Energy Loss
Non-reversible energy dissipation during cyclic loading creates path-dependent stress-strain curves in structural substrates and transducer bodies. Measurement of mechanical hysteresis quantifies the deviation between loading and unloading output responses at identical mechanical strain levels. The phenomenon establishes the baseline precision limit for strain gauge load cells and flexible circuit assemblies.
Loading Deviation
Polymer resin matrices inside FR4 laminates absorb mechanical energy through internal molecular friction when deformed. Strain gauges bonded to deflective board regions exhibit higher bridge output during load removal than during initial load application. Elastic lag in copper foil traces contributes secondary offsets that persist until internal stresses relax completely over time.
Higher strain cycle frequencies increase energy dissipation rates, generating localized thermal gradients within composite substrates. Gauge zero offsets return to baseline only after mechanical relaxation cycles complete. Load cell flexure bodies machined from high purity aluminum alloys display lower hysteretic error than composite circuit board structures.
Peak hysteresis errors occur near the midpoint of full scale rated load ranges during ascending and descending load cycles.
Material Limit
Calibration procedures run cyclic loading sequences to establish repeatable correction factors for sensor bridge circuits. Material selection directly governs hysteretic response, as crystalline metals exhibit tighter strain recovery paths than amorphous resin systems. Operating transducers beyond yield strength limits causes permanent plastic deformation that corrupts hysteresis compensation algorithms.
