The speckle interferometry technique is employed to obtain the experimentally measured deformation field.
While this technique has been used previously to measure deformation fields within soft biomaterials and around migrating fibroblast cells [28], [29], the details of this method have not been fully described.
The globe deformation was only about 1/10th of the measured deformation amplitude at its peak value [ 26].
The in-plane strain field (x- and y-components) was calculated from the measured deformations, and under assumption of plastic incompressibility, the missing strain component (z-direction) was calculated, as shown by Kajberg and Lindkvist (2004).
The experimental process consists of three steps: fabricating the specimen with integrated deformation carriers by 3D printing; measuring the deformation fields by a full-field optical method; identifying the constitutive parameters by VFM.
The measured high-temperature deformation fields of the test sandwich panels reveal that an in-plane homogeneous thermal expansion occurs as expected, while the out-of-plane deformation shows evident axisymmetric distributions with the maximum deflections dependent on the temperature differences between the back and front facets.
DIC-based measuring techniques, when properly compensated for refractive distortion where applicable, can adequately measure relatively homogeneous deformation fields under a variety of conditions.
So, it is necessary to apply practical methods by carrying out field tests and measuring deformations directly.
Deformation fields are measured using full-field digital image correlation (DIC) to reveal a large difference in the strain localisation behaviour of the material depending on the amount of lateral deformation.
Based upon the deformation field measured by high speed imaging and digital image correlation (DIC), a new strain estimation model considering the extrusion process of constraint is proposed in this paper.
