CuZnAl（Mn）合金双程记忆性能的衰减特性

本文探讨了CuZnAl,CuZnAlMn合金的弹簧试样在相变热循环过程中双程记忆性能的变化规律,表明引起铜基形状记忆合金双程记忆性能衰减的主要因素是由于位错增殖;在有外加应力条件下热循环时,还要考虑应力诱发马氏体对记忆性能的贡献。少量Mn的加入使CuZnAl合金在热循环过程中位错增殖加速,同时使应力诱发马氏体容易产生,结果导致在有外加应力条件下热循环时Mn能缓和记忆性能的衰减。     

训练及热循环对CuZnAl合金马氏体形态的影响

本文研究了ＣｕＺｎＡｌ形状记忆合金在训练后以及热循环后热弹性马氏体的形态；分析了马氏体形态对该合金的双程记忆效应的影响。     

训练及热循环对CuZnAl合金马氏体形态的影响

本文研究了ＣｕＺｎＡｌ形状记忆合金在训练后以及热循环后热弹性马氏体的形态；分析了马氏体形态对该合金的双程记忆效应的影响。     

重新训练对Cu—Zn—Al合金组织与记忆性能的影响

用约束训练法对热循环后的Ｃｕ－Ｚｎ－Ａｌ形状记忆合金进行了重新训练。结果表明，热循环导致的记忆衰减可以通过重新训练予以改善。透射电镜和Ｘ射线衍射分析指出，重新训练后，发生了马氏体的再取向，因热循环而引入的细条状，台阶状及交叉状变体大部分消除，马氏体内的位错密度降低，有序度增高，从而改善了合金的记忆性能。     

合金元素及热处理方式对CuZnAl系合金形状记忆恢复力的影响

本文研究了CuZnAl系合金马氏体稳定化去除后,合金元素及热处理方式对形状记忆恢复力的影响。结果表明,合金形状记忆恢复力的大小与其屈服强度有关,改变合金成份或变更热处理方式使合金屈服强度升高,形状记忆恢复力将相应增大,有利于提高合金的恢复性能,合金处于拘束状态时将使恢复温区明显增大,但对恢复开始点As基本没有影响。     

重新训练对Cu－Zn－Al合金组织与记忆性能的影响

用约束训练法对热循环后的Ｃｕ－Ｚｎ－Ａｌ形状记忆合金进行了重新训练．结果表明，热循环导致的记忆衰减可以通过重新训练予以改善．透射电镜和Ｘ射线衍射分析指出，重新训练后，发生了马氏体的再取向，因热循环而引入的细条状、台阶状及交叉状变体大部分消除，马氏体内的位错密度降低，有序度增高，从而改善了合金的记忆性能．     

热循环对Cu—Zn—Al合金双程记忆效应的影响

本文研究了热循环对Ｃｕ－Ｚｎ－Ａｌ形状记忆合金双程记忆效应的影响。结果表明：双程记忆恢复率随着热循环次数的增加而不断衰减。     

热循环对Cu－Zn－Al合金双程记忆效应的影响

本文研究了热循环对Ｃｕ－Ｚｎ－Ａｌ形状记忆合金双程记忆效应的影响。结果表明：双程记忆恢复率随着热循环次数的增加而不断衰减。     

时效工艺对Fe-Mn-Si-Cr-Ni-Zr-C合金形状记忆效应的影响

利用弯曲和拉伸试验研究了时效对 Fe-20Mn-5Si-8Cr-5Ni-0.12C-0.91Zr 合金形状记忆效应的影响,用扫描 电镜、X 射线衍射仪等分析了时效过程中该合金组织形态和组成相的变化.结果表明:该合金经 1 200 ℃ × 2 h(水冷)+800 ℃× 2 h 时效处理,当预应变量 =3.8%时,其形状记忆恢复率为 74%,可恢复应变为 2.81%,其形 状记忆性能优于不含 Zr和 C 的经热机械循环训练的 Fe-20Mn-5Si-8Cr-5Ni合金.     

基于模糊神经网络的移动机器人自适应行为设计

将模糊控制和神经网络相结合,形成模糊神经网络(fuzzy neural network,FNN)控制器,利用联想记忆进行离线训练,用来记忆预先利用强化Q学习(Q-Learning,QL)在线训练获得的移动机器人自适应行为的模糊控制规则。FNN经过离线训练后,把规则隐含地分布在整个网络之中,在控制应用时,不必进行复杂的规则搜索和推理,无需查表,只需通过高速并行的分布计算就可产生最佳输出的自适应行为。仿真结果表明,由于输入模糊子集接近于网络所用的训练模糊子集,所以输出几乎和该条训练规则的结果相同。     

Damping performance of Cu-Zn-Al shape memory alloys in engineering structures

The stress strain curves of two CuZnAI shape memory alloys which have the martensltic 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 CuZnAI shape memory alloy in martensltic state is much larger than that of the alloy in austenltic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, waterquenched, and step-quenched, the CuZnAI alloy takes on more stable shape memory effect, better super-plasticlty and superelasticity (pseudoelasticity). A CuZnAI shape memory alloy damper was designed, produced and installedto 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 CuZnAI shape memory alloy damper is much faster than that without it. And with the help of CuZnAI shape memory alloy damper, the attenuation period reduces to 1/10 of the original.     

双程形状记忆效应的唯象动力学模型

构造可以用于描述一维结构的形状记忆合金（SMA）的双程形状记忆效应的唯象动力学模型. 该模型基于与形状记忆合金中热弹性相变有关的唯象理论,将应力场和热场下的滞回环曲线视为马氏体相变和马氏体变体重构在宏观层面上的表现. 为了模拟温度诱发的相变,构造非凸自由能函数,使得函数的每个局部平衡对应于相变过程中的一个相. 在外部负载（力或者热）的作用下,可以通过模拟系统状态（应变）在不同平衡态之间的转变,研究温度诱发的相变. 相变动力学的控制方程采用拉格朗日方程,以非线性微分方程来表示. 利用非线性常微分方程描述单程形状记忆效应,通过对不同相变过程的加权组合描述双程形状记忆效应. 开展有关力和热负载下的数值实验,模拟热和应力诱发的相变以及热负载下与单程形状记忆效应和双程形状记忆效应有关的滞回环,模拟马氏体重构所导致的单滞回环以及超弹性效应所引起的双滞回环. 从实验结果可以看出,双程形状记忆效应及超弹性效应均可以被提出的模型成功捕捉,验证了该模型的描述能力.     

CuZnAl合金弹簧元件形状记忆的衰减

铜基形状记忆合金是最有工业应用前途的形状记忆合金之一。但铜基形状记忆合金存在着在使用过程中记忆性能易丧失问题而阻碍了它的实用化。 本文利用金相、射线衍射及透射电镜等实验手段,研究了CuZnAl记忆合金弹簧元件的稳定性,分析了其记忆衰减的原因。     

Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

In the past studies, it has been discovered that the shape memory effect(SME) in the Fe-Mn-Si shape memory alloy(Fe-SMA)can gradually be enhanced by a pre-process called as shape memory training process under cyclic thermo-mechanical loading.On the other hand, it has been shown that the SME of Fe-SMA can also be affected by changing the strain rate. Therefore, it is possible to improve the SME by combining the strain rate sensitivity and shape memory training process. However, the improvement of SME caused by the training process under impact condition is still unclear. For the training process under impact condition, it is difficult to interrupt the test at the desired strain level due to many reflections of stress waves, which reload the specimen from the free ends. In this paper, to obtain reliable experimental results of SME after the training process under impact condition, the stress waves after first loading are eliminated by the double momentum-trap structure introduced into the impact tensile testing apparatus based on the split Hopkinson pressure bar method. In order to achieve an optimum design of the structure used in experiments, the finite element simulation of the structure is performed. Then, tensile tests in the training process of Fe-28Mn-6Si-5Cr alloy at different strain rates including the impact level are conducted and temperature change of the specimen is measured during training and heating process. As a result, the improvement of SME in the alloy after the training process under quasi-static and impact loading is compared with that under quasi-static loading through verification processes.     

时效和热循环对CnZnAl系合金记忆性能的影响

本文研究了CuZnAl系合金去稳定化处理后,经马氏体状态长时间时效以及多次热循环时记忆特性的稳定性。结果表明,马氏体稳定化去除彻底的材料,在马氏体时效及热循环过程中记忆特性将基本保持不变,而去稳定化不彻底的材料,在马氏体时效过程中尚有再稳定化现象;在多次热循环过程中仅使A_s有所下降,而恢复率仍保持低值。     

恒定外力对CuZnAl弹簧形状记忆性能和动作温度的影响

研究了外加应力对CuZnAl记忆合金弹簧热循环时的形状记忆性能和其动作温度的影响。研究结果表明,记忆合金弹簧在受到0．7N和1．0N恒定外力的热循环条件下,其形状恢复率比无力作用时有明显改善,记忆合金弹簧热循环时的累积残余伸长量大大减少;加热时记忆合金弹簧的动作始温度与合金中的相变起始温度基本一致,但动作终止温度与相变终止温度存在较大差异。     

CuZnAl合金氩弧焊焊接性能研究

采用与母材同质的焊丝,研究了铜合金CuZnAI氩弧焊的焊接性能,并利用金相显微镜、扫描电镜、电子探针对接头进行了金相检验、力学试验和成分分析。结果表明,接头强度与母材接近,断口呈浅韧窝状,塑性较好;但在焊接时,由于Zn,AI挥发强烈,焊缝成分发生变化,对其形状记忆效应略有影响。