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Dynamic response of blast loaded Hollow Cylindrical and Truncated Conical shells 空心圆柱壳和截锥壳爆炸载荷的动力响应
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.269
Hollow cylindrical and truncated conical shells depict enhanced torsional and shear resistance compared to beams and plates and are ubiquitously used in structures in aeronautics, submarines, wind turbines, pressure vessels, and transmission pylons. Upon extensive localised blast, these elements undergo local and global deformation and failure. The detrimental damage to the shell depends on the stand-off and charge mass and is proportional to the emerged local dynamic stresses and inelastic deformations. Large localised translations relocate the structure’s original pivot point and induce global rotations about the new one which raises the probability of structural collapse. In this work, we examine large plastic deformations of hollow cylindrical and truncated conical shells subject to a range of pulse pressures emanated from high explosives. Fluid-Structure Interaction (FSI)-based Finite Element (FE) models were developed to discern the characteristics of blasts at various stand-offs and functions were proposed to link load parameters to structural, material, and geometric properties.
与梁和板相比,空心圆柱壳和截锥形壳具有更强的抗扭和抗剪切能力,广泛用于航空、潜艇、风力涡轮机、压力容器和输电塔等结构中。在广泛的局部爆炸后,这些构件经历局部和全局的变形和破坏。对壳体的有害损伤取决于隔离和电荷质量,并与产生的局部动应力和非弹性变形成正比。大的局部平移会重新定位结构的原始枢轴点,并引起围绕新枢轴点的全局旋转,这增加了结构崩溃的可能性。在这项工作中,我们研究了空心圆柱形和截锥形壳在高炸药脉冲压力下的大塑性变形。建立了基于流固耦合(FSI)的有限元(FE)模型来识别不同分离点的爆炸特征,并提出了将载荷参数与结构、材料和几何特性联系起来的函数。
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引用次数: 0
Study on optimal design and vibration characteristics of diaphragm spring based on Genetic algorithm 基于遗传算法的膜片弹簧优化设计及振动特性研究
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.289
The parameters of diaphragm spring are optimized and the dimensional parameters in this design are determined with careful derivation. The global optimization feature of the genetic algorithm is used to optimize the diaphragm spring and compared with the damping effect of the standard algorithms. The results show that the optimization design can significantly reduce the force and realize vibration control of the clutch when the design requirements are met. Due to the large error in calculating the vibration characteristics of diaphragm spring by the commonly used A-L method, the finite element method is used to study the influence of the separation finger structure on the load-deflection characteristics of diaphragm spring. To this end, three different window shapes of diaphragm springs are verified in real-life measurements, and the effective pressure test data for three types of diaphragm springs (type A, type B and type C) are selected. Finally, the load displacement of the peak and valley is obtained by summing their averages under loading and unloading of each diaphragm spring model. Moreover, a new method for calculating the vibration characteristics is obtained by introducing the genetic algorithms into the optimal design of diaphragm springs. Compared the A-L method, the finite element method and the proposed method with the measured data, it is verified that the proposed method has high accuracy in calculating the vibration characteristics of diaphragm springs.
对膜片弹簧的参数进行了优化,并进行了详细的推导,确定了膜片弹簧的尺寸参数。利用遗传算法的全局优化特性对膜片弹簧进行了优化,并与标准算法的阻尼效果进行了比较。结果表明,在满足设计要求的情况下,优化设计能显著减小离合器受力,实现离合器振动控制。由于常用的A-L法计算膜片弹簧振动特性误差较大,采用有限元法研究分离指结构对膜片弹簧载荷-挠度特性的影响。为此,在实际测量中验证了膜片弹簧的三种不同窗口形状,并选取了A、B、C三种膜片弹簧的有效压力试验数据。最后,将各膜片弹簧模型在加、卸荷作用下的峰、谷荷载位移的平均值求和,得到峰、谷荷载位移。此外,将遗传算法引入膜片弹簧的优化设计中,得到了一种计算膜片弹簧振动特性的新方法。将A-L法、有限元法和本文方法与实测数据进行比较,验证了本文方法在计算膜片弹簧振动特性方面具有较高的精度。
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引用次数: 0
A Numerical Study to Investigate the Hydrodynamic Properties of Nanowire Motion in Liquid 纳米线在液体中运动的流体力学特性的数值研究
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.333
Manipulating micro(nano)-sized entities in liquid environment is a challenging yet necessary task in nanoscience and nanotechnology development. Due to the small dimensions, viscous behavior dominates the micro(nano)-sized obejcts motion. In this study, a computational fluid dynamic (CFD) approach has been used to investigate hydrodynamic effects on a nanowire (NM) translating an rotating about its long and short axis. Several numerical methods dealing with solid motion in fluid, including some CFD methods and Finite element analysis (FEA), have been compared. The change in drag coefficient with NW length, NW diameter, translational velocity, rotation speed, and wall effects has been researched. As a model, nanowires with 1-10 µm dimensions and 50 nm-250 nm diameters were investigated in liquid, with velocities of 0.5-500 µm/s. Nanowire is rotated about its long axis with an angular velocity of ω=0.25π, 0.5π, 1.0π, 2.0π rad/s, and about its short axis with a fluid flow allow the rotation of the nanowire whose one end is contsrained to a rotational motion around x and y axis. These models were also compared with the existing analytical models. Good agreement was observed between the numerical results and analytical calculations. The FEA model is also repeated in the closed boundary to investigate the wall effects on the nanowire’s motion in liquid environment.
在纳米科学和纳米技术的发展中,在液体环境中操纵微(纳米)尺寸的实体是一项具有挑战性但又必不可少的任务。由于微(纳)级物体的尺寸小,其粘性行为主导着其运动。本研究采用计算流体力学(CFD)方法研究了纳米线(NM)绕其长轴和短轴旋转时的水动力效应。比较了几种处理流体中固体运动的数值方法,包括一些CFD方法和有限元分析方法。研究了阻力系数随NW长度、NW直径、平动速度、转速和壁面效应的变化规律。作为模型,研究了尺寸为1-10µm,直径为50 nm-250 nm的纳米线在液体中,速度为0.5-500µm/s。纳米线绕其长轴以ω=0.25π, 0.5π, 1.0π, 2.0π rad/s的角速度旋转,绕其短轴以流体流动允许纳米线的一端绕x和y轴旋转运动。并与已有的分析模型进行了比较。数值计算结果与解析计算结果吻合较好。在封闭边界中重复有限元模型,研究壁面对纳米线在液体环境中运动的影响。
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引用次数: 0
Atmospheric Ice Accretion on Railway Overhead Powerline Conductors- A Numerical Case Study 大气冰在铁路架空电力线导线上的积聚——一个数值案例研究
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.253
Ice accretion on railway overhead contact wires/conductors can cause various critical operational and safety issues such as overloading, arc formation, mass imbalance, and wire galloping. The focus of this multiphase numerical study is to understand and analyze the ice accretion physics on railway overhead powerline conductors at various operating conditions. In this regard, two different geometric shape conductors of 12 mm diameter, 1) a grooved shape contact wire (like an actual railway conductor); 2) a standard circular shape contact wire are used. Computational Fluid Dynamics (CFD) based numerical simulations are carried out for both geometric configurations at different operating parameters such as wind speed, Liquid Water Content (LWC), cloud droplet size distribution, Median Volume Diameter (MVD), and atmospheric temperature. Analysis shows that variation in the operating weather parameters for both geometric configurations considerably affects the ice accretion, both in terms of accreted ice thickness and mass.
铁路架空接触导线/导线上的冰积会导致各种关键的操作和安全问题,如过载、电弧形成、质量不平衡和导线飞奔。本多相数值研究的重点是了解和分析不同运行条件下铁路架空电力线导线上的冰积物理特性。在这方面,两种不同几何形状的导线直径为12mm, 1)沟槽状接触导线(类似于实际的铁路导线);2)采用标准圆形接触线。在风速、液态水含量(LWC)、云滴大小分布、中位体积直径(MVD)和大气温度等不同运行参数下,对两种几何构型进行了基于计算流体力学(CFD)的数值模拟。分析表明,两种几何构型的运行天气参数的变化对冰的增加有很大的影响,无论是在冰的厚度和质量方面。
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引用次数: 0
Review on Self-Sustainable Power Generation Technologies for Future Typical Wearable Applications 未来典型可穿戴应用的自我可持续发电技术综述
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.349
Wearable technology has broad market prospects in the military, fire protection, medical and health, sports and other fields under its ability to effectively solve practical application needs. Self-powered energy systems with miniaturized, light-weight, highly flexible, stretchable, bendable, and wearable properties have received extensive attention in the industry as they can meet the needs of new-generation wearable electronic devices. Firstly, the article summarizes the recent progress and existing problems of flexible solar cells, flexible triboelectric nanogenerators, flexible piezoelectric nanogenerators, flexible thermoelectric generators, and energy harvesting devices for sweat power generation. Secondly, the development and challenges of flexible lithium-ion batteries and flexible super capacitors for energy storage devices are summarized. The research progress of energy management strategies is also discussed. Then, the main applications of self-powered systems in wearable electronic devices are introduced, including Individual Soldier Equipment, Protective Clothing Devices and Smart Wearable Electronic Devices. Finally, the future development direction of self-powered energy systems for wearable electronic devices is discussed.
可穿戴技术在其有效解决实际应用需求的能力下,在军事、消防、医疗卫生、体育等领域有着广阔的市场前景。自供电能源系统具有小型化、轻量化、高柔韧性、可拉伸、可弯曲、可穿戴等特点,能够满足新一代可穿戴电子设备的需求,受到业界的广泛关注。本文首先综述了柔性太阳能电池、柔性摩擦纳米发电机、柔性压电纳米发电机、柔性热电发电机以及用于汗液发电的能量收集装置的最新进展和存在的问题。其次,总结了柔性锂离子电池和柔性超级电容器储能器件的发展现状和面临的挑战。对能源管理策略的研究进展进行了讨论。然后介绍了自供电系统在可穿戴电子设备中的主要应用,包括单兵装备、防护服装备和智能可穿戴电子设备。最后,讨论了可穿戴电子设备自供电能源系统的未来发展方向。
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引用次数: 0
Study of Airflow Behavior for Duplex Circular Cylinders 双圆柱的气流特性研究
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.235
The modeling of atmospheric ice accretion on duplex cylinders received a limited attention, with modeling carried by Wagner and Qing et al. The publicly available experimental data about the ice accretion on the duplex cylinders is limited to experiments of Qing et al. and Veerakumar et al. When comparing the data of Wagner and Qing et al. with the results of Veerakumar et al., the major difference is the airflow behavior in the wake of the windward cylinder, the extent of the wake and recirculation bubble, and the velocity distribution in the wake. Thus, its needed to study the effect of the turbulence model on the airflow behavior of duplex cylinders, with focus being the behavior of the wake of the windward cylinder. This study reports the simulation results of the complex airflow behavior of duplex circular cylinder bundle obtained using several turbulence models employed by commercial CFD code.
双圆柱体上大气冰堆积的模拟受到了有限的关注,由Wagner和Qing等人进行了模拟。关于双筒冰的吸积的公开实验数据仅限于Qing et al.和Veerakumar et al.的实验。将Wagner和Qing等人的数据与Veerakumar等人的结果进行对比时,主要的差异在于迎风圆柱尾迹中的气流行为、尾迹和再循环气泡的范围以及尾迹中的速度分布。因此,有必要研究湍流模型对双柱体气流特性的影响,重点研究迎风柱体的尾迹特性。本文报道了利用商业CFD程序中几种湍流模型对双圆柱束复杂气流特性的模拟结果。
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引用次数: 0
Experimental investigation into the effect of spindle rotational speed on surface roughness and mechanical properties of aluminium 6082T651 welded by friction stir process 主轴转速对搅拌摩擦焊6082T651铝合金表面粗糙度及力学性能影响的实验研究
Q3 Engineering Pub Date : 2023-09-16 DOI: 10.21152/1750-9548.17.3.315
Selection of the correct parameters during the friction stir welding process is vital. The study entailed an analysis of the mechanical properties and microstructure of aluminium 6082T651 welded by friction stir welding at different spindle rotational speeds (500, 550, 600 and 650 rpm) and constant acceleration of 250 mm/min. Surface roughness of the welded samples was assessed according to ISO 25178. ASTM E384 and ASTM E8/E8M-09 standards were used for hardness and tensile tests respectively. The results show the highest tool rotational speed (650 rpm) to have produced the greatest weld surface roughness, of approximately 19.56 µm. The weldments made by friction stir welding at the highest tool rotational speed of 650 rpm displayed the best mechanical properties.
搅拌摩擦焊工艺参数的正确选择至关重要。研究了6082T651铝合金在不同转速(500、550、600和650 rpm)和恒定加速度(250 mm/min)下的搅拌摩擦焊接力学性能和显微组织。焊接样品的表面粗糙度根据ISO 25178进行评定。硬度和拉伸试验分别采用ASTM E384和ASTM E8/E8M-09标准。结果表明,最高的工具转速(650转/分)可以产生最大的焊缝表面粗糙度,约为19.56微米。在最高转速为650转/分的搅拌摩擦焊条件下,焊接件的力学性能最好。
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引用次数: 0
Convective Transport through Porous Layers 通过多孔层的对流传输
IF 0.7 Q3 Engineering Pub Date : 2020-03-31 DOI: 10.21152/1750-9548.14.1.53
E. Holzbecher
Convective motions are a multi-physics phenomenon, in which flow and transport processes interact in a two-way coupling. The density of the fluid depends on the value of transport variable and this back-coupling leads to non-linear behaviour. For the classical constellation of a closed fluid container heated from below convective motions appear, when a critical threshold for the Rayleigh number is exceeded. The heat transfer due to convection is much higher than in the case of pure conduction. Here systems of three layers are examined in detail. Using numerical CFD modelling it is shown that in layered systems different convective flow patterns appear than in the single layer case. The number and constellation of convection cells characterize steady flow patterns. Using a parametric sweep over the relevant parameter range of layer Rayleigh numbers and layer thicknesses we determine diagrams that show the excess heat or mass transfer of the dominant convection patterns, measured by the Nusselt- or Sherwood numbers.
对流运动是一种多物理场现象,其中流动和输运过程以双向耦合的方式相互作用。流体的密度取决于输运变量的值,这种反向耦合导致非线性行为。对于从下方加热的封闭流体容器的经典星座,当超过瑞利数的临界阈值时,就会出现对流运动。由对流引起的热传递比纯传导的情况下要高得多。这里详细地考察了三层体系。数值模拟表明,在分层系统中,对流流型与单层系统不同。对流细胞的数量和星座是稳定流动模式的特征。通过对层瑞利数和层厚度的相关参数范围进行参数扫描,我们确定了显示主要对流模式的多余热量或传质的图表,由努塞尔数或舍伍德数测量。
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引用次数: 0
Theoretical Analysis of Shear Wave Interference Patterns by Means of Dynamic Acoustic Radiation Forces. 动态声辐射力对横波干涉图样的理论分析。
IF 0.7 Q3 Engineering Pub Date : 2011-03-01 DOI: 10.1260/1750-9548.5.1.9
Kenneth Hoyt

Acoustic radiation forces associated with high intensity focused ultrasound stimulate shear wave propagation allowing shear wave speed and shear viscosity estimation of tissue structures. As wave speeds are meters per second, real time displacement tracking over an extend field-of-view using ultrasound is problematic due to very high frame rate requirements. However, two spatially separated dynamic external sources can stimulate shear wave motion leading to shear wave interference patterns. Advantages are shear waves can be imaged at lower frame rates and local interference pattern spatial properties reflect tissue's viscoelastic properties. Here a theoretical analysis of shear wave interference patterns by means of dynamic acoustic radiation forces is detailed. Using a viscoelastic Green's function analysis, tissue motion due to a pair of focused ultrasound beams and associated radiation forces are presented. Overall, this paper theoretically demonstrates shear wave interference patterns can be stimulated using dynamic acoustic radiation forces and tracked using conventional ultrasound imaging.

与高强度聚焦超声相关的声辐射力刺激剪切波传播,允许剪切波速度和组织结构的剪切粘度估计。由于波的速度是每秒几米,因此使用超声波在扩展视场上进行实时位移跟踪是有问题的,因为帧速率要求非常高。然而,两个空间分离的动力外源可以刺激横波运动,导致横波干涉图样。优点是剪切波可以在较低的帧率下成像,局部干涉图案的空间特性反映了组织的粘弹性特性。本文用动态声辐射力对横波干涉图样进行了理论分析。利用粘弹性格林函数分析,给出了一对聚焦超声光束和相关辐射力对组织运动的影响。总的来说,本文从理论上证明了剪切波干涉模式可以用动态声辐射力来激发,并使用传统的超声成像来跟踪。
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引用次数: 3
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International Journal of Multiphysics
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