽  
Zhigang Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Wear Rate ◽  
Cross Section ◽  
Cross Sections ◽  
Transverse Direction ◽  
Longitudinal Section ◽  
Mg Alloy ◽  
Wear Properties ◽  
Wear Coefficient

In recent years, magnesium (Mg) and its alloy are being studied for their potential use in orthopedic implants with the novel ability to biodegrade after the implant serves its therapeutic function. Pure Mg, by itself, would not be suitable for use in a load-bearing implant application, due to its high corrosion rate and poor tribological properties. However, through proper alloying, this degradable metal is capable of achieving good mechanical properties reasonably similar to bone, a retarded rate of corrosion and enhanced biocompatibility. Previous studies have shown that alloying Mg with aluminum, lithium, rare earth (RE), zinc (Zn), and calcium (Ca) result in lower corrosion rates and enhanced mechanical properties. Despite the growing popularity of Mg and it alloys, there is relatively little information in the literature on their wear performance. In this paper, we report on an investigation of the directional tribological properties of Mg and Mg-Zn-Ca-RE alloy fabricated via two different manufacturing processing routes: as-cast and hot-extruded after casting, with extrusion ratios of 10 and 50. Pure Mg was cast 350°C. After casting, Mg-Zn-Ca-RE alloy was heat-treated at 510°C. Another Mg-Zn-Ca-RE alloy was hot-extruded at 400°C. Dry sliding wear tests were performed on as-cast and hot-extruded pure Mg and Mg-Zn-Ca-RE alloys using a reciprocating test configuration. Wear rate, coefficient of friction and wear coefficient were measured under applied loads ranging from 0.5–2.5N at sliding frequency of 0.2 Hz for 120 cycles, using microtribometery. Wear properties of the extruded specimen were measured in cross-section and longitudinal section. In the longitudinal section studies, wear properties were investigated along the extrusion direction and the transverse direction. Hardness properties were evaluated using microindentation. Cross-section and longitudinal section were indented with a Vickers indenter under applied load of 2.94 N. Alloying and extrusion enhanced the mechanical properties significantly, increased hardness by 80% and wear resistance by 50% compared to pure Mg. Despite the low hardness in both Mg and the Mg alloy cross-sections, the cross-sections for both displayed higher wear resistance compared to the longitudinal section. In the longitudinal section, wear resistance was higher along the transverse direction of the longitudinal section for both Mg and the Mg alloy. The wear coefficient was used to evaluate how the wear behavior of the material varied with respect to alloying, fabrication process, and direction of wear. The wear coefficient of pure Mg decreased as the extrusion ratio increased, thus, increasing the specific wear rate. The opposite behavior was found in the Mg alloy: as the wear coefficient increases, the specific wear rate decreases. The active wear mechanisms observed on the worn surface of Mg were fatigue, abrasive, adhesive and delamination wear. The same wear mechanisms were observed in the Mg alloy except for fatigue wear. Surface microstructure and topographical characterization were conducted using optical microscopy, scanning electron microscopy mechanical stylus profilometry, and optical profilometry.

scholarly journals Analysis and Harmonization of National and International Quality Standards for Compacted Graphite Cast Irons

2020 ◽  
pp. 88-95
Author(s):  
Alena Kropivna ◽  
◽  
Olexandr Kuzyk ◽  
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Chemical Composition ◽  
Quality Indicators ◽  
International Standards ◽  
National Standards ◽  
National Standard ◽  
High Quality ◽  
Foundry Industry ◽  
European Standards

Ensuring and coordination of high quality indicators of materials in the foundry industry is necessary in the development of Ukraine's economy. High quality products need to be enshrined in new national standards, harmonized with international and European standards. Thus, the purpose of this work is to analyze national and international standards for quality indicators of vermicular graphite iron and their harmonization with each other. The foundry industry of Ukraine has developed mainly with the use of interstate standards - GOST, which differ significantly from European and international and requires coordination and other approaches to the development of new standards. Today there are a number of international standards: ISO, SAE, CEN, VDG, ASTM, JIS, GB, STAS, which regulate the properties of cast iron with vermicular graphite. Most standards define the range of permissible content of spherical graphite (0… 20%) in the structure of cast iron with vermicular graphite, as well as determine the shape of samples to determine the properties and provide for the determination of graphite on surfaces formed after machining castings. In accordance with the needs of the automotive industry, the Society of Automotive Engineers (SAE) has created the standard SAEJ1887 JUL2002 for cast iron with vermicular graphite. The DSTU standard in force in Ukraine regulates only the temporary resistance to tensile and elongation laid down in the brand designation. Thus, the improvement, provision and harmonization of the national standard at the vermicular graphite iron by achieving high quality indicators of materials in the foundry industry, will ensure the stability of the technological production process, and further entry into international and European markets and a qualitatively new level of domestic engineering. An analysis of the current standards in Ukraine DSTU for cast iron with vermicular graphite is given, as well as its regulated mechanical properties and recommended chemical composition. The properties of similar international and European standards for cast iron with vermicular graphite according to ISO, SAE, CEN, VDG, ASTM, JIS, GB, STAS standardization are analyzed, as well as cross-references to ISO 16112 to other standard brands of the vermicular graphite iron. The conformity of brands of materials, depending on their chemical composition and mechanical properties given in GOST, international and European indicators is found out.

Cross section of gill filaments in histological preparations helps better identification of the location of myxosporean plasmodia in gill tissues

2018 ◽  
Vol 66 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Kálmán Molnár ◽  
Ádám Varga ◽  
Csaba Székely
Keyword(s):  
Connective Tissue ◽  
Cross Section ◽  
Common Carp ◽  
Cross Sections ◽  
Dense Connective Tissue ◽  
Gill Filaments ◽  
The Common ◽  
Branchial Artery

Location and tissue preference of filamental-type myxosporean plasmodia in histological slides of the gills can be properly identified only in cross sections of the gill filaments. The authors selected three myxosporeans (Myxobolus rutili, M. dispar and Henneguya psorospermica, parasites of the roach, the common carp and the pike, respectively) for studying the problem. The plasmodia of these species studied in longitudinal sections were earlier regarded as developing inside the filamental arteries. Cross sections of the filaments showed that all the three species developed plasmodia in the dense connective tissue constituting the adventitia of gill arteries and covering the cartilaginous gill rays. Myxobolus rutili started its development close to the afferent branchial artery but attached to the cartilaginous gill ray. More developed plasmodia of this species surrounded the rays. Plasmodia of M. dispar were formed on the inner side of the afferent branchial artery, while those of H. psorospermica were located at the external side of the efferent branchial artery.

scholarly journals Durable Nonwoven Fabrics via Fracturing Bicomponent Islands-in-the-Sea Filaments

2008 ◽  
Vol 3 (3) ◽  
pp. 155892500800300 ◽  
Author(s):  
Nagendra Anantharamaiah ◽  
Svetlana Verenich ◽  
Behnam Pourdeyhimi
Keyword(s):  
Mechanical Properties ◽  
Surface Area ◽  
Cross Section ◽  
Cross Sections ◽  
Nonwoven Fabric ◽  
Bicomponent Fibers ◽  
Nonwoven Fabrics ◽  
Fracturing Process ◽  
Fabric Strength

This paper deals in general with fabrics consisting of bicomponent fibers that are fractured/fibrillated and bonded using mechanical and/or thermal means to form micro-denier fibers. Bicomponent filaments produced by the spunbonding process, where two polymers are co-extruded to form a fiber are used to demonstrate the feasibility of fracturing bicomponents. This process of nonwoven fabric manufacture combined with the fiber-fracturing process is discussed. These fabrics are processed using commercially accepted practices. Differences in the physical properties due to the different polymer ratios and cross-sections produced are discussed. In particular, this paper deals with the production of modified ‘Islands-in-the-Sea’ filament cross-sections that enhance the fracturing of such filaments to produce micro-fiber webs that have considerably higher surface area compared to their conventional counterparts. Point-bond calendered bicomponent samples were also tested for their mechanical properties with different island counts and polymer compositions. The optimal bonding techniques for the fabrics were identified. The role of the Islands-in-the-Sea fiber cross-section was demonstrated for optimizing the fabric strength and enhancement of surface area.

scholarly journals Reflections on happiness and a happy life

Ars Aeterna ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 34-44
Author(s):  
Viera Jakubovská ◽  
Jana Waldnerová
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Human Life ◽  
Life Goals ◽  
Philosophical Tradition ◽  
Present Moment ◽  
Happy Life ◽  
The Common ◽  
Human Desire ◽  
The Individual

AbstractThe main objective of the following text is to focus on and exemplify the basic axioms of theories of happiness that come from historical and philosophical tradition and are still, at least in some cases, relevant nowadays. As philosophers claim, the longing for happiness is a naturally human desire that has taken various forms in their thinking: happiness was connected with beatitude (Aristotle), with self-preservation (Spinoza), social helpfulness (Hume), living in the present moment without expostulations or false illusions (Comte-Sponville), and others. The desire for happiness means the main aim of a human life drives particular life goals and the values of individuals. Concepts of happiness have accrued in diachronic and synchronic cross-sections. The Aristotelian/Spinozan conception or Kantian, modern and postmodern traditions formed in a diachronic cross-section. Those that accrued in a synchronic cross-section segregated themselves on the basis of an individual’s spiritual and bodily aspect. Spiritual happiness (spiritual bliss, and inner equilibrium, ataraxis) was preferred by the eudaimonic (ευδαιμονία) tradition (Democritus, Socrates, Aristotle, Hellenism, French materialism and others); bodily pleasures were accentuated by the hedonistic traditions (Lipovetsky, Bauman, Keller). Some conceptions examined the problem of happiness through the optics of society and the individual, stressing general goodness and helpfulness (Plato, Aristotle, Kant); or personal goodness, pleasure and benefit – the contemporary hedonistic concepts (Lipovetsky, Maffesoli, Comte-Sponville) All these conceptions of happiness are united by the common desire of people to live happily; however, their means and ways to reach such a goal are different.

Mechanical properties of the living dog aorta

1962 ◽  
Vol 202 (4) ◽  
pp. 619-621 ◽  
Author(s):  
Robert L. Evans ◽  
Eugene F. Bernstein ◽  
Evelyn Johnson ◽  
Carl Reller
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Cross Sections ◽  
Hooke’S Law ◽  
Before And After ◽  
Hooke's Law ◽  
Pressure Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Propagation Velocities

The variation of living dog aortic cross sections with volemic pressure changes is given for states before and after thoracotomy. The relationship of vessel cross section to pressure is approximately linear, does not follow Hooke's law, and is roughly the same for both dynamic and relatively static changes. The implied and directly measured propagation velocities are comparable to each other.

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