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基于Python-ABAQUS的三维细观凹凸骨料建模及骨料不同形状影响分析

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科学技术与工程 2024年第23期24卷 10022-10031页

作者：孙茂增朱吉鹏南京理工大学物理学院南京210094

为了探究混凝土内部细观尺度下的损伤机理,利用Python语言对ABAQUS进行二次开发,建立了包含界面过渡区的三维细观凹凸型骨料混凝土模型,并提出了一种可直接用于判断凹凸型骨料空间干涉的方法。随后,对该模型进行准静态下的数值模拟,以... 详细信息

为了探究混凝土内部细观尺度下的损伤机理,利用Python语言对ABAQUS进行二次开发,建立了包含界面过渡区的三维细观凹凸型骨料混凝土模型,并提出了一种可直接用于判断凹凸型骨料空间干涉的方法。随后,对该模型进行准静态下的数值模拟,以验证其可靠性。最后,进行了不同骨料形状下的单轴压缩数值模拟分析。研究结果表明,采用本方法可以实现60%以上的骨料体积比的高密实投放。在不同形状的骨料下,混凝土的抗压强度方面影响不大;然而,在导致混凝土裂缝扩展与体积破坏方面,不同形状的骨料产生较大影响。随着骨料表面凹凸性和不规则程度的增加,混凝土受压时的损伤破坏程度逐步加深。这些发现有助于更深入地理解混凝土内部损伤机理,并为混凝土结构设计提供了有益的参考。

关键词：三维细观模型凹凸型骨料 Python 干涉判断骨料形状

中型轻质混凝土夹芯复合自保温砌块性能特点与工程应用研究

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砖瓦 2024年第7期 24-28页

作者：孙茂川山东省调水工程运行维护中心福山管理站山东烟台265500

为了更好地满足北方严寒和寒冷地区建筑节能设计要求和防火设计规定,新型建筑外墙保温结构一体化技术不断涌现,轻质无机材料类自保温砌块陆续在民用建筑非承重外围护结构中推广应用。对比分析泡沫混凝土应用现状和特点、泡沫混凝土砌块... 详细信息

为了更好地满足北方严寒和寒冷地区建筑节能设计要求和防火设计规定,新型建筑外墙保温结构一体化技术不断涌现,轻质无机材料类自保温砌块陆续在民用建筑非承重外围护结构中推广应用。对比分析泡沫混凝土应用现状和特点、泡沫混凝土砌块主要性能和适用性,结合中型自保温砌块墙体构造组成及工程应用性能,指出中型轻质混凝土夹芯复合自保温砌块集合了传统泡沫混凝土的轻质高强、保温隔热和无机防火性能特点,将内外叶掺加固废料的改性块材与纤维增强塑料(FRP)保温板或钢丝焊接网架保温板复合为一体,通过自然养护方式在工厂化预制成型,降低了产品成本,提高了建筑外墙装配率和施工效率,防火和热工性能优良,墙体厚度260mm即可满足北方寒冷地区节能83%标准要求。

关键词：中型砌块自保温砌块夹芯轻质混凝土泡沫混凝土

Wing/body kinematics measurement and force and moment analyses of the takeoff flight of fruitflies

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Acta Mechanica Sinica 2014年第4期30卷 495-506页

作者： mao-Wei Chen mao sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University

In the paper, we present a detailed analysis of the takeoff mechanics of fruitflies which perform voluntary takeoff flights. Wing and body kinematics of the insects during takeoff were measured using Based on the measured data, high-speed video techniques. inertia force acting on the insect was computed and aerodynamic force and moment of the wings were calculated by the method of computational fluid dynamics. Subtracting the aerodynamic force and the weight from the inertia force gave the leg force. The following has been shown. In its voluntary takeoff, a fruitfly jumps during the first wingbeat and becomes airborne at the end of the first wingbeat. When it is in the air, the fly has a relatively large ＂initial＂ pitch-up rotational velocity （more than 5 000~/s） resulting from the jumping, but in about 5 wingbeats, the pitch-up rotation is stopped and the fly goes into a quasi-hovering flight. The fly mainly uses the force of jumping legs to lift itself into the air （the force from the flapping wings during the jumping is only about 5%-10% of the leg force）. The main role played by the flapping wings in the takeoff is to produce a pitch-down moment to nullify the large ＂initial＂ pitch-up rotational velocity （otherwise, the fly would have kept pitching-up and quickly fallen down）.

关键词： Fruitfly· Takeoff flight ·Body and wing kine-matics Aerodynamic and leg forces

Wing Kinematics, Aerodynamic Forces and Vortex-wake Structures in Fruit-flies in Forward Flight

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Journal of Bionic Engineering 2016年第3期13卷 478-490页

作者： XueguangMeng mao sun Institute of Fluid Mechanics Beijing University of Aeronautics and Astronautics Beijing 100191 China

Wing kinematics in forward-flying fruit-flies was measured using high-speed cameras and flows of the flapping wing were calculated numerically. The large lift and thrust coefficients produced by the wing were explained. The wing flaps along a forward-tilting stroke plane. In the starting portion of a half-stroke （an upstroke or downstroke）, the wing pitches down to a small pitch angle; during the mid portion （the wing has built up its speed）, it first fast pitches up to a large pitch angle and then maintains the pitch angle; in the ending portion, the wing pitches up further. A large aerodynamic force （normal to the wing surface） is produced during the mid portion of a half-stroke. The large force is produced by the fast-pitching-up rotation and delayed-stall mechanisms. As a result of the orientation of wing, the thrust that propels the insect is produced by the upstroke and the major part of the vertical force that supports the weight is produced by the downstroke. In producing the thrust the upstroke leaves a ＂vortex ring＂ that is almost vertical, and in producing the vertical force the downstroke leaves a ＂vortex ring＂ that is almost horizontal.

关键词： fruit-fly wing kinematics forward flight Navier-Stokes simulation vortex

The effects of corrugation and wing planform on the aerodynamic force production of sweeping model insect wings

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Acta Mechanica Sinica 2005年第6期21卷 531-541页

作者： Guoyu Luo mao sun Ministry-of-Education Key Laboratory of Fluid Mechanics Institute of Fluid Mechanics Beihang University Beijing 100083 China

The effects of corrugation and wing planform （shape and aspect ratio） on the aerodynamic force production of model insect wings in sweeping （rotating after an initial start） motion at Reynolds number 200 and 3500 at angle of attack 40℃ are investigated, using the method of computational fluid dynamics. A representative wing corrugation is considered. Wing-shape and aspect ratio （AR） of ten representative insect wings are considered; they are the wings of fruit fly, cranefly, dronefly, hoverfly, ladybird, bumblebee, honeybee, lacewing （forewing）, hawkmoth and dragon- fly （forewing）, respectively （AR of these wings varies greatly, from 2.84 to 5.45）. The following facts are shown. （1） The corrugated and flat-plate wings produce approximately the same aerodynamic forces. This is because for a sweeping wing at large angle of attack, the length scale of the corrugation is much smaller than the size of the separated flow region or the size of the leading edge vortex （LEV）. （2） The variation in wing shape can have considerable effects on the aerodynamic force; but it has only minor effects on the force coefficients when the velocity at r2 （the radius of the second ：moment of wing area） is used as the reference velocity; i.e. the force coefficients are almost unaffected by the variation in wing shape. （3） The effects of AR are remarkably small： whenAR increases from 2.8 to 5.5, the force coefficients vary only slightly; flowfield results show that when AR is relatively large, the part of the LEV on the outer part of the wings sheds during the sweeping motion. As AR is increased, on one hand, the force coefficients will be increased due to the reduction of 3-dimensional flow effects; on the other hand, they will be decreased due to the shedding of part of the LEV; these two effects approximately cancel each other, resulting in only minor change of the force coefficients.

关键词： insect flight - Sweeping wing Unsteady aerodynamics Wing corrugation Planform

Aerodynamic Effects of Corrugation in Flapping Insect Wings in Forward Flight

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Journal of Bionic Engineering 2011年第2期8卷 140-150页

作者： Xueguang Meng mao sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beijing University of Aeronautics & Astronautics Beijing 100083 P. R. China

We have examined the aerodynamic effects of corrugation in model wings that closely mimic the wing movements of a forward flight bumblebee using the method of computational fluid dynamics. Various corrugated wing models were tested （care was taken to ensure that the corrugation introduced zero camber）. Advance ratio ranging from 0 to 0.57 was considered. The results shown that at all flight speeds considered, the time courses of aerodynamic force of the corrugated wing are very close to those of the flat-plate wing. The cornlgation decreases aerodynamic force slightly. The changes in the mean location of center of pressure in the spanwise and chordwise directions resulting from the corrugation are no more than 3% of the wing chord length. The possible reason for the small aerodynamic effects of wing corrugation is that the wing operates at a large angle of attack and the flow is separated： the large angle of incidence dominates the corrugation in determining the flow around the wing, and for separated flow, the flow is much less sensitive to wing shape variation.

关键词： insect flapping forward flight wing corrugation aerodynamics

Power Requirements of Vertical Flight in the Dronefly

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Journal of Bionic Engineering 2015年第2期12卷 227-237页

作者： Chong Shen mao sun Institute of Fluid Mechanics Beijing University o[Aeronautics & Astronautics Beijing 100191 China

Power requirements in vertical flight in the dronefly （Eristarlis tenax; also known as hoverfly） are studied using the metnoa of computational fluid dynamics. The flow solution provides the aerodynamic forces and torques; the inertial torques due to the acceleration of the wing-mass are computed analytically. From the aerodynamic and inertial torques, the mechanical power is obtained. It has been shown that at hovering flight, the specific power with 100% elastic energy storage is 43.51 *** · and that without elastic energy storage is 60.12 W·kg-1. During vertical flight, the specific power increases with the ascending ratio K （ratio of the ascending velocity to the tip velocity）; it is proportional to K to the power of about 1.37. When flying upward at an ascending ratio of about 0.3, the power required is the same as that when the insect carries a load of about 50% of its weight.

关键词： insect upward flying Navier-Stokes simulation flight balance flight power

Dynamic flight stability of a model dronefly in vertical flight

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Acta Mechanica Sinica 2014年第6期30卷 828-838页

作者： Chong Shen mao sun Institute of Fluid Mechanics Beijing University of Aeronautics & Astronautics

The dynamic flight stability of a model dronefly in hovering and upward flight is *** method of computational fluid dynamics is used to compute the stability derivatives and the techniques of eigenvalue and eigenvector used to solve the equations of *** major finding is as *** flight of the model dronefly is unstable because of the existence of an unstable longitudinal and an unstable lateral natural mode of *** flight of the insect is also unstable,and the instability increases as the upward flight speed *** force generated by the upward flight velocity coupled with the disturbance in pitching angular velocity is responsible for the enhancement of the instability.

关键词： Insect vertical flight Flight stability Natural modes of motion

Lateral Flight Stability of Two Hovering Model Insects

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Journal of Bionic Engineering 2014年第3期11卷 439-448页

作者： Na Xu mao sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University Beijing 100191 P. R. China

The longitudinal disturbance motion of different insects at hovering flight has the same modal structure. Here, we consider the case of lateral motion. The lateral dynamic flight stability of two model insects, hoverfly and honeybee, at hovering flight is studied. The method of computational fluid dynamics is applied to compute the stability derivatives. The techniques of eigenvalue and eigenvector analysis are used to solve the equations of motion. Results show that the lateral disturbance motion of the hoverfly has three natural modes of motion： an unstable divergence mode, a stable oscillatory mode and a stable subsidence mode, and the flight is unstable; while the honeybee has a different modal structure （a stable slow subsidence mode, a stable fast subsidence mode, and a nearly neutrally stable oscillatory mode） and the flight is nearly neutrally stable. The change in modal structure between the two insects is due to their roll-moment/side-velocity derivative having different sign, and the sign difference is because that the hoverfly has a relatively small, but the honeybee has a relatively large, distance between the wing roots and the center of mass. Thus, unlike the case of longitudinal motion, for lateral motion, some insects have different modal structures and stability properties from others.

关键词： insect hovering flight dynamic flight stability modal structure