Free-Form Deformation Digital Image Correlation (FFD-DIC): A non-invasive spline regularization for arbitrary finite element measurements

Regularizing Finite-Element Digital Image Correlation (FE-DIC) problems is essential when using fine meshes, for instance to get a direct bridge with simulation tools or in view of performing data assimilation. Shape optimization brings comparable concerns so it proposed draw inspiration from this field research. In respect, new general spline-based non-invasive regularization scheme proposed, based on the Free-Form Deformation (FFD) concept that offers opportunity decouple design space actual geometry be updated. The main idea embed input FE mesh, any element type size, into simple cuboid B-spline box and relate nodal dof measured another more regular discretized by box. length thus directly driven refinement. A specific care taken handle possible conditioning caused non-influential control points. From practical point view, method can interpreted as projection reduced basis; therefore, results regularized but conventional which simply computed standard FE-DIC code. developed applied displacement measurement DIC mesh-based stereo-DIC. For latter, novel procedure additional projections over local directions complements FFD full efficiency. performance strategy assessed real images coming various experimental tests comparisons are made other published techniques prove its effectiveness.