Aiming at the problems of demagnetization effect of electromagnetic buffer(EMB)caused by high velocity under intensive impact load and the difficulty and error of machining composite thin-walled long tube,a segmented ...Aiming at the problems of demagnetization effect of electromagnetic buffer(EMB)caused by high velocity under intensive impact load and the difficulty and error of machining composite thin-walled long tube,a segmented EMB is proposed.The inner tube and air-gap are divided into initial segments and the traversing segments.Through theoretical analysis,impact test and simulation,it can be found that the RRF curve has two peaks.Firstly,in order to reduce the resultant resistance force(RRF)peaks,the sensitivity analysis based on optimal Latin hypercube design(OLHD)and polynomial regression was performed.The results show that the smallest contribution ratio to the dynamic response is the seventh and ninth segments of the inner tube,which are less than 1%.Then,fully considering the uncertain factors,important parameters are selected for uncertain optimization after sensitivity analysis.The interval order and interval probability degree methods are used to establish interval uncertain optimization model of the RRF considering robustness.The model was solved using an interval nested optimization method based on radial basis function(RBF)neural network.Finally,the Pareto front is obtained and numerical simulation is performed to verify the optimal value.It indicates that the two kinds of RRF peak is obviously reduced,and the optimization object and strategy are effective.展开更多
Transient stresses around two collinear cracks which lie in parallel with theinterface of the two dissimilar half-planes are studied in this article.The surfaces ofthe cracks are sheared suddenly. Application of the...Transient stresses around two collinear cracks which lie in parallel with theinterface of the two dissimilar half-planes are studied in this article.The surfaces ofthe cracks are sheared suddenly. Application of the Fourier and Laplace transforms technique reduces the problem to that of solving dual integrai equations.To solvethese,the differences of.the crack surface displacements are expanded in a series offunctions which are automatically zero outside of the cracks. The unknown coefficients accompanied in the series are determined by the Schmidt method. The stress intensity .factors are defined in the Laplace transform domain and these are inverted numerically in the physical space .As an example ,the dynamic stress intensity factors around two cracks in a ceramic and steel bonded composite are numerically calculated.展开更多
基金the National Natural Science Foundation of China(grant number 301070603)。
文摘Aiming at the problems of demagnetization effect of electromagnetic buffer(EMB)caused by high velocity under intensive impact load and the difficulty and error of machining composite thin-walled long tube,a segmented EMB is proposed.The inner tube and air-gap are divided into initial segments and the traversing segments.Through theoretical analysis,impact test and simulation,it can be found that the RRF curve has two peaks.Firstly,in order to reduce the resultant resistance force(RRF)peaks,the sensitivity analysis based on optimal Latin hypercube design(OLHD)and polynomial regression was performed.The results show that the smallest contribution ratio to the dynamic response is the seventh and ninth segments of the inner tube,which are less than 1%.Then,fully considering the uncertain factors,important parameters are selected for uncertain optimization after sensitivity analysis.The interval order and interval probability degree methods are used to establish interval uncertain optimization model of the RRF considering robustness.The model was solved using an interval nested optimization method based on radial basis function(RBF)neural network.Finally,the Pareto front is obtained and numerical simulation is performed to verify the optimal value.It indicates that the two kinds of RRF peak is obviously reduced,and the optimization object and strategy are effective.
文摘Transient stresses around two collinear cracks which lie in parallel with theinterface of the two dissimilar half-planes are studied in this article.The surfaces ofthe cracks are sheared suddenly. Application of the Fourier and Laplace transforms technique reduces the problem to that of solving dual integrai equations.To solvethese,the differences of.the crack surface displacements are expanded in a series offunctions which are automatically zero outside of the cracks. The unknown coefficients accompanied in the series are determined by the Schmidt method. The stress intensity .factors are defined in the Laplace transform domain and these are inverted numerically in the physical space .As an example ,the dynamic stress intensity factors around two cracks in a ceramic and steel bonded composite are numerically calculated.
