We present an optical experimental approach and an analytical model to calculate the strain on a brick when an external force-pulse is indirectly applied on its surface. We assumed that the displacement produced on the brick is energy that it transforms to deformation. To measure the displacement, we applied one laser-beam to the brick and took image data of the speckles created by its reflection. The speckles were processed using the digital image correlation technique and allowed us to evaluate the relative displacements caused on the surface of the brick. Then, based on the kinetic energy of forced and damped oscillations, we calculated analytical strain values of the order of ε ≈ 1.52×10-6 .

Digital image processing is a useful tool that improves pictorial information for human interpretation and is mainly used for storage, transmission, and representation of different data. In this chapter, we want to introduce an optical technique which couples physical analysis with image processing for a measurement system. Optical methods were used to obtain the stress-strain relation by different invasive and noninvasive methods. This chapter talks about a novel noninvasive methodology to measure stress-strain evolution; this technique is based upon a single laser beam reflected on the cross section of ductile materials (steel and aluminum) while they are under a compression load. The way we measure one laser beam is by using the Gaussian beam propagation equations; we propose that the reflection area of the laser is going to change as the material surface area is compressed and we analyze these differences by using digital image processing. With this technique we are able to construct a stress-strain diagram.

We present a simple but accurate correlation between an experimental characterization and a simple analytical prediction of a wave propagation induced by the impact of a pendulum in a box filled with fine sand; this research is based on optical measurements and was carried out using the digital image correlation technique to determine the motion on the surface of the box visually observed by the reflection of the laser. We suggest that the reaction to the impact in the body will be similar to an equivalent damped mass-spring system, obtaining an average error of 3.67208 × 10 −4 .

In this research, an impact reaction which was provoked far from its origins was studied. A metal box filled with sand was used to emulate a rigid body in which a steel bar was embedded; these conditions simulated the fuselage and wing, respectively, and the impact was applied to the rigid body and the measurement to the bar. For this, an optical technique was used to measure the relative displacement of the steel bar, and the measurements are obtained by applying digital image correlation; 2D images were obtained from the speckles generated as a reflection of the beam on the material. The results were studied through the modified Gauss–Newton analytical approach obtaining a maximum standard error deviation of 0.144 from the experimental results.