The applicability of shape memory alloys (SMAs) in structural dynamics,particularly as hysteretic damping elements, is limited by the difficulties in modelling theirdeformation characteristics. At typical engineering ...The applicability of shape memory alloys (SMAs) in structural dynamics,particularly as hysteretic damping elements, is limited by the difficulties in modelling theirdeformation characteristics. At typical engineering design levels of loading SMAs exhibitpseudo-elastic properties. A combined experimental and simulation approach suitable for thecharacterisation of novel smart devices based on the pseudo-elastic effect is described.展开更多
The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by di...The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by different heat-treatment conditions. The results show that the area enclosed by hysteresis loop of the CuZnAl shape memory alloy in martensitic state is much larger than that of the alloy in austenitic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, water-quenched, and step-quenched, the CuZnAl alloy takes on more stable shape memory effect,better super-plasticity and superelasticity (pseudoelasticity). A CuZnAl shape memory alloy damper was designed, produced and installed to a 2-layer frame structure. In addition, the vibration experiments were made by dynamic data collecting analysis meter. The velocity of vibration attenuation of frame structure with CuZnAl shape memory alloy damper is much faster than that without it. And with the help of CuZnAl shape memory alloy damper, the attenuation period reduces to 1/10 of the original.展开更多
A local design scheme for origami energy dissipation braces was proposed by combining local Miura units at both ends and a straight segment in the middle.This design was implemented to address the issue of uneven axia...A local design scheme for origami energy dissipation braces was proposed by combining local Miura units at both ends and a straight segment in the middle.This design was implemented to address the issue of uneven axial stiffness observed in global origami braces.Globally and locally designed origami braces were simulated and compared under cyclic loading to validate the advantages of the proposed design scheme in terms of hysteretic properties.Additionally,an analysis was conducted on the designed braces with varying straight segment lengths,geometric angles,and origami plate thicknesses for comparison.Results indicate that the local design significantly increases the tensile bearing load,enhances the anti-buckling capability,and improves the energy dissipation performance compared to the global design.The positive impact on bearing capacity and energy dissipation performance was observed with increased straight segment length,geometric angles,and origami plate thickness.However,excessively large parameter values result in brace buckling under compression,diminishing energy dissipation capacity.展开更多
The land subsidence due to groundwater exploitation has an obvious hysteretic nature with respect to the decrease of the under groundwater level, and the uneven settlement often causes ground fissures. To study these ...The land subsidence due to groundwater exploitation has an obvious hysteretic nature with respect to the decrease of the under groundwater level, and the uneven settlement often causes ground fissures. To study these important features, a visco-elasticplastic constitutive relationship with consideration of the coupling of seepage and soil deformation is proposed, and a finite element model with variable coefficients based on the Biot＇s consolidation theory is built. With the groundwater exploitation and the land subsidence control in Cangzhou City, Hebei Province as an example, the variations of the under groundwater level and the deve- lopment of the land subsidence due to the groundwater exploitation are simulated and ground fissures are predicted by the horizontal displacement calculation. The results show that the lag time between the land subsidence and the under groundwater level descent is about a month, and the simulated results of fissures agree well with the observed data. The model can well reveal the characterization of the interaction between the land subsidence and the groundwater exploitation.展开更多
文摘The applicability of shape memory alloys (SMAs) in structural dynamics,particularly as hysteretic damping elements, is limited by the difficulties in modelling theirdeformation characteristics. At typical engineering design levels of loading SMAs exhibitpseudo-elastic properties. A combined experimental and simulation approach suitable for thecharacterisation of novel smart devices based on the pseudo-elastic effect is described.
文摘The stress strain curves of two CuZnAl shape memory alloys which have the martensitic transformation temperatures of 50 ℃ and -10 ℃ respectively, were measured by using electronic material tester after treated by different heat-treatment conditions. The results show that the area enclosed by hysteresis loop of the CuZnAl shape memory alloy in martensitic state is much larger than that of the alloy in austenitic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, water-quenched, and step-quenched, the CuZnAl alloy takes on more stable shape memory effect,better super-plasticity and superelasticity (pseudoelasticity). A CuZnAl shape memory alloy damper was designed, produced and installed to a 2-layer frame structure. In addition, the vibration experiments were made by dynamic data collecting analysis meter. The velocity of vibration attenuation of frame structure with CuZnAl shape memory alloy damper is much faster than that without it. And with the help of CuZnAl shape memory alloy damper, the attenuation period reduces to 1/10 of the original.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1937202 and 52008064)the Innovation Support Plan-International Cooperation Project(BZ2022049)+1 种基金the Special Foundation for Central Guidance of Local Science and Technology of Shenzhen,China(Grant No.2021Szvup027)The first author acknowledges the scholarship(financial support)received from the China Scholarship Council(202106090085).
文摘A local design scheme for origami energy dissipation braces was proposed by combining local Miura units at both ends and a straight segment in the middle.This design was implemented to address the issue of uneven axial stiffness observed in global origami braces.Globally and locally designed origami braces were simulated and compared under cyclic loading to validate the advantages of the proposed design scheme in terms of hysteretic properties.Additionally,an analysis was conducted on the designed braces with varying straight segment lengths,geometric angles,and origami plate thicknesses for comparison.Results indicate that the local design significantly increases the tensile bearing load,enhances the anti-buckling capability,and improves the energy dissipation performance compared to the global design.The positive impact on bearing capacity and energy dissipation performance was observed with increased straight segment length,geometric angles,and origami plate thickness.However,excessively large parameter values result in brace buckling under compression,diminishing energy dissipation capacity.
文摘The land subsidence due to groundwater exploitation has an obvious hysteretic nature with respect to the decrease of the under groundwater level, and the uneven settlement often causes ground fissures. To study these important features, a visco-elasticplastic constitutive relationship with consideration of the coupling of seepage and soil deformation is proposed, and a finite element model with variable coefficients based on the Biot＇s consolidation theory is built. With the groundwater exploitation and the land subsidence control in Cangzhou City, Hebei Province as an example, the variations of the under groundwater level and the deve- lopment of the land subsidence due to the groundwater exploitation are simulated and ground fissures are predicted by the horizontal displacement calculation. The results show that the lag time between the land subsidence and the under groundwater level descent is about a month, and the simulated results of fissures agree well with the observed data. The model can well reveal the characterization of the interaction between the land subsidence and the groundwater exploitation.
