Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11672230, 11672232) and the Natural Science Basic Research Plan in Shaanxi Province, China (Grant No. 2017JM1029).
Received Date:27 January 2019
Accepted Date:06 June 2019
Available Online:01 September 2019
Published Online:20 September 2019
Abstract:The unique global properties of shape memory alloy are mainly derived from the martensite phase transition and its inverse, which result from the change of temperature and external load. In this paper, the global characteristics of shape memory alloy thin plate system are analyzed with the temperature and harmonic excitation amplitude as control parameters. Based on the method of Poincare map, the complex crisis phenomenon of the system including the sudden change in number, size and type of attractors can be observed through the global multivalued bifurcation diagram. However, the specific crisis type is not clear, it is necessary to be analyzed from the global viewpoint. By computing the global diagram with the composite cell coordinate system method which constructs a composite cell state space by multistage division of the continuous phase space, the attractors, saddles and basins of attraction of the system can be obtained more accurately. The vivid evolutionary processes of the crisis phenomena of the system are illustrated, and it can be found that the system presents a complex global structure with amplitude and temperature changing. There exist two kinds of crises: one is the boundary crisis resulting from the collision between a chaotic/periodic attractor and a chaotic saddle within the basin boundary, which causes the attractor to vanish, and the other is the merging crisis caused by the collision of two or more attractors with the chaotic saddle within the basin boundary where a new chaotic attractor appears. When multiple attractors coexist in the system, the basin boundary may be smooth or fractal, and for any point at boundary, its small open neighborhood always has a nonempty intersection with three or more basins, which is known as Wada basin boundary. It is difficult to predict the dynamic behavior of the system accurately due to the fractal, the Wada-Wada, Wada-fractal and fractal-Wada basin boundary metamorphoses which can be observed along with the variation of temperature and amplitude through the composite cell coordinate system method, which owns a unique advantage in depicting basin boundary. Furthermore, the Wada property is displayed more clearly by refining specified region. The results of this paper provide a theoretical analysis tool for adjusting the dynamic response of shape memory alloy thin plate system and optimizing the deformation and vibration control of mechanical equipment through controlling temperature and excitation intensity. Keywords:shape memory alloy/ global dynamics/ crisis/ fractal basin boundary
当g从0.0471增大到0.0472时, 发生两次逆的边界激变, 如图3所示. A5和A6表示周期为2的吸引子, A5与嵌在吸引域B1, B5边界的鞍S碰撞, A6和嵌入吸引域B2, B6边界的鞍S碰撞, 使得A5, A6和部分边界鞍S突然消失, 成为内部周期鞍IS1, IS2, 同时吸引域B5, B6消失, 吸引域B1, B2变大. 图 3 系统(7)的全局图 (a) g = 0.0471; (b) g = 0.0472 Figure3. Global diagram of the system (7): (a) g = 0.0471; (b) g = 0.0472.
当g从0.0482变化到0.0483时, 系统再次发生两次边界激变, 两个周期1吸引子A1和A2与边界上的鞍S发生碰撞, 变为吸引域B5, B6的内部鞍IS5, IS6, 同时吸引域B1和B2消失, 如图4所示. 图 4 系统(7)的全局图 (a) g = 0.0482; (b) g = 0.0483 Figure4. Global diagram of the system (7): (a) g = 0.0482; (b) g = 0.0483.
当g从0.0491增大到0.0492时, 混沌吸引子A2与吸引域边界上的混沌鞍S发生碰撞, 发生边界激变, 变成新的更大的边界混沌鞍, 吸引域B2随之消失, 状态空间中为四个周期吸引子和混沌边界鞍共存, 如图5所示. 图 5 系统(7)的全局图 (a) g = 0.0491; (b) g = 0.0492 Figure5. Global diagram of the system (7): (a) g = 0.0491; (b) g = 0.0492.
33.2.合并激变 -->
3.2.合并激变
当g从0.0490变化到0.0491时, 混沌吸引子A2和A4不断接近吸引域边界上的混沌鞍S, 发生合并激变, 成为新的混沌吸引子A2, 与此同时吸引域B2, B4合并为新的吸引域B2, 如图6所示. 图 6 系统(7)的全局图 (a) g = 0.0490; (b) g = 0.0491 Figure6. Global diagram of the system (7): (a) g = 0.0490; (b) g = 0.0491.
当g从0.0596变化到0.0597时, 混沌吸引子A1, A2与边界上的混沌鞍S碰撞, 发生合并激变, 变为新的混沌吸引子A1, 如图7(a)和图7(b)所示. 当g从0.0726增大到0.0727时, 发生逆合并激变, 混沌吸引子A1消失, 出现两个新的周期1吸引子A1, A2及混沌边界鞍S, 如图7(c)和图7(d)所示. 图 7 系统(7)的全局图 (a) g = 0.0596; (b) g = 0.0597; (c) g = 0.0726; (d) g = 0.0727 Figure7. Global diagram of the system (7): (a) g = 0.0596; (b) g = 0.0597; (c) g = 0.0726; (d) g = 0.0727.
23.3.域边界突变 -->
3.3.域边界突变
当g = 0.0460时, 系统存在三个周期1吸引子A1, A2, A3和嵌在吸引域B1, B2, B3边界上的混沌鞍S, 此时的域边界呈现出Wada特性. 当g增大到0.0461时, 系统新出现一个周期3吸引子A4, 此时的域边界由4个吸引域构成, 仍具有Wada特性, 系统发生Wada-Wada域边界突变, 如图8所示. 图 8 系统(7)的全局图 (a) g = 0.0460; (b) g = 0.0461 Figure8. Global diagram of the system (7): (a) g = 0.0460; (b) g = 0.0461.
当g从0.0478增大到0.0479时, 吸引子的个数从6个变为7个, 为判断吸引子变化过程, 对区域v ={(x, y)|–0.075 ≤ x ≤ –0.055, 0.068 ≤ y ≤ 0.092}进行细化. 可以发现, 原周期3吸引子A4消失, 并在其附近出现两个新的周期3吸引子A4和A7, 如图9(c)和图9(d). 原吸引域B4分裂为新吸引域B4和B7, 且参数变化前后域边界均呈现Wada特性, 域边界结构更加复杂, 系统再次发生Wada-Wada域边界突变. 图 9 系统(7)的全局图 (a) g = 0.0478; (b) g = 0.0479; (c), (d) 分别对应于(a), (b)图的区域细化 Figure9. Global diagram of the system (7): (a) g = 0.0478; (b) g = 0.0479; (c), (d) the region refinement of panels (a) and (b).
当g = 0.0533时, 状态空间中有4个周期1吸引子共存, 此时域边界仍具有Wada特性. 当g增大到0.0534时, 周期吸引子A3和A4消失, 状态空间中仅剩2个周期1吸引子A1, A2, 此时域边界的Wada特性消失, 只呈现分形特性, 系统发生Wada-分形域边界突变, 如图10所示. 图 10 系统(7)的全局图 (a) g = 0.0533; (b) g = 0.0534 Figure10. Global diagram of the system (7): (a) g = 0.0533; (b) g = 0.0534.
-->
4.1.边界激变
当θ = 0.8379时, 状态空间中两个周期1吸引子A1和A2共存, S为嵌入在分形域边界上的混沌鞍, IS1, IS2是吸引域B1, B2内部的混沌鞍. 当θ增大为0.8380时, 系统出现两个新的吸引子A3和A4, 内部鞍IS1, IS2消失, 系统发生两次逆边界激变, 如图12所示. 图 12 系统(7)的全局图 (a) θ = 0.8379; (b) θ = 0.8380 Figure12. Global diagram of the system (7): (a) θ = 0.8379; (b) θ = 0.08380.