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Influence of physical parameters on the collapse of a spherical bubble

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Theoretical & Applied Mechanics Letters 2022年第6期12卷 395-402页

作者： Bo-Hua Sun School of Civil Engineering&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an 710055China

This paper examines the influence of physical parameters on the collapse dynamics of a spherical bubble filled with diatomic gas(κ=7/5).The problem is formulated by the Rayleigh–Plesset dynamical equation,whose numerical solutions are carried out by Maple.Our studies show that each physical parameter affects the bubble collapse dynamics in different degree,which reveals that bubble collapse dynamics must considers all the parameters including liquid viscosity,surface tension,etc,else the outcome cannot be trusted.

关键词： Bubble collapse Rayleigh's modeling Physical parameters Numerical simulation Maple

An equivalent form of the Navier-Stokes equations

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Acta Mechanica Sinica 2023年第2期39卷 165-166页

作者： Bo-Hua Sun School of Civil Engineering&Institute of Mechanics and Technology Xi'an University of Architecture and TechnologyXi'an 710055China

The Navier-Stokes equations of incompressible flow can be expressed as follows[1-8]:■v/■t+■·■u=-1/ρ■ρ+v■^(2)v,(1)■·v=0(2)Equation(1)is the momentums equation and Eq.(2)is the mass conservation equation.

关键词： equation. Navier equations

Assembly and disassembly mechanics of a spherical snap fit

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Theoretical & Applied Mechanics Letters 2023年第1期13卷 26-32页

作者： Xiao-Lin Guo Bo-Hua Sun School of Civil Engineering&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an 710055China

The snap fit is a common mechanical mechanism.We have studied the spherical snap fit carefully for its physical asymmetry,which is easy to assemble but difficult to disassemble.Because of the complexity of spherical snap fit,it is difficult to get a theoretical formula to describe its physical asymmetry.In this paper,the pushing assembly and pulling disassembly of spherical snap fit are studied by both finite element analysis and experiments.The theoretical formulaes of spherical snap fit have been obtained based on numerical simulations and theoretical results of cylindrical snap fit.

关键词： Snap fit Elasticity Friction Asymmetry Beam Spherical shells

On the number of fractured segments of spaghetti breaking dynamics

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Theoretical & Applied Mechanics Letters 2022年第4期12卷 227-232页

作者： Yi Zhang Xiang Li Yuanfan Dai Bo-Hua Sun School of Civil Engineering&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an 710055China

Why are pieces of spaghetti generally broken into three to ten segments instead of two as one thinks?How can one obtain the desired number of fracture segments?To answer those questions,the fracture dynamics of a strand of spaghetti is modelled by elastic rod and numerically investigated by using finiteelement software ABAQUS.By data fitting,two relations are obtained:the number of fracture segments in terms of rod diameter-length ratio and fracture limit curvature with the rod diameter.Results reveal that when the length is constant,the larger the diameter and/or the smaller the diameter-length ratio D/L,the smaller the limit curvature;and the larger the diameter-length ratio D/L,the fewer the number of fractured segments.The relevant formulations can be used to obtain the desired number of broken segments of spaghetti by changing the diameter-to-length ratio.

关键词： Curvature Brittle cracking Elastic rod Diameter-to-length ratio Spaghetti

Aerodynamic shape and drag scaling law of a flexible fibre in a flowing medium

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Theoretical & Applied Mechanics Letters 2023年第3期13卷 159-163页

作者： Bo-Hua Sun Xiao-Lin Guo School of Civil Engineering&Institute of Mechanics and Technology Xian University of Architecture and TechnologyXi’an 710055China

The study of a flexible body immersed in a flowing medium is one of the best way to find its aerodynamic shape.This Letter revisited the problem that was first studied by Alben et al.(Nature 420,479–481,2002).To determine the aerodynamic shape of the fibre,a simpler approach is proposed.A universal drag scaling law is obtained and the universality of the Alben-Shelley-Zhang scaling law is confirmed by using dimensional analysis.A complete Maple code is provided for finding aerodynamic shape of the fibre in the flowing medium.

关键词： Flexible fibre Flow medium Aerodynamic shape Drag Scaling law

Clamping force of a multilayered cylindrical clamper with internalfriction

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Theoretical & Applied Mechanics Letters 2022年第5期12卷 301-305页

作者： Bo-Hua Sun Xiao-Lin Guo School of Civil Engineering&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an 710055China School of Sciences&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an 710055China

Holding an object by clamping force is a fundamental phenomena.Layered or laminated architectures with internal sliding features are essential mechanism in natural and man-made structural system.In this paper,we combine the layered architecture and clamping mechanism to form a multilayered clamper and study the clamping force with internal friction.Our investigations show that the clamping force and energy dissipation are very much depend on the number of layers,its geometry and elasticity,as well as internal friction.The central goal of studying the multilayered clamp is not only to predict the clamping force,but also as a representative case to help finding some clue on the universal behaviours of multilayered architectures with internal friction.

关键词： Clamping force Multilayer clamper Curvature Bending Friction Dissipation Deflection

基于改进的Prandtl-van Driest混合长度的湍流Poiseuille流动模型

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Acta Mechanica Sinica 2023年第4期39卷 176-183页

作者：孙博华 School of Civil Engineering&Institute of Mechanics and Technology Xi’an University of Architecture and TechnologyXi’an710055China

两个平行板之间的湍流Poiseuille流是最简单的物理情况之一,此问题已经被深入的研究.本文提出了一种改进的Prandtl-van Driest混合长度模型,本模型同时满足边界条件和壁面阻尼效应.使用我们的新公式,我们可以求得问题的数值解,此外,本... 详细信息

两个平行板之间的湍流Poiseuille流是最简单的物理情况之一,此问题已经被深入的研究.本文提出了一种改进的Prandtl-van Driest混合长度模型,本模型同时满足边界条件和壁面阻尼效应.使用我们的新公式,我们可以求得问题的数值解,此外,本文还提出了平均速度的近似解析解.作为我们解决方案的应用,推导了湍流Poiseuille流的近似解析摩擦系数.

关键词： Poiseuille流混合长度平行板近似解析解阻尼效应数值解平均速度边界条件

Progress of photonuclear cross sections for medical radioisotope production at the SLEGS energy domain

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Nuclear Science and Techniques 2023年第12期34卷 77-92页

作者： Xuan Pang Bao‑hua sun Li‑hua Zhu Guang‑Hong Lu Hong‑bo Zhou Dong Yang School of Physics Beihang UniversityBeijing 100191China College of Physics Jilin UniversityChangchun 130012China National Basic Science Data Center Beijing 100190China

Photonuclear reactions using a laser Compton scattering(LCS)gamma source provide a new method for producing radioisotopes for medical applications.Compared with the conventional method,this method has the advantages of a high specific activity and less heat.Initiated by the Shanghai Laser Electron Gamma Source(SLEGS),we conducted a survey of potential photonuclear reactions,(γ,n),(γ,p),and(γ,γ')whose cross sections can be measured at SLEGS by summarising the experimental progress.In general,the data are rare and occasionally inconsistent.Therefore,theoretical calculations are often used to evaluate the production of medical radioisotopes.Subsequently,we verified the model uncertainties of the widely used reaction code TALYS-1.96,using the experimental data of the^(100)Mo(γ,n)^(99)Mo,^(65)Cu(γ,n)^(64)Cu,and^(68)Zn(γ,p)^(67)Cu reactions.

关键词： Medical radioisotope Photonuclear reaction LCS Cross section

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悬链线旋转壳体的对称小变形和应力分析

Acta Mechanica Sinica 2022年第2期38卷 119-129,I0004页

作者：孙博华 School of Civil Engineering&Institute of Mechanics and Technology Xi'an University of Architecture and TechnologyXi'an 710055China

链线旋转壳体由于其优良的力学特性被广泛应用于教堂结构中.为了更好地理解悬链线旋转壳体的变形和应力,我们推导了两种悬链线旋转壳体的主曲率半径,以及悬链线旋转壳体位移型控制方程.对于悬链线旋转壳体的这个位移型方程和Reissner-Me... 详细信息

链线旋转壳体由于其优良的力学特性被广泛应用于教堂结构中.为了更好地理解悬链线旋转壳体的变形和应力,我们推导了两种悬链线旋转壳体的主曲率半径,以及悬链线旋转壳体位移型控制方程.对于悬链线旋转壳体的这个位移型方程和Reissner-Meissner混合型方程进行了数值计算和对比.计算结果显示悬链线旋转壳体的力学性能对于悬链线几何参量c非常敏感.揭示了对于一些荷载情况悬链线旋转壳体的力学性能优于相应的球壳.论文还提供了两个完整的Maple程序.

关键词：旋转壳体 Maple程序悬链线主曲率半径混合型方程荷载情况几何参量