Pierrick Guégan

Critical impact velocity for ice fragmentation

The fragmentation process is a main concern in many engineering applications such as preventing flameouts of aircraft engines. The authors of this article are interested in measuring the critical impact velocity for ice fragmentation. Precisely, a dropweight technique was applied to study the ice ball impacts on glass plates. The influence of ice ball temperature, diameter and impact angle is also investigated. The after-impact ice ball state was found to be classified into two cases: an altered state and a non-altered state. The critical impact velocity is defined as the minimum impact velocity for which the ice ball is altered after impact or the maximum impact velocity for which the ice ball is not altered after impact. The experimental results are analysed by a model, assuming that the alteration regime is observed as soon as the ice ball normal kinetic energy is higher than a critical value of its deformation energy. This model depends on one parameter which is determined in this study. This last result is the major achievement of this article as there is almost no measurement of this parameter in the literature.

Experimental investigation of rubber ball impacts on aluminium plates

Aircraft structures should endure tyre debris impacts. Therefore, numerical simulations which are able to predict such phenomena are highly appreciated for the aircraft structures design. However, these simulations had to be checked by means of experimental data. In this paper, a new experimental set-up, with well-known boundary conditions, has been developed for numerical model validation. This new set-up allows for impacts with angles ranging from 20° to 90° by a step of 5°. In this study, rubber balls, which are 42 mm in diameter, are launched against 500 × 500 mm2 aluminium alloy plates. The impact velocities are in the range of 130 m/s.

High speed experimental analysis of orthogonal planing using high speed infrared camera

An experimental analysis of the orthogonal cutting process is presented. Machining experiments have been performed using advanced techniques. A high-speed camera is coupled with an infrared thermal measurement aid on a dynamic test bench. This continuously reveals the deformations occurring on the flank of a chip, and the infrared camera gives information on the variation of thermal radiation (see the pictures under the abstract). The challenge consists of understanding the effect of machinability improvement treatments on metallic materials.