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.

This research leads with the analysis of a structural joint. Different arrays of steel sheets were joined using bolts. The structures were built in a metallic box filled with Granitic 0/3 sand. This box was used as a rigid body to transmit impacts and the sand as a medium to interact between the body and the structure. Then, an optical set-up was placed to measure the interaction of the impact along the different arrays. Measurements were made 5 cm before and 5 cm after the bolt. Results were analyzed by performing signal filtering and approaching a mathematical solution revealing that impact interaction can be harmonic or damped oscillations with more than $98\%$ accuracy.

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.

This paper is focused on understanding how a wave was transmitted along arrays joined with rivets. The arrays were made of steel plates, and each section was joined to the other with five rivets. A total of three arrays were studied, which were compounded by one, two and three steel plates. To determine the wave transmission, a laser, a lens and a camera were set up in the experiment to calculate the in-plane motion both while the structure was still and during the indirect collisions. Results were studied by means of the general theory of elasticity coupled with spectral analysis from a general mathematical model; the latter fitted all the responses with a mean of 98% accuracy.