GOALI: Design of Rheologically-Complex Soft Materials

许多日常材料不符合流体和固体的经典定义。相反，流变材料可以同时具有这两种状态的性质。虽然工程师通常使用传统的流体和固体材料来实现工程系统所需的功能，但基于流变材料行为的新性能也有很大的机会。GOALI计划研究项目的重点是提出这样一个问题：在给定期望的性能的情况下，需要什么样的流变材料行为，以及什么样的材料配方可以实现这种行为？这里的工作将研究这些复杂软材料的设计和优化技术。研究涉及理论、计算和实验三个方面。该方法旨在改变对新型流变学复杂材料的搜索及其在工程设计中的使用。由此产生的增强的系统性能将影响许多应用领域，例如但不限于软机器人、振动控制、灭火系统和假肢。GOALI伙伴关系将加强新方法与工程实践的相关性，并为新的设计方法提供试验台。与业界的互动也将加强对学生的培训。相关的外展活动将通过开发和使用一个能够对流变材料进行虚拟实验的门户网站来扩大对流变材料的一般了解。这项工作的目标是为流变复杂材料的创造性和合理设计创造一个新的范例。这个项目？S方法直接将系统级性能优化与物料级设计联系起来。一个核心挑战是，流变性是函数，而不是常量。这项工作将定义和组织直接使用描述性材料函数(函数值属性)的适合设计的数学建模方法。流变的复杂性源于时间相关(粘弹性)和振幅相关(非线性)行为，这个二维空间将被用来组织不同本构模型的适用性和局限性，以达到设计的目的。将建立所得到的数学结构的优化方法。一个关键的挑战是函数的优化，例如卷积积分中的核函数。这将通过包括直接转录在内的数字最优控制方法来实现。一旦确定了目标属性，将使用实验来演示最能实现系统性能目标的流变复杂材料组合物的合理设计。这种材料层面的设计将利用已知的结构-流变学模型，考虑多种材料策略，包括聚合体系、胶体体系和复合材料组合。行业目标合作伙伴将与学术团队密切合作，帮助将工作转化为行业，提供对新材料概念的制定的见解，并提供相关的材料配方。该方法将通过剪切变薄和线性粘弹性系统的案例研究进行数值和实验测试。新的范式将为其他具有复杂函数值属性的材料领域的其他集成设计方法奠定基础。

Many everyday materials do not fit classical definitions of fluid and solid. Instead, rheological materials can have properties of both states. While engineers typically use traditional fluid and solid materials to achieve desired functionality of engineering systems, there is great opportunity for novel performance based on rheological material behavior. The focus of this Grant Opportunity for Academic Liaison with Industry (GOALI) Program research project is to ask the question, given a desired performance, what rheological material behavior is needed, and what material formulations achieve this behavior? The work here will study design and optimization techniques for these complex soft materials. The research involves theory, computation, and experiment. The methodology aims to transform the search for novel rheologically-complex materials and their use in engineering design. The resulting enhanced system performance would impact numerous application domains such as, but are not limited to, soft robotics, vibration control, fire-suppression systems, and prosthetics. The GOALI partnership will strengthen the relevance of the new methods to engineering practice and provide a test bed for the new design approach. The interaction with industry will also enhance the training of students. Associated outreach activities will broaden the general understanding of rheological materials via the development and use of a portal enabling virtual experiments on rheological materials.The objective of this work is to create a new paradigm for creative and rational design of rheologically-complex materials. This project?s approach directly connects system-level performance optimization to material-level design. A core challenge is that rheological properties are functions, not constants. The work will define and organize design-appropriate mathematical modeling methods that use descriptive material functions (function-valued properties) directly. Rheological complexity derives from time-dependent (viscoelastic) and amplitude-dependent (nonlinear) behavior, and this two-dimensional space will be used to organize the applicability and limitations of different constitutive models for the purpose of design. Optimization methods for the resulting mathematical structures will be established. A key challenge is the optimization of functions, such as kernel functions in convolution integrals. This will be approached with numerical optimal control methods including direct transcription. Once target properties are identified, experiments will be used to demonstrate rational design of rheologically-complex material compositions that best achieve the system performance objectives. This material-level design will leverage known structure-rheology models by considering multiple material strategies including polymeric systems, colloidal systems, and composite combinations. The industry GOALI partner will work closely with the academic team to help translate the work to industry, provide insight on formulation of new material concepts, and provide relevant material formulations. The methodology will be tested numerically and experimentally with case studies of shear-thinning and linear viscoelastic systems. The new paradigm will lay the foundation for additional integrated design approaches for other materials domains with complex function-valued properties.