Power Harvesting with Magnetic Shape Memory Alloys: Understanding the Mechanisms and Predicting Voltage Output

该奖项支持对磁性形状记忆合金的能量收集机制的基础研究，以及在各种负载条件下准确预测输出功率的工具的开发。利用各种技术，电能可以从风、波浪或结构振动等环境资源中产生。最近，研究表明，利用一种相对较新的材料——磁性形状记忆合金，可以从环境中获取有用的电能。虽然这种材料的这种能力已被实验证明，但其机制尚不清楚。因此，目前这种材料的数学模型无法准确预测功率输出，阻碍了基于磁性形状记忆合金的功率采集器的开发和优化。这项工作的成功完成将大大加深对这种新材料的理解，并可能导致在远程位置（例如监测森林条件）或基础设施（例如监测操作安全）部署的动力或动力辅助传感器的新技术。该项目的主要目标是了解磁性形状记忆合金在能量收集过程中发生的潜在微观结构机制，并将这些机制以数学方式嵌入到材料本构模型中，以准确预测磁化、功率输出和应变的变化。为了了解这些材料的能量收集机制，微观观察将与宏观磁力学表征同时进行；这将允许两个尺度相互关联。观察微观结构的变化，在不同的加载，将纳入一个基于热力学的本构模型的材料。该模型将在各种磁机械加载条件下，根据实验获得的宏观磁化、磁场、应变、应力和功率数据进行验证。了解导致能量收集的潜在机制，包括磁-机械相互依赖关系，并将这些机制嵌入本构模型将是该领域的重大进步，并将产生可用于开发该材料新技术的知识，并可能扩展到理解和建模其他自适应或磁活性材料。

This award supports fundamental research into the mechanisms facilitating power harvesting with magnetic shape memory alloys and the development of tools to accurately predict output power during various load conditions. Power can be generated from environmental sources like wind, waves, or structural vibrations using various technologies. Recently, it has been shown that useful electrical power can be harvested from the environment using a relatively new type of material - magnetic shape memory alloys. While this capability of the material has been demonstrated experimentally, the mechanisms responsible for it are not well understood. Consequently, current mathematical models of this material fail to predict power output accurately, hampering the development and optimization of magnetic shape memory alloy based power harvesters. Successful completion of this work will significantly deepen understanding of this new material and could lead to new technologies to power, or power assist, sensors deployable in remote locations (e.g. to monitor forest conditions) or in infrastructure (e.g. to monitor operational safety).The main objectives of this project are to understand the underlying microstructural mechanisms occurring in magnetic shape memory alloys during power harvesting and to mathematically embed these mechanisms into a material constitutive model that accurately predicts change in magnetization, power output, and strain. In order to understand the mechanisms that lead to power harvesting with these materials, microscopic observations will be performed simultaneously with macroscopic magneto-mechanical characterization; this will allow for the two scales to be correlated. Observations about changes in the microstructure, during various loadings, will be incorporated into a thermodynamics based constitutive model of the material. The model will be validated against macroscopic magnetization, magnetic field, strain, stress, and power data obtained experimentally, under a wide variety of magneto-mechanical loading conditions. Understanding of the underlying mechanisms causing power harvesting, including the magneto-mechanical interdependencies, and embedding these mechanisms into a constitutive model will be a major advance in the field and will yield knowledge that can be employed to develop new technologies with this material and may be extended to understand and model other adaptive or magnetically active materials.