In order to reflect the stochastic characteristics of structures more comprehensively and accurately, a theory and method for modeling of structures with stochastic parameters is presented by using probability finite ...In order to reflect the stochastic characteristics of structures more comprehensively and accurately, a theory and method for modeling of structures with stochastic parameters is presented by using probability finite element method and stochastic experiment data of structures based on the modeling of structures with deterministic parameters. Double-decker space frame is taken as an example to validate this theory and method, good results are gained.展开更多
A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to impr...A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.展开更多
为提高青贮玉米粉碎物料压缩致密过程仿真所需的准确性,构建青贮玉米粉碎物料离散元仿真模型。以青贮玉米粉碎物料为研究对象,利用EDEM软件中的Hertz-Mindlin with JKR接触模型进行离散元仿真模拟。将物理试验测定的青贮玉米粉碎物料的...为提高青贮玉米粉碎物料压缩致密过程仿真所需的准确性,构建青贮玉米粉碎物料离散元仿真模型。以青贮玉米粉碎物料为研究对象,利用EDEM软件中的Hertz-Mindlin with JKR接触模型进行离散元仿真模拟。将物理试验测定的青贮玉米粉碎物料的接触参数作为模拟参数,利用Plackett-Burman试验、最陡爬坡试验和Box-Behnken试验对相关参数进行优化。获得最优参数组合:青贮玉米粉碎物料与物料碰撞恢复系数0.29,青贮玉米粉碎物料与45号钢板碰撞恢复系数0.50、青贮玉米粉碎物料与45号钢板滚动摩擦因数0.25。通过仿真试验对最优参数组合进行验证,仿真堆积角与物理试验堆积角相对误差为0.66%。研究结果表明,标定的参数可靠性高,可为青贮玉米粉碎物料的离散元仿真提供理论参考。展开更多
基金the National Natural Science Foundation of China (5963140) Doctor Point Fund of National Education Committee Parent Company Fund of Aviation Industry
文摘In order to reflect the stochastic characteristics of structures more comprehensively and accurately, a theory and method for modeling of structures with stochastic parameters is presented by using probability finite element method and stochastic experiment data of structures based on the modeling of structures with deterministic parameters. Double-decker space frame is taken as an example to validate this theory and method, good results are gained.
基金National Key Laboratory of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2022-4)to provide fund for conducting experiments。
文摘A reasonable heat treatment process for TC4 ELI titanium alloy is crucial to tune microstructures to improve its explosion resistance.However,there is limited investigation on tuning microstructures of TC4 ELI to improve explosion resistance.Moreover,the current challenge is quantifying microstructural changes'effects on explosion resistance and incorporating microstructural changes into finite element models.This work aims to tune microstructures to improve explosion resistance and elucidate their anti-explosion mechanism,and find a suitable method to incorporate microstructural changes into finite element models.In this work,we systematically study the deformation and failure characteristics of TC4 ELI plates with varying microstructures using an air explosion test and LS-DYNA finite element modeling.The Johnson-Cook(JC)constitutive parameters are used to quantify the effects of microstructural changes on explosion resistance and incorporate microstructural changes into finite element models.Because of the heat treatment,one plate has equiaxed microstructure and the other has bimodal microstructure.The convex of the plate after the explosion has a quadratic relationship with the charge mass,and the simulation results demonstrate high reliability,with the error less than 17.5%.Therefore,it is feasible to obtain corresponding JC constitutive parameters based on the differences in microstructures and mechanical properties and characterize the effects of microstructural changes on explosion resistance.The bimodal target exhibits excellent deformation resistance.The response of bimodal microstructure to the shock wave may be more intense under explosive loading.The well-coordinated structure of the bimodal target enhances its resistance to deformation.
文摘为提高青贮玉米粉碎物料压缩致密过程仿真所需的准确性,构建青贮玉米粉碎物料离散元仿真模型。以青贮玉米粉碎物料为研究对象,利用EDEM软件中的Hertz-Mindlin with JKR接触模型进行离散元仿真模拟。将物理试验测定的青贮玉米粉碎物料的接触参数作为模拟参数,利用Plackett-Burman试验、最陡爬坡试验和Box-Behnken试验对相关参数进行优化。获得最优参数组合:青贮玉米粉碎物料与物料碰撞恢复系数0.29,青贮玉米粉碎物料与45号钢板碰撞恢复系数0.50、青贮玉米粉碎物料与45号钢板滚动摩擦因数0.25。通过仿真试验对最优参数组合进行验证,仿真堆积角与物理试验堆积角相对误差为0.66%。研究结果表明,标定的参数可靠性高,可为青贮玉米粉碎物料的离散元仿真提供理论参考。
