Soft projectile impact forces measurement using Hopkinson bars: application to ice, artificial bird and rubber

Ramón Del Cuvillo,Jose Alfonso Artero-Guerrero,Jorge López Puente,Jesús Pernas-Sánchez

doi:10.1051/epjconf/202125001008

Ramón Del Cuvillo, Jose Alfonso Artero-Guerrero + Show 2 more

Open Access

https://doi.org/10.1051/epjconf/202125001008

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Abstract

This work presents an experimental campaign of impacts of soft projectiles to measure the induced force during the impact. Three different materials acting as soft impactors that could strike against a aeronautical structural component: ice, artificial bird and rubber have been impacted at several velocities against an aluminium Hopkinson bar. This device has been instrumented with semiconductor strain gauges that allow to obtain the induced compression strain. Additionally, all the impacts were recorded using high-speed video cameras, allowing the kinematic analysis of the projectile during the impact. After the results study, it has been concluded that there is a linear dependency between the kinetic energy and the peak force for all three materials. Added to that, it has been proved that the higher peak force corresponds to ice, despite the kinetic energy, followed by rubber and finally the artificial bird. In addition, while ice and artificial bird projectiles get radially dispersed after the impact, rubber spheres rebound due to its different behaviour. The obtained data is of great interest to design structures which could be subjected to impacts of soft materials such as aeronautic structures

Highlights

Aeronautical transportation industries are continuously improving and optimizing their structures with the goal of obtaining more reliable and lightweight components
Three different materials acting as soft impactors that could strike against a aeronautical structural component: ice, artificial bird and rubber have been impacted at several velocities against an aluminium Hopkinson bar
The period of the compression waves is almost equal for gelatine and ice, whereas the wave promoted by the rubber needs more time to get back to the unloaded state (0.6 ms)

Summary

Introduction

Aeronautical transportation industries are continuously improving and optimizing their structures with the goal of obtaining more reliable and lightweight components. Several articles could be found about the effect of impacts on aeronautic structures[1], [2] for instance the authors of the current work have publish several works related to the low and high velocity impact of rigid projectiles on composite laminates [3], [4]. Impactors could be classified using different strategies, being one of them related to its strength (soft and hard bodies). Many efforts have been done in order to understand the influence of the different parameters such as mass or shape when impacting lightweight structures [2], [4]. Soft body impactors have received less attention even if are quite common in the aeronautic industry, and are worth to be studied. In almost all the works found in the literature the characteristic of the projectile have been analysed separately: velocity, mass, shape, etc. The techniques used in these studies were based on impact momentum [8], load cells [9] and stress waves propagation using modified Hopkinson devices [6], [7]

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