Page 78 - Tribology in Machine Design

Elements of contact mechanics 65

ESDU-78027, Part II first approximation to temperature rise;
ESDU-78028, Part III estimation of thermal resistance of an assembly;
ESDU 78029, Part IV - heat transfer coefficient and joint conductance.
Throughout this chapter, references are made to the appropriate ESDU
item number, in order to supplement information on contact mechanics
and thermal effects, offer alternative approach or simply to point out the
source of technical data required to carry out certain analysis.

3.2. Concentrated and The theory of contact stresses and deformations is one of the more difficult
distributed forces on topics in the theory of elasticity. The usual approach is to start with forces
plane surfaces applied to the plane boundaries of semi-infinite bodies, i.e. bodies which
extend indefinitely in all directions on one side of the plane. Theoretically
this means that the stresses which radiate away from the applied forces and
die out rapidly are unaffected by any stresses from reaction forces or
moments elsewhere on the body.
A concentrated force acts at point 0 in case 1 of Table 3.1. At any point Q
there is a resultant stress q on a plane perpendicular to 0Z, directed
2 2
through 0 and of magnitude inversely proportional to (r 4-z ), or the

Table 3.1
Loading case

1. Point

2. Line

3. Knife edge or pivot

4. Uniform distributed load p
over circle of radius a

5. Rigid cylinder (£j >£ 2 )