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考虑混合H2/H∞控制问题的降阶控制器的设计问题.基于线性矩阵不等式(LMI),分别‘给出了连续和离散情形下混合H2/H∞问题的降阶控制器的设计. 相似文献
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基于ABAQUS有限元软件,采用完全耦合热应力分析法,建立了高强度钢的局部加热辊弯有限元模型,并在模型中添加相应的热传导、热对流和热辐射边界条件.通过分析相应的温度、应力与应变场的分布,发现辊弯变形区为主要高温区,此区域的散热量和生热量基本相等.其等效应变主要发生在弯角变形区,逐渐靠近弯角变形区部位的塑性应变逐渐明显并且不断变大,弯角中心的应变最大. 相似文献
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辊弯成形因其高效、节能、节材等特点在许多领域得到广泛应用,而辊弯成形机机构和尺寸设计的合理性对成本和成形精度都有重要影响。将定截面辊弯成形机的模型等效简化,导入到ABAQUS软件中进行板料成形过程的有限元仿真分析,得到与实际生产接近的工作状态下的成形机受力情况,进而对成形机机架中承载的重要零件进行校核分析,并对设计方案的可行性和板料的成形缺陷进行研究。结果表明:数值模拟能为上轴的弹性变形研究和轴承等重要零件的选取提供合理的依据;用螺钉代替调整螺杆承载的方案是可行的;辊弯成形1200 MPa级超高强钢板料时的回弹和纵向弯曲较为明显,需加入过弯和矫正。 相似文献
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An original plastic equivalent model was proposed to solve the problem of excessive FEM simulation time when designing the press bend forming path and optimizing the process parameters of press bend forming of the integrally stiffened aircraft panels. Based on the in-depth analysis of the mechanics of the bending and springback of the detailed model and the equivalent model of the integral panels, the plastic equivalent model of the virtual material with special initial yield stress and hardening coefficients was constructed. FEM results indicate that the objective of getting the similar contour with the same press bend forming path is achieved with the error less than 6%, and the efficiency of FEM simulation is improved by more than 80%. The plastic equivalent model is valuable and essential for the further research on the press bend forming process of large scale complicated integral panels. 相似文献
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In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthe... 相似文献
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Complex loading paths were realized with cruciform specimens and biaxial loading testing machine. Experimental method for determining the subsequent yield locus of sheet metal was established. With this method, the subsequent yield loci of 5754O aluminum alloy sheet were obtained under complex loading paths. Theoretical subsequent yield loci based on Yld2000-2d yield criterion and three kinds of hardening modes were calculated and compared with the experimental results. The results show that the theoretical subsequent yield loci based on mixed hardening mode describe the experimental subsequent yield loci well, whereas isotropic hardening mode, which is widely used in sheet metal forming fields, predicts values larger than the experimental results. Kinematic hardening mode predicts values smaller than the experimental results and its errors are the largest. 相似文献