ARC Collaborative Research Seminar Series
Fall 2014

ARC seminars are free and open to the general public. Center members can download the presentation files on our password-access online portal iARC. Non-ARC members please email arc-event-inquiries@umich.edu with your requests.

If you wish to attend the seminar remotely, please contact William Lim (williamlim@umich.edu) for teleconference details. For parking information, contact Kathie Wolney (kathian@umich.edu).

Refreshments will be served 9:15-9:30am. The talks will begin at 9:30 a.m. sharp.
Venue: Phoenix Memorial Laboratory, room 2000A (ground floor)


September 26, Friday (9:30a.m. - 11a.m.)
University of Michigan, UM North Campus, Phoenix Memorial Lab. 2000A

Thrust Area 1: Dynamics and Control of Vehicles

1. Computational Behavior Modeling: Model Based Systems Engineering for Ground Vehicles
Dave Daniszewski, U.S. Army TARDEC

        The design of ground vehicles has become an increasingly multi-disciplinary endeavor. Mechanical, electrical, and computational elements must be integrated and often lead to conflicting goals for optimization of vehicle performance. This complexity, inherent in the design of modern vehicles, stresses the ability of existing methodologies used to specify accurate requirements, and therefore impact the design and testing approaches that are derived from these requirements. To better manage this complexity TARDEC's System Engineering group has launched a pilot project to demonstrate the use of Model Based System Engineering for vehicle design. This shifts emphasis from a static requirements specification to a functional model of the system, from which requirements specifications can be derived in a dynamic and iterative manner. This approach has proven beneficial for industry. The initial effort and tools being considered will be described.

2. Incorporating Multiple Power Sources on a Ground Robot: Modeling and Optimization (project link)
John Broderick, Dawn Tilbury (PI), University of Michigan

        Ground robot systems are challenged with respect to energy storage and efficient conversion to power on demand. To enable long-duration missions, ground robot systems can contain multiple power sources such as fuel cell, battery and/or ultra capacitor. To optimize performance, we have developed a hybrid systems framework to model the interactions between these different power sources. The hybrid system framework models discrete variables (such as on/off and different modes of operation) together with continuous variables (such as battery charge, temperature, and power output). We apply this framework to a fuel cell/battery power system designed for small unmanned ground vehicles (such as Packbot or TALON) and demonstrate how the power output can be optimized to increase mission duration. This system is initially studied in simulation, using models developed in other ARC projects, and is validated in hardware, using a fuel cell from U.S. Army Ground Systems Power & Energy Laboratory GSPEL. Results will help future robots make better use of limited energy available for extended and potentially autonomous missions.


October 10, Friday (9:30a.m. - 11a.m.)
University of Michigan, UM North Campus, Phoenix Memorial Lab. 2000A

Thrust Area 2: Human Centered Modeling and Simulation

Restraint System Optimization for Occupant Protection in Tactical Vehicles: Initial Testing and Optimization Method Development
Jingwen Hu, Jonathan D. Rupp, Matthew P. Reed, University of Michigan
Zissimos Mourelatos, Dorin Drignei, Oakland University

        Advanced seat belt and airbag technologies have the potential to provide improved occupant protection in military vehicles. However, the optimal implementation of these technologies requires a better understanding of the crash scenarios, restraint systems and injury potential as to where they will provide the most benefit. The crash conditions between military and passenger vehicles are not necessarily the same. The focus of this study is to develop and validate computational models for predicting injury potential of various restraint and occupant configurations for a light tactical vehicle. In the first phase of the project, we have conducted a number of sled tests to quantify the effects of occupant size, military gear condition, and restraint configurations on occupant injury risks. The tests will be used to establish a baseline performance for model validation. A new hybrid calibration/optimization approach is also developed for model validation and restraint design optimization. The test data and the optimization methods allow us to develop a much better understanding of how to obtain an optimal design for occupant protection in tactical vehicles. An overview of our developments so far will be provided.


November 21, Friday (9:30a.m. - 11a.m.)
University of Michigan, UM North Campus, Phoenix Memorial Lab. 2000A

Thrust Area 3: High Performance Structures and Materials

Projects presenting:
1. Topology Optimization of a Tank Track Pad: Targeting Hyper-Elastic Compliance using an Elastic Material Structure (project link)
Georges Fadel, Gang Li, Zachary Satterfield, Clemson University

        A meta-material with a low loss coefficient and compliance comparable to a tank track pad elastomer is currently being designed. Previous work allowed us to extract the nonlinear strain responses for each of the three pure stress conditions in which the current elastomer experiences under each loading cycle. These nonlinear curves are the target of the topology optimization problem currently being pursued. Complexities of this multi-objective topology optimization focus not only on generating one geometry to fit three nonlinear curves but to also generate a geometry that exhibits nonlinear strain response using a linearly elastic base material. Several methods to attack this problem and preliminary results will be presented.

2. Parametric Reduced-Order Models of Battery Pack Vibration Including Structural Variation, Pre-Stress, and Temperature Effects (project link)
Jau-Ching Lu, Kiran D’Souza, and Bogdan I. Epureanu, University of Michigan; Matthew P. Castanier, US Army TARDEC; Ramesh Rebba, General Motors; Sungkwon Hong, Ford

        This research focuses on structural models for fatigue life predictions of hybrid-electric-vehicle battery packs. A novel method is constructed to efficiently predict the structural dynamics of complex battery packs including the influence of parametric variations. Variations come from pre-stress changes in joining cells, and from cell-to-cell structural variations due to manufacturing, temperature differences in charge-discharge cycles, and different states-of-charge among cells. Also, non-linear properties of the cells and the packaging materials are modeled. The new parametric models are built only once based on data from few variation levels in a full-order finite-element model. The new models take different variation levels as inputs and predict the corresponding vibration response of the pack for entire parameter ranges of interest. Results are validated by comparisons with predictions from (much more computationally expensive) full-order models of the same system.


December 5, Friday (9:30a.m. - 11a.m.)
University of Michigan, UM North Campus, Duderstadt Center, room 1180

Thrust Area 4: Advanced and Hybrid Powertrains

Projects presenting:
1. On the Warm-up of Li-ion cells from Sub-zero Temperatures (project link)
Shankar Mohan, Jason Siegel, Anna Stefanopoulou, University of Michigan

        It it well documented that the discharge capacity and available power of the Li-ion batteries are substantially deteriorated/decreased/reduced at subzero temperatures. The recent winter driving data from many plug-in and all-electric vehicles raised several concerns on warm-up strategies because efficiency plummets due to the cold-start phase. In addition, the current military vehicle fleet with conventional PbA battery also suffered cold cranking problem.
To address these problems, we present the development of a Predictive Control based technique that exploits the increased internal resistance of Li-ion cells at sub-zero temperatures to increase the cell’s temperature until a desired power can be delivered. The strategy relies on the optimization of a sequence of bi-directional currents that strike a compromise between heat generated and energy discharged, while at the same time satisfies the battery manufacturer’s voltage and current constraints.
Of course, drawing bidirectional currents necessitates that a temporary energy reservoir for energy shuttling, such as an ultra-capacitor or another battery, be available. When compared with the case when no penalty on energy loss is imposed, simulations indicate that reductions of up to 20% in energy dispensed as heat in the battery as well as in the size of external storage elements can be achieved at the expense of longer warm-up operation time.

2. Nano-Materials Design for Enhanced Thermal and Mechanical Properties (project link)
Siu on Tung, Krista Hawthorne, Ryan Franck, James Mainero, Yi Ding and Levi Thompson University of Michigan, Ann Arbor MI and US Army RDECOM-TARDEC, Warren, MI

        Layered oxides such as LiCoO2 are widely used in the cathodes of lithium ion batteries but their mechanical and thermal properties can lead to safety and reliability (e.g. cycle life) challenges, in particular for military applications. Stresses induced in oxide particles on repeated lithium insertion and extraction, for example, can cause mechanical fracture, a suspected contributor to capacity fade and resistance increases. We hypothesized that the incorporation of pillaring agents between the layers would reduce the strain caused by lithium insertion and enhance lithium diffusion thereby improving cycle-life, high rate capacities and resistance to thermal runaway. This presentation will describe our progress in the preparation of pillared V2O5 and MnO2, and characterization of their structural, compositional, electrochemical, and thermal characteristics.


ARC members can download the presentation files on our password-access online portal iARC.
Non-ARC members please email arcweb-info@umich.edu with your requests.