Warren Distinguished Lecture Series

Vaughan R. Voller
Civil, Environmental and Geo- Engineering, University of Minnesota

Since the time of Fick (mid 1850's), it has been known that the length scale associated with a normal diffusion transport process increases with the square root of time. However, clear evidence shows that diffusion in some systems ( for example, break through of contaminants or foraging patterns of grazers) is anomalous. That is, in anomolous systems the associated length scale changes with a time exponent that is less than (sub-diffusion) or greater than (super-diffusion) the expected value of the square root exponent of n=1/2. Voller presents some simple stochastic, physical and numerical experiments that demonstrate how anomalous diffusion behaviors can be induced. In particular, he considers engineering systems related to infiltration of moisture into porous heterogeneous soils and solidification phase change of metal matrix composites.

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Special Warren Lecture in Honor of Robert Dexter

Robert Connor
Civil Engineering, Purdue University

ABSTRACT: Significant advances have been made in the understanding of fracture mechanics, material toughness, fatigue crack initiation and growth, and fabrication and inspection technologies since the inception of the original fracture control plan (FCP) in 1978. Currently, the components of the FCP are divided between independent specifications addressing material, design, fabrication, and inspection. Combining each of these aspects of fracture prevention with the advances made since the 1978 FCP, a new, integrated FCP can be formed. An integrated FCP has the ability to be reliability-based, making fracture no more likely than any other limit state, thereby increasing steel bridge safety and providing an economic benefit to owners though a better allocation of resources. Connor discusses the components of an integrated FCP and considerations that must be evaluated when forming an integrated FCP. (Photo by Theodore Galambos.)

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Graeme Milton
Mathematics, University of Utah

ABSTRACT: Three-dimensional printing gives us unprecedented abilities to tailor microstructures to achieve desired goals. From the mechanics perspective one would like, for example, to know how to design structures that guide stress in the way that conducting fibers guide current. In that context the natural question is: what are the possible pairs of (average stress, average strain) that can exist in the material? A more grand question is: what are the possible effective elasticity tensors that can be achieved by structuring a material with know moduli? Graeme Milton reviews some of the progress that has been made on this question.

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Yonggang Huang
Civil and Environmental Engineering, Northwestern University

ABSTRACT: Assembly of three-dimensional (3D) micro/nanostructures in advanced functional materials has important implications across broad areas of technology. Existing approaches are compatible, however, only with narrow classes of materials and/or 3D geometries. Huang introduces ideas for a form of Kirigami that allows precise, mechanically driven assembly of 3D mesostructures of diverse materials from 2D micro/nanomembranes with strategically designed geometries and patterns of cuts. Theoretical and experimental studies demonstrate applicability of the methods across length scales from macro to nano, in materials ranging from monocrystalline silicon to plastic, with levels of topographical complexity that significantly exceed those that can be achieved in any other way. A broad set of examples includes 3D silicon mesostructures and hybrid nanomembrane-nanoribbon systems, including heterogeneous combinations with polymers and metals, with critical dimensions that range from 100 nm to 30 mm.

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Ahmed E. Elbanna
Civil and Environmental Engineering, University of Illinois at Urbana-Champaign

ABSTRACT: Granular systems are ubiquitous in our experience, and they control the physics of many natural phenomena that are societally relevant such as slope failures (e.g., landslides and man-made embankments) and earthquakes. Furthermore, grain transportation, pouring, packing, and flowing are essential processes in fields such as food, pharmaceutical, and construction material industries. Thus, developing tools for understanding the dynamics of granular flow, at different strain rates, pressures, and temperatures is crucial for optimization of resources in industry and for development of improved hazard models for our built environments. In this talk, Elbanna reports on his recent progress in computational modeling of granular dynamics with a special focus on applications related to multiscale earthquake physics.

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Jian-Shiuh Chen
Civil Engineering, National Cheng Kung University, Tainan, Taiwan

ABSTRACT:Chen summarizes recent research on asphalt with high content of reclaimed asphalt pavement (RAP). A test road was constructed,and the design, production, construction, and performance characteristics were assessed. Chen describes the challenges facing the paving industry, discusses the lessons learned from this experience, and develops quality guidelines for inclusion of high RAP content. Understanding the practical applications of high RAP content asphalt mixtures enables us to enhance pavement durability and to preserve as virgin aggregate and asphalt binder.

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Jerome P. Lynch
Civil and Environmental Engineering, University of Michigan

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ABSTRACT: The extensive national networks of infrastructure systems are rapidly aging, requiring increasing inspection and management to ensure safety. Fortunately, the confluence of wireless communications and low-power embedded computing has led to the creation of a new generation of wireless sensing technologies that can be deployed at low cost and in high density to monitor critical infrastructure systems. In this presentation, Lynch describes a wireless cyber-physical system framework for dynamically loaded civil infrastructure systems. Validation of the proposed framework is conducted using a permanent wireless monitoring system installed on the Telegraph Road Bridge in Monroe, Michigan.

Dennis Kochmann
Graduate Aerospace Laboratories, California Institute of Technology

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ABSTRACT: Engineering design principles commonly aim to prevent instabilities in solids and structures. In recent years, engineering mechanics has undergone a paradigm shift toward taking advantage of instabilities. Understanding the underlying dynamic phenomena enables us to control various micro- and macro-scale phenomena and to create interesting new mechanical systems that exploit the effects of instability. Kochmann develops the underlying theory and discusses its application to selected examples. Kochmann shows that, even in the linear regime, instabilities create interesting material properties.

Sharon L Wood
Cockrell School of Engineering, University of Texas at Austin

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ABSTRACT: Wood describes the new class of corrosion sensor that she and her research team developed. The sensor provides an econmical and nondestructive means of detecting the initiation of corrosion within concrete. Woodd envisions that this new, low-cost sensor will be embedded in concrete during construction and interrogated intermittently over the service life of the bridge.

Adarsh Krishnamurthy
Mechanical Engineering, Iowa State University

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ABSTRACT: Computational models are beginning to play a significant role in design and manufacturing as well as in translational bio-medical applications, providing designers and clinicians with tools that aid in their decision making process. For widespread adoption, many of these computational models require better geometric algorithms that are computationally efficient and interactive. Krishnamurthy focuses on two main application areas of geometric algorithms that would integrate design and engineering analysis.Complex CAD operations were not previously interactive due to the compute-intensive nature of the geometric computations performed by the CAD system. Krishnamurthy and colleagues have developed geometric algorithms that are accelerated using Graphics Processing Units (GPUs).