• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.806-812
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• 2010

Fuel tanks for rotorcraft have a great influence on the survivability of crews. The philosophy of crashworthy rotorcraft design evolved from the long term effort of the US Army. US army established MIL-DTL-27422D for specifying detail requirements related to crash resistant fuel tank especially for military rotorcraft to prevent post crash fire which is the greatest threat to life in rotorcraft crash. Crashworthiness of the rotorcraft fuel tank could be guaranteed through the crash impact tests which are specified in the MIL-DTL-27422D. Fuel tanks for Korea Helicopter Program have been developed and tested according to MIL-DTL-27422D with minor modifications of flexible fittings. The present study shows some results of the mandatory crash impact tests of the fuel tanks to verify their performances.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.300-310
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• 2008

Through this study, a conceptual design for the next generation high-speed EMU has been derived to meet the crash worthiness requirements of the Korean rollingstock safety regulation. The crashworthiness regulations require some performance requirements for two heavy collision accident scenarios; a train-to-train collision at the relative speed of 36 km/h, and a collision against a standard deformable obstacle of 15 ton at 110km/h. The complete train set will be composed of 2TC-6M with 13 ton axle load, which is different from KTX with the power car of 17 ton axle load. Using theoretical and numerical analyses, a crashworthy conceptual design was derived in terms of mean crush forces and energy absorptions for principal crushable structures and devices. The derived conceptual design was evaluated and improved using one dimensional dynamic simulations for the bar-spring-damper-mass model. It is shown from the simulation results that the suggested conceptual design can easily satisfy domestic crashworthiness requirements.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.1-11
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• 2020

Medium to large post structures installed along the roadside without proper protection can lead to serious vehicle damage and occupant injury at the impact. In North America and Europe, splitting systems such as slip base or breakaway device are used to reduce impacts. But the system has the risk of secondary accident when the splitted post falls down to the traffic or pedestrian. Sliding Post have been proposed as a way to solve this problem. By studying the crash test results of the 1.3ton and 0.9ton vehicle with 60 km/h and 80 km/h to a Rigidly Fixed Post (RFP) and Sliding Post (SP), danger of the conventional RFP and crashworthiness of the SP have been proven. While collision analysis only from the acceleration measured at the center of the vehicle assumes the motion of the post is the same as that of the vehicle, in this paper, by adding high speed film data to the analysis with vehicle acceleration could have separate the post motion from the vehicle motion. It gives better explanations on the movement of post and vehicle in each distinctive time step and provides basics to the crashworthy post design.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.521-530
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• 2011

Since aircraft fuel tanks have many interfaces connected to the airframe as well as the fuel system, they have been considered as one of the system-dependent critical components. Crashworthy fuel tanks have been widely implemented to rotorcraft and rendered a great contribution for improving the survivability of crews and passengers. Since the embryonic stage of military rotorcraft history began, the US army has developed and practised a detailed military specification documenting the unique crashworthiness requirements for rotorcraft fuel tanks to prevent most, hopefully all, fatality due to post-crash fire. The mandatory crash impact test required by the relevant specification, MIL-DTL-27422D, has been recognized as a non-trivial mission and caused inevitable delay of a number of noticeable rotorcraft development programs such as that of V-22. The crash impact test itself takes a long-term preparation efforts together with costly fuel tank specimens. Thus a series of numerical simulations of the crash impact test with digital mock-ups is necessary even at the early design stage to minimize the possibility of trial-and-error with full-scale fuel tanks. In the present study the crash impact simulation of a few fuel tank configurations is conducted with the commercial package, Autodyn, and the resulting equivalent stresses and internal pressures are evaluated in detail to suggest a design improvement for the fuel tank configuration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.343-349
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• 2013

Crashworthy fuel cells have a great influence on improving the survivability of crews. Since 1960's, the US army has developed a detailed military specification, MIL-DTL-27422, defining the performance requirements for rotorcraft fuel cells. In the qualification tests required by MIL-DTL-27422, the crash impact test should be conducted to verify the crashworthiness of fuel cell. Success of the crash impact test means the improvement of survivability of crews by preventing post-crash fire. But, there is a big risk of failure due to huge external load in the crash impact test. Because the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, the failure of crash impact test can result in serious delay of a entire rotorcraft development. Thus, the numerical simulations of the crash impact test has been required at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. Present study performs the numerical simulation using SPH(smoothed particle hydro-dynamic) method supported by a crash simulation software, LS-DYNA. Test condition of MIL-DTL-27422 is reflected on analysis and material data is acquired by specimen test of fuel cell material. As a result, the resulting equivalent stresses of fuel cell itself are calculated and vulnerable areas are also evaluated.