Fabrication of three-dimensional sin-shaped ripples using a multi-tip diamond tool based on the force modulation approach

2021 ◽  
Vol 72 ◽  
pp. 262-273
Author(s):  
Yuzhang Wang ◽  
Pengfei Fan ◽  
Xichun Luo ◽  
Yanquan Geng ◽  
Saurav Goel ◽  
...  
Author(s):  
Yingchun Liang ◽  
Jiaxuan Chen ◽  
Qingshun Bai ◽  
Yulan Tang ◽  
Mingjun Chen

A method of incorporating research is proposed on scratching and uniaxial tension based on molecular dynamics (MD) with embodied atom method (EAM) for single copper in this paper. The process of tri-pyramid diamond tool scratching the single copper on the (010) plane is simulated under different penetrated depths. The details of scratching process and uniaxial tension are depicted in atomic view. The phenomena of heal-up surface, dislocations and burr are shown after the workpiece is scratched and the principle of that is attempted to analyze. The defects of the surface and subsurface of the workpiece scratched are represented and analyzed by the perspective of dislocations and radial distribution function (RDF). Whereafter the uniaxial tensile simulation of the “real” workpiece after scratching is performed. The mechanism of deformation and the details of change under the uniaxial load are analysed through the stress-strain curve that is combined with the perspective of atom. From simulations results, it is found that the dislocations only occur on the surface and subsurface of workpiece at the small scratching depth, while the dislocations are nucleated and emitted in front of tool and beneath the tool under the deep scratching depth. Dislocations disappear when they propagate to the surface. After the tool escapes the workpiece, the atoms on surface of the workpiece scratched heal up to some extent by the inter force of atoms, while some of the pile-up atoms on surface of tool are attracted backwards surface of workpiece, then form the burr, and others of those atoms are absorbed on the tool’s surface. The number of defects from surface and inner of workpiece increase when the scratching depth is doubled. The order of crystal decreases, especially long range order. It is shown that the penetration depth into the workpiece during scratching affects both surface pile-up and residual defect generation that is important in assessing the change of material properties after being scratched. In the process of the simulation of uniaxial load, the yield stress decrease with the increasing depth of cutting, and dislocations are nucleated at the bottom of groove, especially at the position where the tool escaped nearby burr firstly, and dislocations at ∼45° are observed. It shows that groove is the source of the dislocations aroused. The break-up point is near to the middle of workpiece with increasing depth with groove.


Author(s):  
Baoqing Zhang ◽  
Qinghua Wang ◽  
Ninggang Shen ◽  
Hongtao Ding

The mechanical ruling process using a diamond tool is an important method for fabrication of low-density diffraction gratings. In mechanical ruling, a deposited film of aluminum or gold is mechanically burnished by the diamond tool to form equally spaced and high-quality grooves. The goal of this work is to evaluate the effects of Al film properties and ruling tool loading conditions on the resultant groove formation. The microstructure of the Al film is first studied using scanning electron microscope (SEM) and X-ray diffraction (XRD). The mechanical properties of the Al film are measured by nano-indentation and scratch tests. Mechanical ruling experiments are then carried out on a 10.5 μm thick Al film under various ruling loads ranging from 20 to 105 g. The groove geometry is investigated, and the tool wear of the diamond tool is inspected after the mechanical ruling tests. Finally, a three-dimensional (3D) thermomechanical-coupled finite-element (FE) model is developed to predict the deformation and temperature fields for the micron-scale groove formation by incorporating the Al film properties and a strain-gradient plasticity for modeling the size effect. Multiruling pass simulations are performed to analyze the groove formation under different loading conditions. Through comparison of simulation results with experimental measurement, this model is demonstrated as a useful numerical tool for modeling the mechanical ruling process using a diamond tool.


1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.


Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.


Author(s):  
P.L. Moore

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.


Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).


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