In-plane compression behavior of FDM-manufactured hierarchical and hybrid hierarchical hexagonal honeycombs for infrastructural safety applications

2021 ◽  
pp. 251659842110154
Author(s):  
Ashish Kumar Mishra ◽  
Arvind Kumar
Keyword(s):  
Additive Manufacturing ◽  
Energy Absorption ◽  
Uniaxial Compression ◽  
Wall Thickness ◽  
Impact Energy ◽  
Unit Cell ◽  
Fused Deposition ◽  
Cell Dimensions ◽  
Deformation Mechanics ◽  
Unit Cell Dimensions

The infrastructure safety and response to the natural or man-caused calamities has always been a top consideration for any modern project. Impact energy absorption is one such area where advanced measures are being adopted to prevent any damage to the infrastructure from any impact caused by vehicles or other elements. Honeycomb structures have been primarily used in such high impact energy absorption applications. With the advent of modern additive manufacturing practices, drastic modifications to the simple honeycombs generally used are possible, thus expanding the reach and capability of these structures. In this article, in-plane uniaxial compression performance of hybrid and hierarchical hexagonal honeycombs has been studied in the context of strain energy absorption for in-plane impact such as the case of vehicle collision to the pillars of flyover or bridges. The polylactic acid (PLA) filament has been used to manufacture the honeycombs through fused deposition modeling (FDM) additive manufacturing technique. Simple hexagonal honeycombs have been studied first at low deformation speed to understand the deformation mechanics under uniaxial compression and its dependence on the unit cell dimensions and cell wall thickness. The effect of transition to the hybrid and hierarchical hexagonal honeycombs on the compression deformation has been highlighted next. While the hierarchical structures show better energy absorption capabilities and plateau stress, the hybrid hexagonal honeycombs show their high loadresistance. Dependence of the mechanical performance of such structures on the unit cell dimensions, orientation and wall thickness has also been examined through detailed experimental analysis.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

The influence of pH on the synthesis of mixed Fe-Mn oxide minerals

Clay Minerals ◽  
1990 ◽  
Vol 25 (4) ◽  
pp. 507-518 ◽  
Author(s):  
M. H. Ebinger ◽  
D. G. Schulze
Keyword(s):  
Iron Oxides ◽  
Mole Fraction ◽  
Unit Cell ◽  
Mn Oxide ◽  
Cell Dimensions ◽  
The Mean ◽  
Mn Substitution ◽  
Oxide Minerals ◽  
Unit Cell Dimensions ◽  
Influence Of Ph

AbstractMn-substituted iron oxides were synthesized at pH 4, 6, 8, and 10 from Fe-Mn systems with Mn mole fractions (Mn/(Mn + Fe)) of 0, 0·2, 0·4, 0·6, 0·8, and 1·0, and kept at 50°C for 40 days. The Mn mole fraction in goethite was <0·07 at pH 4 but increased to ∼0.47 at pH 6. Goethite and/or hematite formed in Fe and Fe + Mn syntheses at pH 4 and pH 6 at Mn mole fractions ≤0·8, and at Mn mole fractions ≤0·2 at pH 8 and pH 10. Hausmannite and jacobsite formed at pH 8 and pH 10 at Mn mole fractions ≥0·4. In the pure Mn syntheses, manganite (γ-MnOOH) formed at pH 4 and pH 6, whereas hausmannite (Mn3O4) formed at pH 8 and pH 10. As the Mn substitution increased, the unit-cell dimensions of goethite shifted toward those of groutite, and the mean crystallite dimensions of goethite decreased.

Structural studies on crystals found in the intestine of Nematodirus battus

1980 ◽  
Vol 208 (1173) ◽  
pp. 409-414
Keyword(s):  
Electron Microscopy ◽  
Unit Cell ◽  
Structural Studies ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Crystals found in the lumen of the intestine of Nematodirus battus have been studied by electron microscopy. Two of the unit cell dimensions are 16 nm x 23 nm. The possibility of an immunological significance for these crystals is considered.

Crystallization of Helix pomatia agglutinin (HPA), a protein from the edible snail

1999 ◽  
Vol 55 (11) ◽  
pp. 1903-1905 ◽  
Author(s):  
John N. Lisgarten ◽  
James E. Pitts ◽  
Rex A. Palmer ◽  
Colin D. Reynolds ◽  
Minh Hoa Dao-Thi ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Diffraction Pattern ◽  
Helix Pomatia ◽  
Unit Cell ◽  
Hanging Drop ◽  
Helix Pomatia Agglutinin ◽  
Cell Dimensions ◽  
Protein Molecules ◽  
Unit Cell Dimensions ◽  
Drop Technique

Crystals of Helix pomatia agglutinin (HPA) have been grown by the hanging-drop technique using polyethylene glycol as the precipitant at 293 K. Over a period of one to two weeks the crystals grew to maximum dimensions of 0.10 × 0.05 × 0.02 mm. The crystals belong to space group P6322, with unit-cell dimensions a = b = 63.3, c = 105.2 Å and Z = 12 identical monomers of Mr = 13 kDa, aggregating into two 78 kDa hexameric protein molecules per unit cell, each with symmetry 32 (D 3). The diffraction pattern extends to 3.6 Å at 293 K.

scholarly journals Unit cell dimensions of some synthetic olivine group solid solutions

1968 ◽  
Vol 2 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Yoshito Matsui ◽  
Yasuhiko Syono
Keyword(s):  
Solid Solutions ◽  
Unit Cell ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Design for Additive Manufacturing of Cellular Compliant Mechanism Using Thermal History Feedback

2018 ◽  
Author(s):  
Jivtesh Khurana ◽  
Bradley Hanks ◽  
Mary Frecker
Keyword(s):  
Additive Manufacturing ◽  
Energy Absorption ◽  
Thermal History ◽  
Test Problem ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Absorption Capacity ◽  
Unit Cell ◽  
Design For Additive Manufacturing ◽  
Area Of Interest

With growing interest in metal additive manufacturing, one area of interest for design for additive manufacturing is the ability to understand how part geometry combined with the manufacturing process will affect part performance. In addition, many researchers are pursuing design for additive manufacturing with the goal of generating designs for stiff and lightweight applications as opposed to tailored compliance. A compliant mechanism has unique advantages over traditional mechanisms but previously, complex 3D compliant mechanisms have been limited by manufacturability. Recent advances in additive manufacturing enable fabrication of more complex and 3D metal compliant mechanisms, an area of research that is relatively unexplored. In this paper, a design for additive manufacturing workflow is proposed that incorporates feedback to a designer on both the structural performance and manufacturability. Specifically, a cellular contact-aided compliant mechanism for energy absorption is used as a test problem. Insights gained from finite element simulations of the energy absorbed as well as the thermal history from an AM build simulation are used to further refine the design. Using the proposed workflow, several trends on the performance and manufacturability of the test problem are determined and used to redesign the compliant unit cell. When compared to a preliminary unit cell design, a redesigned unit cell showed decreased energy absorption capacity of only 7.8% while decreasing thermal distortion by 20%. The workflow presented provides a systematic approach to inform a designer about methods to redesign an AM part.

Crystal data and X-ray powder diffraction data of 2,4-diiodo-4-nitrophenol (disophenol), C6H3I2NO3. More precise X-ray powder diffraction data of p-nitrophenol, C6H5NO3

1996 ◽  
Vol 11 (4) ◽  
pp. 301-304
Author(s):  
Héctor Novoa de Armas ◽  
Rolando González Hernández ◽  
José Antonio Henao Martínez ◽  
Ramón Poméz Hernández
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Monoclinic Cell

p-nitrophenol, C6H5NO3, and disophenol, C6H3I2NO3, have been investigated by means of X-ray powder diffraction. The unit cell dimensions were determined from diffractometer methods, using monochromatic CuKα1 radiation, and evaluated by indexing programs. The monoclinic cell found for p-nitrophenol was a=6.159(2) Å, b=8.890(2) Å, c=11.770(2) Å, β=103.04(2)°, Z=4, space group P21 or P2l/m, Dx=1.469 Mg/m3. The monoclinic cell found for disophenol has the dimensions a=8.886(1) Å, b=14.088(2) Å, c=8.521(1) Å, β=91.11(1)°, Z=4, space group P2, P2, Pm or P2/m, Dx=2.438 Mg/m3.

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