在相似模拟试验过程中,为使模拟支架尽可能贴近真实情况,基于液压原理研制出了能够监测相似模拟试验支架阻力的试验装置,建立了现场支架工作阻力和模拟支架测量参数之间的函数关系.为检验支架阻力监测装置性能,以辛安矿1402工作面为研...在相似模拟试验过程中,为使模拟支架尽可能贴近真实情况,基于液压原理研制出了能够监测相似模拟试验支架阻力的试验装置,建立了现场支架工作阻力和模拟支架测量参数之间的函数关系.为检验支架阻力监测装置性能,以辛安矿1402工作面为研究对象,进行了相似模拟试验和现场试验.由模拟试验和现场试验对比分析可知:监测装置和现场监测的平均工作阻力分别为额定工作阻力的67.88%和69.6%,相差很小.采场支架工作阻力主要的分布范围和相似模拟试验支架阻力监测装置测得的工作阻力分布范围相同,均为5 000 k N^6 000 k N.相似模拟试验支架阻力监测装置能够模拟现场支架工作阻力,具有良好的可靠性.展开更多
The stent was a major breakthrough in the treatment of atherosclerotic vascular disease. The permanent vascular implant of a stent, however, changes the intra-stent blood flow hemodynamics. There is a growing consensu...The stent was a major breakthrough in the treatment of atherosclerotic vascular disease. The permanent vascular implant of a stent, however, changes the intra-stent blood flow hemodynamics. There is a growing consensus that the stent implant may change the artery wall shear stress distribution and hence lead to the restenosis process. Computational fluid dynamics （CFD） has been widely used to analyze hemodynamics in stented arteries. In this paper, two CFD models （the axisymmetric model and the 3-D stent model） were developed to investigate the effects of strut geometry and blood rheology on the intra-stent hemodynamics. The velocity profile, flow recirculation, and wall shear stress distribution of various stent strut geometries were studied. Results show strong correlations between the intra-stent hemodynamics and strut geometry. The intra-stent blood flow is very sensitive to the strut height and fillet size. A round strut with a large fillet size shows 36% and 34% reductions in key parameters evaluating the restenosis risk for the axisymmetric model and the 3-D stent model, respectively. This suggests that electrochemical polishing, a surface-improving process during stent manufacturing, strongly influences the hemodynamic behavior in stented arteries and should be controlled precisely in order to achieve the best clinical outcome. Rheological effects on the wall shear stress are minor in both axisymmetric and 3-D stent models for the vessel diameter of 4 mm, with Newtonian flow simulation tending to give more conservative estimates ofrestenosis risk. Therefore, it is reasonable to simulate the blood flow as a Newtonian flow in stented arteries using the simpler axisymmetric model. These findings will provide great insights for stent design optimization for potential restenosis improvement.展开更多
The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents,...The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents, a novel stent with triangular wire cross-section was proposed, and numerical simulations were performed to compare the hemodynamic effect of the novel stent with that of traditional ones. Three constructed aneurysm models were treated with a different kin^l of stent separately, including one with bare circular wire cross-section stent （named CM）, one with bare rectangular wire cross-section stent （named RM）, one with bare triangular cross-section stent （named TM）. An unstented aneurysm model was also constructed to serve as a control （named UM）. Numerical simulations of the fluid-structure interaction in these four models were performed under the same boundary conditions using finite element method. The simulation results demonstrated the resistance of the novel stent is lower than RM stent, but higher than that of CM stent. TM stent attributes a higher velocity decreasing and a longer turnover time compared with CM stent. The distribution of wall shear stress indicated the possibility of aneurysm development along the distal wall was higher than the proximal wall, and the top of aneurysm was in the highest risk of rupture.展开更多
文摘在相似模拟试验过程中,为使模拟支架尽可能贴近真实情况,基于液压原理研制出了能够监测相似模拟试验支架阻力的试验装置,建立了现场支架工作阻力和模拟支架测量参数之间的函数关系.为检验支架阻力监测装置性能,以辛安矿1402工作面为研究对象,进行了相似模拟试验和现场试验.由模拟试验和现场试验对比分析可知:监测装置和现场监测的平均工作阻力分别为额定工作阻力的67.88%和69.6%,相差很小.采场支架工作阻力主要的分布范围和相似模拟试验支架阻力监测装置测得的工作阻力分布范围相同,均为5 000 k N^6 000 k N.相似模拟试验支架阻力监测装置能够模拟现场支架工作阻力,具有良好的可靠性.
文摘The stent was a major breakthrough in the treatment of atherosclerotic vascular disease. The permanent vascular implant of a stent, however, changes the intra-stent blood flow hemodynamics. There is a growing consensus that the stent implant may change the artery wall shear stress distribution and hence lead to the restenosis process. Computational fluid dynamics （CFD） has been widely used to analyze hemodynamics in stented arteries. In this paper, two CFD models （the axisymmetric model and the 3-D stent model） were developed to investigate the effects of strut geometry and blood rheology on the intra-stent hemodynamics. The velocity profile, flow recirculation, and wall shear stress distribution of various stent strut geometries were studied. Results show strong correlations between the intra-stent hemodynamics and strut geometry. The intra-stent blood flow is very sensitive to the strut height and fillet size. A round strut with a large fillet size shows 36% and 34% reductions in key parameters evaluating the restenosis risk for the axisymmetric model and the 3-D stent model, respectively. This suggests that electrochemical polishing, a surface-improving process during stent manufacturing, strongly influences the hemodynamic behavior in stented arteries and should be controlled precisely in order to achieve the best clinical outcome. Rheological effects on the wall shear stress are minor in both axisymmetric and 3-D stent models for the vessel diameter of 4 mm, with Newtonian flow simulation tending to give more conservative estimates ofrestenosis risk. Therefore, it is reasonable to simulate the blood flow as a Newtonian flow in stented arteries using the simpler axisymmetric model. These findings will provide great insights for stent design optimization for potential restenosis improvement.
文摘The flow resistance of stent with different shapes of wire cross-section can be considered as a factor that influences the condition of inflow and outflow through the stent wire. Different from the traditional stents, a novel stent with triangular wire cross-section was proposed, and numerical simulations were performed to compare the hemodynamic effect of the novel stent with that of traditional ones. Three constructed aneurysm models were treated with a different kin^l of stent separately, including one with bare circular wire cross-section stent （named CM）, one with bare rectangular wire cross-section stent （named RM）, one with bare triangular cross-section stent （named TM）. An unstented aneurysm model was also constructed to serve as a control （named UM）. Numerical simulations of the fluid-structure interaction in these four models were performed under the same boundary conditions using finite element method. The simulation results demonstrated the resistance of the novel stent is lower than RM stent, but higher than that of CM stent. TM stent attributes a higher velocity decreasing and a longer turnover time compared with CM stent. The distribution of wall shear stress indicated the possibility of aneurysm development along the distal wall was higher than the proximal wall, and the top of aneurysm was in the highest risk of rupture.
