Endommagement et écaillage par laser

Nous exploitons des résultats expérimentaux sur les effets thermomécaniques induits dans des cibles métalliques après interaction avec le rayonnement de la chaîne diagnostic du laser impulsionnel Phébus. Les simulations numériques des phénomènes induits par le dépôt d'énergie laser ont été effectuées à l'aide des codes monodimensionnels FCI1 et EFFET1 qui traitent le dépôt d'énergie laser, la formation, la propagation et l'atténuation des contraintes qui en résultent ainsi que l'endommagement et l'écaillage. Cette exploitation a permis de restituer correctement les contraintes enregistrées par une jauge à quartz et de caler les paramètres de différents modèles de fracture.Phebus laser-driven shock wave is used to study dynamic damage and spallation in aluminium and copper targets. Numerical simulations are performed to calculate the ablation pressure, the shock induced and the stress evolution in the targets with the one-dimensional codes FCI1 and EFFET1. We calculate also the spall widths with two damage criteria. Theoretical calculations of the stresses in quartz gauge and the scab thicknesses are in good agreement with the experimental results

Neuroergonomic and psychometric evaluation of full-face crew oxygen masks respiratory tolerance: a proof-of-concept study

Introduction Preventing in-flight hypoxia in pilots is typically achieved by wearing oxygen masks. These masks must be as comfortable as possible to allow prolonged and repeated use. The consequences of mask-induced facial contact pressure have been extensively studied, but little is known about mask-induced breathing discomfort. Because breathlessness is a strong distractor and engages cerebral resources, it could negatively impact flying performances. Methods Seventeen volunteers (age 20–32) rated respiratory discomfort while breathing with no mask and with two models of quick-donning full-face crew oxygen masks with regulators (mask A, mask B). Electroencepha- lographic recordings were performed to detect a putative respiratory-related cortical activation in response to inspir- atory constraint (experiment 1, n=10). Oxygen consump- tion was measured using indirect calorimetry (experiment 2, n=10). results With mask B, mild respiratory discomfort was reported significantly more frequently than with no mask or mask A (experiment 1: median respiratory discomfort on visual analogue scale 0.9 cm (0.5–1.4), experiment 1; experiment 2: 2 cm (1.7–2.9)). Respiratory-related cortical activation was present in 1/10 subjects with no mask, 1/10 with mask A and 6/10 with mask B (signifi- cantly more frequently with mask B). Breathing pattern, sigh frequency and oxygen consumption were not different. Conclusions In a laboratory setting, breathing through high-end aeronautical full-face crew oxygen masks can induce mild breathing discomfort and activate respirato- ry-related cortical networks. Whether or not this can occur in real-life conditions and have operational consequences remains to be investigated. Meanwhile, respiratory psychometric and neuroergonomic approaches could be worth integrating to masks development and evaluation processes