Ed Bock of APEX Electrical Interconnection Consultants explains how to increase contact performance by pre-stressing to achieve greater strength and expanded dynamic range.

 

Stress TestIn examining the consequences of residual stress that develop in a contact beam subjected to stresses beyond the material’s elastic limit, we can see how residual stress may be beneficial, or if not properly configured, may actually be very harmful to a contact spring.In examining the consequences of residual stress that develop in a contact beam subjected to stresses beyond the material’s elastic limit, we can see how residual stress may be beneficial, or if not properly configured, may actually be very harmful to a contact spring.

Definitions of both the elastic limit and residual stress are important in understanding how this increase or decrease in performance occurs.

  • Elastic limit – This defines a range of stress characterized by the absence of a permanent deformation upon release of the load. In essence, we have complete springback. A stress in excess of the elastic limit will lead to a permanent set upon release of the load.
  • Residual stress – Residual stresses are induced whenever a material is plastically deformed (pushed beyond the elastic limit). The resulting permanent strai