Point Concentration
Configuration of strain gauges where multiple sensing elements are bonded directly on top of each other to minimize the footprint on a surface. The stacked rosette enables the measurement of principal strains at a single point in space. This arrangement is particularly useful on small or densely populated circuit boards where horizontal space is limited.
Measurement Advantage
Errors caused by strain gradients are reduced because all sensors share the same geometric center. In a standard planar layout, different elements might experience slightly different loads if the stress field changes rapidly across the board surface. The stacked rosette eliminates this spatial offset and provides a more accurate calculation of the Mohr circle.
Mathematical models benefit from this point-coincident data when calculating the principal angles and the magnitude of the tensile stress in highly congested areas.
Thermal Dissipation
Heat generated by the excitation current can become trapped between the layers of the gauge. This localized temperature rise affects the resistance of the sensing foil and introduces drift into the data. Precision measurements often require lower excitation voltages or pulsed power to mitigate the self-heating effects inherent in the stacked rosette design.
Physical Thickness
Multiple layers of polyimide and adhesive increase the overall height of the sensor. A stacked rosette may interfere with tight-fitting enclosures or adjacent components during a mechanical test. Selection of the sensor must account for this vertical clearance to avoid damaging the gauges or the assembly under study.
