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Inverse identification of the mechanical parameters of a pipeline hoop and analysis of the effect of preload

Frontiers of Mechanical Engineering 2019年第3期14卷 358-368页

作者： Ye GAO Wei SUN School of Mechanical Engineering and Automation Northeastern University Shenyang 110819 China Key Laboratory of Vibration and Control of Aero-Propulsion Systems Ministry of Education of China Northeastern University Shenyang 110819 China

To create a dynamic model of a pipeline system effectively and analyze its vibration characteristics, the mechanical characteristic parameters of the pipeline hoop, such as support stiffness and damping under dynamic load, must be obtained. In this study, an inverse method was developed by utilizing measured vibration data to identify the support stiffiiess and damping of a hoop. The procedure of identifying such parameters was described based on the measured natural frequencies and amplitudes of the frequency response functions (FRFs) of a pipeline system supported by two hoops. A dynamic model of the pipe-hoop system was built with the finite element method, and the formulas for solving the FRF of the pipeline system were provided. On the premise of selecting initial values reasonably, an inverse identification algorithm based on sensitivity analysis was proposed. A case study was performed, and the mechanical parameters of the hoop were identified using the proposed method. After introducing the identified values into the analysis model, the reliability of the identification results was validated by comparing the predicted and measured FRFs of the pipeline. Then, the developed method was used to identify the support stiffness and damping of the pipeline hoop under different preloads of the bolts. The influence of preload was also discussed. Results indicated that the support stiffiiess and damping of the hoop exhibited frequency-dependent characteristics. When the preloads of the bolts increased, the support stiffness increased, whereas the support damping decreased.

关键词： inverse identification pipeline hoop fiequency response function mechanical parameters preload

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Experimental characterization of anisotropic tensile mechanical behavior of pure titanium tube

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Journal of Iron and Steel Research International 2019年第1期26卷 91-101页

作者： Jin-biao Zhou Peng-yan Sun Chang-yu Zhou Xiao-hua He School of Mechanical and Power Engineering Nanjing Technology UniversityNanjing 211816JiangsuChina

The anisotropic tensile mechanical properties of pure titanium(TA2)tubes were studied by means of theoretical analysis,finite element simulation and tensile *** on the stress analysis of circumferential tensile of TA2 tube,an equation for calculating the tangential force of circumferential tensile specimen was established,and the relationship among tangential force,friction and position of ring specimen was *** finite element simulation analysis of circumferential tensile process of TA2 ring specimen was carried out,which verified the tangential force equation derived from theoretical *** effect of gauge length and friction on necking and tensile load was analyzed,and the optimal gauge length was selected for the ring hoop tensile ***,the axial and circumferential tensile digital image correlation experiments were carried out to verify the theoretical and finite element simulation *** friction coefficient between TA2 tube and D-blocks(using Teflon lubricant)was determined by the inverse finite element method and the friction experiment,and the true stress-strain curve of TA2 tube was *** results show that the axial and circumfere ntial mechanical behaviors of TA2 tubes are significantly different and an isotropic.

关键词： Pure titanium(TA2)tube Ring hoop tensile test Digital image correlation An isotropy Strain rate

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The Use of High Tunnels to Produce Fruit and Vegetable Crops in North America

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Agricultural Sciences 2017年第7期8卷 692-715页

作者： Rhonda R. Janke May Elfar Altamimi Mumtaz Khan Department of Crop Sciences College of Agriculture and Marine Science Sultan Qaboos University Muscat Oman Department of Horticulture Forestry and Recreation Resources 2021 Throckmorton Kansas State University Manhattan USA

High tunnels have been used in the United States for more than 50 years, and growers are encouraged to use them more frequently through government cost-share programs. Research on fruits and vegetable production systems has focused on high value crops such as tomato, salad greens, and several fruit crops. Maintaining soil quality and controlling insects and diseases are all issues that growers face. This review looks at current research on these issues as well as economic considerations addressed in the scientific literature. Global statistics and reports are also reviewed that complement the North American studies. Gaps in our understanding are identified, and directions for future research are suggested.

关键词： hoop Houses Plasticulture Protected Agriculture Season Extension

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Study of the Effect of Changes on the Technological and Physical-Mechanical Properties of Knitting in a New Structure

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Engineering（科研） 2021年第6期13卷 287-299页

作者： Shahboz Shokirjonugli Shogofurov Iroda Ibrohimovna Kamalova Kurbonali Madaminovich Xolikov Faculty of Technology of Light Industry Namangan Institute of Engineering and Technology Namangan Uzbekistan

In this article, we compared four types of knitted fabrics with high two-ply shape retention. Experimental samples of a two-layer knitted fabric have been developed and graphic symbols have been applied on a flat-need... 详细信息

关键词： Knitwear Double Knit hoop Yarn Flat Dimensional Lightness hoop Height Surface Density Pattern Density hoop Strip Length Polyacrylonitrile

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Rolling Over into the Age of Algorithm

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World Journal of Mechanics 2017年第3期7卷 39-42页

作者： Francisco J. Dalby Advanced Dynamics C.B. Madrid Spain

This paper is an extract of the prologue to the book: New Paradigm in Physics—Theory of Dynamic Interactions [1], published by Gabriel Barceló. This summary describes the elements that constitute the characteristics of the Theory of Dynamic Interactions, and certain circumstances of it. The author recalls that the Theory of Dynamic Interactions arrives at unheard of conclusions which, even with the level of dissemination reached by this theory over recent years, have not been scientifically refuted.

关键词： Theory of Dynamic Interactions Spinning Top Boomerang Hula hoop Celestial Bodies Use of Data Rotating Object Non-Concurrent Accelerations

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