Precision Analog Converter Gain Drift under Dynamic Thermal PCB Stress
Dynamic PCB thermal gradients cause substrate flexing that alters converter resistor ladder ratios via piezoresistive strain, driving gain drift.
DIC Strain Mapping
Surface Metrology
Non-contact deformation measurement relies on tracking the movement of stochastic patterns on a material surface. High-speed digital cameras capture images of the specimen to facilitate dic strain mapping across the entire visible area. The technique provides a dense vector field of displacements by comparing the loaded state to a reference image.
Correlation Algorithm
Mathematical sub-pixel registration identifies the translation and rotation of small pixel subsets. The software calculates the local deformation by minimizing the difference between the intensity patterns in the two images. Results are then transformed into a strain field through spatial differentiation.
Optical Resolution
Speckle size limits the spatial sensitivity of the results. Fine speckles are necessary for accurate dic strain mapping at small scales.
Error Source
Atmospheric turbulence and camera self-heating introduce false displacements into the data set. Proper calibration involves the use of a target with known dimensions to establish the scale factor and correct for lens distortion. Because the cameras must remain stationary, any vibration of the mounting rig appears as artificial strain.
Verification of the results often involves a comparison with traditional bonded gauges on a standardized tensile specimen. This process confirms that the virtual strain gauge length matches the physical requirements of the test.