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Ziegert, John C.
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Computational Method to Examine Spoke Dynamics in a High Speed Rolling Wheel

Clemson University-Kranti K. Manga, Lonny L. Thompson, John C. Ziegert
Michelin Americas Research Company-Timothy B. Rhyne, Steven M. Cron
Published 2009-04-20 by SAE International in United States
This paper describes a computational approach to investigating spoke vibrations in cast polyurethane spoked wheels during high-speed rolling. It focuses on four aspects: 1) Creating a two-dimensional finite element model of a cast polyurethane rolling wheel which is in contact with a rigid plane to observe the spoke vibrations. 2) Investigating the effect of rolling speed on the observed spoke vibrations. 3) Investigating the effect of spoke thickness on spoke vibration frequencies. 4) Creating a three-dimensional spoke model to investigate spoke vibrations which exhibit both symmetric and anti-symmetric out-of-plane modes.
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Compliant Link Suspension

BMW Group USA-Andreas Obieglo
Clemson University-John C. Ziegert, Beshah Ayalew, Vincent Lee, Souharda Raghavendra
Published 2009-04-20 by SAE International in United States
This paper discusses a compliant link suspension concept developed for use on a high performance automobile. This suspension uses compliant or flexible members to integrate energy storage and kinematic guidance functions. The goal of the design was to achieve similar elasto-kinematic performance compared to a benchmark OEM suspension, while employing fewer components and having reduced mass and complexity, and potentially providing packaging advantages. The proposed suspension system replaces a control arm in the existing suspension with a ternary supported compliant link that stores energy in bending during suspension vertical motion. The design was refined iteratively by using a computational model to simulate the elasto-kinematic performance as the dimensions and attachment point locations of the compliant link were varied, until the predicted performance closely matched the performance of the benchmark suspension. A mock-up of the proposed compliant link suspension was built together with an adjustable test fixture, and experiments were carried out to validate the results from simulations. The new suspension is less complex and weighs less than the original suspension without sacrificing basic elasto-kinematic performance.
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Effects of High Productivity Machining on Ti-6Al-4V Surface Topography

University of Florida-Aditya Modgil, John K. Schueller, John C. Ziegert, Abhijit Bhattacharyya
Published 2004-09-21 by SAE International in United States
Surface defects were demonstrated to result from high productivity machining (HPM) as well as conventional machining of a titanium alloy Ti-6Al-4V, with HPM causing the larger sized defects. These defects could act as initiation sites for fatigue cracks showing that machining would affect fatigue strength and life of the part produced. A finishing pass appears to remove the defects. Better understanding is needed of the relationships between machining, surfaces, and strength.
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High Speed Machining of Helicopter Gearcases

Bell Helicopter TEXTRON-Edmund P. Leigh
University of Florida-John K. Schueller, Sharath A. Cugati, Ahmed Yousuf, John C. Ziegert
Published 2004-09-21 by SAE International in United States
High speed machining of aluminum and magnesium helicopter gearcases was experimentally demonstrated to be five times more productive than contemporary conventional commercial practice for suitable operations. Appropriate techniques and performance characteristics are discussed for face milling, endmilling and planetary milling operations. Potential problem areas, such as surface characteristics and machine tool performance requirements are discussed.
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Stiffness of Structures and Drives in Fast Milling Machines

University of Florida-Jiri Tlusty, John C. Ziegert, Shannon Ridgeway
Published 1999-06-05 by SAE International in United States
A stiffness requirement for high speed milling machines is determined by examining the stiffness of current generation high speed spindles. The desire for stability against chatter dictates that the stiffness of the machine structure and drives, when reflected to the tool tip exceed the spindle/tool holder/tool stiffness. The stiffness characteristics of a classical serial machine tool designed expressly for high speed milling are shown. Another potential design for high speed machining applications, the parallel kinematic or hexapod structure is also examined. It is found that hexapod structures exhibit lower structural stiffness than can be achieved in serial machines when using the same drive components. Furthermore, the stiffness of the hexapod structure varies widely across the workspace, leading to difficulties in control and limiting the achievable accuracy. Theoretically derived stiffnesses are compared with experimentally measured stiffnesses for two hexapod machines and are found to show good agreement.
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