摘要
针对有限元建模中由于各种误差(如建模误差等)会给计算结果精度带来影响的问题,提出了一种利用模型修正来提高有限元计算结果精度的方法。首次使用了一阶优化方法,以所测试的模态频率和振型为参考,对有限元模型进行修正。首先,以某航空发动机模拟机匣为研究对象,对其进行模态测试,得到其模态频率和振型。然后,以机匣的前10阶计算模态频率与测试模态频率之间误差最小为优化目标,使用Nastran软件对各部件有限元模型中单元的弹性模量进行了修正,并计算了模型修正前后的机匣模态频率和振型,同时与测试模态频率和振型进行对比。结果表明,修正后的有限元模型计算结果与测试结果吻合良好,二者模态振型一致,模态频率的最大误差不超过1%。由此说明修正弹性模量的模型修正方法合理、可行,适用于工程上大型复杂结构的有限元准确建模。
In finite element modeling, there exist various errors affecting the precision of the calculated results, a method utilizing model updating to improve the calculation accuracy of the finite element calculated results is proposed. The first-order optimization model updating method based on measured modal frequencies and modes of vibration is first used to update finite element models. Firstly, an aero-engine simulation casing is taken as the research object, and modal test is carried out on the simulation casing to obtain its measured modal frequencies and vibrational modes. Then, taking the minimum error between the first ten calculated modal frequencies and test modal frequencies of the simulation casing as the optimization objective, the Nastran software is employed to update the element elastic modulus in the finite element model of each component. Meanwhile, the modal frequencies and vibrational modes of the casing before and after model updating are calculated, and they are compared with the corresponding measured modal frequencies and modes of vibration. The results demonstrate that the calculated results of the updated models are in good agreement with the test results. The vibrational modes of them are consistent with each other, and the maximum error of the modal frequencies between the calculated and measured results is less than 1%, which shows that the model updating method based on the elastic modulus updating is reasonable and feasible and it is appropriate for the accurate finite element modeling of those large and complex structures in engineering.
出处
《应用力学学报》
CAS
CSCD
北大核心
2016年第5期917-923,943,共7页
Chinese Journal of Applied Mechanics
基金
航空科学基金(08B08001
20102108002
2014ZD08007)
关键词
模拟机匣
模态测试
有限元建模
模型修正
弹性模量
simulation casing
modal test
finite element modeling
model updating
elastic modulus
