• International Journal of Highway Engineering
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• v.15 no.1
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• pp.65-73
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• 2013

PURPOSES: This paper presents the results of computer simulations of roadside safety barrier, called by safety roller guardrail, consisting of rotational roller, rotation control plate, post and subsidiary members. The rotation roller and rotation control plate are made by EVA(ethylene vinyl acetate), and PE(polyester), respectively. METHODS: The occupant risk analysis has been carried out under vehicle crash condition for high containment level of SB-4 for the purpose of local road. Simulations are performed with the finite element code LS/DYNA-3D. RESULTS: The numerical results obtained by LS/DYNA-3D software from the viewpoints of vehicle stability, vehicle trajectory, occupant risk, etc. CONCLUSIONS: It is noted that not only impact severity is drastically reduced but also vehicle trajectory is improved due to the characteristics of energy absorption and rotation pattern of EVA rollers connected by control plates.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.892-896
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• 2012

CFRP composites with light weight, high strength, and high elasticity by comparing with metal are widely used rather than previous steel plates. However, CFRP composite material has the weakness at hydrothermal and collapsed impact environment. Especially, moisture absorption into composite material can change molecule arrangement and chemical properties under hydrothermal environment. And static collapse experiment is the research in the differences of absorbed energy and deformation mode between moisture and non-moisture absorbed specimens. This study is compared and analyzed on the progress change of moisture absorption ratio after setting up the temperatures of 60 and 80 degrees C in order to comprehend how the change in the temperature influences on moisture absorption status inside CFRP composite materials.

• Steel and Composite Structures
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• v.22 no.4
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• pp.777-796
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• 2016

In this paper, the behavior of woven E-glass fabric composite laminate was experimentally investigated under quasi-static indentation and high velocity impact by flat-ended, hemispherical, conical (cone angle of $37^{\circ}$ and $90^{\circ}$) and ogival (CRH of 1.5 and 2.5) cylindrical perforators. Moreover, the results are compared in order to explore the possibility of extending quasi-static indentation test results to high velocity impact test results in different characteristics such as perforation mechanisms, performance of perforators, energy absorption, friction force, etc. The effects of perforator nose shape, nose length and nose-shank connection shapes were investigated. The results showed that the quasi-static indentation test has a great ability to predict the high velocity impact behavior of the composite laminates especially in several characteristics such as perforation mechanisms, perforator performance. In both experiments, the highest performance occurs for 2.5 CRH projectile and the lowest is related to blunt projectiles. The results show that sharp perforators indicate lower values of dynamic enhancement factor and the flat-ended perforator represents the maximum dynamic enhancement factor among other perforators. Moreover, damage propagation far more occurred in high velocity impact tests then quasi-static tests. The highest damage area is mostly observed in ballistic limit of each projectile which projectile deviation strongly increases this area.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.30-38
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• 1998

In this study, in order to measure energy-absorbing characteristics in impact test of CFRP thin-walled laminates and interpret the cause of decreasing age when collapse test is carried out under the environments of high temperatures and hygrothermals, the moisture absorbing behavior according to the variety of orientation angle is observed and impact collapse characteristics of no moisture absorbing status is compared with that under the environments of high temperatures and hygrothermals. Especially, we try to obtain quantitative design data to develop CFRP thin-walled laminates with energy characteristics of optimum impact absorbing. The value of the maximum loading, mean loading, rate of energy absorption energy per unit volume and mass in CFRP thin-walled laminates on the high temperatures and hygrothermals is measured much lower than under no moisture absorbing. The maximum collapse loading in dynamic impact test is taken measurements lower than in static collapse test CFRP circular laminates in high temperatures and hygrothermals. But the absorbed energy per unit mass and volume is almost same each other and the biggest amount of energy is shown in CFRP circular laminates with orientation angle of $15^{\circ}$. Therefore, in the case of using CFRP circular laminates with axisymmetric mode, CFRP thin-walled structural members with orientation angle of $10^{\circ}$, $15^{\circ}$ has generally best condition.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.149-155
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• 2006

This paper is concerned with the weight reduction of front side member of a vehicle considering the application of high strength steel sheet. The influence of steel sheet grade and thickness on the energy absorption, impact load and deformed shape of front side member is investigated by using reverse engineering and FE-analysis. The reverse engineering is applied to obtain 3D model of front side member from B.I.W for the FE simulation. FE analysis is carried out with commercial crash analysis SW PAM-CRASH. The crashworthiness of front side member is considerably improved with steel sheet strength and thickness increase. From the result of this study the weight reduction in automotive parts for the improvement of the fuel efficiency can be easily achieved with replacing high strength steel without deterioration of crashworthiness.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.7-14
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• 2012

CFRP composite material has the superior specific strength and rigidity compared to metallic materials, and is widely adopted in the various fields. However, CFRP composite material has the weakness in hygrothermal and crash environment. Especially, moisture ingress into composite material under hygrothermal environment can change molecule arrangement and chemical properties. In addition, interface characteristics and material component properties can be degraded. A collapse experiment has been made to research the differences of absorbed energy and deformation mode between absorbed specimens of moisture and non-moisture. As a result of this study, the effect of moisture absorption and impact loads of about 30~50% reduction in strength are shown.

• International Journal of Railway
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• v.6 no.3
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• pp.85-89
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• 2013

The purpose of this paper is investigating the effect and influence rates of utilizing thin walled energy absorption tubes for improving crashworthiness parameter by increasing energy absorption of the body in high speed railcars. In order to find this, a proper profile of available tubes is chosen and added to the structure of selected high speed train in Iranian railway network (Pardis Trainset) and then examined in the scenario of impact with other moving rolling stock. Because of the specific features of LS-DYNA 3D software at collision analysis, the dynamic simulation has been performed in LS-DYNA 3D. The results of the analysis clearly indicate the improvement of train crashworthiness as the energy absorption of structure increases more than 30 percent in comparison with the original body. This strategy delays and reduces the shock to the structure. The verification of the simulation is by using ECE R66 standard.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1323-1324
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.247-248
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• 2013

• Composites Research
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• v.36 no.4
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• pp.270-274
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• 2023

The stacking configuration of fiber-reinforced polymer (FRP) composites, achieved via the filament winding process, exhibits distinct variations compared to conventional FRP composite stacking arrangements. Consequently, it becomes challenging to ascertain the influence of mechanical properties based on the typical stacking structures. Thus, it becomes imperative to enhance the mechanical behavior and optimize the interleaved structures to improve overall performance. Therefore, this study aims to investigate the impact of incorporating amorphous halloysite nanotubes (A-HNTs) within different layers of five unique layer arrangements on the low-velocity impact properties of interleaved carbon fiber-reinforced polymer (CFRP) structures. The low-velocity impact characteristics of the laminate were validated using a drop weight impact test, wherein the resulting impact damage modes and extent of damage were compared and evaluated under microscopic analysis. Each interleaved structure laminate according to whether nanoparticles are added was compared at impact energies of 10 J and 15 J. In the case of 10 J, the absorption energy showed a similar tendency in each structure. However, at 15 J, the absorption energy varies from structure to structure. Among them, a structure in which nanoparticles are not added exhibits the highest absorption energy. Additionally, various impact fracture modes were observed in each structure through optical microscopy.