Mechanical stability as used in this guideline refers to the prevention of any of the three types of fretting motion.
a.High contact forces tend to produce highest stability.
b.Large interface areas tend to be more stable—particularly against rocking and rotational motions.
c.An interface consisting of two or more discrete contact points, spaced apart from each other, tend to be more stable against disturbance motions.
d.Motions due to differential thermal expansions of the contact housing/mounting hardware are insidious and dangerous, and are often overlooked in design. Thermal cycling of the mated connector will show up this problem. It is controlled by choice of materials and/or by designing the contact configuration such that the expansion/contraction is accommodated somewhere other than the movement of the contact interface. As for instance, by elastic deflections of the contact members or their mountings.
Fretting Motions
_-_p70a.png)
Single Point
_-_p70b.png)
More Stable
_-_p70c.png)
Rotation or Twisting
_-_p70d.png)
Translation
_-_p70e.png)
High Stability
_-_p70f.png)
Rocking
–68–
