• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.795-798
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• 1997

This study is about the dynamic behavior of steel(SM45C). Dynamic tests were performed using SHPB(Split Hopkinson Pressure Bar) which is designed and modified to be used in both tensile and compressive modes. Quasi-static compression tests were also carried out for the comparison to the dynamic results. Not only the dynamic mechanical properties but also the effect of the notch of the specimen on stress-strain curve were investigated. The dynamic test results reveal that strain and stress are sensitively affected by the notch. The depth and the number of notch increase the stress and decrease the strain.

• Transactions of Materials Processing
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• v.5 no.1
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• pp.18-26
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• 1996

In order to investigate the effect of pre-cooling of ingot on void closure in hot plate forging the internal strain and stress distributions are examined quantitatively by using ABAQUS. Simula-tions are carried out on a large slab ingot having the same temperature and the temperature gradient induced by air-cooling. It is shown that pre-cooling produces little effect on the strain behavior but remarkable effect on the hydrostatic stress at the central zone of ingot. The main factors for crushing micro-voids are the effective strain and the time integral of hydrostatic stress in the region surrounding the voids. Based on regression analysis it was found that the distortion of void can be expressed as a polynomial function of the two factors.

• Computers and Concrete
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• v.30 no.1
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• pp.9-17
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• 2022

This paper discusses the effect of high temperatures (T_s) on the compressive strength and stress-strain curve of recycled fine aggregate concrete (RFAC), based on the experimental results. A total of 90 prisms (100 mm×100 mm×300 mm) were tested. The results show that the compressive strength and elastic modulus of RFAC specimens decreased significantly with increasing T values. As T increased, the strain corresponding to peak stress decreased first when T<200℃ and then increased afterwards. With increasing T values, the stress-strain curves became flat gradually, the peak stress dropped gradually, and ε_p decreased when T<200℃ and increased in the T range of 400-800℃. A stress-strain relations for RFAC exposed to high T_s is proposed, which agree quite well with the test results and may be used to practical applications.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.59-60
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• 2021

To measure the effect of the stress-strain dispersion across the installed waterproofing layer on the concrete surface, a strain gauge was attached to the gap between the waterproofing layer and the concrete structure at specified points of upper, center and bottom of the load-displacement simulation specimen, and the peak stress-strain at the displacement interface were measured and compared with stress-strain at other areas to analyze each material types' stress-strain dispersion ratio properties. Based on the results of the testing, it was shown that materials with high load-displacement resistance performance accordingly had high stress-strain dispersion ratio results, and the materials from highest performance to lowest performance were; CAS, SAS, PUC and CSC.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.6
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• pp.38-47
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• 1989

The Finite Element Method has been employed to calculate the effect of particle size, matrix, and volume fractions on the stress-strain relations of .alpha.-.betha. titanium alloys. It was found that for a given volume fraction, the calculated stress-strain curve was higher for a finer particle size than for a coarse particle size within the range of the strains considered, and this behavior was seen for all the different volume fraction alloys considered. The calculated stress-strain curves for three vol. pct .alpha. alloys were compared with their corresponding experimental curve, and in general, good agreement was found.

• Steel and Composite Structures
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• v.29 no.1
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• pp.125-138
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• 2018

The research on the confinement behavior of ultra high performance concrete without and with the use of steel fibers (UHPC and UHPFRC) has been extremely limited. In previous studies, authors experimentally investigated the axially compressive behavior of circular steel tube confined concrete (STCC) short and intermediate columns with the employment of UHPC and UHPFRC. Under loading on only the concrete core, the confinement effect induced by the steel tube was shown to significantly enhance the utimate stress and its corresponding strain of the concrete core. Therefore, this paper develops a simplified stress - strain model for circular STCC columns using UHPC and UHPFRC with compressive strength ranging between 150 MPa and 200 MPa. Based on the regression analysis of previous test results, formulae for predicting peak confined stress and its corresponding strain are proposed. These proposed formulae are subsequently compared against some previous empirical formulae available in the literature to assess their accuracy. Finally, the simplified stress - strain model is verified by comparison with the test results.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.95-104
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• 2003

The material properties of rubber was determined by the experiments of uniaxial tension, uniaxial compression, planer tension, equi-biaxial tension and volumetric compression. In compression test, it is difficult to obtain the pure state of compression stress and strain due to friction force between the specimen and compression platen. In this study, the stress and strain data from the equi-biaxial tension test were converted to compression stress and strain and compared to a pure state of simple compression data when friction was zero. The compression test device with the tapered platen was proposed to overcome the effect of friction. It was fumed out that the relationship of the stress and strain using the tapered platen was in close agreement with the pure compressive state.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1250-1264
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• 2023

This paper presents approximate in-depth residual stress and plastic strain profiles for laser-peened alloy 600 surface via FE analysis. In approximations, effects of the initial welding residual stress and the number of shots are quantified. Based on FE analysis results, residual stress profiles are quantified by two variables; the maximum difference in stress before and after LSP, and the depth up to which the compressive residual stress exists. Plastic strain profiles are quantified by one variable, the maximum equivalent plastic strain at the surface. The proposed profiles are validated by comparing with published LSP experimental results for welded plates. Effects of the initial welding residual stress and the number of shots on these variables are discussed. The proposed profile can be directly applied to predict the mitigation effect of LSP on PWSCC and to efficiently perform structural integrity assessment of laser peened nuclear components.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.51-56
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• 2003

It is important to evaluate the fracture initiation behaviors of steel structure. It has been well known that the ductile cracking of steel would be accelerated by triaxial stress state. Recently, the characteristics of critical crack initiation of steels are quantitatively estimated using the two-parameters, that is, equivalent plastic strain and stress triaxiality, criterion. This study is paid to the fundamental clarification of the effect of notch radius, which can elevate plastic constraint due to heterogeneous plastic straining on critical condition to initiate ductile crack using two-parameters. Hense, the crack initiation testing were conducted under static loading using round bar specimens with circumferential notch. To evaluate the stress/strain state in the specimens was used thermal elastic-plastic FE-analysis. The result showed that equivalent plastic strain to initiate ductile crack expressed as a function of stress triaxiality obtained from the homogeneous specimens with circumferential notched under static loading. And it was evaluated that by using this two-parameters criterion, the critical crack initiation of homogeneous specimens under static loading.

• Computers and Concrete
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• v.1 no.1
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• pp.77-98
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• 2004

This paper presents a numerical model for simulating the nonlinear response of reinforced concrete (RC) shear walls subject to cyclic loadings. The material behavior of cracked concrete is described by an orthotropic constitutive relation with tension-stiffening and compression softening effects defining equivalent uniaxial stress-strain relation in the axes of orthotropy. Especially in making analytical predictions for inelastic behaviors of RC walls under reversed cyclic loading, some influencing factors inducing the material nonlinearities have been considered. A simple hysteretic stress-strain relation of concrete, which crosses the tension-compression region, is defined. Modification of the hysteretic stress-strain relation of steel is also introduced to reflect a pinching effect depending on the shear span ratio and to represent an average stress distribution in a cracked RC element, respectively. To assess the applicability of the constitutive model for RC element, analytical results are compared with idealized shear panel and shear wall test results under monotonic and cyclic shear loadings.