• International Journal of Highway Engineering
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• v.10 no.1
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• pp.87-95
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• 2008

One way to shield an atypical structure to secure the occupant safety of an impact vehicle is to stack energy absorbing material modules around the structure. To be applicable to a cushion module, material must have enough energy absorbing capabilities while satisfying the safety requirements of the vehicle occupant. Static compression test of the potential materials gives a good indication which material is good for a slacking module. This paper presents the mechanical properties that a cushion material must have to satisfy the safety requirements. Static tests are performed for Quard-Guard system module, sand bag, recycled tires, Geo-Container, Geo-Cell and Expanded Polystyren (EPS) Blocks. Static test results are discussed and EPS block of $30kg/m^{3}$ density showed good potential for a cushion module. To check the dynamic effect of EPS block, drop tests have been made up to 35.6km/h impact speed. Drop test results are compared with static test results and no appreciable difference was found. To improve the EPS module property, making holes to the block is suggested and drop test are performed for the modified blocks. From the drop test results, design values are suggested.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.120-127
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• 2001

The potential pollution problems resulting from tanker collision necessitate the requirement for an effective structural design and the development of relevant safety regulations. During a few decades, the great effort has been made by the international Maritime Organization and the Administration, etc, to reduce oil spillage from collision accidents. However there is still a need for investigation in the light of structural evaluation method for the experiments and rational analysis, and design development for an operational purpose of ships. This study aims for investigating a complicated structural response of bow structures of simplified models and oil carriers for assessing the energy dissipation and crushing mechanics of the striking vessels through a methodology of the numerical analysis for the various models and its design changes. Through these study an optimal bow construction absorbing great portion of kinetic energy at the least penetration depth prior to reach to the cargo area and an effective location of collision bulkhead are investigated. In order to obtain a rational results in this study, three stages of collision simulation procedures have been performed step by step as follows; 1) 16 simplified ship models are used to investigate the structural response against bow collision with variation of primary and secondary members. Mass and speed are also varied in four conditions. 2) 21 models consisted of 5 sizes of the full scaled oil carriers are used to perform the collision simulation with the various sizes and deadweight delivered in a recent which are complied with SOLAS and MARPOL. 3) 36 models of 100l oil carrier are used to investigate the structural response and its influence to the collision bulkhead against bow collision in variation with location of collision bulkhead, primary members, framing system and colliding conditions, etc. By the first study using simplified models the response of the bow collision is synthetically evaluated for the parameters influencing to the absorbed energy, penetration depth and impact force, etc.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.119-126
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• 2001

The potential pollution problems resulting from tanker collision necessitate the requirement for an effective structural design and the development of relevant safety regulation. During a few decades, the great effort has been made by International Maritime Organization and the Administration, etc, to reduce oil spillage from collision accidents. However there is still a need for investigation in the light of structural evaluation method for the experiments and rational analysis, and design development for an operational purpose of ships. This study is aimed at investigating a complicated structural response of bow structures of oil carriers for assessing the energy dissipation and crushing mechanics of striking vessel through a methodology of the numerical analysts for the various models and its design changes. Through this study an optimal bow construction absorbing great portion of kinetic energy in the least penetration depth prior to reach to the cargo area and an effective location of collision bulkhead are investigated. In order to obtain a rational results in this study, three stages of response analysis procedures are performed as follows; 1). 16 simplified ship models are used to investigate the structural response against bow collision with variation of primary and secondary members. Mass and speed are also varied in two conditions. 2). 21 models conisted of 5 size of full scaled oil carriers are used to perform the collision simulation with the various sizes and deadweight delivered in a recent which are complied with SOLAS and MARPOL. 3). 36 models of 100k oil carrier are used to investigate the structural response and its influence to the collision bulkhead against bow collision in variation with location of collision bulkhead, primary mombers, framing system and colliding conditions, etc.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.9-15
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• 2017

Recently, flexible cages have been introduced in an attempt to absorb and reduce the abnormal load transfer along the anterior parts of the spine. They are designed to be used with the pedicle screw systems to allow some mobility at the index level while containing ROM at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the flexible cage when combined with pedicle screws with flexible rods. The post-operated models were constructed by modifying the L4-5 of a previously-validated 3-D FE model of the intact lumbar spine (L2-S1): (1) Type 1, flexible cage only; (2) Type 2, pedicle screws with flexible rods; (3) Type 3, interbody fusion cage plus pedicle screws with rigid rods; (4) Type 4, interbody fusion cage plus Type 2; (5) Type 5, Type 1 plus Type 2. Flexion/extension of 10 Nm with a compressive follower load of 400N was applied. As compared to the Type 3 (62~65%) and Type 4 (59~62%), Type 5 (53~55%) was able to limit the motion at the operated level effectively, despite moderate reduction at the adjacent level. It was also able to shift the load back to the anterior portions of the spine thus relieving excessively high posterior load transfer and to reduce stress on the endplate by absorbing the load with its flexible shape design features. The likelihood of component failure of flexble cage remained less than 30% regardless of loading conditions when combined with pedicle screws with flexible rods. Our study demonstrated that flexible cages when combined with posterior dynamic system may help reduce subsidence of cage and degeneration process at the adjacent levels while effectively providing stability at the operated level.