Dome structures have been used extensively for industrial,residential,and military infrastructure.Therefore,it is necessary to understand the damage risk potential for such structures for blast-resistant design consid...Dome structures have been used extensively for industrial,residential,and military infrastructure.Therefore,it is necessary to understand the damage risk potential for such structures for blast-resistant design considerations.This paper investigates the effect of blast load variability on the design value and the structural dynamic response.Therefore,the sources of uncertainty in the external blast load on dome structures were discussed firstly.Then based on the probabilistic blast load model for the dome,the rationality of a deterministic mass-increase safety method was assessed.It was found that previous deterministic design method cannot provide a consistent and sound assurance factor or reliability index on the entire dome roof.In addition,it was also proved that the assurance-based load method fails to ensure compliance with structural safety design standards on the dome roof when compared with the reliability-based blast method.A sensitivity analysis on the probabilistic blast load was conducted,and the results indicate that stand-off distance and explosive mass both act as dominant sources to influence the mean and variability of blast load.Therefore,based on the Latin hypercube sampling method,a reliability-based external blast load factor technique was proposed.This technique was further used to estimate structural damage levels of a single-layer reticulated dome under different reliability requirements,associated with a low,medium,and high level of protection grades for a specific explosion scenario,and it indicated that this technique can be useful in the building design to achieve a higher structural anti-explosion capacity.This study herein can serve as a reference for the calculation method of designed blast load.展开更多
设计满足特定需求的三维有序多孔的微桁架点阵结构,是解决航空航天领域某些构件轻量化问题的方法之一。首先,基于具有惩罚的实体各向同性材料(Solid isotropic microstructure with penalization,SIMP)拓扑优化算法,以最小柔度为目标,...设计满足特定需求的三维有序多孔的微桁架点阵结构,是解决航空航天领域某些构件轻量化问题的方法之一。首先,基于具有惩罚的实体各向同性材料(Solid isotropic microstructure with penalization,SIMP)拓扑优化算法,以最小柔度为目标,在不同载荷边界条件下进行点阵胞元的优化,随后对拓扑优化的点阵胞元进行几何重构。采用三维数值均匀化算法分析胞元在不同相对密度下的弹性矩阵及弹性模量曲面,对比4种胞元的各项力学性能;对选择性激光烧结(Selective laser sintering,SLS)增材制造技术制备的试件进行物理试验并对比试验结果,得到不同构型点阵结构胞元的力学性能。最后,以三点弯曲梁为例分析应力分布,并按照应力分布对梁结构进行Octet胞元的变密度点阵结构设计;同时设计均匀点阵结构作为对照,并通过三点弯曲试验对比变密度点阵结构与均匀点阵结构的力学性能。结果表明,优化并重构的4种胞元的三维数值均匀化模拟与压缩试验结果吻合良好;S Star Tet胞元的弹性模量最大,Octet胞元具有最高的剪切模量和较好的各向同性。相较于均匀点阵结构,变密度点阵结构的弯曲刚度和弯曲强度分别提高了162.6%和250.5%。展开更多
为研究变密度结构设计对三维机织角联锁复合材料面外力学性能的影响,设计制备了三维机织角联锁不变密度复合材料、三维机织角联锁经纱变密度复合材料和三维机织角联锁纬纱变密度复合材料。结合扫描电子显微镜、数字图像相关技术和X射线...为研究变密度结构设计对三维机织角联锁复合材料面外力学性能的影响,设计制备了三维机织角联锁不变密度复合材料、三维机织角联锁经纱变密度复合材料和三维机织角联锁纬纱变密度复合材料。结合扫描电子显微镜、数字图像相关技术和X射线计算机断层扫描等检测技术,对角联锁变密度复合材料的面外压缩力学行为、内部损伤量化和渐进损伤等进行了测试与表征。研究结果表明:上疏下密角联锁纬纱变密度复合材料展现出优异的压缩性能,其压缩比强度比不变密度复合材料高3.40%;同时,上疏下密角联锁纬纱变密度复合材料损伤体积仅为11.64 mm 3,远低于不变密度复合材料的26.90 mm 3。进一步分析得到,不变密度复合材料压缩破坏以剪切失效为主,而上疏下密角联锁纬纱变密度复合材料则为基体开裂。展开更多
基金supports from and Na-tional key research and development program of China(project No.2018YFC0705703)the National Natural Science Foundation of China(project No.51708521,51778183).
文摘Dome structures have been used extensively for industrial,residential,and military infrastructure.Therefore,it is necessary to understand the damage risk potential for such structures for blast-resistant design considerations.This paper investigates the effect of blast load variability on the design value and the structural dynamic response.Therefore,the sources of uncertainty in the external blast load on dome structures were discussed firstly.Then based on the probabilistic blast load model for the dome,the rationality of a deterministic mass-increase safety method was assessed.It was found that previous deterministic design method cannot provide a consistent and sound assurance factor or reliability index on the entire dome roof.In addition,it was also proved that the assurance-based load method fails to ensure compliance with structural safety design standards on the dome roof when compared with the reliability-based blast method.A sensitivity analysis on the probabilistic blast load was conducted,and the results indicate that stand-off distance and explosive mass both act as dominant sources to influence the mean and variability of blast load.Therefore,based on the Latin hypercube sampling method,a reliability-based external blast load factor technique was proposed.This technique was further used to estimate structural damage levels of a single-layer reticulated dome under different reliability requirements,associated with a low,medium,and high level of protection grades for a specific explosion scenario,and it indicated that this technique can be useful in the building design to achieve a higher structural anti-explosion capacity.This study herein can serve as a reference for the calculation method of designed blast load.
文摘设计满足特定需求的三维有序多孔的微桁架点阵结构,是解决航空航天领域某些构件轻量化问题的方法之一。首先,基于具有惩罚的实体各向同性材料(Solid isotropic microstructure with penalization,SIMP)拓扑优化算法,以最小柔度为目标,在不同载荷边界条件下进行点阵胞元的优化,随后对拓扑优化的点阵胞元进行几何重构。采用三维数值均匀化算法分析胞元在不同相对密度下的弹性矩阵及弹性模量曲面,对比4种胞元的各项力学性能;对选择性激光烧结(Selective laser sintering,SLS)增材制造技术制备的试件进行物理试验并对比试验结果,得到不同构型点阵结构胞元的力学性能。最后,以三点弯曲梁为例分析应力分布,并按照应力分布对梁结构进行Octet胞元的变密度点阵结构设计;同时设计均匀点阵结构作为对照,并通过三点弯曲试验对比变密度点阵结构与均匀点阵结构的力学性能。结果表明,优化并重构的4种胞元的三维数值均匀化模拟与压缩试验结果吻合良好;S Star Tet胞元的弹性模量最大,Octet胞元具有最高的剪切模量和较好的各向同性。相较于均匀点阵结构,变密度点阵结构的弯曲刚度和弯曲强度分别提高了162.6%和250.5%。
文摘为研究变密度结构设计对三维机织角联锁复合材料面外力学性能的影响,设计制备了三维机织角联锁不变密度复合材料、三维机织角联锁经纱变密度复合材料和三维机织角联锁纬纱变密度复合材料。结合扫描电子显微镜、数字图像相关技术和X射线计算机断层扫描等检测技术,对角联锁变密度复合材料的面外压缩力学行为、内部损伤量化和渐进损伤等进行了测试与表征。研究结果表明:上疏下密角联锁纬纱变密度复合材料展现出优异的压缩性能,其压缩比强度比不变密度复合材料高3.40%;同时,上疏下密角联锁纬纱变密度复合材料损伤体积仅为11.64 mm 3,远低于不变密度复合材料的26.90 mm 3。进一步分析得到,不变密度复合材料压缩破坏以剪切失效为主,而上疏下密角联锁纬纱变密度复合材料则为基体开裂。
