Shimmed Double-Nut Screw Assembly for Clear Preload Sensing

The patent introduces recesses or holes at specific locations on the shim to create localized stress concentration areas. By attaching the force sensor to these specific locations rather than the general outer surface, the sensor detects significantly amplified strain signals. This local modification approach maintains the overall shim structure while creating targeted high-strain zones that improve measurement resolution and reduce noise susceptibility.

The patent modifies the physical parameters of the shim by introducing recesses or holes, which change the stress distribution pattern. These geometric modifications transform the uniform low-strain state into a localized high-strain state at specific positions, enabling the force sensor to detect preload with higher resolution and reduced noise interference.

The recesses or holes are strategically positioned and dimensioned to create localized stress concentration only at the sensor attachment area. The rest of the shim maintains its full contact area and structural integrity. This localized approach allows stress amplification where needed for detection while preserving overall shim rigidity for mechanical function.

The patent applies partial action by reducing the contact area only at specific localized regions (where recesses or holes are present) rather than reducing the overall contact area. This selective reduction provides sufficient stress amplification for sensor detection while maintaining adequate overall rigidity for the shim's mechanical support function.