Micro Asperity Contact Mechanics in Millimeter Wave Test Socket Interfaces
Mechanical preload across socket micro asperities defines insertion loss stability and constriction resistance in millimeter wave automated device testing.
Elasto-Plastic Deformation
Meaning
Mechanical response of a material that has been stressed beyond its elastic limit but has not yet reached total failure. Elasto-plastic deformation involves a recoverable portion of strain and a permanent set that remains after the load is removed. This behavior is common in spring terminals and metal housings that are bent during assembly.
Stress Threshold
Materials transition from purely elastic to elasto-plastic at the yield point. Below this point, the part returns to its original dimensions like a perfect spring. Above this point, the internal structure of the metal shifts, which results in a lasting change to the geometry of the component.
Contact Geometry
Permanent changes in shape can affect how a connector fits its mate. While some elasto-plastic deformation is often designed into a part to ensure a tight fit, excessive movement leads to loose connections. Engineers model these changes to predict the final resting position of a pin after it has been inserted.
Fatigue Resistance
Repeated loading into the plastic range reduces the total lifespan of the part. Each cycle of elasto-plastic deformation creates small defects in the metal that eventually grow into cracks. Controlling the depth of this deformation is a primary requirement for high reliability systems.
Materials that experience frequent cycling are tested to find the limit where permanent damage starts to affect the electrical path.