• 한국자동차공학회논문집
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• 제21권4호
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• pp.128-134
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• 2013

High bending collapse performance (maximum resistance force and mean resistance force) of body center pillar is an important design target for vehicle safety against side impact. In this study, effect of the upper section shape and the thickness of outer reinforcement on bending collapse performance was investigated for the center pillar of a large passenger car. First, through bending collapse analyses using simple models with uniform section, an optimized center pillar upper section was chosen. Next, bending collapse performance for various models of the actual center pillar with changing the thickness of outer reinforcement were analyzed. The finally designed model showed distinctive enhancement in bending collapse performance nearly without weight increase.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.454-457
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• 2008

Effects of patenting temperature on bending fatigue resistance of pearlitic steel filaments were investigated experimentally. The fatigue resistance of steel filaments was carried out by using hunter machine, specially designed for ultra fine-sized steel wires, in the controlled conditions. The transmission electron microscopy (TEM) was used for observing the overall microstructure. It revealed that the fatigue resistance as well as tensile strength increased together with increase of patenting temperature from 510 to $600^{\circ}C$, while the endurance ratio ($\sigma_e/\sigma_{TS}$) of filaments decreased. It is believed that this variation of mechanical properties with change of patenting temperature should be strongly influenced by the change of microstructure. The bending fatigue properties of steel filaments were discussed based on microstructural parameters.

• Steel and Composite Structures
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• 제15권4호
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• pp.425-438
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• 2013

A new-styrofoam-concrete composite sandwich slab with function of heat insulation is designed. Four full-scale simply supported composite sandwich slabs with different shear connectors are tested. Parameters under study are the thickness of the concrete, the height of profiled steel sheeting, the influence of shear connectors including the steel bars and self-drilling screws. Experimental results showing that four specimens mainly failed in bending failure mode; the shear connectors can limit the longitudinal slippery between the steel profiled sheeting and the concrete effectively and thus guarantee the good composite action and cooperative behavior of two materials. The ultimate sagging bending resistance can be determined based on plastic theory. This new composite sandwich slab has high sagging bending resistance and good ductility. Additionally, these test results help the design and application of this new type of composite sandwich slab.

• Journal of Dental Anesthesia and Pain Medicine
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• 제21권2호
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• pp.139-153
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• 2021

Background: In anesthetic techniques, touching bones can cause needle bending. Theoretically, a needle should support such deflection without fracturing. However, it is possible that a needle may fracture depending on the quality and type of needle used. This study evaluated the physical, chemical, and micromorphological characteristics of long and short dental anesthetic needles, as well as the mechanical properties of flexural load and bending resistance when needles are subjected to different bending angles. Methods: Long and short needles (30G, Jets, Misawa, Selekto, Terumo, Unoject and 27G, Dencojet, Injex, Jets, Misawa, Procare, Setoject XL, Terumo) were evaluated. Scanning electron microscopy was used to evaluate the needle bevels and energy-dispersive X-ray spectroscopy was used for the chemical analysis of needle compositions. Flexural loading and bending strength assessments were performed using a universal testing machine by bending the needles (n = 5) to angles of 30°, 60°, or 90°, or until fracture occurred. Results: The Injex 27G, Jets 27G, and Septoject XL 27G needles were all less than 30 mm in length. There were small percentage variations in the chemical compositions of the needles. Superior smoothness was observed for the Unoject 30G needle, which exhibited the highest fracture resistance at 60°. The Jets 30G needle exhibited greater resistance to fractures at 90°. The Procare 27G needle exhibited the highest load resistance to bending, followed by the Septoject XL 27G needle, and both needles were tied for the lowest fracture resistance. No needle fractured when bent to 30° or at less than three bends to 60° or 90°. Conclusions: Greater needle resistance to bending increases the probability of early fracturing. Thinner and shorter needles are more resistant than longer and thicker needles. Performing a single bend does not result in any significant risk of fracture or obliterate the lumen, allowing for the continued passage of anesthetic liquid.

• Steel and Composite Structures
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• 제27권4호
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• pp.401-416
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• 2018

Composite beams with web openings are vulnerable to Vierendeel bending failure. The available methods provide quite conservative estimates of Vierendeel bending resistance. An alternative design method to compute the resistance was proposed in this study, based on quadratic nonlinear interactions of normalized shear force, axial force and Vierendeel bending moment. The interactions of the top and bottom Tee section must satisfy mutual conditions to prevent the Vierendeel failure. The normalized shear force and Vierendeel bending moment of the composite part were used instead in the top Tee interaction. The top Tee axial force was computed based on force equilibrium. Based on a rigid-plastic model, the composite resistance is estimated using an effective slab width of the vertical shear resistance. On using the proposed method, nonlinear reductions due to shear loads and axial forces are not required, in contrast to prior methods. The proposed method was validated against experiments from literature. The method limitations and accuracy as well as the Vierendeel behavior were investigated by finite element simulations, with varied composite beam parameters. The proposed design loads are less conservative than earlier estimates and deviate less from the simulations.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.728-736
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• 2017

In this study, the bending behavior of cross-laminated timber (CLT) connected by nails were investigated. Especially, the load-carrying capacity of the nail-jointed CLT under out-of-plane bending was predicted by the lateral resistance of the used nails. Three-layer nail-jointed CLT specimens and a nail connection were manufactured by 30 mm (thickness) ${\times}$ 100 mm (width) domestic species (Pinus koraiensis) laminas and Ø$3.15{\times}82mm$ nails using a nail-gun. Shear test for evaluating the nail lateral resistance and bending test for evaluating the load-carrying capacity of the nail-jointed CLT under out-of-plane bending were carried out. As a result, two lateral resistance of the used nail, the 5% fastener offset value and the maximum value, were 913 N and 1,534 N, respectively. The predicted load-carrying capacity of the nail-jointed CLT by the 5% offset nail lateral resistance was similar to the yield points on the actual load-displacement curve of the nail-jointed CLT specimens. Meanwhile, the nail-jointed CLT specimens were not failed until the tension failure of the bottom laminas occurred beyond the maximum lateral resistance of the nails. Thus, the measured maximum load carrying capacities of the nail-jointed CLT specimens, approximately 12,865 N, were higher than the predicted values, 7,986 N, by the maximum nail lateral resistance. This indicates that the predicted load-carrying capacity can be used for designing a structural unit such as floor, wall and roof able to support vertical loads in a viewpoint of predicting the actual capacities more safely.

• Restorative Dentistry and Endodontics
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• 제39권4호
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• pp.270-275
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• 2014

Objectives: This study compared the mechanical properties of various instruments for canal exploration and glide-path preparations. Materials and Methods: The buckling resistance, bending stiffness, ultimate torsional strength, and fracture angle under torsional load were compared for C+ file (CP, Dentsply Maillefer), M access K-file (MA, Dentsply Maillefer), Mani K-file (MN, Mani), and NiTiFlex K-file (NT, Dentsply Maillefer). The files of ISO size #15 and a shaft length of 25 mm were selected. For measuring buckling resistance (n = 10), the files were loaded in the axial direction of the shaft, and the maximum load was measured during the files' deflection. The files (n = 10) were fixed at 3 mm from the tip and then bent $45^{\circ}$ with respect to their long axis, while the bending force was recorded by a load cell. For measuring the torsional properties, the files (n = 10) were also fixed at 3 mm, and clockwise rotations (2 rpm) were applied to the files in a straight state. The torsional load and the distortion angle were recorded until the files succumbed to the torque. Results: The CP was shown to require the highest load to buckle and bend the files, and the NT showed the least. While MA and MN showed similar buckling resistances, MN showed higher bending stiffness than MA. The NT had the lowest bending stiffness and ultimate torsional strength (p < 0.05). Conclusions: The tested instruments showed different mechanical properties depending on the evaluated parameters. CP and NT files were revealed to be the stiffest and the most flexible instruments, respectively.

• Journal of Welding and Joining
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• 제32권5호
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• pp.1-6
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• 2014

This study aims at manufacturing SA welded API-X70 line-pipe with sour gas resistance. A pipe was manufactured by JCO bending process and SA welding using the API-X70 plate guaranteed HIC resistance. SA welded pipe was expanded in order to reduce the residual stress. The evaluation of a pipe for resistance to HIC and SSCC were performed by the RS D 0004 and RS D 0005 standards. For verification that a pipe has acceptable resistance to HIC, fullscale test was carried out. Results showed no cracking for the HIC and SSCC.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.897-902
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• 2002

The failure of flat plate connection is successive failure process accompanying with stress redistribution, hence it is necessary to compute the contributions of each resistance components at ultimate state. In the present study, the interactions of resultant forces at each faces of connection, i.e. shear, bending moment and torsional moment are considered in the assessment of strength of slab. As a result the strength prediction model for connection is made up as combination of bending resistance, shear resistance and torsional resistance. The proposed method is verified by the experimental data and numerical data of continuous slabs.

• Advances in concrete construction
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• 제1권1호
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• pp.1-27
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• 2013

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.