A nonlinear explicit dynamic finite element formulation based on the generalized beam theory(GBT)is proposed and developed to simulate the dynamic responses of prismatic thin-walled steel members under transverse impu...A nonlinear explicit dynamic finite element formulation based on the generalized beam theory(GBT)is proposed and developed to simulate the dynamic responses of prismatic thin-walled steel members under transverse impulsive loads.Considering the rate strengthening and thermal softening effects on member impact behavior,a modified Cowper-Symonds model for constructional steels is utilized.The element displacement field is built upon the superposition of GBT cross-section deformation modes,so arbitrary deformations such as cross-section distortions,local buckling and warping shear can all be involved by the proposed model.The amplitude function of each cross-section deformation mode is approximated by the cubic non-uniform B-spline basis functions.The Kirchhoff s thin-plate assumption is utilized in the construction of the bending related displacements.The Green-Lagrange strain tensor and the second Piola-Kirchhoff(PK2)stress tensor are employed to measure deformations and stresses at any material point,where stresses are assumed to be in plane-stress state.In order to verify the effectiveness of the proposed GBT model,three numerical cases involving impulsive loading of the thin-walled parts are given.The GBT results are compared with those of the Ls-Dyna shell finite element.It is shown that the proposed model and the shell finite element analysis has equivalent accuracy in displacement and stress.Moreover,the proposed model is much more computationally efficient and structurally clearer than the shell finite elements.展开更多
目的观察米索前列醇对宫内节育器取出术绝经期女性软化宫颈的效果。方法选取2019年4月-2020年12月在我中心行宫内节育器取出术的绝经期女性62例,随机分为对照组和观察组,每组31例。对照组术前口服戊酸雌二醇,观察组术前阴道放入米索前...目的观察米索前列醇对宫内节育器取出术绝经期女性软化宫颈的效果。方法选取2019年4月-2020年12月在我中心行宫内节育器取出术的绝经期女性62例,随机分为对照组和观察组,每组31例。对照组术前口服戊酸雌二醇,观察组术前阴道放入米索前列醇。比较两组手术成功率、临床手术指标、疼痛评分、宫颈软化有效率以及不良反应发生情况。结果观察组手术成功率高于对照组的(96.77%vs 83.87%),差异有统计学意义(P<0.05);观察组手术时间、术中出血量均小于对照组,差异有统计学意义(P<0.05);观察组疼痛评分小于对照组,差异有统计学意义(P<0.05);观察组宫颈软化有效率高于对照组(100.00%vs 80.65%),差异有统计学意义(P<0.05);观察组不良反应发生率低于对照组(0 vs 12.90%),差异有统计学意义(P<0.05)。结论绝经期女性宫内节育器取出术前给予米索前列醇,可提高手术成功率,减轻疼痛评分,提高宫颈软化有效率,缩短手术时间,减少术中出血量,减轻患者的痛苦,同时阴道给药途径可降低临床不良反应,提高用药安全性,值得临床加以应用。展开更多
基金The National Natural Science Foundation of China(No.51078229)the Specialized Research Fund for the Doctoral Program of Higher Education(o.20100073110008)
文摘A nonlinear explicit dynamic finite element formulation based on the generalized beam theory(GBT)is proposed and developed to simulate the dynamic responses of prismatic thin-walled steel members under transverse impulsive loads.Considering the rate strengthening and thermal softening effects on member impact behavior,a modified Cowper-Symonds model for constructional steels is utilized.The element displacement field is built upon the superposition of GBT cross-section deformation modes,so arbitrary deformations such as cross-section distortions,local buckling and warping shear can all be involved by the proposed model.The amplitude function of each cross-section deformation mode is approximated by the cubic non-uniform B-spline basis functions.The Kirchhoff s thin-plate assumption is utilized in the construction of the bending related displacements.The Green-Lagrange strain tensor and the second Piola-Kirchhoff(PK2)stress tensor are employed to measure deformations and stresses at any material point,where stresses are assumed to be in plane-stress state.In order to verify the effectiveness of the proposed GBT model,three numerical cases involving impulsive loading of the thin-walled parts are given.The GBT results are compared with those of the Ls-Dyna shell finite element.It is shown that the proposed model and the shell finite element analysis has equivalent accuracy in displacement and stress.Moreover,the proposed model is much more computationally efficient and structurally clearer than the shell finite elements.
文摘目的观察米索前列醇对宫内节育器取出术绝经期女性软化宫颈的效果。方法选取2019年4月-2020年12月在我中心行宫内节育器取出术的绝经期女性62例,随机分为对照组和观察组,每组31例。对照组术前口服戊酸雌二醇,观察组术前阴道放入米索前列醇。比较两组手术成功率、临床手术指标、疼痛评分、宫颈软化有效率以及不良反应发生情况。结果观察组手术成功率高于对照组的(96.77%vs 83.87%),差异有统计学意义(P<0.05);观察组手术时间、术中出血量均小于对照组,差异有统计学意义(P<0.05);观察组疼痛评分小于对照组,差异有统计学意义(P<0.05);观察组宫颈软化有效率高于对照组(100.00%vs 80.65%),差异有统计学意义(P<0.05);观察组不良反应发生率低于对照组(0 vs 12.90%),差异有统计学意义(P<0.05)。结论绝经期女性宫内节育器取出术前给予米索前列醇,可提高手术成功率,减轻疼痛评分,提高宫颈软化有效率,缩短手术时间,减少术中出血量,减轻患者的痛苦,同时阴道给药途径可降低临床不良反应,提高用药安全性,值得临床加以应用。
