scholarly journals Stress Distribution within Cell Wall of Wood Subjected to Tensile Force in Transverse Direction

1977 ◽  
Vol 26 (284) ◽  
pp. 433-438 ◽  
Author(s):  
Toshimasa OHGAMA ◽  
Minoru MASUDA ◽  
Tadashi YAMADA
Keyword(s):  
Cell Wall ◽  
Stress Distribution ◽  
Transverse Direction ◽  
Tensile Force

Residual Stress Distribution of Non-Uniform Quenching in Al-Zn-Mg-Cu Aluminum Alloy Thick Plate

2020 ◽  
Vol 1003 ◽  
pp. 11-19
Author(s):  
Ya Nan Li ◽  
Yong An Zhang ◽  
Hong Lei Liu ◽  
Xin Yu Lv ◽  
Xi Wu Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Aluminum Alloy ◽  
Heat Transfer Coefficient ◽  
Stress Distribution ◽  
Transfer Coefficient ◽  
Stress Level ◽  
Transverse Direction ◽  
Residual Stress Distribution ◽  
Surface Quenching

Effect of multi-section linear non-uniform heat transfer coefficient on quenching residual stress distribution in 27mm-thick Al-Zn-Mg-Cu aluminum alloy plate was simulation studied by using the finite element method, and the surface quenching residual stress distribution was measured by the X-ray diffraction method and hole-drilling method. The results show that the surface quenching residual stress represents the same distribution with non-uniform heat transfer coefficient in the transverse direction and the stress level maintains initial stress level of the heat transfer coefficient at each location. The distribution of the quenching residual stress in the center of the plate is approximately uniform and the stress level is approximately equal to average of maximum and minimum initial stress level. The measured surface quenching residual stress shows a wavy distribution in the transverse direction, which is similar to the simulated surface stress distribution without considering the stress level. The measurement results can be explained by the multi-section linear non-uniform quenching model.

scholarly journals Effect of Lamination Angle and Thickness on Analysis of Composite Plate Under Thermo Mechanical Loading

2017 ◽  
Vol 67 (1) ◽  
pp. 5-22 ◽  
Author(s):  
Arnab Choudhury ◽  
Samar Chandra Mondal ◽  
Susenjit Sarkar
Keyword(s):  
Stress Distribution ◽  
Mechanical Loading ◽  
Composite Plate ◽  
Stress Ratio ◽  
Epoxy Composite ◽  
Tensile Force ◽  
Finite Element Software ◽  
Marine Application ◽  
Matlab Programming ◽  
Ply Orientation

Abstract Analytical formulation and solution of stress analysis of composite plate subjected to thermo mechanical loading for various ply orientation and thickness of lamina are studied. The main aim of the paper is to investigate how mechanical and thermo mechanical loading would affect the stress ratio and stress distribution of composite plate. The plate is composed of layers of glass-epoxy composite and the orientation of the layers is assumed to be antisymmetric about the neutral axis of the laminate. The plate is subjected to a combined mechanical loading of tensile force and moment along x direction. The thermo mechanical stress is calculated for different ply orientation and thickness ratio, subjected to a temperature change and mechanical loading. The effect of number of lamina and varying thickness of laminate on the stress ratio and stress distribution is studied. The results in this paper are obtained by use of MATLAB Programming and by Finite element software ANSYS 14. Results obtained from both the methods are compared. Such type of loading finds wide application in aircraft flying at high altitude, marine application, medical devices etc.

scholarly journals Steel I-joists calculating method with the heel joint partial restraint

2020 ◽  
Vol 7 (3) ◽  
Author(s):  
Dmitry Kuznetsov ◽  
Svetlana Belyaeva ◽  
Vitaliy Sazykin
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Numerical Models ◽  
Tensile Force ◽  
Three Dimensional ◽  
Numerical Calculations ◽  
Test Models ◽  
Flexural Member ◽  
Strain Stress ◽  
Three Dimensional Finite Element

Steel joists in general, are widely used in modern building practice and I-joist systems in particular. That is why close attention to the structural concept development or joist construction is paid. That would significantly reduce the material consumption, including changing the flexural member strain-stress distribution. The classic pin joint for supporting steel joist involves a bolted connection in the lower third of the knife-edge height. The constructive solution considered in this article contains additional requirements for the heel joint: tight installation clearance filling between two adjacent joist knife-edges, bolt installation that satisfy the strength condition. These requirements ensure the tensile force transfer from a couple of forces emerging on the pier. We proposed a method for calculating steel I-joist, with the account of the obtained partial restraint effect. This method developed based on numerical calculations of three-dimensional finite element beams models using the binodal unilateral connection, however, with proper justification, the results transfer to the core design schemes. Modeling and calculations are performed in the SCAD Office computer complex. The steel I-joist floor beams studied in this paper have 15 m spans. The restraining effect is estimated based on a results comparison of finite element models numerical calculations of a single joist and two adjacent simultaneously working steel joists. Joist test models are made using shell finite elements with zero Gaussian curvature. As the study result of the operation compatibility of the joist structures heel joint and the analysis of the system strain-stress distribution, a moment redistribution from the span to the heel joint was revealed. With the increase in the span, the restrain effect was found fading. The partial restrain accounting method allows us to assign more economical sections during similar structures designing, due to the introduction of binodal unilateral connection in the heel joint of the joist numerical models. This technique can be used for verification calculations during the technical examination. This paper shows that the bolt junction sections selection for connecting steel joists on a pier can be performed according to the reactions obtained in unilateral connection. Using this calculation methodology in practice for actual construction design provides an opportunity to increase the joist systems’ efficiency and reliability that part of constructional buildings and structures complex.

scholarly journals Multinet Growth in the Cell Wall of Nitella

1960 ◽  
Vol 7 (2) ◽  
pp. 289-296 ◽  
Author(s):  
Paul B. Green
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Transverse Direction ◽  
Quantitative Description ◽  
Polarized Light ◽  
Axial Direction ◽  
Plant Cell Walls ◽  
Transverse Orientation ◽  
Inner Surface ◽  
Crystalline Matrix

Plant cell walls typically consist of crystalline microfibrils embedded in a non-crystalline matrix. The growing cylindrical Nitella cell wall contains microfibrils predominantly oriented in the transverse direction. The present study has shown that the transversely oriented microfibrils are primarily located toward the inner surface of the wall and that, proceeding outward from the inner surface, the wall contains microfibrils of ever poorer transverse orientation, the fibrils being randomly or axially arranged in the outermost regions of the wall. Because cell expansion is primarily in the axial direction, the texture of the fibrillar elements of the wall can be explained by assuming that new microfibrils of transverse orientation are added only at the inner surface of the wall and that they become passively reoriented to the axial direction during cell elongation. The described structure corresponds to that proposed by Roelofsen and Houwink for cells showing "multi-net growth." The demonstration of a continuous gradient of microfibrillar arrangement and its partial quantitative description was accomplished by the analysis, with the polarized light and interference microscopes, of wedge-like torn edges of developing cell walls which were 1 micron or less in optical thickness.

scholarly journals The Inducible Accumulation of Cell Wall-Bound p-Hydroxybenzoates Is Involved in the Regulation of Gravitropic Response of Poplar

2021 ◽  
Vol 12 ◽  
Author(s):  
Yunjun Zhao ◽  
Xiao-Hong Yu ◽  
Chang-Jun Liu
Keyword(s):  
Cell Wall ◽  
Tensile Force ◽  
Cellulose Fibers ◽  
Crystalline Cellulose ◽  
Gravitropic Response ◽  
Syringyl Lignin ◽  
Lignin Modification ◽  
In The Wild ◽  
Mechanical Bending ◽  
Major Chemical

Lignin in Populus species is acylated with p-hydroxybenzoate. Monolignol p-hydroxybenzoyltransferase 1 (PHBMT1) mediates p-hydroxybenzoylation of sinapyl alcohol, eventually leading to the modification of syringyl lignin subunits. Angiosperm trees upon gravistimulation undergo the re-orientation of their growth along with the production of specialized secondary xylem, i.e., tension wood (TW), that generates tensile force to pull the inclined stem or leaning branch upward. Sporadic evidence suggests that angiosperm TW contains relatively a high percentage of syringyl lignin and lignin-bound p-hydroxybenzoate. However, whether such lignin modification plays a role in gravitropic response remains unclear. By imposing mechanical bending and/or gravitropic stimuli to the hybrid aspens in the wild type (WT), lignin p-hydroxybenzoate deficient, and p-hydroxybenzoate overproduction plants, we examined the responses of plants to gravitropic/mechanical stress and their cell wall composition changes. We revealed that mechanical bending or gravitropic stimulation not only induced the overproduction of crystalline cellulose fibers and increased the relative abundance of syringyl lignin, but also significantly induced the expression of PHBMT1 and the increased accumulation of p-hydroxybenzoates in TW. Furthermore, we found that although disturbing lignin-bound p-hydroxybenzoate accumulation in the PHBMT1 knockout and overexpression (OE) poplars did not affect the major chemical composition shifts of the cell walls in their TW as occurred in the WT plants, depletion of p-hydroxybenzoates intensified the gravitropic curving of the plantlets in response to gravistimulation, evident with the enhanced stem secant bending angle. By contrast, hyperaccumulation of p-hydroxybenzoates mitigated gravitropic response. These data suggest that PHBMT1-mediated lignin modification is involved in the regulation of poplar gravitropic response and, likely by compromising gravitropism and/or enhancing autotropism, negatively coordinates the action of TW cellulose fibers to control the poplar wood deformation and plant growth.

scholarly journals Various scenarios of the cell pattern formation in Arabidopsis lateral root

2014 ◽  
Vol 83 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Jolanta Białek ◽  
Izabela Potocka ◽  
Joanna M. Szymanowska-Pułka
Keyword(s):  
Cell Wall ◽  
Pattern Formation ◽  
Stress Distribution ◽  
Lateral Root ◽  
Morphological Features ◽  
Local Change ◽  
Cell Pattern ◽  
Cell Divisions ◽  
Early Stages ◽  
In Cells

During lateral root (LR) development a coordinate sequence of cell divisions, accompanied by a change of the organ form takes place. Both the order of anatomical events and morphological features may vary for individual primordia. At early stages of LR primordia development oblique division walls are inserted in cells that are symmetrically located on both sides of the axis of the developing LR primordium, and thereby allow for the protrusion of the LR. We hypothesize that both oblique cell wall insertion and continuous changes in primordium form could be a consequence of a local change in stress distribution in the region of the LR initiation.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

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