scholarly journals Nonlinear Acoustic Modeling and Measurements during the Fatigue Process in Metals

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 607
Author(s):  
Wenhan Lyu ◽  
Xianmei Wu ◽  
Weijiang Xu
Keyword(s):  
Early Stage ◽  
Acoustic Method ◽  
Spring Model ◽  
Spring Stiffness ◽  
Fatigue Process ◽  
Micro Cracks ◽  
Expansion Stage ◽  
Three Stages ◽  
Nonlinear Acoustic ◽  
Fatigue Evaluation

The nonlinear spring model combined with dislocation dipole theory was applied to describe the acoustic nonlinearity during the fatigue process in metals. The spring stiffness changes with fatigue degree. For the early stage, spring stiffness approaches infinity, and the heavier nonlinearity mainly results from the increase of dislocation density. Further fatigue leads to the occurrence of micro-cracks, during which spring stiffness begins to decrease. Abundant micro-crack sprouting accelerates the crack’s expansion, and spring stiffness drops quickly, which causes the obvious decline in the transmitted harmonic amplitudes. Solutions obtained from the nonlinear wave equation with dislocation terms were added into the spring model. Varying spring stiffness was chosen for simulating the fatigue process. Then, nonlinear harmonic variation during this process was observed, which was classified into three stages: (I) the early dislocation fatigue stage; (II) the micro-crack sprouting stage; (III) the crack expansion stage. Nonlinear acoustic measurements were carried out on an aluminum alloy specimen during its fatigue process until cracks could be seen clearly. Harmonic variations in experiments can also be classified into the same three stages as the numerical results, which provides a theoretical and experimental reference for fatigue evaluation in metals using the nonlinear acoustic method.

scholarly journals Pelatihan Strategi Penulisan Artikel Ilmiah pada Jurnal Bereputasi Nasional dan Internasional bagi Guru di SMKN 1 Sekotong Kabupaten Lombok Barat

2020 ◽  
Vol 1 (2) ◽  
pp. 139
Author(s):  
Taufik Suadiyatno ◽  
Dedi Sumarsono ◽  
Muliani Muliani ◽  
Moh. Arsyad Arrafii ◽  
Abdul Kadir Bagis
Keyword(s):  
Community Service ◽  
Early Stage ◽  
Scientific Article ◽  
Service Program ◽  
Evaluation Stage ◽  
Three Stages ◽  
Implementation Stage ◽  
Program Team

This community service program aimed to improve teachers’ anthusiastic in SMKN 1 Sekotong, West Lombok to conduct articles to be published in national accredited and international journal. The method used in this program divided into three stages such as 1) early stage includes koordination between the program team with the principle of SMKN 1 Sekotong; 2) implementation stage includes scientific article training; and 3) evaluation stage that used as the overview of the next program. The materials in this program was presented mostly in term of describing the technique of writing good articles therefore they deserve to be published in national accredited or international journal. This community service program was conducted in SMKN 1 Sekotong which was followed by the pcinciple and 23 teachers. The conclusion of this program was there was an improvement of teachers’ anthusiastic to publish their scientific articles in national accredited and international journal.

Nonlinear acoustic method for bubble density measurements in water

1998 ◽  
Vol 103 (5) ◽  
pp. 2377-2384 ◽  
Author(s):  
A. M. Sutin ◽  
S. W. Yoon ◽  
E. J. Kim ◽  
I. N. Didenkulov
Keyword(s):  
Acoustic Method ◽  
Density Measurements ◽  
Bubble Density ◽  
Nonlinear Acoustic

Stability Analysis of Planar Grasp with 2D-Virtual Spring Model

1999 ◽  
Vol 11 (4) ◽  
pp. 274-282 ◽  
Author(s):  
Takayoshi Yamada ◽  
◽  
Sushanta Kumar Saha ◽  
Nobuharu Mimura ◽  
Yasuyuki Funahashi ◽  
...  
Keyword(s):  
Contact Force ◽  
External Disturbance ◽  
Rolling Contact ◽  
Initial Contact ◽  
Spring Model ◽  
Spring Stiffness ◽  
Grasp Stability ◽  
Stiffness Matrices ◽  
The Relationship ◽  
Special Case

We analyze stability of planar grasp using a 2D virtual spring model. A 2D virtual spring model is widely used to explore frictionless grasp, but the direction of contact force has not been studied for a grasped object displaced by external disturbance. Finger displacement is restricted to the normal at initial contact. We introduce a 2D spring model for a frictionless case. The direction of contact force is explicitly formulated. Using potential energy, we analyze stability of frictionless grasp and show that the 1D-spring model is a special case of our proposed 2D-spring model. Frictional grasp stability is also studied using rolling contact. Numerical examples of 2-fingered grasp demonstrate the effects of parameters such as spring stiffness and contact force. It is shown that an optimum force exists for stabilizing frictionless grasp. It is proved that friction enhances grasp stability from the relationship between frictionless and frictional stiffness matrices. Stiffness conditions for stabilizing 3-fingered grasp is clarified.

scholarly journals Multifeature Extraction of Three-Dimensional Topography of Carbon Steel Specimen during Fatigue Process

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tao Liu ◽  
Jingxiong Wu ◽  
Jingfa Lei ◽  
Xue Wang ◽  
Bingqi Zhang ◽  
...  
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Fatigue Damage ◽  
Feature Fusion ◽  
Early Stage ◽  
Three Dimensional ◽  
Mean Deviation ◽  
Height Distribution ◽  
Fusion Method ◽  
Fatigue Process

In order to investigate the variation of three-dimensional metal surface topography during fatigue process, a three-dimensional (3D) topography acquisition platform was built with an in situ tensile tester and a three-dimensional profilometer. Q235 steel specimens were chosen as research objects, and the three-dimensional surface topography information at various stages of fatigue damage was obtained. Through the characterization of three-dimensional roughness, combined with surface height distribution and multifractal analysis, the variations of metal surface topography in the fatigue process were described. Results show that the arithmetic mean deviation of the surface (Sa), the width of the multifractal spectrum (Δα), and the mean value of surface height distribution (μ) and its standard deviation (δ) increase nonlinearly with the increase of fatigue cycles. The rate of fatigue damage is slow in the early stage and high in the middle and late stages. The surface height distribution amplitude (A) decreases with the increase of fatigue cycles, which indicates that the height data concentration decreases, and the metal surface becomes uneven. The Bayesian data fusion method was applied to establish a nonlinear mapping between the topography features and the damage, with the above five characteristic parameters (Sa, Δα, A, μ, and δ) as the data layer. Finally, a surface topography feature fusion method is proposed, and a case study is conducted to verify its applicability. The research results can provide reference for fatigue damage assessment.

scholarly journals Study on the Microstructure of the Pinctada martensii Pearls and Its Significance

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Wenlong Wu ◽  
Liping Zhang ◽  
Zhijun Yang ◽  
Weisheng Hou
Keyword(s):  
Raman Spectra ◽  
Early Stage ◽  
Formation Processes ◽  
High Quality ◽  
Middle Stage ◽  
Pinctada Martensii ◽  
Medium Quality ◽  
Three Stages ◽  
Last Stage ◽  
Crystalline Plane

The results of a microscopy, SEM-EDS, XRD, FTIR, and Raman spectra study of the nacres of the Pinctada martensii pearls from Zhanjiang city, China shows that they can be classified as the high-quality, medium-quality, and inferior-quality pearls. Aragonite, the main inorganic mineralogy in the nacres, was crystallized and grown up in the compartments formed by the silk and radial organic sheets originating from organic matters secreted by the mantle of mollusks. The crystalline orientations of aragonite tablets were changed from the (002), (012) and (102) crystalline plane nets in the early to the (002) crystalline plane net only in the later. The formation processes of the microstructure of the nacres could be divided into three stages. In the early stage, the precursor particles of aragonite nucleated and grew up fast; then, porous aragonite aggregates consisting of the fine aragonite crystals were formed. In the middle stage, the aragonite crystals directionally grew up to form the aragonite tablets and microlayers. The surface of the aragonite tablets and microlayers are rough and few porous, and the edges of the crystals were serrated. In the last stage, the aragonite tablets in the aragonite microlayer mixed perfectly together to form high-quality aragonite layer whose surface was smooth and perfect.

scholarly journals Pengolahan Sampah Organik dan Limbah Biomassa dengan Teknologi Olah Sampah di Sumbernya

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
I Made Indradjaja M. Brunner ◽  
Arief Norhidayat ◽  
Satria M. Brunner
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Early Stage ◽  
Calorific Value ◽  
Ash Content ◽  
Waste Processing ◽  
Biomass Waste ◽  
Aerobic Activity ◽  
Three Stages ◽  
Biomass Pellet

Solid Waste Processing Technology at the Source (TOSS) is an alternative method in processing organic and biomass waste on a communal scale. The processing of organic and biomass waste material is carried out in three stages of the process: biodrying which utilizes the aerobic activity of microorganisms; chopping which is intended to refine the material, and pelletization to compact the material into biomass pellets. The biodrying process in bamboo boxes is able to reduce the water content in organic and biomass waste within 4-5 days. Sorting of non-organic materials can be done at an early stage before or after the biodrying process. Sorting is required before chopping and pelletizing process to avoid unnecessary machine break down. The biomass pellet which is the final product has a diameter of about 10 mm with a length between 10-40 mm, a calorific value between 3000-4000 kcal/kg, and a moisture content of up to 15%. Compared to coal, biomass pellets tend to have higher volatile and ash content, while lower ash and sulfur content.

scholarly journals Growth Pattern and Trends in Startup Funding in INDIA

2019 ◽  
Vol 8 (12) ◽  
pp. 3721-3724
Keyword(s):  
Growth Pattern ◽  
Early Stage ◽  
Experimental Phase ◽  
Chi Square ◽  
Professional Qualification ◽  
Funding Sources ◽  
Start Up ◽  
Expansion Stage ◽  
Chi Square Test ◽  
Prime Objective

This paper presents the trend and growth pattern of startup ventures, their types and different stages of funding in India. The prime objective of this research was to study growth pattern of the startups and stages of funding received by these startups. The analysis has shown Indian start-up companies prefer primarily funding in four different stages, such as early stage, growth stage, expansion stage and bridge funding. The result has also shown that maximum funding was received in the expansion stage in the financial years. Bridge funding is becoming more and more prevalent, almost 10 per cent of deals. Further, it is noticed that the entrepreneurs find financial support from other funding sources, after the initial experimental phase. The results of chi-square test revealed that there is no significant association between stages of funding and level of development of startup. Further, the test also revealed no significant association between financing methods and professional qualification of promoters of startup.

scholarly journals The Impact of Zhuangzi’s Thought on Sanmao’s Writing Style

Humaniora ◽  
2015 ◽  
Vol 6 (4) ◽  
pp. 520
Author(s):  
Xuc Lin
Keyword(s):  
Early Stage ◽  
Life Changes ◽  
Writing Style ◽  
Library Research ◽  
Three Stages ◽  
The Impact

This paper describes the impact of Zhuangzi’s thought on the San Mao’s writing style. Research was conducted by applying library research. The data for research were collected from papers, books, so on both printed and online. It is found that San Mao's writing style was divided into three stages: early stage, wanderingstage, and regression stage. These three stages are influenced by the San Mao's life changes. As a conclusion, although those three stages of writing use a completely different form, but Zhuangzi's thought influenced over her life. It also makes her always demonstrate a simple, real, and natural writing style. 

The in situ degradability of dry matter, neutral detergent fibre and starch in whole-crop wheat harvested at three stages of maturity

1998 ◽  
Vol 1998 ◽  
pp. 147-147
Author(s):  
T.C. Moos ◽  
J.D. Sutton
Keyword(s):  
Dairy Cows ◽  
Dry Matter ◽  
Early Stage ◽  
Neutral Detergent Fibre ◽  
Lactating Dairy Cows ◽  
Aerobic Stability ◽  
Three Stages

The choice of optimal stage of maturity at harvest for whole-crop wheat remains controversial. Problems of aerobic stability with crops harvested and ensiled at an early stage led to increased interest in harvesting at a later stage and preserving the crop with urea. However recent studies have shown low starch and fibre digestibility with such crops when fed to lactating dairy cows (Sutton et al.,1991). The purpose of the present work was to determine the effect of harvesting wheat at three stages of maturity on the in situ degradability of dry matter (DM), neutral detergent fibre (NDF) and starch.

Sign in / Sign up

Export Citation Format

Share Document