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建立了某车身地板结构动力学有限元模型,通过分析自由模态固有频率和多点激励下频率响应,验证了车身地板数值分析模型的有效性。以地板结构各激励点最大振动速度的平方和最小化作为目标函数,建立了多目标拓扑优化模型。通过解读优化结果,提出了地板结构改进方案。改进后的车身地板结构各阶自由模态固有频率增加达10%以上,各激励点速度响应大大降低,NVH特性明显提高。研究表明,减小振动速度的多目标拓扑优化设计是一种改善车身NVH特性的有效方法。  相似文献   
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在以往的大地震中输电塔的破坏时有发生,输电塔倒塌的部分原因是由于相邻塔在地震动多点激励下异相振动产生的导线拉力引起。本文考虑导线的几何非线性,建立了输电塔-线体系三维有限元模型,分析了非平整场地上的结构体系在地震动纵向多点激励下的反应。基于经验相干函数和修正金井清功率谱密度函数模型模拟了空间变化地震动,分别考察了地震波视波速和相干损失对于结构体系地震反应的影响。结果表明,假定地震动一致激励不能准确评估结构体系的反应,地震动空间变化效应放大了输电塔和导线的地震反应,在强震作用下,忽略地震动的空间变化会严重低估输电塔-线体系的反应。  相似文献   
3.
关联规则的多支持度挖掘在销售数据中的应用   总被引:6,自引:1,他引:6  
李铭 《计算机工程》2003,29(8):92-93,99
介绍了一种关联规则的多支持度挖掘算法,并将该算法改进后用于超市销售数据的智能挖掘系统中,取得了成功的应用。  相似文献   
4.
The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This paper studied the fre-quency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical simulation.To avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation range.An optimization method was introduced in this paper to obtain the optimal clamp position.The experiments were intro-duced to validate the optimization results,and the theoretical optimization results can agree well with the test.With regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration frequency.And the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after optimization.Additionally,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration frequency.And the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to resonance.The sensitivity analysis results revealed the changing relationships between different clamp position and natural frequency.This study can provide helpful guidance on the analysis and design of practical aircraft pipeline.  相似文献   
5.
Seismic design for steel trussed arch to multi-support excitations   总被引:1,自引:0,他引:1  
The behavior of steel trussed arch to multi-support excitations is studied. The spatial variation of ground motion is modeled by an empirical coherency loss function. Numerical results indicate that horizontal multi-support excitations have a quite large amplification effect on the seismic responses of the trussed arch. This amplification effect cannot be ignored in the seismic design of such structures. Vertical multi-support excitations reduce the seismic responses of the trussed arch. Therefore the assumption that vertical free-field ground motions are spatially uniform is available to assure the degree of seismic safety reliability of the trussed arch. An average response spectrum method is subsequently introduced to calculate the arch response to multi-support excitations. The advantage of the method is that the linear peak seismic response of the arch to multi-support excitations can be obtained as conveniently as the conventional response spectrum method does. The good agreement of results between the time-history method and the average response spectrum method shows the validity of the latter method.  相似文献   
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