scholarly journals Merging Focal Pairs for Improved Particle Selection and Orientation Determination

2002 ◽  
Vol 8 (S02) ◽  
pp. 216-217
Author(s):  
Steven J. Ludtke ◽  
Wah Chiu
Author(s):  
H. Weiland ◽  
D. P. Field

Recent advances in the automatic indexing of backscatter Kikuchi diffraction patterns on the scanning electron microscope (SEM) has resulted in the development of a new type of microscopy. The ability to obtain statistically relevant information on the spatial distribution of crystallite orientations is giving rise to new insight into polycrystalline microstructures and their relation to materials properties. A limitation of the technique in the SEM is that the spatial resolution of the measurement is restricted by the relatively large size of the electron beam in relation to various microstructural features. Typically the spatial resolution in the SEM is limited to about half a micron or greater. Heavily worked structures exhibit microstructural features much finer than this and require resolution on the order of nanometers for accurate characterization. Transmission electron microscope (TEM) techniques offer sufficient resolution to investigate heavily worked crystalline materials.Crystal lattice orientation determination from Kikuchi diffraction patterns in the TEM (Figure 1) requires knowledge of the relative positions of at least three non-parallel Kikuchi line pairs in relation to the crystallite and the electron beam.


2019 ◽  
Vol 56 (1) ◽  
pp. 22-33
Author(s):  
U. Mühle ◽  
M. Löffler ◽  
T. Schubert ◽  
T. E. M. Staab ◽  
R. Krause-Rehberg ◽  
...  

2004 ◽  
Author(s):  
Michael P. MacDonald ◽  
Steven Neale ◽  
Lynn Paterson ◽  
Andrew Riches ◽  
Gabriel C. Spalding ◽  
...  

2019 ◽  
Vol 25 (1) ◽  
pp. 187-207 ◽  
Author(s):  
Yicha Zhang ◽  
Ramy Harik ◽  
Georges Fadel ◽  
Alain Bernard

Purpose For part models with complex shape features or freeform shapes, the existing build orientation determination methods may have issues, such as difficulty in defining features and costly computation. To deal with these issues, this paper aims to introduce a new statistical method to develop fast automatic decision support tools for additive manufacturing build orientation determination. Design/methodology/approach The proposed method applies a non-supervised machine learning method, K-Means Clustering with Davies–Bouldin Criterion cluster measuring, to rapidly decompose a surface model into facet clusters and efficiently generate a set of meaningful alternative build orientations. To evaluate alternative build orientations at a generic level, a statistical approach is defined. Findings A group of illustrative examples and comparative case studies are presented in the paper for method validation. The proposed method can help production engineers solve decision problems related to identifying an optimal build orientation for complex and freeform CAD models, especially models from the medical and aerospace application domains with much efficiency. Originality/value The proposed method avoids the limitations of traditional feature-based methods and pure computation-based methods. It provides engineers a new efficient decision-making tool to rapidly determine the optimal build orientation for complex and freeform CAD models.


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