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Search Results: 1 - 10 of 47666 matches for " 邢誉峰 "
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有限长Timoshenko梁弹性碰撞接触瞬间的动态特性

力学学报 , 1999, DOI: 10.6052/0459-1879-1999-1-1995-006
Abstract: 给出了质点与有限长Timoshenko梁横向弹性碰撞接触问题的半解析解,分析了该碰撞问题在碰撞接触瞬间的动态响应特性揭示了其中的波传播现象.
弹性地基上矩形薄板自由振动的精确解
徐腾飞,
工程力学 , 2014, DOI: 10.6052/j.issn.1000-4750.2012.12.0962
Abstract: 根据分离变量法得到了Winkler弹性地基上矩形薄板自由振动问题的精确解,分析了地基模量对频率的影响,其中边界条件为CCCC、SCCC和SSCC情况的精确解过去被认为是难以得到的。在分离变量方法中,不需要事先人为的选取满足某一组对边边界条件的挠度函数,而是直接利用控制方程本征根给出振型函数通解的一般解析形式,再利用边界条件得到振型函数系数和频率方程的精确形式。数值结果与有限元结果及文献结果吻合较好,验证了该文方法和结果的的正确性。
动力学平衡方程的Euler中点辛差分求解格式
杨蓉
力学学报 , 2007, DOI: 10.6052/0459-1879-2007-1-2006-026
Abstract: 给出了动力学方程${\pmbM}\ddot{\pmbx}+{\pmbC}\dot{\pmbx}+{\pmbK\pmbx}={\pmbR}$的二阶Euler中点隐式差分求解格式,分保守系统、无阻尼受迫振动系统和阻尼系统3种情况,讨论了算法中Jacobi矩阵${\pmbA}$的性质,譬如${\pmbA}$是否为辛矩阵以及谱半径等.对于无阻尼系统,证明了无论是否存在外载荷,Jacobi矩阵都是辛矩阵.证明了辛矩阵的所有本征值的模为1,其谱半径永远为1,以及$\delta=0.5$和$\alpha=0.25$的Newmark算法就是Euler中点隐式差分格式,对保守系统它们都是辛算法.严格证明了Euler中点辛格式是严格保持系统能量的.通过算例详细讨论了保辛算法用于求解非保守系统动态特性的优越性,如广义保结构特性等;分析了保辛算法的相位误差以及由其引起的系统的附加能量特性;分析了保辛算法和$\delta\ne0.5$的Newmark算法的精度随着激励频率与系统固有频率比的变化情况等
与结构动特性协同的自适应Newmark方法
,郭静
力学学报 , 2012, DOI: 10.6052/0459-1879-12-033
Abstract: 提出了一种与结构动特性协同的自适应Newmark方法,其参数可基于数值弥散和数值耗散最小化的条件用解析方法求得.对线性单自由度动力学系统,该方法的相位误差精确为零并且谱半径为1.对线性多自由度系统和非线性系统,该方法在所有二阶积分解法中最精确.数值结果验证了新提出格式的高精度和结论.
形函数分段定义的弯矩梁特征单元
杨阳
力学学报 , 2008, DOI: 10.6052/0459-1879-2008-2-2007-263
Abstract: 基于势能原理,根据梁单胞在单位弯矩作用下的静力特性分析,提出了一种允许单元内部存在材料和几何性质不连续的新的梁特征单元,称之为弯矩梁特征单元.与已有特征单元方法、均匀化方法和一般有限元方法进行了数值比较和分析,位移、内力和频率结果说明了弯矩梁特征单元在精度和效率方面的优越性.弯矩梁特征单元具有双尺度特征,为构造编织等周期性复合材料结构的宏细观力学行为分析提供了一种思想和方法.
单步辛算法的相位误差分析及修正
杨蓉
力学学报 , 2007, DOI: 10.6052/0459-1879-2007-5-2006-561
Abstract: 若一个算法的幅值误差和相位误差都不累加,则该算法就是最理想的算法,但这样的算法难以构造.辛几何算法解决了幅值误差的累加问题,但相位误差累加问题仍然存在.给出了单步隐式辛算法相位误差的精确估计公式,提出了简单而实用的修正方法.以Euler中点隐式辛差分格式为例,针对几个线性动力学系统,对相位误差进行了数值分析和修正.
梁纵向与横向耦合非线性振动分析
Nonlinear vibration analysis of longitudinal-transverse coupled beam

,梁昆
- , 2015, DOI: 10.13700/j.bh.1001-5965.2014.0556
Abstract: 摘要 纵向振动和横向振动耦合是捆绑火箭等结构中的典型振动现象.以Rayleigh梁为研究对象,通过Hamilton变分原理推导了考虑应变二次项的纵向振动与横向振动耦合控制方程,并用有限元方法对该非线性系统的行为进行了模拟.针对线性系统固有振动频率和非线性纵横耦合动态响应情况,把所得结果与NASTRAN结果进行了比较,二者结果吻合,证明了本方法的正确性.在此基础上,借助振动控制方程和模拟结果,讨论了非线性系统频率与模态的时变特性,非线性动态响应频率成分特性,横向振动和纵向振动相互影响以及共振现象等.研究结果为本方法的实际应用提供了理论基础.
Abstract:The coupling phenomenon of longitudinal and transverse vibration is representative in boost rocket. Taking longitudinal and transverse vibration coupling into account by using the second order term of longitudinal strain, the governing differential equations of Rayleigh beam was derived through Hamilton variational principle, and the finite element method was employed to explore the behaviors of this nonlinear coupling system. As for the inherent frequency of the corresponding linear system and the dynamic responses of nonlinear longitudinal and transverse coupling system, the obtained results were in agreement with those of NASTRAN, which validated the correctness of present method and results. According to characteristics of the viberation governing equations and the results of finite element method, the analyses focused on the time-variable property of nonlinear system frequency, the amplitude-frequency characteristic of nonlinear dynamical responses, the mutual effects of the longitudinal and transverse vibration and resonant phenomenon when the combinations of frequencies of exciting forces are closer to the frequency of the nonlinear system. The results of present study lie the theoretical foundation for the practical application of the present method.
THE CHARACTERISTICS OF TIMOSHENKO BEAM DURING THE PROCESS OF ELASTIC IMPACT AND CONTACT
有限长Timoshenko梁弹性碰撞接触瞬间的动态特性

Xing Yufeng,

力学学报 , 1999,
Abstract: In this paper, the semi-analytical solutions for a particle impacting on simply-supported Timoshenko beam with finite length is obtained by using the method of mode superposition. The characteristics of impact loads varying with respect to time is given, several interesting conclusions about the impact loads are presented, and the exact values of impact loads at initial moment of impact is derived and verified. The propagating characteristics of longitudinal waves and shear waves in a finite-length beam is also presented. The influences of lateral shear waves and longitudinal waves on impact loads, shear forces and bending moment are thoroughly analyzed through numerical results. And it can be concluded from the results of this paper that the effects of shear waves on impact loads and impact-contact time is lager than that of longitudinal waves.
A MATHEMATICAL CONVERGENCE ANALYSIS OF THEDUAL METHOD BY EXPANSION OF ORIGINAL/RECIPROCALVARIABLES BASED ON THE CUMULATIVE INFORMATIONAT TWO POINTS
基于两点累积信息原/倒变量展开的对偶优化方法的收敛性分析

,钱令希
计算数学 , 1996,
Abstract: Abstract This paper is concerned with the Dual method by Expansion of Original/ Reciprocal variables based on the Cumulative information at Two points, which isabbreviated to DEORCT. We give here a mathematical convergence analysis ofthis method.
变质量梁的自适应Newmark法
王宇楠,
北京航空航天大学学报 , 2014, DOI: 10.13700/j.bh.1001-5965.2013.0400
Abstract: 用变质量梁来模拟推进剂减少的液体火箭.先以一弹簧-变质量小球系统为例,用其求解结果与解析解进行比较.再以时不变的简支梁为算例,确定多自由度系统下与结构动特性协同的自适应Newmark方法中的参数选取.最后用时变的简支梁模型模拟贮箱质量的实际变化方式,运用与结构动特性协同的自适应Newmark方法、模态叠加法、Newmark平均加速度方法(NMA法)和Fox-Goodwin方法(NMF法)对其求解.比较结果证明自适应Newmark算法对于时变系统的适用性,尤其具有高精度特性.
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