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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。
Aiming at the problem that the accuracy of the calculation result will be affected by various errors (such as modeling errors) in the finite element modeling, a method of using the model correction to improve the accuracy of the finite element calculation result is proposed. For the first time, the first-order optimization method was used. Based on the modal frequencies and vibration modes tested, the finite element model was modified. First of all, with aeroengine simulator casing as the research object, modal test was carried out to obtain its modal frequency and mode shape. Then, the minimum error between the modal frequency and the test modal frequency of the first ten orders of the casing is optimized, and the elastic modulus of each element in the finite element model of each component is corrected by using Nastran software. The model correction The modal frequencies and modes of the front and rear casings are compared with the test modal frequencies and modes. The results show that the modified finite element model is in good agreement with the test results. The mode shapes of the two modes agree well and the maximum error of modal frequencies does not exceed 1%. Therefore, it is reasonable and feasible to correct the moduli of the elastic modulus model, which is suitable for accurate finite element modeling of large and complex structures in engineering.