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A Multi-mechanism Model Describing Reorientation and Reorientation-Induced Plasticity of NiTi shape memory alloy

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Acta Mechanica Solida Sinica 2018年第4期31卷 445-458页

作者： Xiang Xu Bo Xu Han M. Jiang Guo-zheng Kang Qian-hua Kan State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

The recovery force or recovery strain is an important indicator of NiTi-based shape memory alloy devices. However, the restoring force or recoverable strain is partially restrained due to an interaction between reorientation and reorientation-induced plasticity. Therefore, a macroscopic multi-mechanism constitutive model was constructed to describe the degeneration of shape memory effect based on the phase diagram. The residual strain after cooling consists of reorientation strain and reorientation-induced plastic strain. An internal variable, i.e., the detwinned stress, and its evolution equation were introduced into the transformation kinetics equation to describe the nonlinear hardening characteristics induced by the combined reorien- ration and detwinning mechanisms during mechanical loading. Finally, the proposed model was numerically implemented to simulate the experiments of shape memory effect at different peak strains. Comparisons between the experimental and simulated results show that the proposed model can reasonably describe the degeneration of shape memory effect.

关键词： shape memory alloy shape memory effect Residual strain Constitutive model Plastic strain

Microstructural evolution and superelastic properties of ultrafine-graine d NiTi-base d shape memory alloy via sintering of amorphous ribbon precursor

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Journal of Materials Science & Technology 2023年第7期138卷 80-92页

作者： W.S.Cai H.Z.Lu H.Z.Li Z.Liu H.B.Ke W.H.Wang C.Yang National Engineering Research Center of Near-net-shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China

NiTi-based shape memory alloys(SMAs)are considered as cutting-edge intelligent functional ***,it remains a great challenge to obtain ultrafine-grained(UFGed)bulk materials with mm-scale size as well as outstanding superelastic ***,UFGed bulk Ti_(35)Zr_(15)Ni_(35)Cu_(15)NiTi-based SMA is successfully prepared via spark plasma sintering of amorphous ribbon precursor at different sintering temperatures,and microstructural evolution and superelastic properties are symmetrically *** is found that its grain size ranges from UFG to micro-grain with increased sintering temperature regard-less of the predominant B2 matrix in all bulk ***,the orientation relationships between B2 matrix and nano-scale fcc(Ti,Zr)_(2)Ni precipitate evolve from coherent to ***,the UFGed samples exhibit perfect superelasticity with the high recoverable strain of∼5.8%,the stable recov-ery rate above 99%,and the great critical stress inducing martensitic transformation higher than 1 GPa,far superior to the corresponding ones of suction-cast micro-grained TiZrNiCu ***,the perfect superelasticity is attributed to the good resistance to dislocation slip or grain boundary slip by residual nano-scale amorphous phase or secondary phase of coherent and semi-coherent fcc(Ti,Zr)_(2)Ni *** addition,the gentle superelastic plateau is associated to the favorable transfer stress and the strong ability to accommodate dislocation movement,which is generated by the coherent interface between nano-scale fcc(Ti,Zr)_(2)Ni and UFGed B2 *** results suggest that spark plasma sintering of amorphous alloy precursor is a feasible route to obtaining excellent superelasticity in NiTi-based SMAs.

关键词： shape memory alloy Amorphous alloy Microstructure Superelasticity

A new isolation device using shape memory alloy and its application for long-span structures

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Earthquake Engineering and Engineering Vibration 2011年第2期10卷 239-252页

作者： Ding Youliang Chen Xin Li Aiqun Zuo Xiaobao Key Laboratory of Concrete and Prestressed Concrete Structure of Ministry of Education Southeast University Nanjing 210096 China Department of Civil Engineering Nanjing University of Science ＆ Technology Nanjing 210094 China

The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys （SMA） are the constitutive model, the SMA isolation device and the analysis method. In this paper, a simplified constitutive model based on the classic theory of plasticity is proposed to simulate the behavior of the superelasticity of the SMA, in which the martensite volume fraction is considered as one of the state variables. Comparisons between simulation results and experimental results are made and indicate that the proposed constitutive model yields stress-strain curves that are in good agreement with the experimental ones. Thus, the proposed model can correctly simulate the yield mechanism and energy dissipation capacity of the SMA. Next, in order to make full use of the superelasticity of SMA, a new SMA isolator composed of pre-tensioned SMA bars is presented. Then, a finite element analytical model is established to simulate the behavior of the SMA isolator according to its configuration and simplified constitutive model. Finally, a simplified design method for long-span structures installed with SMA isolators is proposed, which is further used to investigate the isolation effects of a space grid structure. Results show that the SMA isolator can reduce the seismic responses of the structure effectively, which indicates the effectiveness of the proposed SMA isolation method.

关键词： shape memory alloy super-elasticity constitutive model seismic response structural isolation space gridstructure

Simulation of isothermal precision extrusion of NiTi shape memory alloy pipe coupling by combining finite element method with cellular automaton

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Journal of Central South University 2017年第3期24卷 506-514页

作者： ZHANG Yan-qiu JIANG Shu-yong ZHAO Ya-nan ZHU Xiao-ming College of Mechanical and Electrical Engineering Harbin Engineering University Harbin 150001 China

In order to present the microstructures of dynamic recrystallization(DRX) in different deformation zones of hot extruded NiTi shape memory alloy(SMA) pipe coupling,a simulation approach combining finite element method(FEM) with cellular automaton(CA) was developed and the relationship between the macroscopic field variables and the microscopic internal variables was *** results show that there exists a great distinction among the microstructures in different zones of pipe coupling because deformation histories of these regions are *** plastic deformation may result in fine recrystallized grains,whereas the recrystallized grains may grow very substantially if there is a rigid translation during the deformation,even if the final plastic strain is very *** a consequence,the deformation history has a significant influence on the evolution path of the DRX as well as the final microstructures of the DRX,including the morphology,the mean grain size and the recrystallization fraction.

关键词： shape memory alloy dynamic recrystallization cellular automaton finite element method extrusion

A Design of Tunable Band Gaps in Anti-tetrachiral Structures Based on shape memory alloy

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Acta Mechanica Solida Sinica 2023年第6期36卷 802-816页

作者： Zhuxin Mao Shutian Liu State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China

Benefitted from the properties of band gaps,elastic metamaterials(EMs)have attracted extensive attention in vibration and noise ***,the width and position of band gaps are fixed once the traditional structures are *** is difficult to adapt to complex and changeable service ***,research on intelligent tunable band gaps is of great importance and has become a hot issue in *** achieve smart control of band gaps,a design of tunable band gaps in anti-tetrachiral structures based on shape memory alloy(SMA)is proposed in this *** governing the phase transition process of SMA,the geometric configuration and material properties of structures can be changed,resulting in tunable band ***,the energy band structures and generation mechanism of tunable band gaps in different states are studied,realizing intelligent manipulation of elastic *** addition,the influence of different geometric parameters on band gaps is investigated,and the desired bandgap position can be customized,making bandgap control more *** summary,the proposed SMA-based anti-tetrachiral metamaterial provides valuable reference for the application of SMA materials and the development of EMs.

关键词： Elastic metamaterials Anti-tetrachiral structures Tunable band gaps shape memory alloy

Simultaneous enhancement of mechanical and shape memory properties by heat-treatment homogenization of Ti_(2)Ni precipitates in TiNi shape memory alloy fabricated by selective laser melting

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Journal of Materials Science & Technology 2022年第6期101卷 205-216页

作者： H.Z.Lu L.H.Liu C.Yang X.Luo C.H.Song Z.Wang J.Wang Y.D.Su Y.F.Ding L.C.Zhang Y.Y.Li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Musculoskeletal Oncology Department Sun Yat-Sen University Cancer CenterGuangzhouGuangdong ProvinceChina Shenyang Aircraft Design and Research Institute Shenyang 110035China Guangdong Huayi Plumbing Fittings Industry Co. Ltd.Kaiping 529321China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SMAs) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SMA fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SMA exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SMAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SMAs and will accelerate the wider application of SMAs.

关键词： shape memory alloy Selective laser melting Heat treatment Mechanical properties shape memory properties

Fatigue Crack Propagation Behavior of TiNi_(50.6)shape memory alloy

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Journal of Materials Science & Technology 2001年第4期17卷 403-408页

作者： Guangbin RAO, Jianqiu WANG, We KE and Enhou HAN The State Key Laboratory of Corrosion and Protection, Institute of M-tal Research, Chinese Academy of Sciences,Shenyang 110016, China Chinese Acad Sci State Key Lab Corros & Protect Inst Met Res Shenyang 110016 Peoples R China

The fatigue crack propagation behavior of TiNi50.6 shape memory alloy was studied. The ex- periment results showed that the crack propagation properties of this alloy display difference and similarity in comparison with common metallic materials. Because of the stress concentra- tion there was stress induced martensite transformation (SIMT) near the crack tip though the nominal stress was lower than the threshold stress of SIMT. The position and the amount of SIMT was in situ observed by a quester remote measurement system (QRMS). The observation results showed that the position of SIMT was beside the crack tip and was not in the plastic zone of common metallic materials (in front of the crack tip). The SIMT zone at an angle of about 45°to the direction of the crack propagation, like a butterfly,appeared in the loading process, disappeared in the unloading process and grew larger with the increase of K. The crack propagation rate(da/dN) followed the linear law in lg-lg plot. Observation of the crack surface showed fatigue striation clearly. The relationship between the site and the size of the plastic zone and the SIMT zone is discussed and a model is given to explain both the similarity and the difference of the crack propagation property of TiNi50.6 to common metal materials.

关键词： Fatigue Crack Propagation Behavior of TiNi shape memory alloy

Performance of a base isolator with shape memory alloy bars

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Earthquake Engineering and Engineering Vibration 2007年第4期6卷 401-408页

作者： Fabio Casciati Lucia Faravelli Karim Hamdaoui Dept. of Structural Mechanics University of Pavia Pavia Italy

A new and innovative base isolation device is introduced in this paper based on extensive research carried out by the authors and their co-workers. A prototype of the device was built and experimentally tested on the shaking table. The new base isolation device consists of two disks, one vertical cylinder with an upper enlargement sustained by three horizontal cantilevers, and at least three inclined shape memory alloy （SMA） bars. The role of the SMA bars is to limit the relative motion between the base and the superstructure, to dissipate energy by their super-elastic constitutive law and to guarantee the re-centring of the device. To verify the expected performance, a prototype was built and tested under sinusoidal waves of displacement of increasing frequency with different amplitudes. It is shown that the main feature of the proposed base isolation device is that for cyclic loading, the super-elastic behavior of the alloy results in wide load-displacement loops, where a large amount of energy is dissipated.

关键词： base isolator dynamic excitation energy dissipation shape memory alloy shaking table test

Experimental study of a highway bridge with shape memory alloy restrainers focusing on the mitigation of unseating and pounding

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Earthquake Engineering and Engineering Vibration 2012年第2期11卷 195-204页

作者： Guo, Anxin Zhao, Qingjie Li, Hui School of Civil Engineering Harbin Institute of Technology Harbin 150090 China School of Civil Engineering the 2nd Campus Harbin Institute of Technology P.O. Box 2537 Harbin 150090 China

This paper presents an experimental study to investigate the performance of shape memory alloy(SMA) restrainers for mitigating the pounding and unseating of highway bridges when subjected to seismic *** property tests of the SMA wire used in the restrainers are conducted first to understand the pseudo-elastic characteristics of the ***,a series of shaking table tests are carried out on a highway bridge *** structural responses of the highway bridge model equipped with SMA restrainers,installed in the form of deck-deck and deck-pile connections,are analyzed and compared with the uncontrolled *** test results of this study indicate that the SMA restrainers are not only effective in preventing unseating but also in suppressing the seismic-induced pounding of the highway bridge model used in this study.

关键词： shape memory alloy restrainer unseating pounding highway bridge