Friction and Lubrication in Mechanical Design Episode 1 Part 5 pptx

80

0.6 : Region 2

0.5

0.4

Chapter 3

0.9 - I

0.7:

o.o,..,..,..,..,..,..,..,..,..,.,,,.,..,..

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

(4 Total Applied Force (x 103 Ibf)

= 0.32

z 0.2:

6 -0.3:

-0.5 i

-0.4 1

= 0.3

0.1

z 0.2

6 -0.3:

-0.5 i

-0.4 1

Region 1

A-A-A-~A-A-A-~~A-A-A-A-A-A-~

(b) Total Applied Force (x 10 Ibf)

Figure 3.19 (a) Tangential load sharing between the two contact zones at differ￾ent applied loads. (b) Distance between the line of action of the resultant frictional

resistance and centroid at different applied loads.

Traction Distribution and Microslip in Frictional Contacts 81

f2= 0.12 p2= 10000 psi

/

f2= 0.12 p2= 20000 psi

500 600 700 800 900 650 1000 1Ox) 1100 1150 1200 1250 1280 1296

Figure 3.20 Development of slip regions on a discrete contact area with increas￾ing tangential load.

3.4.3 Iterative Procedure

The modified linear programming formulation is first implemented with an

initial guess for the center of rotation in order to find the discretized traction

forces whose directions are predetermined by the preprocessor. Now the

residual forces (the rectangular components of the sum of the traction

forces) can be calculated. These residual forces must be equal to zero

when the real center of rotation is found, since no tangential forces are

applied. The residual forces are then used to modify the center of rotation

and the process is repeated until the residual forces vanish. The real center of

rotation, the traction force distribution, the microslip region, and the angle

of rigid body rotation are determined by this iterative procedure, as depicted

in the flow chart (Fig. 3.22).