电磁热形状记忆合金与磁流变液楔挤自加压复合传动机理及应用研究

The project aims to propose a composite transmission system of shape memory alloy combined with wedge self-squeezing effect of Magnetorheological fluids under control of electric field, magnetic field and thermal field shape memory alloy combined with wedge self-squeezing effect of Magnetorheological fluids, in which the transmit torque becomes higher and more stable at high temperature to avoid the shortcomings of insufficient output torque and transmission failure under thermal effect..It attempts to establish the relationships of the magnetic field intensity, material parameter, properties of spring, number of coil and magnetic conductivity shape memory alloy spring's output displacement with the temperature based on the magnetocaloric effect of shape memory alloy. Moreover, the relationship between driving force of spring, electric field, thermal field, shearing strain and dimension of spring is built. Based on the rheological properties of magnetorheological fluid, microstructure of chain transformation of MRF because of electromagnetic effect of SMA is investigated, and the influence factors of yield stress, such as parameters of magnetic field, friction coefficient and wedge gap is analyzed. Furthermore, Based on wedge self-squeezing effect, the relationship between torque of composite transmission, yield stress of MRF, driving force and dimension of SMA is worked out. The relationship between wedge gap clearance dimension, effective volume of MRF, power, rotational speed, controllable torque ratio, the yield stress of magnetorheological fluid under magnetic saturation and the driving force of SMA under thermal saturation is established based on the expected transmission performance of composite transmission.

针对磁流变液（MRF)传动传递转矩不大，特别是在高温下传动性能下降等缺点，提出了一种电磁热形状记忆合金(SMA)弹簧与MRF楔挤自加压复合传动方法，其传递转矩可由电磁热场控制，由于楔挤自加压强化效应，传递转矩显著提高，在高温下也能保持传动性能的稳定性。.基于电磁热效应机理，建立磁场强度与材料、弹簧及铜丝圈数、磁导率等参数的关系，弹簧驱动力与电场、温度场、剪应变、尺寸等参数的关系；基于磁流变效应机理，研究SMA弹簧电磁效应下MRF微观结构的链化模型，建立MRF楔挤压和压力驱动复合屈服应力与磁场、磁导率、磁性颗粒、摩擦系数、楔形间隙等的关系；基于楔挤自加压效应机理，建立复合传动转矩与MRF复合屈服应力、SMA弹簧驱动力及尺寸等参数的关系；基于复合传动预期功能，建立楔形间隙尺寸和MRF有效体积与功率、转速、可控转矩比、磁饱和MRF复合屈服应力、热饱和SMA弹簧驱动力等参数的关系。

形状记忆合金（SMA）和磁流变液（MRF）作为新型智能材料，因其独特的力学性能及其广阔的应用前景，引起了国内外学者对SMA和MRF特性及其应用研究高度重视。针对MRF传动传递转矩不大，特别是在高温下性能下降等缺点，提出了一种电热SMA弹簧与MRF楔挤自加压复合传动方法，其传递转矩显著提高，在高温下也能保持性能稳定性。. 项目主要研究内容及重要结果如下：. 1）基于电热效应机理，提出了一种新型电热SMA弹簧驱动器及其设计概念，建立了其驱动力以及驱动位移与电流强度、温度场、线圈匝数和尺寸等参数的关系；通过搭建的电热SMA弹簧热机械性能综合测试平台，验证了驱动方程的准确性；. 2）基于磁流变效应机理，分析了MRF微观结构的链化模型，建立了MRF剪切屈服应力与挤压应力、磁场强度、材料参数、磁导率和温度等参数的关系，并通过数字全息显微技术观测到不同磁场强度下的MRF微观结构；. 3）对电磁力挤压的MRF传动进行了磁场与结构场有限元分析，建立了电磁挤压的MRF与SMA弹簧复合传递的转矩与电磁力、剪切应力、SMA压紧力、关键尺寸、线圈匝数、材料等参数的关系；通过搭建MRF传动性能测试平台，验证了MRF挤压强化模型和电磁热耦合的复合传动机理的正确性；. 4）分析了MRF楔挤自加压效应机理，建立了楔形间隙尺寸与功率、转速、可控转矩比、MRF屈服应力、SMA弹簧驱动力等参数的关系；通过楔挤自加压MRF传动实验，验证了MRF楔挤压理论的正确性。. 项目的科学意义如下：. 1）建立的新型电热SMA复合弹簧驱动力和位移方程，解释了其产生压紧力和输出位移机理。. 2）建立的MRF的剪切应力方程和挤压强化方程，解释了MRF传力及强化机理；. 3）建立的电磁热MRF与SMA复合传动方程，揭示了其复合传动机理；. 4）建立的MRF楔挤压和楔形间隙尺寸方程，为设计制造大功率MRF传动器件提供了科学依据和工程应用的设计计算方法。