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1 – 10 of over 1000Zhenwei Li, Zhixun Wen, Cheng Wang, Ying Dai and Peng Fei He
This paper aims to provide SIF calculation method for engineering application.
Abstract
Purpose
This paper aims to provide SIF calculation method for engineering application.
Design/methodology/approach
In this paper, the stress intensity factors (SIFs) calculation method is applied to the anisotropic Ni-based single crystal film cooling holes (FCHs) structure.
Findings
Based on contour integral, the anisotropic SIFs analysis finite element method (FEM) in Ni-based single crystal is proposed. The applicability and mesh independence of the method is assessed by comparing the calculated SIFs using mode of plate with an edge crack. Anisotropic SIFs can be calculated with excellent accuracy using the finite element contour integral approach. Then, the effect of crystal orientation and FCHs interference on the anisotropic SIFs is clarified. The SIFs of FCH edge crack in the [011] orientated Ni-based single crystal increases faster than the other two orientations. And the SIF of horizontal interference FCHs edge crack is also larger than that of the inclined interference one.
Originality/value
The SIFs of the FCH edge crack in the turbine air-cooled blade are innovatively computed using the sub-model method. Both the Mode I and II SIFs of FCHs edge crack in blade increase with crack growing.
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Fevzi Karsli and Mustafa Dihkan
The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and a…
Abstract
Purpose
The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and a comparison is carried out with conventional watershed segmentation algorithm.
Design/methodology/approach
Polished granite plates were prepared to designate the metrics of CSD measurements. There are many important metrics for measurements on CSD. Some of them are orientation, size, position, area, aspect ratio, convexity, circularity, perimeter, convex hull, bounding box, eccentricity, shape, max-min length of CSD's fitted and corrected ellipse, and population density in a per unit area. Prior to image processing stage, camera calibration was performed to remove the image distortion errors. Image processing techniques were applied to corrected images for detecting the CSD parameters.
Findings
The proposed algorithm showed the improved preservation of size and shape characteristics of the crystal material when compared to the watershed segmentation. According to the experimental results, proposed algorithm revealed promising results in identifying CSDs more easily and efficiently.
Originality/value
This paper describes CSD of granitic rocks by using automated grain boundary detection methods in polished plate images. Some metrics of CSDs were detected by employing a new procedure. A computer-based image analysis technique was developed to measure the CSDs on the granitic rock plates. A validation is done by superimposing digitally detected CSD metrics to original samples.
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Ru Zhang, Chuanzhen Huang, Jun Wang, Hongtao Zhu and Hanlian Liu
The purpose of this study is to fabricate high-aspect-ratio grooves with high surface quality by femtosecond laser (FS) to improve the machinability of silicon carbide (SiC) and…
Abstract
Purpose
The purpose of this study is to fabricate high-aspect-ratio grooves with high surface quality by femtosecond laser (FS) to improve the machinability of silicon carbide (SiC) and optimize the process parameters in micromechanical applications.
Design/methodology/approach
Four contrast experiments are reported to characterize the FS laser grooving process for SiC with polarization direction, crystal orientation, multi-pass scanning and z layer feed, respectively. The effects of different experimental conditions on the groove characteristics, material removal rate (MRR), aspect ratio, heat affected zone (HAZ) and surface roughness Ra are analyzed.
Findings
The influence of increasing laser fluence and multi-scanning pass on the groove depth is greater than on the groove width. The MRR, aspect ratio, HAZ and Ra increased with the increase of laser fluence and multi-scanning pass. The direction of laser polarization affects the direction of hot electron injection but has little effect on the material characteristics. FS laser ablation is an isotropic process and there is no obvious change in different crystal orientations. The z-layer feed can significantly increase the groove width and depth and reduce HAZ and Ra. The maximum aspect ratio of 82.67% was fabricated.
Originality/value
The results contribute to the understanding of the removal mechanism and reduce the friction of the microfluidic device and improve the flowability in the FS laser ablation of SiC. This paper provides suggestions for the selection of suitable process parameters and provides a wider possibility for the application of micro-texture on SiC.
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In America, the National Bureau of Standards is investigating the primary processes of corrosion to solve some of the practical engineering problems encountered today. Large…
Abstract
In America, the National Bureau of Standards is investigating the primary processes of corrosion to solve some of the practical engineering problems encountered today. Large single metal crystals are employed in some of the research to correlate corrosion with the arrangement of atoms in the crystal lattice. Other studies include the electrical phenomena, the mechanism of the formation of oxide films and the effect of illumination on the corrosion reaction.
Ribeka Takahashi, David T. Fullwood, Travis M. Rampton, Darrell J. Skousen, Brent L. Adams and Christopher A. Mattson
Microstructure-sensitive design (MSD), for optimal performance of engineering components that are sensitive to material anisotropy, has largely been confined to the realm of…
Abstract
Purpose
Microstructure-sensitive design (MSD), for optimal performance of engineering components that are sensitive to material anisotropy, has largely been confined to the realm of theory. The purpose of this paper is to insert the MSD framework into a finite element environment in order to arrive at a practical tool for improved selection and design of materials for critical engineering situations.
Design/methodology/approach
This study applies the recently developed Hybrid Bishop-Hill (HBH) model to map the yield surface of anisotropic oxygen free electronic copper. Combining this information with the detailed local stresses determined via finite element analysis (FEA), a “configurational yield stress” is determined for the entire component. By varying the material choice/processing conditions and selecting the directionality of anisotropy, an optimal configuration is found.
Findings
The paper provides a new FEA-based framework for MSD for yield-limited situations. The approach identified optimal directionality and processing configurations for three engineering situations that are particularly sensitive to material anisotropy.
Research limitations/implications
The microstructure design space for this study is limited to a selection of eight copper materials produced by a range of processing methods, but is generalizable to many materials that exhibit anisotropic behavior.
Originality/value
The introduction of MSD methodology into a finite element environment is a first step toward a comprehensive designer toolkit for exploiting the anisotropy of general materials (such as metals) in a way that is routinely undertaken in the world of fiber-based composite materials. While the gains are not as sizeable (due to the less-extreme anisotropy), in many applications they may be extremely important.
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Man He, Bo Wang, Weisheng Xia, Shijie Chen and Jinzhuan Zhu
The purpose of this paper is to study the microstructure and mechanical behaviour of smaller microbumps for high density solder interconnects.
Abstract
Purpose
The purpose of this paper is to study the microstructure and mechanical behaviour of smaller microbumps for high density solder interconnects.
Design/methodology/approach
The microstructure was analyzed by scanning electron microscopy and electron backscatter diffraction tests to determine the Sn grain number of the resultant microbumps. The nanomechanical properties of Sn microbumps were investigated by the nanoindentation and shearing tests to understand the failure mechanism and assess the reliability of ultra-high density solder interconnects with numbered grains.
Findings
Only one Sn grain is observed in the interconnect matrix when the microbumps are miniaturized to 40 μm or less. Because of the body-centred tetragonal lattice of ß-Sn unit cell, the mechanical properties of the one-grain Sn microbumps are remarkably anisotropic, which are proved by the difference of the elastic modulus and the stiffness in the different orientations. The shearing tests show that the one-grain Sn microbump has a typical brittle sliding fracture of monocrystal at different shearing speeds.
Practical implications
The paper provides a comparable study for the performance of the bigger solder joints and also makes preliminary research on the microstructure and mechanical behaviour of Sn microbumps with the diameter of 40 μm.
Originality/value
The findings in this paper provide methods of microstructure study by combination of EBSD test and metallographic analysis, mechanical study by combination of nanoindentation test and shearing test, which can provide good guidelines for other smaller microbumps. The strain rate sensitivity exponent of the one-grain Sn microbumps is consistent with the Pb-free bulk solder. This implies that the one-grain Sn microbump has a comparable flow stress to Sn37Pb solder, which is beneficial for Pb-free replacement in higher density microelectronic packaging.
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Gilad Sharon, Rachel Oberc and Donald Barker
The development of micro‐electro‐mechanical systems (MEMS) for use in military and consumer electronics necessitates an analysis of MEMS component reliability. The understanding…
Abstract
Purpose
The development of micro‐electro‐mechanical systems (MEMS) for use in military and consumer electronics necessitates an analysis of MEMS component reliability. The understanding of the reliability characteristics of SCSi within MEMS structures should be improved to advance MEMS applications. Reliability assessments of MEMS technology may be used to conduct virtual qualification of these devices more efficiently. The purpose of this paper is to create a simple, inexpensive test methodology to use the dynamic fracture strength of a MEMS device to predict its reliability, and to verify this method through experimentation.
Design/methodology/approach
The dynamic fracture strength of single crystal silicon (SCSi) was used to model MEMS devices subjected to high shock loading. Experimentation with SCSi MEMS structures was performed following the proposed test methodology. A probabilistic distribution for bending of Deep Reactive Ion Etching (DRIE) processed SCSi around the <110> directions was generated as a tool for assessing product reliability.
Findings
Post shock test inspections revealed that failures occurred along {111} planes. Additional experiments provided preliminary estimates of the fracture strength for bending of DRIE processed SCSi around the <100> directions in excess of 1.1 GPa.
Originality/value
This paper proposes a test methodology for an efficient method to assess the reliability of processed SCSi based on dynamic fracture strength.
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Srinivas Rao Sriram, Saidireddy Parne, Venkata Satya Chidambara Swamy Vaddadi, Damodar Edla, Nagaraju P., Raji Reddy Avala, Vijayakumar Yelsani and Uday Bhasker Sontu
This paper aims to focus on the basic principle of WO3 gas sensors to achieve high gas-sensing performance with good stability and repeatability. Metal oxide-based gas sensors are…
Abstract
Purpose
This paper aims to focus on the basic principle of WO3 gas sensors to achieve high gas-sensing performance with good stability and repeatability. Metal oxide-based gas sensors are widely used for monitoring toxic gas leakages in the environment, industries and households. For better livelihood and a healthy environment, it is extremely helpful to have sensors with higher accuracy and improved sensing features.
Design/methodology/approach
In the present review, the authors focus on recent synthesis methods of WO3-based gas sensors to enhance sensing features towards toxic gases.
Findings
This work has proved that the synthesis method led to provide different morphologies of nanostructured WO3-based material in turn to improve gas sensing performance along with its sensing mechanism.
Originality/value
In this work, the authors reviewed challenges and possibilities associated with the nanostructured WO3-based gas sensors to trace toxic gases such as ammonia, H2S and NO2 for future research.
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Germán Omar Barrionuevo, Jorge Andrés Ramos-Grez, Magdalena Walczak, Xavier Sánchez-Sánchez, Carolina Guerra, Alexis Debut and Edison Haro
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through…
Abstract
Purpose
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through microstructure control. Because the LPBF generates a textured microstructure associated with high anisotropy, it is of interest to determine the fabrication plane that would generate the desired property distribution within a component.
Design/methodology/approach
The microstructure of 316 L produced by LPBF was characterized experimentally (optical, scanning electron microscopy, glow discharge emission spectrometry and X-ray diffraction), and a finite element method was used to study the microstructure features of grain diameter, grain orientation and thermal parameters of cooling rate, thermal gradient and molten pool dimensions.
Findings
The computational tool of Ansys Additive was found efficient in reproducing the experimental effect of varying laser power, scanning speed and hatch spacing on the microstructure. In particular, the conditions for obtaining maximum densification and minimum fusion defects were consistent with the experiment, and the features of higher microhardness near the component’s surface and distribution of surface roughness were also reproduced.
Originality/value
To the best of the author’s knowledge, this paper is believed to be the first systematic attempt to use Ansys Additive to investigate the anisotropy of the 316 L SS produced by LPBF.
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Reviews intelligent structures through surface‐ and bulk‐micromachining. Examines the merits of these techniques and their past, present and future applications to real‐life…
Abstract
Reviews intelligent structures through surface‐ and bulk‐micromachining. Examines the merits of these techniques and their past, present and future applications to real‐life problems.
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