• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.670-682
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• 2018

This paper presents the experimental and numerical investigation results of the response of low-temperature steel (LT-FH32 grade steel) beams under repeated impacts at room temperature and a single impact at a sub-zero temperature. After conducting tensile tests at room and sub-zero, repeated impact tests were conducted on two clamped single-beam models at room temperature, and single-impact tests of two other clamped single-beam models were conducted at $-50^{\circ}C$. The single and repeated impact tests were conducted by releasing a knife-edge striker using a drop testing machine. The permanent deflection of the model measured after each impact gradually increased with increasing number of impacts. Under the reduced temperature, the permanent deflection of the models slightly decreased. The numerical analyses were also performed to predict the damage response of the tested single-beam models. A comparison of the numerical prediction with those of experiments showed quite reasonable agreement.

• Structural Engineering and Mechanics
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• v.13 no.2
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• pp.171-186
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• 2002

Static and dynamic penetration tests of reinforced concrete (RC) slab specimens are described and discussed. The experimental study was aimed at a better understanding of mechanisms that are involved in dynamic penetration, through their identification in static tests, and by establishing their relative influence in similar dynamic cases. The RC specimens were $80{\times}80-cm$ square plates, and they were made of 30 MPa concrete. The non-deforming steel penetrator was a 50-mm diameter steel rod with a conical nose of 1.5 aspect ratio. Impact penetration tests were carried out with an air gun, which launched the projectiles at velocities of up to 300 m/sec. The static tests were conducted using a closed loop displacement control actuator, where the penetrator was pushed at a constant rate of displacement into the specimen. The static tests reveal important mechanisms that govern the penetration process and therefore contribute to a better understanding of RC barriers resistance to non-deforming projectiles impact.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2105-2113
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• 1995

The compressive tests under impact conditions were performed to establish a design guide for impact damage tolerance. The composition of layup was selected for the real cases of composite aircraft structure. The energy level of visible of visible damage threshold was determined as 7 Joules. It was found that the normalized bending stiffnesses in the direction of closely fixed boundary affected the area of damage. Graphite/epoxy used in the tests exhibited 60% reduction in compression strength at the energy level of visible damage threshold. Wet-conditioned specimens represented 9% reduction in residual compressive strength in comparison with room temperature ambient specimens. In this study, a design factor of 2.1 was proposed for the low velocity impact damage.

• Journal of KSNVE
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• v.5 no.1
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• pp.95-106
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• 1995

Flow-induced vibration in heat exchanger (or fuel rod) in nuclar power plant can cause dynamic interactions between tubes and tube supports resulting in fretting-wear. To increase the reliability and design life of heat exchanger components, design criteria that establish acceptable limits of vibration and minimize fretting wear are necessary. The fretting-wear rate is dependent upon material combination, contact configuration, environmental conditions and tube-to tube support dynamic interaction. It is demostrated that the fretting -wear rate correlates well with tube-to-support contact force or work rate. The tube-to-support dynamic interaction, which consists of dynamic contact forces and tube motion, is used to relate single-span wear data to real heat exchanger configurations consisting of multi-span tube bundles. This paper describes the test facility to measure tube-to-support dynamic impact force and reports its dynamic characteristics through the four impact tests - a force transduces independent and external impact tests, central ring inside impact test and additional cylinder impact test. Through the tests the impact parameter change dependent upon the material difference of impacting ball is studied, and the impact parameters of Force Transducer Assembly components are measured. And also the dynamic behavior of Force Transducer Assembly is analyzed. The force measurement technique herein is shown to provide a reasonable measure of dynamic contact forces.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.12-17
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• 2014

The number of vehicle accidents related to the side impact has increased since 1990 in Korea, thus the side impact test has been performed as one of the major vehicle evaluations of the Korean New Car Assessment Program(KNCAP) in 2003. A total of 77 vehicles of eight different types(compact, small, semi-midsize, midsize, and large sedans and small, midsize, and large sports utility vehicles) were tested in side impact and side pole impact conditions. In this study, the head and thorax injury values(HICs and chest deflections) of the side impact tests performed between 2003 and 2013 were investigated in terms of vehicle type, test year, and test condition. The recent vehicles showed better safety performances(lower injury values) and similar injury patterns were obtained between side impact and pole side impact tests.

• Composites Research
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• v.26 no.6
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• pp.343-348
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• 2013

In the present study, quasi-static tests and impact tests were performed for investigating the mechanical behaviour of EPP (Expanded polypropylene) and EPS (Expanded polystyrene). Four different density cylindrical type specimens were prepared for EPP and EPS and 0.001 $s^{-1}$ and 0.1 $s^{-1}$ of strain rate conditions for quasi-static tests and 100 J, 200 J and 300 J of incident energy conditions for the instrumented impact tests were considered.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.93-96
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• 2002

Instrumented impact tests and compression-after-impact(CAI) tests have been used to evaluate the effect of temperature on the low-velocity impact characteristics of phenolic matrix composites reinforced with various woven glass fabric. Impact characteristics and damage area in laminates are evaluated by C-scan. It is shown that the extent of damage and residual compressive strength of the laminates vary with energy level and impact test temperature. The damage area increases with increasing impact energy and temperature. All these observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1142-1146
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• 2007

In this studies, subjective evaluation of heavy-weight floor impact sound through classification was conducted. Heavyweight impact sounds generated by an impact ball were recorded through dummy heads in apartment buildings. The recordings were classified according to the frequency characteristics of the floor impact sounds which are influenced by the floor structure with different boundary conditions and composite materials. The characteristics of the floor impact noise were investigated by paired comparison tests and semantic differential tests. Sound sources for auditory experiment were selected based on the actual noise levels with perceptual level differences. The results showed that roughness and fluctuation strength as well as loudness of the heavy-weight impact noise had a major effect on annoyance.

• Composites Research
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• v.16 no.4
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• pp.66-73
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• 2003

The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests. CAI strength and open hole compressive strength tests using 3 mm thick composite plates($[45/-45/0/90]_{3s}$- IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels(between 5.4 J and 18.7 J) follow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. It is identified that the failure behaviour of the specimens from the CAI strength tests was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths art: in good agreement with the measured open hole compressive strengths. considering the impact damage site area, an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1894-1903
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• 2003

It is necessary to have a dummy that describes the anthropometry of a victim with accuracy. This study presents three scaled side impact dummies constructed for the use of MADYMO. They represent five, fifty and ninety-five percentile Korean males ranged from the age of 25 through 39. Thirty-five anthropometric data were used to scale input files required for MADYSCALE. Geometries, inertia, joints and other parameters for dummies were scaled based on the configurations of EuroSID-1. This study proposes the lateral impact response requirements for head, thorax and pelvis of Korean side impact dummies. A lateral drop impact test was conducted for the head at the height of 200 mm. Lateral pendulum impact tests were also carried out for thorax and pelvis at three specific impact velocities. All these test results were obtained from simulation based on MADYMO. All the procedures of the three tests followed the requirement of ISO/TR 9790.