Mechanism for deformation of wood as a honeycomb structure II: First buckling mechanism of cell walls under radial compression using the generalized cell model

1999 ◽  
Vol 45 (3) ◽  
pp. 250-253 ◽  
Author(s):  
Kosei Ando ◽  
Hitoshi Onda
Keyword(s):  
Cell Walls ◽  
Cell Model ◽  
Honeycomb Structure ◽  
Radial Compression

scholarly journals Representative Cell Analysis for Damage-Based Failure Model of Polymer Hexagonal Honeycomb Structure under the Out-of-Plane Loadings

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 52
Author(s):  
Muhammad Salman Khan ◽  
Ainullotfi Abdul-Latif ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů ◽  
Mohd Nasir Tamin
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cell Model ◽  
Failure Process ◽  
Honeycomb Structure ◽  
Core Structure ◽  
Fracture Plane ◽  
Plane Shear ◽  
Representative Cell ◽  
Out Of Plane

The honeycomb (HC) core of sandwich structures undergoes flexural loading and carries the normal compression and shear. The mechanical properties and deformation response of the core need to be established for the design requirements. In this respect, this article describes the development of the smallest possible representative cell (RC) models for quantifying the deformation and failure process of the Nomex polymer-based hexagonal HC core structure under the out-of-plane quasi-static loadings. While the hexagonal single and multi-cell models are suitable for the tension and compression, a six-cell model is the simplest RC model developed for shear in the transverse and ribbon direction. Hashin’s matrix and fiber damage equations are employed in simulating the failure process of the orthotropic cell walls, using the finite element (FE) analysis. The FE-calculated load–displacement curves are validated with the comparable measured responses throughout the loading to failure. The location of the fracture plane of the critical cell wall in the out-of-plane tension case is well predicted. The wrinkling of the cell walls, leading to the structural buckling of the HC core specimen in the compression test, compares well with the observed failure mechanisms. In addition, the observed localized buckling of the cell wall by the induced compressive stress during the out-of-plane shear in both the transverse and ribbon direction is explained. The mesoscale RC models of the polymer hexagonal HC core structure have adequately demonstrated the ability to predict the mechanics of deformation and the mechanisms of failure.

scholarly journals Investigation of a low-stress and low-contamination clamping method for large-aperture optics

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988010
Author(s):  
Hui Wang ◽  
Kai Long ◽  
Zheng Zhang ◽  
Congzhi Yi ◽  
Xusong Quan ◽  
...  
Keyword(s):  
Contact Stress ◽  
Field Experiments ◽  
Sol Gel ◽  
Damage Mechanism ◽  
Honeycomb Structure ◽  
Initial Contact ◽  
Radial Compression ◽  
Large Aperture ◽  
Gel Film ◽  
Contact Seal

Motivated by the need to decrease initial contact seal stress on Nd:glass coated with SiO2 sol–gel film and effectively control the surface contaminants from film debris induced by stress in the assembly process, a novel vacuum clamping method is studied to achieve the purpose of low stress and low contamination. In this article, theoretical analyses, numerical simulations, and field experiments are used to verify the feasibility of this method. Mechanical simulation results indicate that under the same radial compression conditions, the higher the hollowness of the O-ring rubber, the less the contact stress on Nd:glass. In addition, microstructures of the SiO2 sol–gel film are observed by scanning electron microscopy, and the damage mechanism is analyzed in order to optimize assembly stress. By optimizing the distribution of hollowness, the honeycomb structure is proved to have lower contact stress due to its larger deformation. Finally, experimental results verify that the low-stress vacuum clamping method can meet the strict surface cleanliness requirements of Nd:glass. This study also provides a promising method for clean assembly of other large-aperture optics.

Experimental Investigation on the Energy Absorption Capability of Foam-Filled Nomex Honeycomb Structure

2013 ◽  
Vol 393 ◽  
pp. 460-466 ◽  
Author(s):  
Wan Luqman Hakim Wan Abdul Hamid ◽  
Yulfian Aminanda ◽  
Mohamed Shaik Dawood
Keyword(s):  
Experimental Investigation ◽  
Cell Walls ◽  
Honeycomb Structure ◽  
Polyurethane Foams ◽  
Low Density ◽  
Static Compression ◽  
Compression Loading ◽  
Foam Filled ◽  
Nomex Honeycomb ◽  
Quasi Static Compression

The effect of low density filler material comprising polyurethane foam on the axial crushing resistance of Nomex honeycomb under quasi-static compression conditions was analyzed. Honeycombs with two different densities, two different heights and similar cell size, along with five different densities of polyurethane foams were used in the research. A total of 14 unfilled Nomex honeycombs, 15 polyurethane foams, and 39 foam-filled Nomex honeycombs were subjected to quasi-static compression loading. The crushing load and capability of foam-filled Nomex honeycomb structure in absorbing the energy were found to increase significantly since the cell walls of honeycomb were strengthened by the foam filler; the walls did not buckle at the very beginning of compression loading. The failure mechanism of the foam-filled honeycomb was analyzed and compared with the unfilled honeycomb.

Cell wall changes under compression combined with steam treatment in relation to wood hygroscopicity

IAWA Journal ◽  
2020 ◽  
pp. 1-14
Author(s):  
Jiangping Yin ◽  
Juan Guo ◽  
Jianxiong Lyu ◽  
Yafang Yin
Keyword(s):  
Compression Ratio ◽  
Cell Walls ◽  
Treated Wood ◽  
Nitrogen Adsorption ◽  
Cellular Level ◽  
Steam Treatment ◽  
Chemical Components ◽  
Radial Compression ◽  
Dynamic Vapor Sorption ◽  
Amorphous Cellulose

Abstract Compression combined with steam (CS) treatment is postulated to be an environmentally friendly and efficient modification method to improve the dimensional stability, durability, and mechanical strength of wood. The influences of CS treatment with different radial compression ratios (RCRs) (25% and 50%) and different steam temperatures (140, 160 and 180°C) on chemical components, porosity, and hygroscopicity of earlywood and latewood in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were investigated respectively on a cellular level by imaging Fourier Transform Infrared (FT-IR) microscopy, Confocal Raman Microscopy (CRM), nitrogen adsorption and dynamic vapor sorption (DVS). The results indicated that the degradation of carbonyl groups of the glucuronic acid component of xylan in earlywood and latewood was mainly responsible for the low hygroscopicity of CS-treated wood. Also, a significant decrease in the amount of C=O and C=C linked to the lignin aromatic skeleton involved in either crosslinking reactions or the degradation reactions could be another contributor to the reduction in wood hygroscopicity. CS-treated wood with a steam temperature of 180°C possessed a lower hygroscopicity that correlated well with the depolymerization of crystalline and amorphous cellulose. A more deformed structure of CS-treated wood led to the formation of greater amounts of mesopores in the cell walls, which could lead to increased degradation of the chemical components of wood cell walls. Furthermore, a higher equilibrium moisture content (EMC) level was found for CS-treated wood with a 50% compression ratio compared to a 25% compression ratio.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

An ultrastructural study of vegetative incompatibility in plants

1978 ◽  
Vol 36 (2) ◽  
pp. 436-437
Author(s):  
Randy Moore
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Growth And Development ◽  
Solanum Pennellii ◽  
Initial Product ◽  
Basic Aspect ◽  
Tissue Interactions ◽  
Graft Interface ◽  
Antigen Antibody ◽  
Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

Cryosectioning plant roots prepared by high-pressure freezing

1987 ◽  
Vol 45 ◽  
pp. 662-663
Author(s):  
R.E. Crang ◽  
M. Mueller ◽  
K. Zierold
Keyword(s):  
High Pressure ◽  
Cell Walls ◽  
Plant Tissues ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Vitreous State ◽  
Radial Depth ◽  
Irregular Topography ◽  
Considerable Depth ◽  
Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

Morphologic alteration in the muscles of patients with hypokalemic periodic paralysis or myopathy

1990 ◽  
Vol 48 (3) ◽  
pp. 222-223
Author(s):  
T. Shimizu ◽  
Y. Muranaka ◽  
I. Ohta ◽  
N. Honda
Keyword(s):  
Clinical Manifestations ◽  
Quadriceps Muscle ◽  
Honeycomb Structure ◽  
Periodic Paralysis ◽  
Ultrastructural Changes ◽  
Hypokalemic Periodic Paralysis ◽  
Electron Microscopic ◽  
Tubular Aggregates ◽  
Hypokalemic Myopathy ◽  
Transmission Electron

There have been many reports on ultrastructural alterations in muscles of hypokalemic periodic paralysis (hpp) and hypokalemic myopathy(hm). It is stressed in those reports that tubular structures such as tubular aggregates are usually to be found in hpp as a characteristic feature, but not in hm. We analyzed the histological differences between hpp and hm, comparing their clinical manifestations and morphologic changes in muscles. Materials analyzed were biopsied muscles from 18 patients which showed muscular symptoms due to hypokalemia. The muscle specimens were obtained by means of biopsy from quadriceps muscle and fixed with 2% glutaraldehyde (pH 7.4) and analyzed by ordinary method and modified Golgimethod. The ultrathin section were examined in JEOL 200CX transmission electron microscopy.Electron microscopic examinations disclosed dilated t-system and terminal cistern of sarcoplasmic reticulum (SR)(Fig 1), and an unique structure like “sixad” was occasionally observed in some specimens (Fig 2). Tubular aggregates (Fig 3) and honeycomb structure (Fig 4) were also common characteristic structures in all cases. These ultrastructural changes were common in both the hypokalemic periodic paralysis and the hypokalemic myopathy, regardless of the time of biopsy or the duration of hypokalemia suffered.

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