טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSalib Jiries
SubjectElastic Plastic Contact under Normal and Tangential Loading
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Emeritus Izhak Etsion
Dr. Yuri Kligerman
Full Thesis textFull thesis text - English Version


Abstract

Wear is a common problem that occurs between contacting surfaces under combined normal and tangential loading. Over the past few decades, the research of such wear has proved to be of a large complexity. Although many wear regimes act simultaneously and lead to the degrading of the contacting surfaces, each regime has been researched separately. One of these regimes is adhesive wear, which occurs as a result of the sliding of two surfaces with adhesive contact between them while a normal load is applied.

A new approach for adhesive wear modelling based on first principles that eliminate the use of any empirical wear coefficient is presented. The model consists of a deformable elastic-plastic sphere in contact with a rigid flat that is subjected to a combined normal and tangential loading with full stick contact condition at the interface. The model predicts dimensionless volume of a potential wear particle that can be detached from the sphere at sliding inception. Due to the full stick contact condition, the sliding can occur at a certain interface beneath the contact where material experiences a certain maximum shear strain. The volume contained between this interface and the rigid flat forms a potential wear particle that would adhere to the moving flat and result in material transfer. An explicit relation between the dimensionless potential wear volume, material properties and dimensionless normal load is obtained. An empirical expression for predicting wear coefficient which depends on the normal load and material properties is also presented. Some recommendations for a dynamic modelling to allow actual detachment of wear particles rather than prediction of a potential wear particle are indicated.