Hugh A. Bruck - US grants

Curriculum Enhancement to Introduce
Product Development with Bio-Inspired Concepts
Hugh Bruck, Satyandra Gupta, Edward Magrab, and Elisabeth Smela

Mechanical Engineering Department
University of Maryland, College Park, Maryland

Bio-inspired products and devices take their inspiration from nature. Current mechanical engineering curricula do not cover design concepts or manufacturing techniques needed to develop such products and devices. We propose to enhance the mechanical engineering undergraduate curriculum by integrating recent advances in the design, analysis, and manufacturing of bio-inspired products and devices through the following objectives:
1. Insert a new sequence of instructional materials on bio-inspired concepts into the mechanical
engineering curriculum.
2. Develop a new senior elective entitled Product Development Using Bio-inspired Concepts.
3. Revise two senior electives in micro-electromechanical systems area to include more complete
treatments of special manufacturing processes that can be used to realize bio-inspired products.
4. Assess the projects of the undergraduate mechanical engineering students in their capstone design
course to evaluate their retention and utilization of the new material.
5. Conduct one workshop to transfer the new materials and establish a feedback mechanism for
enhancing the curriculum.
6. Disseminate the materials developed for the new modules and the course notes for the new senior
elective through a dedicated web site.
7. Present a summary of our experiences at two conferences.

The result of the proposed curriculum enhancement will be a new generation of mechanical engineers who can develop products and conduct research for a wide variety of applications utilizing bio-inspired concepts. The proposed project will (1) integrate emerging manufacturing technologies and new design analyses based on biological principles into the Mechanical Engineering curriculum, (2) utilize multi-media technology for disseminating course content, and (3) train graduate students and faculty participating in its implementation in an emerging technology and thereby contribute to faculty development.

This project is developing a laboratory curriculum and laboratory based on the concept and facilities of the Materials Testing Instructional Laboratory at the University of Illinois, Urbana-Champaign. The laboratory is providing undergraduate students in the Departments of Aerospace (AERO), Materials Science (MSE), and Mechanical Engineering (MECH) at the University of Maryland (UMD) with an integrated lab experience that connects the nanoscale structure of materials to the macroscopic physical properties. Two experimental systems are being developed, which will facilitate the changes in the curriculum through the use of miniature test specimens: 1) a pair of micro-tensile testers, one for conventional uniaxial testing and one with state-of-the-art biaxial testing capability, and 2) an integrated nanoindentation/AFM testing system. The laboratory curriculum and facilities are being shared across (at least) three Departments at UMD through the use of a common college-wide undergraduate laboratory for the testing and characterization of materials. This sharing of joint undergraduate laboratory facilities across Departments and fields represents a new interdisciplinary view of the undergraduate curriculum that emphasizes micro- and nano-technology, and connection of nanometer and micron scale characterization to macroscopic properties.

The curriculum being developed and associated laboratory facilities integrates recent research in materials characterization and testing into the undergraduate curriculum. The research covers the use of atomic force microscopy and nanomechanical testing of materials along with fabrication and testing of micromechanical systems. These techniques and concepts have not been covered in the undergraduate curriculum and represent the transference of current topics and developments into the educational system. The lab modules being developed will expose students to this rapidly developing field and provide training with direct application in modern manufacturing in the areas of microelectronics, packaging, and MEMs. The lab modules and procedures developed in this revised laboratory curriculum will be provided on the web with metadata for indexing in the National Science Digital Library to allow other institutions to either adopt or modify the materials for their own use. This laboratory will benefit close to 400 students a semester, of which approximately 20% are women and 15% are minorities. This laboratory will also aid the extensive outreach activities for high school students already in place at UMD.

This award by the Division of Materials Research is to develop theoretical principles and computational tools to design materials with self-assembled microstructures controlled through fabricating graded mesoscopic architectures. Professors Roytburd and Bruck will apply these principles to fabricate shape-memory film materials with enhanced deformation response, increased frequency response, and improved reliability. Using a graded architecture, the self-assembling polydomain structure can be controlled through the constraint imposed by a gradient in composition, grain size, texture, and/or temperature. The combination of engineered graded mesostructures and self-organized micro- and nano-polydomain structures presents broad opportunities to design new materials with well-controlled structures at multiple length scales. To achieve these research goals the following tasks will be accomplished: (1) Theory and modeling of non-isothermal martensitic transformations in graded self-assembled materials; (2) Processing and characterization of graded self-assembled microstructures; (3) Characterization of internal stress distributions in graded self-assembled films; and (4) Characterization of actuation properties of graded self-assembled films. Accomplishing the goals of the project requires a combination of three scientific research areas: Functionally Graded Materials, Martensitic Phase Transformations, and Heat Transfer. The research plan unites the expertise and capabilities of Dr. A. Roytburd, a theorist specializing in martensitic phase transformations, and Dr. H.A. Bruck, an experimentalist specializing in graded material fabrication and characterization.

Intellectual contributions from this research are in two areas: (1) Development of a new self-consistent, experimentally verified model for nonisothermic martensite transformation in graded self-assembled films, and (2) Characterization of structural gradients and internal stress distributions within graded self-assembled films. Broader impacts are expected in the following areas: (1) development of microdevices with optimized actuation properties; (2) development of a theory for phase transformations in graded self-assembled materials; (3) a basis for formulating problems involving complex thermomechanical behavior using self-consistent mathematical formulations; (4) mimicry of the actuation behavior of biological materials using graded self-assembled films; (5) strengthening the practical knowledge and experience of students who will serve as future researchers in the functional materials and MEMS communities by using state-of-the-art research and education tools; and (6) enhanced diversity within the mechanics and materials community through the participation of underrepresented minorities in the proposed research efforts.

The objective of this research is to develop a novel multi-stage molding process for creating a new class of articulated devices that have mesoscopic features essential to the miniaturization of products in a cost-competitive manner. The approach that will be employed consists of several steps. First, interfacial adhesion phenomena encountered during the multi-stage molding process will be characterized and their relationship to process variables will be established. This knowledge will be utilized to explore alternative ways to limit adhesion at interfaces and hence create articulated joints by easily separating discrete components without breaking them. Second, viability of various cavity shape change methods and ejection mechanisms will be assessed for realizing mesoscopic joints using multi-stage molding. This knowledge will be utilized to optimize tooling configurations for making mesoscopic articulated devices. Finally, an improved understanding of the influence that process parameters for microscale electrical discharge machining have on the resulting surface characteristics and dimensional accuracies will be developed. This knowledge will be utilized to create mold inserts to be used in the new molding process that will be essential to defining the limitations on the size of the mesoscopic features.
The proposed project is expected to have the following broader impacts. First, for mesoscopic articulated devices that can be manufactured using the new molding process, the process can be easily scaled down in size and scaled up in production quantity. Hence, this research is expected to enable new possibilities for miniaturizing products. Second, the new molding process will significantly reduce assembly operations and make manufacturing significantly less labor-intensive. Therefore manufacturing of mesoscopic devices can be done quickly and easily inside the US in a cost-competitive manner. Therefore the proposed research effort will enhance the competitiveness of the US manufacturing sector. Finally, the research results will be integrated in the manufacturing curriculum to educate a new generation of engineers ready to exploit emerging manufacturing technologies to create new products.

TECHNICAL SUMMARY

In this research project, a new class of materials with controlled transversely modulated heterophase nanostructures (TMNS) will be developed. The research will integrate theory, modeling, experimental characterization, and design of TMNS with controlled scale and morphology. The basic idea of this research effort is to design TMNS by exploiting epitaxial self-assembling of constituent phases on a crystalline substrate. Formation of such self-assembled nanostructures requires establishing epitaxial relations between each phase and the substrate. These epitaxial relations lead to self-organization of constituent phases and formation of 3D heteroepitaxial nanostructures with coherent or semi-coherent interfaces. By selecting different substrates or substrate orientations and changing the thickness of the nanostructured layer, it is possible to control morphology of the self-assembled nanostructures on a scale that is difficult to obtain with other techniques. Because of the nanoscale of the component phases, dislocation-mediated mechanisms are suppressed resulting in significant elastic strain. Therefore, controlling this stress becomes a new mechanism for manipulating film properties, similar to semiconductor heterostructures. The goal of this research is to develop experimentally verified theoretical principles and computational tools to design materials with modulated nanostructures using epitaxial control. The ability to control morphology, scale, and stress state will be demonstrated. Self-assembled modulated structures on substrates will be formed as a result of either: (a) solid-solid phase transformation (polymorphic, martensitic, or eutectoid), or (b) eutectic crystallization from an amorphous or liquid phase. As a consequence of this research, new principles of design will be developed for thin film materials consisting of controlled heterophase nanostructures for tailoring of interfaces at the nanoscale, as well as the associated processing, characterization, and modeling techniques necessary to realize TMNS.

NON-TECHNICAL SUMMARY

Nanostructured materials are important for a wide spectrum of structural and functional applications, such as sensors, actuators, magnetic recording media, wear resistant coatings, high temperature or corrosion resistant structural materials, and thermoelectric devices. This research will provide an entirely new principle for designing materials with controlled heterophase nanostructures that will lead to materials that are stronger, better at sensing, and more durable, as well as new materials that would not otherwise be possible such as multilayered composite structures whose properties can be actively tuned through self-assembly of the nanostructures. Broader impacts of this research include a coupled theoretical and experimental approach to research and education that ensures broad access to the knowledge needed to enhance the interest and skills of future engineers and researchers using sputtering techniques, nanoindentation, and computational materials science.

The objective of this research is to enable better training of robots by enabling them to physically communicate via human touch using new compliant multifunctional structures. To achieve this, arrays of conducting polymers will be developed to form a system similar to the human nervous system that can sense shape and forces distributions. This sensor array will be integrated into composite foam structures using a scalable additive manufacturing process. To support development of models and to serve as proof-of-concept for these multifunctional structures on robotic platforms, simulated co-robotics experiments will be conducted using a robotic arm interacting with objects of varying compliance. Experimental details of the associated contact mechanics will be quantified in real-time using Digital Image Correlation and conventional video imaging. Output from the sensor array will then be related to shape and force distributions by solving the nonlinear inverse problem using a novel Singular Value Decomposition method. Research results will be documented and disseminated, and the experiments will be converted to STEM demonstrations targeted at educating young girls.

This research will lead to new compliant, scalable, sensing structures that simultaneously monitor in real-time both global and local shapes, as well as force distributions. Since compliant multifunctional sensing structures do not yet exist for robots, it is envisioned that the proposed work will enable realization of new bio-inspired control principles for training robots. This will significantly advance the ability to make safer interactions and decisions in co-robotics by differentiating robotic interactions with humans from other objects in their environment. The proposed integration of research and education will train new mechanical engineers to create multifunctional products that enable new products and new capabilities in existing products in critical areas such as healthcare. The new fabrication methods will enable these structures to be manufactured in the United States in a cost-competitive manner, increasing employment.

This Research Experiences for Undergraduates (REU) Site program at the University of Maryland (UMD)College Park offers new and exciting summer research opportunities to diverse and talented cohorts of undergraduates, from institutions with limited or no research opportunities in the field of bioinspired robotics (defined as robots that are inspired by natural systems such as insects, birds, mammals, and reptiles). Bioinspired robots will be used to target the efforts of first responders after a natural disaster and provide a number of tasks to assist humans (e.g., carrying extra goods, repairing damaged goods, building structures, etc.). However, designing, fabricating, and applying these robots is a long-term scientific and engineering challenge. Each summer, this REU site will provide 10 undergraduates with resources and opportunities to begin tackling some of these challenges. The program will collaborate with UMD's Women in Engineering program and the Center for Minorities in Science and Engineering to better recruit and assess the impact of this program on women and underrepresented minority students who traditionally suffer from the "leaky pipeline" in which percentages of these students decrease as they move up through the ranks of research positions. This problem will be addressed by focusing on career and academic development (seminars and graduate student mentors) in addition to providing a new network of role models through a diverse mentoring pool. A more diverse group of highly educated researchers in this critical research field will create a larger workforce to solve the nation's toughest environmental, technical, and national security challenges.

Bioinspired robotics offer a truly interdisciplinary systems research challenge that encompasses biology, materials, mechanical design, control, sensors and actuators, power, and electronics. To provide the collaborations necessary to solve some of these challenges and encourage students toward future research careers, the program will: 1. Define diverse teams of faculty, graduate student mentors, and undergraduate researchers. 2. Provide exciting research topics covering many aspects of bioinspired robotics. 3. Encourage collaboration and discussion through non-traditional means, including social media forums like Facebook and informal lunch talks among students. 4. Offer tutorial and professional development seminars in addition to field trips to local labs. 5. Assess project success through short-term, long-term, quantitative and qualitative metrics. The discoveries made during these collaborations will be communicated to the broader scientific community via publications and presentations.