共查询到20条相似文献,搜索用时 62 毫秒
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基于大挠度动力控制方程,应用有限差分离散求解,研究了阶跃载荷作用下弹塑性悬臂梁的动力行为。通过对动力响应早期内力、变形以及能量分布规律的分析,考察了悬臂梁的弹塑性响应模式和变形机制,并与已有的刚塑性分析进行了系统的比较。数值计算表明,阶跃载荷的不同幅值使得梁的响应模式存在较大差异,弹塑性分析肯定了刚塑性理论在处理中载情形的准确性,同时也指出了其在处理低载和高载情形时的缺陷。通过与小变形理论计算结果的比较,指出了考虑大变形效应的必要性,为今后的大变形刚塑性动力分析提出了建议。 相似文献
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分别利用方程推导法、量纲分析法推导出了温度和压力作用下软岩线弹性变形范围内及流变过程中的相似准则,并进行了简单分析。以抗压强度、抗拉强度、弹性模量、泊松比、内聚力、内摩擦角、导热系数相似准则为指导,制备了一种以石蜡为粘结剂、河砂为主要骨料的页岩相似材料,并测定了其力学参数及导热系数。通过实验数据与相似准则计算数据的比较,结果表明,此种页岩相似材料与页岩原型材料具有较高的相似性,相似准则对于模型实验开展具有重要的指导意义。研究丰富了软岩流变相似理论体系,对于深部软岩工程开挖及支护具有重要的实用价值。 相似文献
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直杆碰撞刚性壁弹塑性动力后屈曲有限元分析 总被引:1,自引:0,他引:1
利用显式动力学有限元方法对直杆弹塑性动力后屈曲进行了分析,模拟了直杆轴向碰撞动力屈曲的变形及发展过程。分析中在直杆碰撞端局部临界屈曲长度范围内引入半正弦波形式的初始缺陷,计算结果与文献中的实验数据获得了很好的一致。分析结果表明,随着碰撞过程中所产生的应力波逐渐向前传播,后屈曲变形过程中所呈现的多个半波形式的高阶屈曲模态由初始具有单个半波形式的简单屈曲模态迅速演变而成。分析结果同时也揭示了直杆动力屈曲变形发展的机理,以及轴向应力波和屈曲变形的相互作用规律。 相似文献
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对于受轴向冲击载荷作用的薄壁圆管动态响应的相似律问题,由于圆管的薄壁特性导致厚度无法与高度和半径按相同的比例进行结构缩放,从而产生模型的几何畸变,此时传统的相似律已无法描述原型与畸变模型之间的动态响应规律。基于薄壁圆管轴向冲击问题的控制方程,通过能量守恒和量纲分析,推导了考虑几何畸变条件下轴向冲击载荷作用的理想弹塑性薄壁圆管动态响应的相似律。通过在给定应变与应变率区间上建立比例模型预测的流动屈服应力与原型流动屈服应力的最佳逼近关系,将几何畸变相似律进一步推广至包含应变率和应变硬化的材料。通过数值方法验证了提出的几何畸变模型相似律的适用性。分析结果表明,提出的考虑厚度畸变的受轴向冲击薄壁圆管的相似律可用于预测原型结构的冲击动态响应,并显著降低比例模型与原型结构平均载荷和能量的偏差。 相似文献
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盾构法隧道模型试验中的相似关系 总被引:4,自引:1,他引:3
盾构法是在软土中建造隧道常用的施工法.讨论其模型试验和实物之间的转换问题.根据Goodier理论建立相似关系,考虑了土体的黏弹塑性性质和大变形问题,包括推进压、推进速度、出土量、土体损失率、以及注浆量等施工参数对地层移动的影响.给出的公式可用于盾构法隧道的实验设计和数据分析. 相似文献
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A set of similarity relationships is developed and discussed for use in the study of transient and steadystate thermal displacements, strain and stresses between model and prototype. The similarity relationships are shown to be dependent upon the existing state of stress in the thermally loaded member. Their utilization in the design or analysis of data for such experimental techniques as photoelasticity and the moiré method is cited. 相似文献
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In the preceding article[1],the relation between thermodynamics condition andinceptive cavitation stage has been discussed.In this paper.we try to introduce thevolume function of inceptive cavitation bubbles.zo(r),instead of the energyequation used in the reference[1],for discussing cavitation similarity problem insimilar flow systems.Under this condition,theoretical result shows that theinception cavitation number K_i increases with a rise of geometry linear scale.Inother words,if two flow systems are kept with similar pattern and liquid,it isimpossible to satisfy the cavitation similarity,This conclusion accords withpractice. 相似文献
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This work discloses similarity properties of a high-aspect-ratio pulsating jet with lateral confinement exhibiting axis switching in a region close to the jet exit. The analysis is conducted separately within the major and minor planes of the jet source. The similarity relations derived from the in-plane flow equations are combined with experimental data collected in a recent three-dimensional velocimetry study of a glottal-like jet. Empirically, non-collapsing profiles are shown to rescale as collapsing profiles in the similarity variables within ranges of the streamwise coordinate, which are determined by the analysis. The similarity properties are shown to be useful to make predictions on the jet axis-switching characteristics. 相似文献
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Prof. S. S. Kutateladze 《Heat and Mass Transfer》1982,16(1):3-7
Fundamental problems of the heat transfer theory and physical hydrodynamics are associated with the most complicated processes of macrophysics: turbulence, multiphase and multi-component interactions and physico-chemical conversions of substances. In this field there are no good and sufficiently universal model equations. Moreover, the principal vista of their derivation is still obscure. The probabilistic essence of these processes in the small and almost classical determinancy on the average are the most important here. Similarity methods, mathematical and physical simulation, separation of conservative characteristics and elucidation of asymptotic processes are of the decisive character here. The German school of research workers has made a significant contribution to these studies.A compact representation of several important problems of this kind is just the subject of the present communication. Several data are the original results of the studies which have been performed by the author since 1935.The paper is preceded by a preface devoted to Professor U. Grigull on his 70th birthday.
Nomenclature U scale flow velocity (e.g., velocity outside boundary layer or average flow-rate velocity in channel) - R characteristic linear dimensions (e.g., tube radius, equivalent drop or bubble radius) - kinematic viscosity - density - surface tension coefficient - g gravitational acceleration - r latent heat of evaporation - T s saturation temperature - C specific heat - heat fransfer coefficient. Accents and correspond to liquid and gas (vapor), respectively Dedicated Prof. Dr.-Ing. Grigull on his 70th birthday. 相似文献
ähnlichkeitsanalyse und asymptotische Modelle
Zusammenfassung Die grundlegenden physikalischen Probleme der Wärmetransporttheorie und Hydrodynamik stellen sehr komplizierte Prozesse der Makrophysik dar wie: Turbulenz, die gegenseitige Einwirkung mehrphasiger und mehrkomponentiger Systeme sowie physico-chemische Umwandlung von Stoffen.Auf diesen Gebieten existieren keine guten und universellen Modellgleichungen. Darüber hinaus ist der prinzipielle Weg ihrer Herleitung noch immer unklar. Hier ist von Bedeutung, daß die Wirkung der Prozesse mit Hilfe klassischer Methoden durch mittlere Größen beschrieben werden können. ähnlichkeitsmethoden, mathematische und physikalische Simulation, Trennung von konservativen Merkmalen und die Betrachtung von asymptotischen Prozessen sind hier die entscheidenden Merkmale. Forscher der deutschen Schule haben hier einen bedeutenden Beitrag geleistet.Eine geraffte Darstellung verschiedener wichtiger Probleme dieser Art ist Thema des vorliegenden Beitrages. Einige Untersuchungen stellen Originalergebnisse dar, die vom Autor selbst seit 1935 durchgeführt wurden.
Nomenclature U scale flow velocity (e.g., velocity outside boundary layer or average flow-rate velocity in channel) - R characteristic linear dimensions (e.g., tube radius, equivalent drop or bubble radius) - kinematic viscosity - density - surface tension coefficient - g gravitational acceleration - r latent heat of evaporation - T s saturation temperature - C specific heat - heat fransfer coefficient. Accents and correspond to liquid and gas (vapor), respectively Dedicated Prof. Dr.-Ing. Grigull on his 70th birthday. 相似文献
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SIMILARITYSOLUTIONSOFTHESUPERKdVEQUATIONYuHuidan(俞慧丹)Zhang.Jiefang(张解放)(physicsDepartment,ZhejiangNormalUniversity,Jinhua,231... 相似文献
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The nature of the layers near the electrode, which occur in the case of dissipative flow of plasma in the channel of a powerful flow accelerator with a natural magnetic field, depends basically on the extent of the manifestation of the Hall effect [1, 2]. The nature of the layers nearthe electrode can be assessed according to the magnitude of the similarity parameter given below.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 117–118, January–February, 1972. 相似文献
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Theκ-εturbulence model,considering the effect of buoyancy on turbulentkinetic energy and its dissipation rate,is adopted to present a mathematical model forround plumes and jets.There are similarity solutions in the uniform environment.Taking into account the conservation of momentum and heat flux.Finite AnalyticMethod is applied to obtain the similarity functions of velocity,temperature andturbulent kinetic energy.The agreement between the calculated and experimental datais good. 相似文献