Intracranial aneurysm(IA)is a prevalent cerebrovascular disease associated with high mortality and disability rates upon rupture.The hemodynamics of IA,which are significantly influenced by geometric parameters,direct...Intracranial aneurysm(IA)is a prevalent cerebrovascular disease associated with high mortality and disability rates upon rupture.The hemodynamics of IA,which are significantly influenced by geometric parameters,directly impact its rupture.This study focuses on investigating the transient flow characteristics in saccular IA models fabricated using a water droplet-based method,specifically examining the influence of neck widths.Particle image velocimetry technique and numerical simulation were employed to investigate the dynamic evolution of flow structures within three IA models.The results reveal that neck width(W)has a substantial effect on flow characteristics in the neck region,subsequently impacting the deep flow inside the sac.Three distinct patterns were observed during flow evolution inside the sac:for W=2 mm,two vortices occur and then disappear with relatively low average flow velocity;for W=4 mm,enhanced effects of a high-speed jet result in periodic pulsatile flow velocity distribution while maintaining stable vortex core position;for W=6 mm,significant changes in flow velocity occur due to size expansion and intensity increase of vortices.These findings demonstrate that neck widths play a complex role in influencing transient flow characteristics within IAs.Overall,this research contributes to further understanding transient flow behaviors in IAs.展开更多
熔丝成型(Fused-filament fabrication,FFF)是当今应用最广泛的3D打印技术之一,构成FFF产品的挤出材料丝之间的结合颈对其成型质量及机械性能有着至关重要的影响,然而相应的机理仍不明确。将理论与试验相结合,针对不同打印层厚度及路径...熔丝成型(Fused-filament fabrication,FFF)是当今应用最广泛的3D打印技术之一,构成FFF产品的挤出材料丝之间的结合颈对其成型质量及机械性能有着至关重要的影响,然而相应的机理仍不明确。将理论与试验相结合,针对不同打印层厚度及路径宽度对FFF样件结合颈的影响规律进行研究,首先基于挤出材料丝的黏性烧结现象创建结合颈的理论模型;然后,完成FFF样件的制备以及试验准备工作,进而使用扫描电子显微镜(Scanning electron microscope,SEM)对样件的结合颈进行分析及测量;最后,对比分析理论与试验结果,确定打印层厚度及路径宽度对FFF样件结合颈的影响规律,验证理论模型的正确性。结果表明增大打印层厚度会增大纵向结合颈,减小横向结合颈;而增大路径宽度可以增大横向结合颈,减小纵向结合颈。总体上,增大打印层厚度或路径宽度可以提高FFF样件的层间结合质量,并阐明相应的机理。研究成果将为FFF技术在改善成型质量方面提供理论参考和技术支持。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12172017 and 11872083)Project of Beijing Municipal Education Commission(Grant Nos.KZ202210005006 and KZ202110005007).
文摘Intracranial aneurysm(IA)is a prevalent cerebrovascular disease associated with high mortality and disability rates upon rupture.The hemodynamics of IA,which are significantly influenced by geometric parameters,directly impact its rupture.This study focuses on investigating the transient flow characteristics in saccular IA models fabricated using a water droplet-based method,specifically examining the influence of neck widths.Particle image velocimetry technique and numerical simulation were employed to investigate the dynamic evolution of flow structures within three IA models.The results reveal that neck width(W)has a substantial effect on flow characteristics in the neck region,subsequently impacting the deep flow inside the sac.Three distinct patterns were observed during flow evolution inside the sac:for W=2 mm,two vortices occur and then disappear with relatively low average flow velocity;for W=4 mm,enhanced effects of a high-speed jet result in periodic pulsatile flow velocity distribution while maintaining stable vortex core position;for W=6 mm,significant changes in flow velocity occur due to size expansion and intensity increase of vortices.These findings demonstrate that neck widths play a complex role in influencing transient flow characteristics within IAs.Overall,this research contributes to further understanding transient flow behaviors in IAs.
文摘熔丝成型(Fused-filament fabrication,FFF)是当今应用最广泛的3D打印技术之一,构成FFF产品的挤出材料丝之间的结合颈对其成型质量及机械性能有着至关重要的影响,然而相应的机理仍不明确。将理论与试验相结合,针对不同打印层厚度及路径宽度对FFF样件结合颈的影响规律进行研究,首先基于挤出材料丝的黏性烧结现象创建结合颈的理论模型;然后,完成FFF样件的制备以及试验准备工作,进而使用扫描电子显微镜(Scanning electron microscope,SEM)对样件的结合颈进行分析及测量;最后,对比分析理论与试验结果,确定打印层厚度及路径宽度对FFF样件结合颈的影响规律,验证理论模型的正确性。结果表明增大打印层厚度会增大纵向结合颈,减小横向结合颈;而增大路径宽度可以增大横向结合颈,减小纵向结合颈。总体上,增大打印层厚度或路径宽度可以提高FFF样件的层间结合质量,并阐明相应的机理。研究成果将为FFF技术在改善成型质量方面提供理论参考和技术支持。
