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Naval vessels may undergo high strain rate loading, including impact, wave slamming and blast loading. Predicting the behaviour of composite sandwich structures to such loading is complicated, hence representative experiments are required. Two panels with hybrid carbon-and glass-fibre skins were fabricated and subjected to full-scale air blast loading. The panels were 1.7 × 1.5 m in size and were subjected to a 100 kg nitromethane charge at a stand-off distance of 15 m. 3D Digital Image Correlation (DIC) was implemented behind each of the panels to record the full-field out-of-plane displacement of the panels. In addition, the panels were instrumented with foil strain gauges on the front skins to record the response of the panel side in contact with the blast. The results revealed that the combination of glass-and carbon-fibre improves the blast resilience when compared to previous blast testing on panels with exclusively glass-fibre or carbon-fibre skins. However, the order in which the glass-and carbon-fibre layers were arranged did not have a significant effect on the overall panel performance. In addition, panels with the same hybrid skins were subjected to high velocity impact testing. An aluminium projectile with 25 mm diameter was fired at small scale panels (160 × 160 mm) using a laboratory gas gun at a velocity of 78 ms−1. 3D DIC was again used to record the out-of-plane displacement of these panels. In contrast to the blast experiment, the impact results showed that the order in which glass-and carbon-fibres were arranged did affect both the out-of-plane displacement and damage to the panels. The least damage occurred when glass-fibre layers were placed on the outermost layers impacted by the projectile.

This study offers improved safety design guidelines for high explosives (HE), creating impact insensitive geometries, capitalising on the potential for additive layer manufacturing techniques. There are numerous safety concerns when considering energetic materials and HEs, the primary concern, subject of this work, is the risk of unplanned detonation from impact. There are multiple potential causes for unplanned detonation due to impact; one of which is the impact from a high‐speed foreign object. Despite this substantial risk, the problem has not been publicly addressed by means of adjusting the design of the charge itself. Therefore, investigations into the internal design of the charge were executed, whereby the inclusion of various sized and shaped voids are assessed, to establish their effect upon the reactivity of the HE. Using computational modelling, allows for numerous designs to be assessed and developed, and the impact sensitivity of the charge to be tested across a range of scenarios. The proposed validated computational model enables designs to be optimised in a safe and efficient manner, reducing the number of physical tests required, and thus minimising time, cost and the environmental impact. [ABSTRACT FROM AUTHOR]

Globally, over three million women participate in rugby union, yet injury prevention and training strategies are predominantly based on androcentric data. These strategies may have limited generalisability to females, given the cervical spine is more susceptible to whiplash and less adept at resisting inertial loading. A total of 53 university rugby union players (25 female, 28 male, 20.7 ± 1.8 years) had their isometric neck strength measured. Bespoke instrumented mouthguards were used to record the magnitude of head impact events in six female and seven male competitive matches. Mean female maximal isometric neck strength was 47% lower than male. Independent samples Mann–Whitney U tests showed no significant differences for peak linear head acceleration (female: median 11.7 g, IQR 7.9 g; male: median 12.5 g, IQR 7.0 g p=.23) or peak rotational head acceleration (female: median 800.2 rad·s−2, IQR 677.7 rad·s−2; male: median 849.4 rad·s−2, IQR 479.8 rad·s−2; p=.76), despite the mean male body mass being 24% greater than female. Coded video analysis revealed substantial differences in head-impact mechanisms; uncontrolled whiplash dominated >50% of all recorded female impact events and <0.5% in males. Direct head-to-ground impacts comprised 26.1% of female and 9.7% of male impacts, with whiplash occurring in 78.0% and 0.5%, respectively. Overall, the data provided in this study do not support the generalisation of male-derived training and injury-prevention data to female rugby athletes. These results suggest a considerable research effort is required to identify specific weakness of female rugby players and derive appropriate training, injury prevention and return to play protocols. Highlights Video analysis revealed substantial differences in head-impact mechanisms, with uncontrolled whiplash dominating >50% of all recorded female impact events but rarely in males. Isometric neck strength was 47% lower in female players than males. Direct head-to-ground impacts accounted for 26.1% and 9.7% of female and male impacts, with whiplash occurring in 78.0% and 0.5%, respectively. [ABSTRACT FROM AUTHOR]

: The present paper investigates a reliability model for a system wherein an inspection is carried out on failure to find out as to which part needs to be repaired/replaced. However, there are chances of wrong diagnosis and hence the second opinion is taken. If the second opinion is in consonance with the first opinion, the necessary part/component of the system is repaired/replaced. However, if the two opinions are contradictory, the system is undertaken by an expert for inspection and repair. The possibility of improper diagnosis cannot be ruled out even if the two opinions are in consonance and the same is revealed some time after putting the system under observation during its operation and then also the system goes under repair of the expert repairman. System is analyzed by making use of regenerative point technique. Various measures of system effectiveness have been attained. Profit of the system is evaluated. Numerical examples are given to validate the derived indices. [ABSTRACT FROM AUTHOR]