Temat: 24 Model - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: An application of 24Model to analyse capsizing of the Eastern Star ferry
Autorzy:: Suo, X.
Fu, G.
Wang, C.
Jia, Q.
Tematy:: Eastern Star ferry accident
24 Model
systematic accident causation model
accident analysis
hazards; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258602.pdf Link otwiera się w nowym oknie
Opis:: In the present study, the Eastern Star ferry accident was analyzed via 24Model. 24Model, as an accident causation model based on system thinking, holds that all causations of the accident are hazards and all hazards in the system need to be identified and comprehensively controlled in accident prevention. The result showed that five factors were the main causes of the accident. First, the direct causes: bad weather, the bad condition of the hull and the unsafe acts of the captain. Second, the indirect cause: the lack of safety awareness and safety knowledge of both the captain and the company’s senior management. Third, there were loopholes in safety management system, including the training, supervision and execution of the company. Forth, the root cause: the company didn’t establish a good safety culture. Last, the external causes: the severe market pressure, excessive regulatory authorities with puzzled relations and responsibilities—seriously hindered effective supervision. In order to prevent this kind of accident and to secure shipping system, the shipping companies and the relevant regulatory units should draw lessons from the five factors mentioned above, and take measures to identify and control those hazards.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Validation of the FEM model of the Mi-24 tail boom and vertical stabilizer
Autorzy:: Reymer, P.
Tematy:: finite element method
Mi-24 helicopter numerical model
validation; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/242236.pdf Link otwiera się w nowym oknie
Opis:: The scope of this work was the validation process of the numerical model of the Mi-24 helicopter tail boom and vertical stabilizer. In order to obtain a detailed geometry of the actual structure the sophisticated reversed engineering techniques were used. The measurement was performed using two separate techniques: one based on digitalphotogrammetry and other based on a three dimensional laser scanning with ATOSIII scanner. The numerical model was created with use of the obtained geometry, available technical documentation and detailed inspection of the structure. The obtained FEM model was validated using strain measurements of the real structure during characteristic flight maneuvers. A system of foil strain gauges was installed on the tail boom in previously selected locations. Calibration process, using known loads, was performed in order to determine response of the measurement system. To enable a quick and reasonable comparison of results from the experiment and calculations a special element was introduced in the FEM model. Their task was to monitor local strains in places corresponding to those where the strain gauges were installed. Detailed analysis of results confirmed, that after some minor modifications, the developed finite element model represents the actual structure reasonably well. Particular attention was paid to the representation of the boundary conditions and how to implement loads, which can significantly affect the obtained results. The analysis carried through confirms, that the presented validation technique, based on strain measurements, allows verifying a complicated numerical model in a relative cheap, fast and reliable way.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Global FEM model of combat helicopter
Autorzy:: Gmurczyk, G.
Reymer, P.
Kurdelski, M.
Tematy:: Mi-24 global FEM model
photogrammetry
3D scanning
reverse engineering
FEM; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/242175.pdf Link otwiera się w nowym oknie
Opis:: Air structures like Mi-24 were designed in last decades of the XX century, when computer aided design was not available. Philosophy of the exploitation so-called "safe life" postulate exploitation is defined by the manufacturer time. Such attitude turned out very uneconomical because of the various profiles of the use of aircrafts. Extending the initial period of exploitation is a quite common way to extend an aircrafts' life. Such solutions are accepted in the majority of countries, even the richest. In order to obtain detailed geometry of the real structure reversed engineering techniques were used. The geometry was obtained using two methods: digital photogrammetry and optical scanning using ATOS scanner from GOM Company. Geometric model, which was used for numerical Finite Element Method model, was developed based on the data from measurements, available technical documentation and detailed inspection of the structure. Global FEM model is being used for finding critical elements of aircraft's structure. Structure elements such as stringers, ribs or frames were modelled using bar and beam elements with specially defined properties and cross sections. Structure elements which didn't take part in transferring the loads, but with significant mass were made in a simplified manner so that their weight in the model correspond to actual or were modelled as concentrated masses.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Rheological Properties of DNAN/HMX Melt-cast Explosives : Maximum Packing Density Calculation and Modified Viscosity Model
Autorzy:: Meng, Jun-jiong
Luo, Yi-ming
Wang, Wei
Jiang, Qiu-li
Wang, Hong-xing
Miao, Fei-chao
Tematy:: 2,4-dinitroanisole
DNAN
grade ratio
maximum packing density
rheological properties
empirical model; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Powiązania:: https://bibliotekanauki.pl/articles/59115417.pdf Link otwiera się w nowym oknie
Opis:: The study of suspensions with high solid content and low viscosity has become a very active topic for melt-cast explosives, for both research and industry. Previous studies have described how the viscosity of high-solid-content suspensions can be decreased by optimizing the grade ratio, that is, increasing the particle packing density. This paper numerically simulates the maximum packing density (Φm) for different grade ratios at which the suspension viscosity approaches infinity, using the overlapping discrete element cluster method. According to this method, the shape of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) particles was modeled as a group of overlapping, rigidly connected hard spheres. The results showed that the numerical simulation value can be used as the real value of Φm for any grade ratio in engineering applications. The rheological properties of 2,4-dinitroanisole (DNAN)/HMX suspensions with various grade ratios of three HMX samples with different d50 values were investigated using a rotational viscometer over a range of mass solids content (ϕ = 20-75 wt.%) in the shear rate range of 0.1-100 s⁻¹. An empirical model incorporating the reduced solid content (Φ, equal to ϕ divided by Φm) and shear rate (γ) was modified to predict the relative viscosity of DNAN/HMX suspensions. This modified model has a strong correlation with the experimental data and can be used to accurately predict the viscosity of DNAN/HMX suspensions. In addition, the applicability of different classical models to DNAN/HMX suspensions is discussed.
Dostawca treści:: Biblioteka Nauki

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