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Photo of Mahmoud Assaad

Mahmoud Cherif Assaad PhD

The Goodyear Tire & Rubber Company, Technical Center, Numerical Methods, Global Simulation Technology, Akron, Ohio

Curriculum Vitae

R&D Associate in the Numerical Methods, Global Simulation Technology Department at the Goodyear Technical Center, Akron, Ohio, USA.
In 1979 he received a M.S. degree in Structural Engineering from Iowa State University, Ames, Iowa, a Ph.D. from the same university in 1983 with Engineering Mechanics as a Major and Applied Mathematics as a minor. In 1990, he received a second M.S. degree in Polymer Science from the University of Akron, Ohio. In 1983, he started his industrial career with Goodyear as a Senior Research Engineer. His present research interests include investigating failure models and fracture criteria of rubber composites to predict tire lifetime, Multi-physics simulation of tire performance including structural, thermal and oxidative response.
  • He was an Adjunct Assistant Professor in the Civil Engineering Department at the University of Akron, Ohio where he taught a graduate course on Boundary Element Method. He also was a lecturer at The University of Toledo, Ohio.
  • He is a member of various scientific and professional societies, author of 16 publications.
  • Co-author of the Composite segment of The Pneumatic Tire book.
  • Taught short courses on Plastics and Elastomers in Engineering Design in Pisa-Italy, Mersh-Luxembourg, Garmish-PartenKirchen and Hamburg Germany.
  • Invited speaker to the Gordon conference on Fibers science.
  • Recipient of the special Achievement Award from NASA for his meritorious accomplishments, dedicated work, and special efforts.
  • Winner of the "2008 Create the future design contest" in the machinery/equipment category (more Information)
  • Featured in the National Geographic web site as one of the inventors who helped save the planet and lives: (more Information)
  • Received an "Honorable mention award for excellence of presentation & significant of content" from the 2007 Tire society conference for his paper on "Thin Film Heat Flux Sensor for Measuring Film Coefficient of Rubber Components of a Rolling Tire"
  • Technical chairman for the 26th Anniversary of The Tire Society conference.
  • Holds over 55 U.S., European patents and trade secrets.
His Topic of Materials' Days 2009:

Structural Analysis of the Non-Pneumatic Lunar Vehicle Rover Using Transient Explicit Dynamics

The carcass of the Lunar Vehicle Rover is made of a wire woven mesh shaped into a toroid and fastened to a solid rim. The wires are zinc coated high carbon steel, the rim is spun out of aluminum and connected to a stiff inner frame made from titanium used to prevent the carcass from over deflecting. The desired performance response encompasses many features including the tire spring rate and the geometric characteristics of the footprint shape.
The primary objective of this summary report is to detail the numerical approach used to model the structural response defined by the vertical stiffness and by the shape of the footprint of the tire when pressed against a solid rigid surface.
The tire model was generated with explicit representation of the wires, the crimps geometry was modeled with the joints represented by ball joints. The tread elements were represented as thin shell elements. The quasi-static solution proved to be a cumbersome approach to obtain a converged solution with an iterative solver for a tire being deflected without any induced stiffness usually supplied by the inflation pressure. By switching to the solver based on the explicit dynamics, the resultant load-deflection curve was in agreement with the laboratory results including the behavior where the bump stop was engaged. In addition, it was demonstrated that the footprint shape was changing with the magnitude of the applied load: full contact at the lower load level followed immediately with line contact for larger load as the tire started oil-canning and the center loses contact with the road. This summary report will detail the modeling approach and will demonstrate its effectiveness by delineating the excellent agreement between the numerical and laboratory results.