在地震动过程中,土介质中的剪切波速往往出现显著的降低现象,体现出强烈的非线性性质。本文将随机振动的虚拟激励原理、土非线性分析的等效线性化方法与工程波动理论散射问题的求解方法相结合,建立了开放系统中一致激励条件下考虑岩土...在地震动过程中,土介质中的剪切波速往往出现显著的降低现象,体现出强烈的非线性性质。本文将随机振动的虚拟激励原理、土非线性分析的等效线性化方法与工程波动理论散射问题的求解方法相结合,建立了开放系统中一致激励条件下考虑岩土介质非线性的工程场地地震动随机场数值模拟方法。该方法将随机输入下的波动分析问题转换为虚拟激励下的确定性波动分析问题,非线性土体峰值剪应变的统计特征可通过剪应变均方差和峰值因子获得。结合具体算例及M on te—C arlo模拟方法对所提出方法的合理性进行了验证,在此基础上应用该方法对一致激励下实际工程场地的地震动相干性进行分析,结果表明场地的局部条件对地震动相干性有重要影响。展开更多
A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to ...A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.展开更多
Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate...Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the octagon elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90° phase difference voltages were applied to the ceramics on vertical surfaces. When the AC voltage with 90° phase difference was applied in ceramics, the elliptical displacement of unimorph bars was generated by generating bending vibration. To find the maximum displacement model that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As a result, the speed and torque are increased linearly by increasing the input voltage and the speed of motors can be controlled by changing the applied voltages.展开更多
Many high earth-rockfill dams are constructed in the west of China. The seismic intensity at the dam site is usually very high, thus it is of great importance to ensure the safety of the dam in meizoseismal area. A 3D...Many high earth-rockfill dams are constructed in the west of China. The seismic intensity at the dam site is usually very high, thus it is of great importance to ensure the safety of the dam in meizoseismal area. A 3D FEM model is established to analyze the seismic responses of Shiziping earth-rockfill dam. The nonlinear elastic Duncan-Chang constitutive model and the equivalent viscoelastic constitutive model are used to simulate the static and dynamic stress strain relationships of the dam materials, respectively. Four groups of seismic waves are inputted from the top of the bedrock to analyze the dynamic responses of the dam. The numerical results show that the calculated dynamic magnification factors display a good consistency with the specification values. The site spectrum results in larger acceleration response than the specification spectrum. The analysis of relative dynamic displacement indicates that the displacement at the downstream side of the dam is larger than that at the upstream side. The displacement response reduces from the center of river valley to two banks. The displacement responses corresponding to the specification spectrum are a little smaller than those corresponding to the site spectrum. The analysis of shear stress indicates that a large shear stress area appears in the upstream overburden layer, where the shear stress caused by site waves is larger than that caused by specification waves. The analysis of dynamic principal stress indicates that the minimum dynamic stresses in corridor caused by specification and site waves have little difference. The maximum and minimum dynamic stresses are relatively large at two sides. The largest tensile stress occurs at two sides of the floor of grouting corridor, which may result in the crack near the corridor side. The numerical results present good consistency with the observation data of the grouting corridor in Wenchuan earthquake.展开更多
文摘在地震动过程中,土介质中的剪切波速往往出现显著的降低现象,体现出强烈的非线性性质。本文将随机振动的虚拟激励原理、土非线性分析的等效线性化方法与工程波动理论散射问题的求解方法相结合,建立了开放系统中一致激励条件下考虑岩土介质非线性的工程场地地震动随机场数值模拟方法。该方法将随机输入下的波动分析问题转换为虚拟激励下的确定性波动分析问题,非线性土体峰值剪应变的统计特征可通过剪应变均方差和峰值因子获得。结合具体算例及M on te—C arlo模拟方法对所提出方法的合理性进行了验证,在此基础上应用该方法对一致激励下实际工程场地的地震动相干性进行分析,结果表明场地的局部条件对地震动相干性有重要影响。
基金Projects(51275235, 50975135) supported by the National Natural Science Foundation of ChinaProject(U0934004) supported by the Natural Science Foundation of Guangdong Province, ChinaProject(2011CB707602) supported by the National Basic Research Program of China
文摘A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.
基金Project supported by the Second Stage of Brain Korea 21 Projectssupported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MEST) [No.2011-0030806]
文摘Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the octagon elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90° phase difference voltages were applied to the ceramics on vertical surfaces. When the AC voltage with 90° phase difference was applied in ceramics, the elliptical displacement of unimorph bars was generated by generating bending vibration. To find the maximum displacement model that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As a result, the speed and torque are increased linearly by increasing the input voltage and the speed of motors can be controlled by changing the applied voltages.
基金Foundation item： Project（IRTl125） supported by the Program for Changjiang Scholars and Innovative Research Team in Universities of China Project（B13024） supported by the ＂111＂ Project Project（BK2012811） supported by the Natural Science Foundation of Jiangsu Province, China
文摘Many high earth-rockfill dams are constructed in the west of China. The seismic intensity at the dam site is usually very high, thus it is of great importance to ensure the safety of the dam in meizoseismal area. A 3D FEM model is established to analyze the seismic responses of Shiziping earth-rockfill dam. The nonlinear elastic Duncan-Chang constitutive model and the equivalent viscoelastic constitutive model are used to simulate the static and dynamic stress strain relationships of the dam materials, respectively. Four groups of seismic waves are inputted from the top of the bedrock to analyze the dynamic responses of the dam. The numerical results show that the calculated dynamic magnification factors display a good consistency with the specification values. The site spectrum results in larger acceleration response than the specification spectrum. The analysis of relative dynamic displacement indicates that the displacement at the downstream side of the dam is larger than that at the upstream side. The displacement response reduces from the center of river valley to two banks. The displacement responses corresponding to the specification spectrum are a little smaller than those corresponding to the site spectrum. The analysis of shear stress indicates that a large shear stress area appears in the upstream overburden layer, where the shear stress caused by site waves is larger than that caused by specification waves. The analysis of dynamic principal stress indicates that the minimum dynamic stresses in corridor caused by specification and site waves have little difference. The maximum and minimum dynamic stresses are relatively large at two sides. The largest tensile stress occurs at two sides of the floor of grouting corridor, which may result in the crack near the corridor side. The numerical results present good consistency with the observation data of the grouting corridor in Wenchuan earthquake.
