Sandwich structures possess a high bending stiffness compared to monolithic structures with a similar weight.This makes them very suitable for lightweight applications,where high stiffness to weight ratios are needed....Sandwich structures possess a high bending stiffness compared to monolithic structures with a similar weight.This makes them very suitable for lightweight applications,where high stiffness to weight ratios are needed.Most common manufacturing methods of sandwich structures involve adhesive bonding of the core material with the sheets.However,adhesive bonding is prone to delamination,a failure mode that is often difficult to detect.This paper presents the results of delamination testing of fully additive manufactured(AM)AlSi10Mg sandwich structures with pyramidal lattice truss core using Laser Powder Bed Fusion(LPBF).The faces and struts are 0.5 mm thick,while the core is 2 mm thick.The inclination of the struts is 45°.To characterise the bonding strength,climbing drum peel tests and out-of-plane tensile tests are performed.Analytical formulas are derived to predict the expected failure loads and modes.The analytics and tests are supported by finite element(FE)calculations.From the analytic approach,design guidelines to avoid delamination in AM sandwich structures are derived.The study presents a critical face sheet thickness to strut diameter ratio for which the structure can delaminate.This ratio is mainly influenced by the inclination of the struts.The peel tests resulted in face yielding,which can also be inferred from the analytics and numerics.The out-of-plane tensile tests didn’t damage the structure.展开更多
目的构建科学、实用的出血中心护士核心素养培训体系,为出血中心护士的培养和课程设置提供参考。方法检索PubMed、Web of Science、中国生物医学文献服务系统(CBM)、中国知网(CNKI)、万方等数据库中的文献,并结合患者、家属及医护人员...目的构建科学、实用的出血中心护士核心素养培训体系,为出血中心护士的培养和课程设置提供参考。方法检索PubMed、Web of Science、中国生物医学文献服务系统(CBM)、中国知网(CNKI)、万方等数据库中的文献,并结合患者、家属及医护人员访谈结果,小组讨论后初步拟定出血中心护士培训体系,最后应用德尔菲法对12个省21名专家进行2轮函询,确定了三级指标体系。结果第1轮函询问问卷有效回收21/21份,第2轮专家函询问卷有效回收19/21份。出血中心护士核心素养培训体系专家咨询判断系数0.99,权威系数0.89,Miller金字塔理论专家咨询判断系数0.72,权威系数0.85,熟悉程度0.80。最终确立出血中心护士培训体系涵盖理论、应用、技能及实际表现能力4个层面,培训内容、培训管理及考核评价等3个部分。其中,培训内容一级指标22个、二级指标96个、三级指标78个;培训管理一级指标4个,二级指标8个,三级指标12个;考核评价一级指标5个,二级指标16个。结论基于Miller金字塔理论构建的出血中心护士核心素养培训体系专家意见集中,可信度高,能为出血中心护士开展培训提供参考。展开更多
The equation of motion of sandwich beam with pyramidal lattice core in the supersonic flow considering geometric nonlinearity is formulated using Hamilton＇s principle. The piston theory is used to evaluate aerodynami...The equation of motion of sandwich beam with pyramidal lattice core in the supersonic flow considering geometric nonlinearity is formulated using Hamilton＇s principle. The piston theory is used to evaluate aerodynamic pressure. The structural aeroelastic properties are analyzed using frequency- and time-domain methods, and some interesting phenomena are observed. It is noted that the flutter of sandwich beam occurs under the coupling effect of low order modes. The critical flutter aerodynamic pressure of the sandwich beam is higher than that of the isotropic beam with the same weight, length and width. The influence of inclination angle of core truss on flutter characteristic is analyzed.展开更多
The reaction of molybdenum hexacarbonyl with C6H5CH2OC6H4ONa and Et4NBr in CH3CN at 60 ℃ afforded the di-nuclear Mo（0） compound [Et4N]3[Mo2（CO）6（μ-OC6H4OCH2C6H5）3] 1. 1 crystallizes in monoclinic, space group ...The reaction of molybdenum hexacarbonyl with C6H5CH2OC6H4ONa and Et4NBr in CH3CN at 60 ℃ afforded the di-nuclear Mo（0） compound [Et4N]3[Mo2（CO）6（μ-OC6H4OCH2C6H5）3] 1. 1 crystallizes in monoclinic, space group P21/c with a = 15.359（2）, b = 18.378（3）, c = 24.952（2） A, β = 102.268（4）°, V = 6882.3（1 6） A^3, Mr = 1348.34, Z = 4, Dc = 1.301 g/cm^3, F（000） = 2832 and μ= 0.424 mm^-1 The final R = 0.0606 and wR = 0.1552 for 9396 observed reflections （I 〉 2σ（I））. I contains a [Mo2O3]^3 core in triangular bi-pyralnidal configuration and each Mo atom adopts a distorted octahedral geometry with three carbon atoms from carbonyls and three ,μ-O atoms from C6H5CH2OC6H4O^- bridging ligands. The Mo…Mo distance is 3.30（8） A, indicating no metalmetal bonding. A formation pathway via forming a di-molybdenum（0） di-bridging OR compound [Mo2（μ-OR）2（CO）8]2 has been figured out and the reaction of Mo（CO）6 with alkoxide has also been discussed.展开更多
基金Part of this work was supported by the German Federal Ministry for Economic Affairs and Energy(BMWi)(Grant No.20E1713B).
文摘Sandwich structures possess a high bending stiffness compared to monolithic structures with a similar weight.This makes them very suitable for lightweight applications,where high stiffness to weight ratios are needed.Most common manufacturing methods of sandwich structures involve adhesive bonding of the core material with the sheets.However,adhesive bonding is prone to delamination,a failure mode that is often difficult to detect.This paper presents the results of delamination testing of fully additive manufactured(AM)AlSi10Mg sandwich structures with pyramidal lattice truss core using Laser Powder Bed Fusion(LPBF).The faces and struts are 0.5 mm thick,while the core is 2 mm thick.The inclination of the struts is 45°.To characterise the bonding strength,climbing drum peel tests and out-of-plane tensile tests are performed.Analytical formulas are derived to predict the expected failure loads and modes.The analytics and tests are supported by finite element(FE)calculations.From the analytic approach,design guidelines to avoid delamination in AM sandwich structures are derived.The study presents a critical face sheet thickness to strut diameter ratio for which the structure can delaminate.This ratio is mainly influenced by the inclination of the struts.The peel tests resulted in face yielding,which can also be inferred from the analytics and numerics.The out-of-plane tensile tests didn’t damage the structure.
文摘目的构建科学、实用的出血中心护士核心素养培训体系,为出血中心护士的培养和课程设置提供参考。方法检索PubMed、Web of Science、中国生物医学文献服务系统(CBM)、中国知网(CNKI)、万方等数据库中的文献,并结合患者、家属及医护人员访谈结果,小组讨论后初步拟定出血中心护士培训体系,最后应用德尔菲法对12个省21名专家进行2轮函询,确定了三级指标体系。结果第1轮函询问问卷有效回收21/21份,第2轮专家函询问卷有效回收19/21份。出血中心护士核心素养培训体系专家咨询判断系数0.99,权威系数0.89,Miller金字塔理论专家咨询判断系数0.72,权威系数0.85,熟悉程度0.80。最终确立出血中心护士培训体系涵盖理论、应用、技能及实际表现能力4个层面,培训内容、培训管理及考核评价等3个部分。其中,培训内容一级指标22个、二级指标96个、三级指标78个;培训管理一级指标4个,二级指标8个,三级指标12个;考核评价一级指标5个,二级指标16个。结论基于Miller金字塔理论构建的出血中心护士核心素养培训体系专家意见集中,可信度高,能为出血中心护士开展培训提供参考。
基金Project supported by the National Natural Science Foundation of China(Nos.11572007 and 11172084)
文摘The equation of motion of sandwich beam with pyramidal lattice core in the supersonic flow considering geometric nonlinearity is formulated using Hamilton＇s principle. The piston theory is used to evaluate aerodynamic pressure. The structural aeroelastic properties are analyzed using frequency- and time-domain methods, and some interesting phenomena are observed. It is noted that the flutter of sandwich beam occurs under the coupling effect of low order modes. The critical flutter aerodynamic pressure of the sandwich beam is higher than that of the isotropic beam with the same weight, length and width. The influence of inclination angle of core truss on flutter characteristic is analyzed.
基金This research was supported by NNSFC (No. 90203017 29733090), NBRP (2004CB7201005) and SKLSC
文摘The reaction of molybdenum hexacarbonyl with C6H5CH2OC6H4ONa and Et4NBr in CH3CN at 60 ℃ afforded the di-nuclear Mo（0） compound [Et4N]3[Mo2（CO）6（μ-OC6H4OCH2C6H5）3] 1. 1 crystallizes in monoclinic, space group P21/c with a = 15.359（2）, b = 18.378（3）, c = 24.952（2） A, β = 102.268（4）°, V = 6882.3（1 6） A^3, Mr = 1348.34, Z = 4, Dc = 1.301 g/cm^3, F（000） = 2832 and μ= 0.424 mm^-1 The final R = 0.0606 and wR = 0.1552 for 9396 observed reflections （I 〉 2σ（I））. I contains a [Mo2O3]^3 core in triangular bi-pyralnidal configuration and each Mo atom adopts a distorted octahedral geometry with three carbon atoms from carbonyls and three ,μ-O atoms from C6H5CH2OC6H4O^- bridging ligands. The Mo…Mo distance is 3.30（8） A, indicating no metalmetal bonding. A formation pathway via forming a di-molybdenum（0） di-bridging OR compound [Mo2（μ-OR）2（CO）8]2 has been figured out and the reaction of Mo（CO）6 with alkoxide has also been discussed.
