共查询到20条相似文献，搜索用时 375 毫秒
1.
An analytical sandwich beam model for piezoelectric bender elements is derived based on the first-order shear deformation theory （FSDT）, which assumes a single rotation angle for the whole cross-section and a quadratic distribution for coupled electric potential in piezoelectric layers. Shear coefficient is introduced to correct the effect of transverse shear strain on shear force and the electric displacement integration. Static and free vibration analyses of simply-supported bender elements are carried out for the sensor function. The results illustrate the high accuracy of the present model compared with the exact 2D solutions. 相似文献
2.
Correlation of liquefaction resistance with shear wave velocity based on laboratory study using bender element 总被引：1，自引：0，他引：1
INTRODUCTION Evaluation of soil liquefaction resistance is an important aspect of geotechnical engineering practice, and several types of evaluating procedures have evolved over the last three decades. The well known “simplified procedure” originated by Seed and Idriss (1971) can be used to evaluate liquefaction resistance based on standard penetration test (SPT) blow counts. Over the years, the simplified procedure has been modified and updated with additional data, and has become th… 相似文献
3.
INTRODUCTION Adequate information on dynamic soil proper-ties, especially dynamic shear modulus and dampingratio, is essential for accurate computations of groundresponse and soil-structure interaction problems.Many experimental investigations carried out onsandy soils through resonant column test or improvedcyclic triaxial test in early studies (Hardin and Richart1963; Hardin and Black, 1968; Drnevich and Richart,1970; Seed and Idriss, 1971; Kokusho, 1980) showedthat the small … 相似文献
4.
5.
蜂窝结构抗剪性能实验研究及其数值模拟 总被引：2，自引：0，他引：2
蜂窝结构以优异的力学性能,如比刚度大、比强度大、重量轻、良好的隔音隔热等,在建筑、工业锅炉、航空等结构中得到广泛的应用。抗剪性能是蜂窝结构主要力学性能之一,本文利用剪切实验和四点弯曲实验对PVC材料的圆形错排蜂窝结构的等效剪切模量及抗剪强度进行了实验研究,并利用有限元软件ANSYS对两种实验进行了三维有限元数值模拟。两种实验测得的等效剪切模量结果和数值模拟结果比较吻合。结果表明可以通过数值模拟对蜂窝结构的力学性能参数进行估算,并通过数值模拟为实验设计和工程实际设计理论依据和指导。 相似文献
6.
A three-dimensional finite element model was established for a large span concrete filled steel tubular (CFST) arch bridge which is currently under construction. The arch rib, the spandrel columns, the prestressed concrete box-beam, the cast-in-situ concrete plate of bridge deck, the steel box-beam and the crossbeams connecting the two pieces of arch ribs, were modeled by three-dimensional Timoshenko beam elements (3DTBE). The suspenders were modeled by three-dimensional cable elements (3DCE). Both geometric nonlinearity and prestress effect could be included in each kind of element. At the same time a second finite element model with the same geometric and material properties excepted for the sectional dimension of arch rib was set up. Static dynamic analyses were performed to determine the corresponding characteristics of the structure. The results showed that the arch rib's axial rigidity could be determined by static analysis. The stability and vibration of this system could be separated into in-plane modes, out-of-plane modes and coupled modes. The in-plane stability and dynamic characteristics are determined by the arch rib's vertical stiffness and that of out-of-plane is determined by the crossbeams' stiffness and arch rib's lateral stiffness mainly. The in-plane stiffness is much greater than that of out-of-plane for this kind of bridge . The effect of geometric nonlinearity and prestress effect on bridge behavior is insignificant. 相似文献
7.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｎｏｎｃｏｎｆｏｒｍｉｎｇｆｉｎｉｔｅｅｌｅｍｅｎｔＱ6(Ｗｉｌｓｏｎｅｔａｌ.,1 973)ｉｍｐｒｏｖｅｓｔｈｅａｃｃｕｒａｃｙｏｆｃｏｎｆｏｒｍ ｉｎｇｆｉｎｉｔｅｅｌｅｍｅｎｔＱ4ｂｙｉｎｃｏｒｐｏｒａｔｉｎｇｈｉｇｈｅｒｏｒ ｄｅｒｎｏｎｃｏｎｆｏｒｍｉｎｇｄｉｓｐｌａｃｅｍｅｎｔｓｗｈｉｃｈｒｅｄｕｃｅｔｈｅｓｈｅａｒｌｏｃｋｉｎｇ,ｓｏｆｔｅｎｔｈｅｓｔｉｆｆｎｅｓｓｏｆｃｏｍｐａｔｉ ｂｌｅｅｌｅｍｅｎｔｓａｎｄｉｎｃｒｅａｓｅｔｈｅｉｎｔｅｒｐｏｌａｔｉｏｎａｃ… 相似文献
8.
In this paper, a stabilized finite element technique, actualized by streamline upwind Petrov-Galerkin (SUPG) stabilized method
and three-step finite element method (FEM), for large eddy simulation (LES) is developed to predict the wind flow with high
Reynolds numbers. Weak form of LES motion equation is combined with the SUPG stabilized term for the spatial finite element
discretization. An explicit three-step scheme is implemented for the temporal discretization. For the numerical example of
2D wind flow over a square rib at Re=4.2×105, the Smagorinsky’s subgrid-scale (SSGS) model, the DSGS model, and the DSGS model with Cabot near-wall model are applied,
and their results are analyzed and compared with experimental results. Furthermore, numerical examples of 3D wind flow around
a surface-mounted cube with different Reynolds numbers are performed using DSGS model with Cabot near-wall model based on
the present stabilized method to study the wind field and compared with experimental and numerical results. Finally, vortex
structures for wind flow around a surface-mounted cube are studied by present numerical method. Stable and satisfactory results
are obtained, which are consistent with most of the measurements even under coarse mesh. 相似文献
9.
通过对中频液压弯管机基本结构和工作原理的介绍,说明了液压弯管机系统的角度控制要求,设计了以PLC为控制核心,采用旋转编码器控制弯管角度的测控系统,分析了角度测量的计算方法,研究了提高角度测量精度的方法,通过检测旋转编码器在单位时间内输出的脉冲数,与标准脉冲数进行比较,控制压机的进给值,从而控制压机的行程.给出PLC与旋转编码器组成的闭环控制系统的电路原理及主要控制程序的设计方法.其简洁的电路设计和典型的控制方法具有较高的参考价值,实际运行证明了系统自动化程度高,降低了对工人的技能要求,提高了加工的效率和质量. 相似文献
10.
WANG Yan-lei HAO Qing-duo OU Jin-ping 《重庆大学学报(英文版)》2007,6(3):221-226
In-plane shear properties of composite material laminates are very important in structural design of composite material. Four commonly used in-plane shear test methods were introduced in this paper. In order to study the differences of various shear test methods, two ASTM standard in-plane shear test methods for composite material laminates were experimentally investigated. They are ±45° tensile shear test (ASTM D3518) and V-notched rail shear test (ASTM D7078). Five types of composite material laminates composed of E-glass fiber fabric and vinyl ester resin were utilized, whose stacking sequences are 03s, 0/903s, CSM/0/902s, ±453s and (0/90)2/(±45)2/(0/90)2s, respectively. The test results indicate that the ±45° tensile shear test can predict shear moduli of composite material laminates accurately. However, the predictions of shear strength using ±45° tensile shear test are significantly lower than those of V-notched rail shear test. 相似文献
11.
阐述了一种以柔性铰链为核心部件的压弯微调机构,应用理论力学、材料力学等传统力学方法及结合数学知识对这种压弯微调机构进行了详细的力学分析和推导。表明了压弯微调机构所受外加载荷和晶体压弯曲率半径的函数解析式,说明了晶体尺寸和压弯机构参数对晶体压弯精度的影响,且推导出的压弯晶体曲率半径函数式可以为类似的压弯机构设计提供力学基础。 相似文献
12.
李克杰 《马钢职工大学学报》2013,(1):38-42
以结构基本自振周期的变化率作为自变量,构造识别精度较高的对数函数,将其作为结构损伤的表征量,借助有限元分析设计软件ETABS对14层钢筋混凝土纯剪力墙结构进行数值模拟,揭示了地震波属性（峰值速度与加速度之比）、结构高宽比及等效损伤位置、损伤程度对整体结构抗震性能的影响规律,提出了适用于RC剪力墙结构剩余抗震能力的评价模型。 相似文献
13.
The Wilson and Taylor elements Q6 and QM6, the representative nonconforming finite element method (FEM), have been successfully
developed and implemented in the finite element code SAP for improved displacement and stress analysis. This paper formulates
an improved convergent nonconforming axisymmetric element AQM6 over the corresponding axisymmetric Q6 and QM6 elements. The
proposed modified nonconforming axisymmetric element AQM6 satisfies the engineering patch test condition for convergence,
and also meets the condition for suppression of spurious shear stress by using a special remedying procedure. The numerical
test results are in agreement with the element performance.
Project supported by CAO Guangbiao High-Tech F. of Zhejiang Univ. (No. U19902), Zhejiang Edu. Committee SRF for Outstanding
Returned Overseas Scholars (No. G59990), US NSF (No. DDM-9313204) and Seiko Epson-Rutgers Univ. Project (No. 4-27365). 相似文献
14.
The effects of element or compound preexposure and retention interval were examined in three experiments with the taste-aversion paradigm. In Experiment 1, preexposure to the elements of a compound flavor produced less latent inhibition to the compound than did preexposure to the compound itself when a 1-day preexposure-conditioning interval was used. However, preexposing the elements or the compound resulted in equivalent latent inhibition effects when a 21-day retention interval was used. In Experiment 2, a similar pattern of results was observed when the conditioning-test interval was manipulated. Experiment 3 explored the effect of element or compound preexposure when preexposure and test were carried out in different contexts. Attenuated latent inhibition following preexposure to the elements was found when preexposure and test were carried out in the same context. In contrast, preexposure to the elements resulted in as much latent inhibition as did preexposure to the compound when the context was switched from preexposure to testing. The implications of these findings for a retrieval-oriented view of latent inhibition are discussed. 相似文献
15.
The free vibration and transient wave in a prestressed Rayleigh-Timoshenko beam subject to arbitrary transverse forces are analyzed by the newly developed method of reverberation-ray matrix （MRRM）. The effects of shear deformation and rotational inertia are taken into consideration. With a Fourier transform technique, the general wave solutions with two sets of unknown amplitude coefficients are obtained in the transformed domain for an unbonded prestressed beam under the action of arbitrary external excitations. From the coupling at joints and the compatibility of displacements in each member, the free and forced vibration responses of a beam with various boundary conditions are finally evaluated through certain numerical algorithms, Results are presented for a simply-supported beam subject to either a point fixed load or moving load. Good agreement with the finite element method （FEM） is obtained. The present work is instructive for high-speed railway bridge design and structural health monitoring. 相似文献
16.
陆惠云 《昆明师范高等专科学校学报》2008,30(1):61-63
测试员是影响测试效度直至真实性的最重要因素。普通话水平测试成绩主要来自测试人员的以下方面：1．评判标准;2．语言的感知能力;3．方音隔离;4．测试观与语音审美的趋向。要保证测试成绩的真实性和有效性,需要从三个因素来考虑对策：第一,测试的总体有用性需要实现最大化而不是强调某个影响测试有效性的独立因素;第二,测试的单个要素不能单独评价而是需要对它们对总体有用性的联合作用进行评价;第三,测试的有效性以及各个要素之间的合理平衡由特定的测试环境来决定。 相似文献
17.
The interaction between geogrid and soil is crucial for the stability of geogrid-reinforced earth structure. In finite element (FE) analysis, geogrids are usually assumed as beam or truss elements, and the interaction between geogrid and soil is considered as Coulomb friction resistance, which cannot reflect the true stress and displacement developed in the reinforcement. And the traditional Lagrangian elements used to simulate soil always become highly distorted and lose accuracy in high-stress blocks. An improved geogrid model that can produce shear resistance and passive resistance and a soil model using the Eulerian technique, in combination with the coupled Eulerian-Lagrangian (CEL) method, are used to analyze the interaction between geogrid and soil of reinforced foundation test in ABAQUS. The stress in the backfill, resistance of geogrid, and settlement of foundation were computed and the results of analysis agree well with the experimental results. This simulation method is of referential value for FE analysis of reinforced earth structure. 相似文献
18.
肖寿庄 《福建工程学院学报》2004,2(2):231-234
论述了钢筋混凝土薄板在两个平面内正应力和一个剪应力作用下的几种破坏类型，解释了破坏类型图的含义，给出了其计算过程，计算结果与试验结果吻合较好，并指出了其它文献中存在的不合理之处。 相似文献
19.
文中对PVC材料圆形错排蜂窝结构的拉压等效模量及抗拉、抗压强度进行了实验研究,并利用ANSYS进行了三维有限元数值模拟.通过实验结果和数值模拟结果的比较得出,拉伸情况下,等效弹性模量和拉伸强度受夹具与蜂窝结构间的粘胶性质影响比较大;压缩情况下,等效弹性模量和压缩强度大于拉伸情况,并且结构的主要破坏形式为剪切破坏。对蜂窝结构进行强度设计必须以实验数据为依据。 相似文献
20.
Up/down和"上/下"是英汉语中纵向位移的典型表达方式,在隐喻或转喻机制的作用下,又可描述横向位移。在两种用法中,这些词语之间的异同之处都与词义中融合的语义成分密切相关。Up/down和"上/下"的原型义都可概括为"位移"和"纵向",但"上/下"作为动词来源于方位名词,词义中分别融合了"接触/附着"和"接触/脱离"义,这个词源特征是造成英汉词语表达具体位移时差异的主要原因。 相似文献