装配式预应力混凝土梁与高强钢筋约束混凝土柱连接节点抗震性能试验研究

提出了一种新型全装配式预应力混凝土梁与高强钢筋约束混凝土柱端板螺栓连接节点形式,在低周反复水平荷载作用下,进行了6个装配式预应力中间节点试件和1个现浇节点试件的对比试验,得到了试件的破坏形态、滞回曲线、骨架曲线、延性系数、刚度退化以及耗能能力等抗震指标,确定了该新型装配式梁-柱连接节点的抗震性能。试验结果表明,新型全装配式预应力混凝土梁与高强钢筋约束混凝土柱端板螺栓连接节点试件均实现了"强柱弱梁"的设计目标。试件的滞回曲线饱满,抗震性能良好,研究成果可为预制装配式框架在地震区的推广应用提供理论依据和技术支持。     

双矩管装配式防屈曲支撑螺栓设计理论研究

装配式防屈曲支撑的外围约束构件主要通过高强螺栓连接形成整体,螺栓的布置及直径选取直接关系到外围构件是否能有效约束内核构件的侧向变形。为此,该文在双矩管装配式防屈曲支撑外围约束构件刚度取值及其设计方法较完善的前提下,通过考虑外围约束构件的螺栓布置间距、内核多波变形波长以及因外围约束构件板件局部变形引起的撬力影响来确定跨中螺栓内力;此外,还提出了端部螺栓的内力计算公式及端部螺栓加强方案,完善了双矩管装配式防屈曲支撑螺栓设计理论。     

一种分段式结构的变桨距垂直轴风力发电机研究

针对国内风电频率不稳定的问题,提出了一种分段式结构的变桨距垂直轴风力发电机方案.简要介绍了该变桨距垂直轴风力发电机的特点,并采用叶素理论和数值仿真方法对其气动性能进行了研究,结果表明此结构的变桨距垂直轴风力发电机在变桨距性能及叶片的强度和刚度方面更加优越,相信将对我国风力发电的发展起到一定的推动作用．     

损伤可控型钢框架边节点的试验研究

该文提出一种损伤可控型钢框架节点(DCSF节点)。在梁端腹板上设置连接钢板,通过高强摩擦螺栓将梁、柱拼接在一起,并在梁内布置预应力筋来提供节点的复位能力。在小震作用下,通过高强螺栓来提供节点的初始刚度和抗弯承载力;在中震作用下,通过螺栓杆在螺栓孔壁内的滑移来改善节点的耗能,以此避免梁、柱主体构件受到损伤。共设计完成了4个足尺试件的低周往复加载试验,分别考虑了连接钢板的不同接触表面、预应力筋的初张拉值以及高强螺栓预紧力对该类节点的初始刚度、损伤特征、滞回性能和自复位能力的影响。研究结果表明:高强螺栓在螺栓孔内的滑移为节点提供了良好的耗能能力;预应力筋能够减少结构的残余变形,提供节点的自复位能力;当层间位移角达2.4%时,主体构件未发现明显损伤,螺栓杆与孔壁发生挤压破坏,更换连接钢板后,节点的承载力和耗能能力基本不变,DCSF节点具有良好的抗震性能;节点的连接无需现场施焊,施工方便、快捷,可在地震区推广应用。     

新型单边拧紧高强度螺栓摩擦型连接扭矩系数及抗剪性能试验研究

为促进钢结构装配式建筑和可拆卸钢结构的连接技术发展,该文介绍了一种基于传统高强度螺栓的新型单边连接方式,并设计了5个摩擦型连接接头试件。通过开展抗剪试验,研究了其扭矩系数、抗滑移系数、抗剪承载力、抗剪机理等,并与《钢结构设计标准》(GB 50017—2017)的相关设计方法进行了对比分析。采用有限元软件ABAQUS建立了高强度螺栓连接接头试件的有限元模型,验证了有限元模型的准确性和适用性,并对该新型螺栓连接接头进行了参数分析。结果表明,该文提出的新型单边拧紧高强度螺栓摩擦型连接方式安装简单、易于施工和拆卸,抗剪连接破坏前螺栓预拉力损失值在15%~20%,其抗滑移系数、抗剪承载力仍可按照现行标准进行设计计算。研究成果能够为此类新型单边连接技术的工程应用提供基础。     

边柱失效后预应力拼接连接装配式结构抗连续倒塌机理研究

为了研究边柱失效工况下预应力拼接连接装配式结构的抗连续倒塌机理,在实验室开展了4个1/2缩尺预制梁-柱子结构模型试验。试验采用静载方式研究了3种预制装配式连接类型的抗连续倒塌性能。试验结果表明:采用不同连接类型的预制装配式子结构表现出不同的破坏模式;预应力拼接连接是一种有效抵抗连续倒塌的连接方式;采用混合连接结构抗力总是大于或等于钢绞线与角钢连接单独连接抗力之和;较高初始预应力可以增大试件在小变形阶段的抗力,但是会明显降低其大变形阶段的抗力。最后,通过商用有限元软件ANSYS/LSDYNA建立有限元模型,并在验证模型之后分析了试验中没有量测的关键结果,比如梁端弯矩变化,随后对关键设计参数开展了拓展参数分析。有限元结果表明:采用有粘结预应力较无粘结预应力结构抗力提高明显。当增大混凝土强度时,结构抗力也会随之提升。增大轴压比,会加重边柱的P-Δ效应,从而降低结构的变形能力和极限承载力。     

装配式干式连接剪力墙的设计方法研究

近年来,装配式剪力墙在实际工程中得以广泛应用。在其施工过程中,水平向相邻的两块预制墙板通常通过预留的后浇带装配在一起。该方法仍然需要大量的现场浇筑作业。因此,干式连接成为了进一步提高装配式结构施工效率和抗震性能的优化方案之一。该文针对一种新型装配式干式连接剪力墙的数值模拟及其设计方法开展了研究。建立了单层装配式干式连接剪力墙的有限元模型,并对其模拟了与前序拟静力试验相同的加载方案。模拟结果与试验结果吻合较好,从而验证了模型的有效性。基于以上建模方法,建立了2个具有不同参数的10层干式连接剪力墙的有限元模型,开展了Pushover分析,优化了干式连接件在高层结构中的设计。根据数值分析结果,提出了装配式干式连接剪力墙在高层建筑结构中基于振型的设计公式。     

基于SMA连接的装配式梁柱钢节点滞回性能数值研究

采用形状记忆合金(SMA)作为节点连接材料,可限制装配式钢结构在强震作用下的塑性变形,提升结构抗震韧性。该文以一种采用SMA连接的韧性抗震装配式钢节点为研究对象,建立精细化实体有限元模型,并通过试验验证模型的有效性,进而分析SMA螺栓预紧力和SMA束初始拉应力对装配式钢节点受力状态和滞回性能的影响。研究结果表明：建立的有限元模型可以较好地模拟装配式梁柱钢节点的滞回行为;SMA束连接的装配式梁柱钢节点具有极好的抗震韧性,在低周循环往复荷载作用下梁柱钢构件及其连接件基本维持在弹性范围内,且残余位移近似为零;提高螺栓预紧力可增大螺栓与钢板的摩擦力,进而提高梁柱节点的承载能力和耗能能力,但增大SMA束初始拉应力对梁柱节点的受力状态和滞回性能影响不显著。     

风力发电机组叶片连接高强螺栓的断裂原因分析

某风电场多台3MW风力发电机组在运行1.5a(年)后,叶片连接螺栓频繁发生断裂。通过化学成分分析、力学性能测试、金相分析及断口分析等方法,对其中一台风力发电机组的叶片连接螺栓断裂原因进行了分析。结果表明:该风电场叶片连接螺栓的断裂原因主要是材料中存在大量的氧化硅夹杂物,以及制造过程中热处理工艺控制不当导致的晶粒粗大等原因。且叶片连接螺栓安装及定期维护时预紧力分散度较大,使得螺栓在运行中受到复杂的应力条件下发生疲劳断裂失效。     

风力发电机塔筒紧固用高强螺栓断裂失效分析

某电力公司风力发电机塔筒底座紧固用高强螺栓使用4a(年)后,在进行检修时发现个别断裂现象。通过对螺栓断口进行宏观检验以及扫描电镜分析,并对螺栓材料进行化学成分分析、金相检验以及硬度测试,查明了螺栓断裂原因。结果表明:该螺栓断裂属于低应力高周疲劳断裂,螺栓在调质处理过程中发生严重的表面脱碳,导致螺栓表面硬度和强度降低,于是在应力集中的螺纹根部萌生裂纹,并疲劳扩展直至断裂。     

A computational procedure for prebending of wind turbine blades

Prebending of wind turbine blades constitutes a viable engineering solution to the problem of tower clearance, that is, ensuring that during wind turbine operation there is sufficient distance between the rotor blades and the tower to avoid collision. The prebent shape of the blade must be such that when the turbine rotor is subjected to wind and inertial loads, the blades are straightened into their design configuration. In this paper, we propose a method for accurate prediction of the prebent shape of wind turbine blades. The method relies on a stand‐alone aerodynamics simulation that provides the wind loads on a rigidly spinning rotor, followed by a series of structural mechanics simulations to determine the stress‐free prebent shape of the blade. This procedure involves only one‐way coupling between the fluid and structural mechanics, which avoids the challenges of solving the coupled fluid–structure interaction problem. The proposed methodology, which has no limitations on the blade geometry and structural modeling, is successfully applied to prebending of a 63‐m offshore wind turbine blade. Copyright © 2011 John Wiley & Sons, Ltd.     

考虑不同截面翼型选取的风电机组叶片优化设计方法

传统叶片优化设计中缺乏对截面翼型的考虑,导致叶片设计难以达到最优效果。为解决此问题,提出了考虑不同截面翼型的风电机组叶片优化设计方法,以截面翼型、弦长和扭角为设计变量,以年发电量最大化为目标,兼顾考虑相对厚度和相对弯度限制,建立了叶片参数设计遗传算法优化模型。以某1.5 MW风电机组为例,验证所提出优化设计方法的有效性。结果表明：考虑截面翼型等参数优化后的叶片功率系数明显增大;机组特性曲线在较大范围内均能保持在最佳功率系数附近,更易控制在最大风能捕捉效率点运行,从而提升了年发电量;同时,增加考虑相对厚度和相对弯度限制以更贴近实际工程应用。     

A parametric study of skin laminates used in the composite layup of large-scale wind turbine blades

To reach an optimal design solution for the composite layup of large-scale wind turbine blades, subjected to various design load conditions, while, fulfilling numerous design requirements, is a challenging task to accomplish. Since, a large-scale blade is a slender beam structure, therefore, its thin composite layup can be assumed to be under plane stress condition. Consequently, a parametric study of the skin laminates used in the blade composite layup, is conducted to explore and identify the possible design improvements. The results show that the use of off-axis fiber angles of the skin laminate lower than the conventional 45° are more favorable to achieve higher laminate stiffness, strength, bucking stability, fatigue resistance, and bend-twist coupling value, thereby, demonstrating the potential improvements to the existing composite layup design of large-scale wind turbine blade.     

Structural Analysis and Design of the Composite Wind Turbine Blade

The wind turbine blade sustains various kinds of loadings during the operation and parking state. Due to the increasing size of the wind turbine blade, it is important to arrange the composite materials in a sufficient way to reach the optimal utilization of the material strength. Most of the composite blades are made of glass fibers composites while carbon fibers are also employed in recent years. Composite materials have the advantages of high specific strength and stress. This study develops a GUI interface to construct the blade model for the stress analysis using ANSYS. With the aid of visualization interface, the geometric model of the blade can be constructed by only a few data inputs. Based on the numerical stress analysis of the turbine blade, a simple iterative method was proposed to design the structure of the composite blade.     

考虑叶片旋转效应的风力发电塔架结构风-震耦合响应分析EI北大核心CSCD

中国风电场大多不可避免的建于地震频发地段,在风荷载作用下风机正常工作时发生地震是一概率极大的事件。因此,该文以西北地区某2.5 MW风力发电机为原型,对考虑叶片旋转效应的风电塔架结构在风-震耦合作用下的响应展开研究。利用谐波叠加法生成考虑叶片与塔筒的空间相干性的模拟脉动风速时程;基于叶素动量理论,计算考虑叶片旋转效应的叶轮载荷,并采用尾流模型计算塔筒尾流区塔筒面的载荷;基于有限元软件ABAQUS建立考虑叶片及机舱偏心的集中质量有限元模型并对风力发电塔筒结构在风-震耦合作用下的响应进行分析;探讨了地震输入时刻对于风-震耦合作用下风电塔筒响应的影响。研究结果表明:叶轮旋转效应及尾流对于风荷载的计算影响较大;风-震耦合作用可能使塔顶位移较风荷载单独作用下的小,基底应力接近地震单独作用下的基底应力值;地震动输入时刻对风-震耦合分析有较大影响,建议在设计时予以考虑。     

Modeling Smart Structure of Wind Turbine Blade

With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for aerodynamic control systems with build-in intelligence on the blades. The paper aims to provide a way for modeling the adaptive wind turbine blades and analyze its ability for vibration suppress. It consists of the modeling of the adaptive wind turbine blades with the wire of piezoelectric material embedded in blade matrix, and smart sandwich structure of wind turbine blade. By using this model, an active vibration method which effectively suppresses the vibrations of the smart blade is designed.     

小型H型垂直轴风车叶片的设计分析

风力发电机(简称风车),是一种将风能转化为机械能,电能或热能的转换装置。比较了垂直轴风力发电机与水平轴风力发电机的优势后,对小型H型垂直轴风车叶片的进行了分析,给出了在不同工作环境中的载荷分析,并对叶片的应力计算及校核方法作了讨论,为小型H型垂直轴风车的叶片设计提供了参考。     

大型水平轴风力发电机桨叶稳定性研究

大型水平轴风力发电机桨叶为流-刚-柔耦合的周期时变多体系统。本文暂未考虑风载荷,分析了重力载荷和桨叶预锥角、转速等因素的变化对稳定性的影响。力学建模中,考虑了桨叶挥舞、摆振、扭转和轴向运动以及根部铰的挥舞、摆振和变矩等刚体运动。利用有限元法形成5节点18自由度的刚-柔混合梁单元模型,应用Hamilton原理建立桨叶动力学方程,求得对应的摄动方程,采用Newmark隐式积分方法求解。根据Floquet理论判断运动稳定性,计算了相关转换矩阵的特征值。结果表明预锥角对桨叶运动稳定性影响不容忽视。在通常的工况下,桨叶能够稳定地运转。     

A coupled aeroelastic damage progression model for wind turbine blades

The prediction of damage progression in composite wind turbine blades, especially under dynamic aeroelastic conditions, is usually a cumbersome multi-step process with significant manual user intervention. In this paper a novel approach is presented where the different components of this process – dynamical structural analysis under varying aerodynamic and deterministic loads, and damage progression – are integrated into one reduced-order model capable of predicting the occurrence and progression of damage in real time. Key to this integration is the use of an effective one-dimensional model of the turbine blade known as thin-wall beam model, which allows for the reconstruction of a three-dimensional stress field of a volume given by the blade. This stress field can then be used to assess damage and locally modify the structural properties to account for the presence of damage, leading to a reduced load carrying capacity. The model was previously tested in its components, demonstrating a good agreement of the predicted structural and static damage progression behaviour compared to detailed high-order finite-element models of the same blade. Once validated, the model was applied to severe load cases and the potential for real-time predictions of damage progression was demonstrated.     

Aerodynamic design and analysis of a 10 kW horizontal-axis wind turbine for Tainan,Taiwan

The purpose of the present study is to develop a small-scale horizontal-axis wind turbine (HAWT) suitable for the local wind conditions of Tainan, Taiwan. The wind energy potential was first determined through the Weibull wind speed distribution and then was adapted to the design of the turbine blade. Two numerical approaches were adopted in the design and analysis of the HAWT turbine blades. The blade element momentum theory (BEMT) was used to lay out the shape of the turbine blades (S822 and S823 airfoils). The geometry of the root region of the turbine blade was then modified to facilitate integration with a pitch control system. A mathematical model for the prediction of aerodynamic performance of the S822 and S823 airfoils, in which the lift and drag coefficients are calculated using BEMT equations, was then developed. Finally, computational fluid dynamics (CFD) was used to examine the aerodynamic characteristics of the resulting turbine blades. The resulting aerodynamic performance curves obtained from CFD simulation are in agreement with those obtained using BEMT. It is also observed that separation flow occurred at the turbine blade root at the tip speed ratios of 5 and 7.