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settings to create realistic contacts sometimes required the integrator step size to be modified as well. Another problem was encountered when using actual values for mass and inertia, which caused constraint drift as described in (Studer and Glocker 2005). Either reducing the mass or decreasing the step size below the value used for the results section alleviated this problem. Conclusions A new methodology for handling simulations with many rigid body frictional contacts has been shown to work well for systems with many bodies and simple geometry. A model of a tracked subsystem of a hydraulic excavator with complex geometry was created and simulated in two multibody dynamic engines and results were compared. In order to leverage the fast new method, only convex geometry was used, which led to a time-consuming manual convex decomposition of the complex geometry. This procedure is prone to error because the collision model must be created manually and there are limited metrics which can be used to determine how accurate a collision shape actually is. Also, large ratios of masses and inertias in the system can cause constraint drift, and the exact nature of the phenomenon is not well known and merits further study. Simulation results have shown that multibody dynamic models with many rigid body frictional contacts can be simulated in a computationally efficient manner with the new methodology; however, representing complex geometry easily and accurately is still one of the major hurdles. Currently, the Simulation Based Engineering Lab (SBEL) is investigating simulations in ChronoEngine in which bodies with complex geometry are represented as sphericaldecompositions. This is a process which takes the original CAD model, breaks it down into a mesh, then uses decomposition parameters to automatically create a collision model made entirely out of spheres. This allows for fast collision detection and collision forces to be computed in parallel on Graphics Processor Cards. Figure 6 shows a spherical decomposition of the track shoe CAD model from Figure 2. Figure 6. Spherical Decomposition of a track shoe collision model. 24
References Anitescu, M. (2006). "Optimization-based simulation of nonsmooth dynamics." Mathematical Programming 105(1): 113-143. Anitescu, M. and F. A. Potra (1997). "Formulating dynamic multi-rigid-body contact problems with friction as solvable linear complementarity problems." Nonlinear Dynamics 14(3): 231-247. Anitescu, M., F. A. Potra, et al. (1999). "Time-stepping for three-dimensional rigid body dynamics." Computer Methods in Applied Mechanics and Engineering 177(3-4): 183-197. Madsen, J. (2007). High Fidelity Modeling and Simulation of Tracked Elements for Off-Road Applications Using MSC/ADAMS: Technical Report TR-2007-02. Madison, WI, Simulation- Based Engineering Laboratory, University of Wisconsin, Madison. Madsen, J., N. Pechdimaljian, et al. (2007). Penalty versus complementarity-based frictional contact of rigid bodies: a CPU time comparison: Technical Report TR-2007-05. Madison, WI, Simulation-Based Engineering Laboratory, University of Wisconsin, Madison. Studer, C. and C. Glocker (2005). Simulation of Non-smooth Mechanical Systems with many Unilateral Constraints. ENOC. Eindhoven, Netherlands. Tasora, A. (2006). An iterative fixed-point method for solving large complementarity problems in multibody systems. 16th Italian Congress on Computational Mechanics, Bologna, Italy. 25
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Space Grant Consortium wisconsin UN
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THE CASSINI ENCOUNTER WITH THE GEM
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Th he proceedinngs of our 199th Ann
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Wisconsin Space Grant Consortium Un
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Part 3: NASA Reduced Gravity Progra
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EAA Women Soar - You Soar, Lee Siud
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Elijah High Altitude Balloon Projec
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Our experience with the HALO II lau
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which had been a problem in the pas
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Figure 6: 3-D GPS Generated Track o
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Results The seeds tested in the lab
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hour as we assumed the flight in th
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Experimental Results There are two
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A series of tests were done in a co
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380 360 340 320 23.3 Temp. (Celsius
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First Place, Non-Engineering: Schmi
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of the basis for fin designs came f
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ejection charge from the motor fire
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using rip-stop nylon cloth. To atta
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Post-flight recovery. A field searc
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Thus, it is believed that the main
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[2] Public Missiles Ltd. Frequently
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Design Features The chief requireme
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The joint between the dart and the
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Area dramatically influenced by flo
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Altitude [ft] 6000 5000 4000 3000 2
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Page 60 and 61: Our Design Our rocket uses the basi
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Page 67 and 68: Background and Context: Student Roc
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Page 74 and 75: The angle of repose of a granular m
Page 76 and 77: Experiment Design The experiment co
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Page 94 and 95: Introduction The analysis of wake v
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Page 98 and 99: References ¹ Burnham, D.C., and Ha
Page 101 and 102: Validation of Novel Rigid Body Fric
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Page 122 and 123: 7. Lemmon, E. W.; Huber, M. L.; McL
Page 124 and 125: Throughout each of the run cycles,
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Figure 3. (a) Seasonal cycle of lak
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Figure 5. Model pCO2 at the surface
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Marshall, J., A. Adcroft, C. Hill,
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numerical weather prediction (NWP)
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High Resolution Radiometer (AVHRR)
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On the morning of 26 May 2008, ther
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References Behnke, C., 2005: Synopt
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Figure 3 Figure 3 contains base ref
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A Comparative Study of Type IIb Sup
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Fig. 3.— Cartoon Image of SN blas
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Fig. 4.— Light curve of SN 2008bo
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type IIn Supernova SN 1995N,” 200
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and then can spiral in to the black
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Understanding the Evolution of Supe
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Radio  measurements  of  supe
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In the equations on the p
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SN 2008ax in NGC 4490 SN2008ax is a
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References Chevalier, R. A., “Int
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Computational Fluid Dynamical Model
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context of the k − ɛ model invol
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Figure 3: Experimental results (•
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direction results in the terminal s
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121 (2000). [Blue Ridge Numerics, I
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concentrated our effort specificall
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density, and Ps is a pressure tenso
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Properties of the GEM problem Recon
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Figure 1: Increase in reconnection
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Figure 3: Examples of agreement of
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Reflection and Refraction of Vortex
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Experimental Procedure The left han
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frames in the upper left corner, wh
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Vortex ring reflection. Similarly,
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References L Bernal and J Kwon. Vor
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group started in 1997 with the goal
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I conducted five semi-structured in
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In the example of the guinea pig pr
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explain t his t rend. F rom t alkin
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Research. Washington, DC: Pan Ameri
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Our team has two goals: 1. To put S
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fluctuating humidity, drying winds,
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western border of the Arkansas Rive
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adjusted to less than .4millisecond
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Cacti Experiment 18 has produced 10
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13. What N decomposer's are needed
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Abstract Toxic Offgassing Analysis
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The chambers were sealed and baked
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Tables 4 and 5 show offgassing comp
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there was no dichlorobenzene peak.
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eneficiation reagents. Ionic liquid
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Figure 3: Current versus voltage da
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Abstract New Initiatives in the Pro
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was noticed above the gel. A discol
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delicate structures (hairs). N o fu
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and A. Y. Rozanov, Eds., SPIE, Vol.
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Combining Writing Across the Curric
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But the study also reported a consi
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Educators’ Aerospace Workshop for
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2008-2009 Evaluation Educators’ A
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Some comments from participants 200
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The cost of a one credit graduate c
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EAA WOMEN SOAR - YOU SOAR Dr. Lee J
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� Incorporated the technology res
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Evaluation Results: At the conclusi
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Educational Standards: The National
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curriculum development, to provide
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and applications of GIS technology
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• A significant new outcome for t
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The design of this project and appl
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Activities at the workshop involved
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to give our students a series of PR
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In the past we have not focused on
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Providing High School Students with
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that th e current generations of s
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instruction a s pa rt o f t heir ow
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Wisconsin Space Grant Consortium &
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11:45-1:00 pm Lunch *** Concurrent
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Moderator: David B lock, A ssociate
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Second Place, E ngineering, Drew an
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Wisconsin Space Grant Consortium
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