Design of the Airbag Inflation System Applicable to Conventional and Autonomous Vehicles

The emergency transformation of various aspects of life and business these days requires prompt evaluation of autonomous vehicles. One of the primary reassessments deals with the applicability of the vehicle passive safety system to the protection of arbitrarily positioned passengers. To mitigate possible risks caused by the simultaneous deployment of several big airbags, a new principle of their operation is required. Herein, the aspirated inflator for a driver airbag is developed that can provide 50L-airbag inflation within 30–40 ms. As a result, about 3/4 of the air is to be entrained into an airbag from the vehicle compartment. The process is initiated by a supersonic pulse jet (1/3 air volume) generated pyrotechnically. Then the Prandtl–Meyer problem formulation enables guiding linear and angular dimensions of the essential parts of the device. Accordingly, a family of experimental models of varied geometry is fabricated and tested to determine their operational effectiveness in a range of motive pressure within ~ 3–7 MPa. Experiments are performed on a specially designed facility equipped with compressed-air tanks and a high-speed valve to mimic the inflator operation with the pyrotechnic gas generator. The aspirated inflator operability is characterized using multivariate measurements of pressure fields, high-speed video-recording of the airbag inflation process, and evaluation of aspiration (entrainment) ratio. The average volume aspiration ratio measured at 300 K is found to reach 2.8 and it’s expected to almost double at 1200 K.

Numerical Assessment of a Safety System to Minimize Injuries during a Cyclist Run-Over

Background. The World Health Organization has reported that 1.35 million people die on the roads every year due to road traffic accidents. This paper focuses on exploring a passive safety system that reduces lesions in the overtaking run-over scenario. Methods. Head Injury Criterion (HIC) and Combined Thoracic Index (CTI) were evaluated through numerical simulations using LS-Dyna®; in order to compare the computed results, three different speed scenarios were carried out (velocity of running over 40, 50, 60 km/h). Results. The computed results were divided into groups, A for the run-over test without a passive security system and B for the run-over test with a passive security system. For case A.1, the HIC15 was 3325. For case A.2, the HIC15 was 1510, and for case A.3, the HIC 15 was 1208. For case B.1, the HIC15 2605, for case B.2, the HIC15 was 1282, and for case B.3, the HIC was 730. Conclusion. The comparative results show that the passive safety system installed on the bicycle has an increased benefit impact on the severity of the injury on vulnerable road users, decreasing the probability of cranioencephalic lesions in all study cases. In addition, the thorax injuries are cut down only in the impact scenario at a speed of 40 km/h.

Increasing the safery of railway passenger and freight traffic

In 2020, the Ukrainian Government conducted an audit of the Ukrainian economy for nearly 30 years of independence and decided on the vectors of economic development aimed at European and Euro-Atlantic integration. The audit of the Ukrainian railways showed that most of the railway assets are critically worn. The audit and the vectors became a starting point for the development of the National Economic Strategy of Ukraine up to 2030, which was approved on March 3, 2021. One of the priorities of this strategy is the development of the transport sector by a succession of steps, including railway track and vehicle renewal, the introduction of high-speed passenger transport, and increasing railway traffic safety and environment safety on the Urrainian railways. The aim of this paper is to work out recommendations on increasing the safety of passenger and freight traffic in Ukraine. The paper generalizes the experience gained over the years of Ukrainian independence in the fundamental and applied transport-oriented reseach conducted at the Department of Sttistical Dynamics and Multidimensional Mechanical Systems, Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine. This experience may be useful in the implementation of the above steps on the way to the sustainable development of the Ukrainian railway transport. In the paper, emphasis is on new investigations into the passive propection of the cars of a motor car train in emergency collisions whose scenarios are specified by Ukrainian State Standard DSTU EN 15227. Based on a mathematical model of a collision of identical motor car trains, a mathematical model was developed to simulate a collision of a motor car train with a large vehicle at a crossing with account for a specified force characteristic of interaction of the leading car equipped with a passive safety system with a deformable obstacle. The model developed was used in analyzing dynamic loads on the cars of a motor car train with a passive safety system in its collision at 110 km/h with a 15 t large vehicle at a railway crossing. With consideration for the results of previous investigations into the dynamics of emergency collisions of a motor car train with an identical train and a fright car, recommendations were worked out on the passive protection of a home-made leading car in accordance with the requirements of normative documents. The proposed mathematical models and designs of energy-absorbing devices, the research results, and the practical recommendations worked out may be used in designing new motor car train vehicles for the Ukrainian railways in accordance with the DSTU EN 15227 requirements for passive protection in emergency collisions.

Investigation of effects of nonavailability of passive safety systems on the reactor behaviour during LOCA Scenario in AP600

The AP600 is a Westinghouse Advanced Passive PWR with a two–loop 1 940 MWt. This reactor is equipped with advanced passive safety systems which are designed to operate automatically at desired set-points. On the other hand, the failure or nonavailability to operate of any of the passive safety systems may affect reactor safety. In this study, modeling and nodalization of primary and secondary loops, and all passive reactor cooling systems are conducted and a 10-inch cold leg break LOCA is analyzed using ATHLET 3.1A Code. During loss of coolant accident in which the passive safety system failure or nonavailability are considered, four different scenarios are assumed. Scenario 1 with the availability of all passive systems, scenario 2 is failure of one of the accumulators to activate, scenario 3 is without actuation of the automatic depressurization system (ADS) stages 1–3, and scenario 4 is without actuation of ADS stage 4. Results indicated that the actuation of passive safety systems provide sufficient core cooling and thus could mitigate the accidental consequence of LOCAs. Failure of one accumulator during LOCA causes early actuation of ADS and In-Containment Refueling Water Storage Tank (IRWST). In scenario 3 where the LOCA without ADS stages 1–3 actuations, the depressurization of the primary system is relatively slow and the level of the core coolant drops much earlier than IRWST actuation. In scenario 4 where the accident without ADS stage-4 activation, results in slow depressurization and the level of the core coolant drops earlier than IRWST injection. During the accident process, the core uncovery and fuel heat up did not happen and as a result the safety of AP600 during a 10-in. cold leg MBLOCA was established. The relation between the cladding surface temperature and the primary pressure with the actuation signals of the passive safety systems are compared with that of RELAP5/Mode 3.4 code and a tolerable agreement was obtained.