• Steel and Composite Structures
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• v.16 no.6
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• pp.595-609
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• 2014

The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.731-737
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• 2002

Nonlinear vibration of the CRT shadow mask with impact damping wires is analyzed in consideration of the mask tension distribution and the effect of wire impact damping. A reduced order FEM model of the shadow mask is obtained from dynamic condensation of the mass and stiffness matrices, and damping wire is modeled using the lumped parameter method to effectively describe its contact interactions with the shadow mask. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. The analysis model of the shadow mask with damping wires is experimentally verified through impact tests of shadow masks performed in a vacuum chamber.

• Composites Research
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• v.25 no.1
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• pp.14-18
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• 2012

The structural adhesives have the advantage of improving automobile performances and are being applied to joining light weight materials like aluminium and composite. In order to characterize the impact behavior of structural adhesive, instrumented impact tests were performed with respect to pin-ring adhesively bonded joint specimens. Also dynamic FE analysis was carried out using LS-DYNA to compare the results with experiments.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.1-9
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• 2001

Impact tests are performed on the high strength structural steel that is being developed for the submarine material. Especially, the impact characteristics of this structural steels at low temperatures are investigated by charpy impact testing. Hyperbolic tangent curve fitting method is used to evaluate the LSE(lower shelf energy), USE(upper shelf energy) and DBTT(ductile-brittle transition temperature). Proportional equations between charpy impact energy and lateral expansion are obtained using the test results. Effect of temperature on the fracture appearance is investigated by using SEM.

• Journal of Construction Engineering and Project Management
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• v.4 no.2
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• pp.41-46
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• 2014

RCC consumes large quantities of natural resources like gravel stone and steel, and there is a need to investigate on an innovative material that utilizes limited quantities of natural resources but should have good mechanical strength. This study deals with the experimental investigation of strength evaluation of cementitious composites reinforced with polyolefin fibers from 0% to 2.5% (with interval of 0.5%), namely Polyolefin Fiber Reinforced Cementitious Composites (PL-FRCC) and developing statistical regression models for compressive strength, splitting-tensile strength, flexural strength and impact strength of PL-FRCC. Paired t-tests (for each PL fiber percentage 0 to 2.5%) bring out that there is significant difference in compressive and splitting-tensile strength when curing periods (3, 7, 28 days) are varied. Also, a strong relationship exists between the compressive and flexural strength of PL-FRCC. The proposed mathematical models developed in this study will be helpful to ascertain the mechanical strength of FRCC, especially, when the fiber reinforcing index is varied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1378-1381
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• 2003

Recently, high-performance composite materials have been used for various industrial fields because of their superior high strength, high stiffness and lower weight. In this study, manufactured fiber reinforced metal laminate materials are composed of two parts. One is hard-anodized A15083-O alloy as a face material and the other is high strength aramid fiber (Twaron CT709) and polyethylene fiber(Dyneema HB25) laminates as a back-up material. Resistance to penetration is determined by protection ballistic limit(V$\sub$50/, a static velocity with 50% probability for complete penetration) test method. V$\sub$50/ tests with 0$^{\circ}$ obliquity at room temperature were conducted with 5.56mm ball projectiles that were able to achieve near or complete penetration during high velocity impact tests.

• International Journal of Concrete Structures and Materials
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• v.5 no.1
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• pp.19-28
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• 2011

This paper documents an experimental study of dynamic response of reinforced concrete beams following instantaneous removal of a bearing column. Four half-scale specimens representing two-span beam bridging across the removed column were tested. The test boundary conditions simulated rotational and longitudinal restraints imposed on a frame beam by the neighboring structural components. The gravity loads were simulated by attaching mass blocks on the beams at three locations. Dynamic loading effects due to sudden removal of a column were simulated by quickly releasing the supporting force at the middle of the specimens. The experimental study investigated the load-carrying capacity of beams restrained longitudinally at the boundaries and dynamic impact on forces. The tests confirmed the extra flexural strength provided by compressive arch action under dynamic loading. The tests also indicated that the dynamic amplification effects on forces were much lower than that assumed in the current design guideline for progressive collapse.

• Journal of the Korean Society for Railway
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• v.6 no.1
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• pp.15-20
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• 2003

The computer simulation techniques were adopted to evaluate the effects of seating positions of passenger under various accident scenarios. The baseline of computer simulation model was tuned by the sled impact tests which conducted under the upright and standard seating positions. This study shows the effect of relative velocity between occupant and struck vehicle while occupant is impacted to a front seat's seatback. Although, base on the current accident scenarios, The KHST is performed well enough to protect average adult male occupants. However, Results from the tests indicate small size occupant or higher impact speed may cause sever neck and femur injuries.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.248-255
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• 1997

The structural behaviors under wheel loads are much different from those under uniform loads which are generally adopted for the design of parking garage. In such a viewpoint, the structural behavior of a Half-PC concrete underground parking garage under wheel loads was investigated using the site instrumentations. The static wheel loads were applied on the structure to evaluate the actual static resistance, and moving load tests were also performed to evaluate the impact factors of the structure. Besides, the impact tests were also conducted to estimate the modal parameters of the structure. Through the experimental investigations, it was found that the structural performance of the underground parking garage can be improved by use of structural type such as Half-PC concrete structures.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.60-65
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• 2002

The computer simulation techniques were adopted to evaluate effects of seating positions of passenger under the various accident scenarios. The baseline of computer simulation model was tunned by the sled impact tests which conducted under the upright and standard seating positions. This study shows the effect of relative velocity between occupant and struck vehicle while occupant is impacted to a front seat's seatback. Although, base on the current accident scenarios, KHST is performed well enough to protect average adult male occupants. However, Results from the tests indicate small size occupant or higher impact speed may cause sever neck and femur injuries.