Wed., April 21st, 2010 at 6:00 p.m
FATIGUE CRACK PROPAGATION TESTING
OF ORTHOPAEDIC IMPLANT MATERIAL
Ahamed Shabeer, Ph. D.
3883 East Eagle Drive, Anaheim, California 92807
Ph: (714) - 630-3003, Fax: (714)-630-4443
Knee and Hip replacements are the most common orthopaedic procedures. During a hip or knee replacement surgery, the damaged ball and socket joint is replaced with an artificial implant. The materials used in the artificial implants depend on several factors, including the age and the activity level of the patient. Although wide range of implants materials are available, metal and ultra high molecular weight polyethylene (UHMWPE) implants are commonly used these days. Ultra high molecular weight polyethylene is the material of choice because of its lower wear rate and better fatigue performance when compared to other polymers. However recent developments to minimize wear in joint replacements by cross linking UHMWPE resins led to reduction in toughness and fatigue crack resistance.
Due to the cyclic nature of the loads applied to joint replacements, the fatigue resistance of UHMWPE is of great interest. The damage can result from microscopic cracks that form in the polymer because of stress or due to pre-existing effects. Under repeated cyclic loading, these cracks propagate until final fracture. To determine the rate at which the crack grow under an applied cyclic stress, fatigue crack growth testing has to be carried out. Traditional approach to design under cyclic loading has involved (S-N curve) data. However, this approach does not separate out crack initiation and propagation stages. By characterizing crack growth using fracture mechanics parameters, it is possible to predict number of cycles required for a crack to extend from initial length to a predetermined length of interest to the designer. This talk will provide a general overview of the testing methods employed to characterize sub-critical crack growth in high performance polymeric implant material.
Dr. Shabeer consults in the areas of plastic failure analysis, material selection, product design evaluation, and characterization of polymers, elastomers, and polymer composites. His areas of specific expertise are in polymer failure mechanisms and structure property relationship in polymeric material. Dr. Shabeer manages projects involving a broad range of products, such as: automotive parts, plumbing, medical devices, aerospace composites and other consumer products. In additional Dr.Shabeer also has expertise in polymer degradation mechanisms, polymer rheology, product development, service life studies, process evaluation from part analysis and comparison of physical property results with application requirements.
Dr. Shabeer received his Ph.D from Missouri University of Science and Technology (formerly known as University of Missouri-Rolla) in 2005. He also received the Gold Medal from the Indian Plastics Institute for the best candidate in polymer engineering in 2001. He has worked on over 20 failure analysis cases. He was actively involved in technical investigations and failure analyses that required the use of many laboratory analysis techniques, including optical microscopy, fractography, electron microscopy, non-destructive, and destructive evaluation and chemical analysis.
Dr. Shabeer has authored many technical papers on polymer failure analysis and bio based composites.
The Jagerhaus in Anaheim, 2525 East Ball Road, just west of the 57 Freeway, on the North side of Ball.
Turn right at the first driveway. Phone 714-520-9500. GoogleMap Link
6:00 pm Social • 7:00 pm Dinner • 8:00 pm Speaker — Member or guest dinner $20.
Student (with student ID) dinner $10. No cost for Program only.
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