Purdue University

Purdue University

Mechanical Engineering
Tribology Laboratory

Ben Leonard

Ph.D. Candidate
M.S., Purdue University, West Lafayette, 2008
B.S., Rose-Hulman Institute of Technology, 2005

Office Address:
585 Purdue Mall ME
Room# G005
West Lafayette, IN 47907

Office Phone: 765-494-0308
email: bdleonar@purdue.edu





Effects of contact geometry, material, and the third body effect on fretting wear

The fretting phenomena caused by small scale reciprocating motion.  It causes failure through wear loss and fatigue cracking and is one of the leading causes of breakdown in industrial machinery.  Due to the small amplitude of the fretting motion wear particles are not immediately ejected from the contact but build up to form a “third body” separating the surfaces.  A number of methods are used protect components from fretting damage but some of these measures are harmful under certain conditions.  The purpose of my investigation is to develop an experimental rig and numerical model to study fretting wear and use these tools to quantitatively analyze the effectiveness of coatings.  A fretting wear test rig (FWTR) was designed and constructed to study Hertzian point contacts which quickly eject wear particles and flat on flat contacts which tend to retain them.  The FWTR allows elevated temperatures, in situ observation of wear debris, and evaluation of wear coefficients.  A combined finite discrete element model (FDEM) in which multiple finite element bodies interact as distinct bodies was developed to study fretting wear using the Archard and dissipated energy approaches.  The FDEM has the unique ability to study systems containing large numbers of deformable bodies.  The FDEM is used to analyze the effect of coating parameters including modulus of elasticity, coefficient of friction, and thickness on fretting wear in Hertzian line and flat on flat contacts.  The FWTR and FDEM are used to compare and evaluate the Archard and dissipated energy equations for modeling and predicting wear.  An efficient wear mapping method drawing upon both theories is presented for quantifying the fretting resistance of a contact across a wide range of conditions.

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