• Journal of Ship and Ocean Technology
• /
• v.8 no.4
• /
• pp.17-25
• /
• 2004

Hull girder stress monitoring system for container ship uses four long-base-strain-gages at mid-ship to monitor the resultant stresses and the applied moment components of horizontal, vertical and torsional moments. The bending moments are estimated by using the conventional strain-moment relations, however, the torsional moment related to the warping strain requires the assumption of the shape of torsional moments over the hull girder. Though this shape could be a sine function with an adequate period, it largely depends upon certain empirical formulas. This paper introduces additional four long-base-strain-gages at mid-ship to derive the longitudinal slope of the warping strain because this slope is directly related to the torsional moment by Bi-moment concept. An open-channel-type cantilever beam has been selected as a simplified model for container ship and the result has proved that the suggested concepts can estimate the torsional component accurately. Finally this method can become reliable technique to derive all external moments in hull girder stress monitoring system for container ships.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1993.10a
• /
• pp.369-374
• /
• 1993

Measurements of strain near a crack tip with electrical resistance strain gages do not usually provide a reliable value of stress intensity factor (K sub I) because of local yielding and limited regions for strain-gage placement. This paper attempted to define a valid region and to indicate procedures for locating and orienting the strain-gage to determine stress intensity factor accurately from one stain-gage readings.

• Korean Journal of Materials Research
• /
• v.26 no.5
• /
• pp.281-286
• /
• 2016

In the present study, the tensile properties and dynamic strain aging of an Fe-24.5Mn-4Cr-0.45C alloy were investigated in terms of strain rate. During tensile testing at room temperature, all the stress-strain curves exhibited serrated plastic flows related to dynamic strain aging, regardless of the strain rate. Serration appeared right after yield stress at lower strain rates, while it was hardly observed at high strain rates. On the other hand, strain-rate sensitivity, indicating a general relationship between flow stress and strain rate at constant strain and temperature, changed from positive to negative as the strain increased. The negative strain-rate sensitivity can be explained by the Portevin Le Chatelier effect, which is associated with dynamic strain aging and is dependent on the strain rate because it is very likely that the dynamic strain aging phenomenon in high-manganese steels is involved in the interaction between moving dislocations and point-defect complexes.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.4
• /
• pp.148-153
• /
• 2004

It is well-known that the mechanical behavior of fiber-reinforced composites under hydrostatic pressure environment is different from that of atmospheric pressure environment. It is also known that the mechanical behavior of fiber-reinforced composites is affected by a strain rate. In this work, we investigated the effect of strain rate on the compressive elastic modulus, fracture stress, and fracture strain of carbon/epoxy composites under hydrostatic pressure environment. The material used in the compressive test was unidirectional carbon/epoxy composites and the hydrostatic pressures applied was 270㎫. Compressive tests were performed applying three strain rates of 0.05％/sec, 0.25％/sec, and 0.55％/sec. The results showed that the elastic modulus increased with increasing strain rate while the fracture stress was little affected by the strain rate. The results also showed that the fracture strain decreased with increasing strain rate.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.4C
• /
• pp.175-182
• /
• 2009

The stress-strain relationship of an unsaturated soil was analyzed by Bishop stress descriptions in this study. The failure criteria could be defined uniquely by the Bishop stress and were also independent of matric suctions. In the low level of matric suctions the failure criteria have a linear relationship and the estimated criterion fitted the measured accurately. Deformation moduli in the small strain level were linearly increased generally with respect to Bishop stress.

• Journal of Technologic Dentistry
• /
• v.33 no.4
• /
• pp.307-312
• /
• 2011

Purpose: The purpose of this study is a porous cube mechanical analysis for the dental implant. Methods: The porous cube with a side length of 10mm was designed for dental implant. To choose proper design, porous hexagon with a side 10mm which was drilled as a regular hexagon with diameter 0.8mm, 1.0mm, 1.2mm and a side 0.4mm, 0.5mm, 0.6mm each using Computer AUTO CAD(Autodesk, 2008). Each cube was carried out in the mechanical analysis. Results: The result of mechanical analysis was observed that the H0.8 was minimum stress 0.045068MPa, maximum stress 9.4565MPa and minimum strain $0.00389{\times}10^{-4}Mpa$, maximum strain $0.816{\times}10^{-4}Mpa$, the H1.0 minimum stress 0.001147MPa, maximum stress 9.099MPa and minimum strain $0.000099{\times}10^{-4}Mpa$, the maximum strain $0.784{\times}10^{-4}Mpa$, the H1.2 minimum stress 0.099393MPa, maximum stress 13.137MPa and minimum strain $0.0112{\times}10^{-4}Mpa$, maximum strain $1.13{\times}10^{-4}Mpa$. Conclusion: The mechanical analysis of porous hexahedron was that H1.0 is the best result. It will be applicable to the porous implants.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.06b
• /
• pp.445-450
• /
• 2006

The stress and strain properties of KOCC were modified to improve the performance of KOCC as a packaging raw material. The refining consistency, refining degree and the grammage of handsheet were varied. The stress strain properties, tensile energy absorption were measured for prepared handsheets. The refining improved significantly the stress and strain properties of paper, especially at lower refining consistency. The increase of grammage also had contributed to improve the stress and strain of paper. It was also found that both refining and grammage contributed to the improvement of tensile energy absorption. However, it is strongly recommended to introduce the combination of refining consistency, refining degree and mechanical treatment.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.7 no.2
• /
• pp.27-40
• /
• 1970

The distribution of stress and strain in elastic stages is investigated by the experiments of two dimensional photoelastic coating and Moire fringe method. Center block type and cover plate type of fillet welds are used as specimens in the test. The results are as follows. 1) Center block type gets less uniform stress distribution than cover plate type. And its stress concentration factor, especially at root, is larger than that at toe. 2) When main plate and cover plate closely contact and it cause friction, stress concentration decreases more than that in case of slit. That is because stress can be transmitted on the contact surface. 3) When slit is made, the outside of fillet gets more stress than the inside of it. 4) While the plastic strain distribution of center block type reaches the maximum at root and differs very slightly from that under lower loading, the plastic strain distribution of cover plate type is inclined to get the maximum at the outside of fillet rather than at root. 5) When the plastic strain value of cover plate type is compared with that of center block type at toe and root, the relations between the former and the latter shows root<toe and root>toe. 6) Because stress distribution becomes changed according to loading, fracture angle cannot be estimated by the peaks of elastic stress distribution. 7) The strain distribution just before fracture can be found by Moire fringe method.

• Structural Engineering and Mechanics
• /
• v.74 no.3
• /
• pp.351-363
• /
• 2020

Based on the dynamic tests of recycled aggregate concrete (RAC) short columns confined by the hoop reinforcement, the dynamic failure mechanism and the mechanical parameters related to the constitutive relation of confined recycled aggregate concrete (CRAC) were investigated thoroughly. The fracturing sections were relatively flat and smooth at higher strain rates rather than those at a quasi-static strain rate. With the increasing stirrup volume ratio, the crack mode is transited from splitting crack to slipping crack constrained with large transverse confinement. The compressive peak stress, peak strain, and ultimate strain increase with the increase of stirrup volume ratio, as well as the increasing strain rate. The dynamic confining increase factors of the compressive peak stress, peak strain, and ultimate strain increase by about 33%, 39%, and 103% when the volume ratio of hoop reinforcement is increased from 0 to 2%, but decrease by about 3.7%, 4.2%, and 9.1% when the stirrup spacing is increased from 20mm to 60mm, respectively. This sentence is rephrased as follows: When the stirrup volume ratios are up to 0.675%, and 2%, the contributions of the hoop confinement effect to the dynamic confining increase factors of the compressive peak strain and the compressive peak stress are greater than those of the strain rate effect, respectively. The dynamic confining increase factor (DCIF) models of the compressive peak stress, peak strain, and ultimate strain of CRAC are proposed in the paper. Through the confinement of the hoop reinforcement, the ductility of RAC, which is generally slightly lower than that of NAC, is significantly improved.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.717-720
• /
• 1999

Recently, the fiber composite materials such as carbon fiber, glass fiber, or aramid, have been frequently used in strengthening reinforced concrete structures. The fiber composite materials typically have orthotropic characteristic and the strength changes significantly acording to the direction of fibers and the method of the lamination. In this study, an algorithm to estimate the stress-strain relationship of the composite materials which have different fiber directions and symmetric or non-symmetric lamination has been developed by using Tsai-Hill and Tsai-Wu failure criteria and progressive laminate failure theory. This algorithm has been implemented to several stress-strain models for the laterally confined concrete compression members such as Mander, Hosotani, and Nakatsuka. The evaluated stress-strain behaviors by the different models are discussed.