• Structural Engineering and Mechanics
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• v.69 no.6
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• pp.677-691
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• 2019

In recent years, interest is growing in the engineering community on the experimental assessment and the theoretical prediction of the out-of-plane (OOP) seismic response of unreinforced masonry (URM) infills, which are widespread in Reinforced Concrete (RC) buildings in Europe and in the Mediterranean area. In the literature, some mechanical-based models for the prediction of the entire OOP force-displacement response have been formulated and proposed. However, the small number of experimental tests currently available has not allowed, up to current times, a robust and reliable evaluation of the predictive capacity of such response models. To enrich the currently available experimental database, six pure OOP tests on URM infills in RC frames were carried out at the Department of Structures for Engineering and Architecture of the University of Naples Federico II. Test specimens were built with the same materials and were different only for the thickness of the infill walls and for the number of their edges mortared to the confining elements of the RC frames. In this paper, the results of these experimental tests are briefly recalled. The main aim of this study is comparing the experimental response of test specimens with the prediction of mechanical models presented in the literature, in order to assess their effectiveness and contribute to the definition of a robust and reliable model for the evaluation of the OOP seismic response of URM infill walls.

• Steel and Composite Structures
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• v.31 no.4
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• pp.409-417
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• 2019

The choice of individual material for industrial application is primarily based on knowledge of its behavior in similar applications and similar environmental conditions. Contemporary design implies knowledge of material behavior and knowledge in the area of structural analysis supported by large capacity computers. Bearing this in mind, this paper presents and analyzes the experimental results related to the mechanical properties of the material considered (30CrNiMo8/1.6580/AISI 4340) at different temperatures as well as its creep and fatigue behavior. All experimental tests were carried out as uniaxial tests. The test results related to the mechanical properties are presented in the form of engineering stress-strain diagrams. The results related to the creep behavior of the material are shown in the form of creep curves, while the fatigue of the material is shown in the form of stress - life (S - N) diagram. Based on these experimental results, the values of the following properties are determined: ultimate tensile strength (${\sigma}_{m,20}=696MPa$), yield strength (${\sigma}_{0.2,20}=355.5MPa$), modulus of elasticity ($E_{,20}=217GPa$) and fatigue limit (${\sigma}_{f,20,R=-1}=280.4MPa$). Results related to fatigue tests were obtained at room temperature and stress ratio R = -1.

• Geomechanics and Engineering
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• v.33 no.4
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• pp.327-339
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• 2023

The expansion capacity and strength of expansive grout have a significant influence on the stress state of a supported rock mass and the strength of a grout-rock mass structure. The expansion and strength characteristics are vital in grouting preparation and application. To analyze the expansion performance and mechanical properties of expansive grout, uniaxial compressive strength (UCS) tests, expansion ratio tests, XRD, SEM, and microscopic scanning tests (MSTs) of expansive grout under different curing pressure conditions were conducted. The microevolution was analyzed by combining the failure characteristics, XRD patterns, SEM images, and surface morphologies of the specimens. The experimental results show that: (1) The final expansion ratio of the expansive grout was linear with increasing expansion agent content and nonlinear with increasing curing pressure. (2) The strength of the expansive grout was positively correlated with curing pressure and negatively correlated with expansion agent content. (3) The expansion of expansive grout was related mainly to the development of calcium hydroxide (Ca(OH)2) crystals. With an increase in expansion agent content, the final expansion ratio increased, but the expansion rate decreased. With an increase in the curing pressure, the grout expansion effect decreased significantly. (4) The proportion of the concave surfaces at the centre of the specimen cross-section reflected the specimen's porosity to a certain extent, which was linear with increasing expansion agent content and curing pressure.

• Agricultural and Biosystems Engineering
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• v.1 no.1
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• pp.43-48
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• 2000

Mechanical properties of the apple flesh were tested with compression test apparatus constructed by this study. The computer program was developed for measuring mechanical properties, and analyzing data obtained from the study. Compression tests on the apple flesh were performed at four levels of specimen diameter, three levels of specimen length, and at constant loading rate(25mm/min). Five replications were made at each treatment combination. Effect of specimen size on the mechanical properties of the apple flesh was investigated.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.25-33
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• 1990

Recently developed austempered ductile irons(A.D.I.) have good mechanical properties. However it is still needed to examine the relationships between microstructures related to banitic reaction and the mechanical properties. From the mechanical tests such as impact test, hardness test, tensile test, and the microstructure observations, we concluded that the good mechanical properties of A.D.I. came from the fine banitic ferrite structure formed during the first stage of the austempering reaction.

• Structural Engineering and Mechanics
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• v.68 no.1
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• pp.17-38
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• 2018

In this paper, we compare and assess the performance of the standard 3- and 6-node MITC shell elements (Lee and Bathe 2004) with the recently developed MITC triangular elements (Lee et al. 2014, Jeon et al. 2014, Jun et al. 2018) which were based on the partitions of unity approximation, bubble node, or both. The convergence behavior of the shell elements are measured in well-known benchmark tests; four plane stress tests (mesh distortion test, cantilever beam, Cook's skew beam, and MacNeal beam), two plate tests (Morley's skew plate and circular plate), and six shell tests (curved beam, twisted beam, pinched cylinder, hemispherical shells with or without hole, and Scordelis-Lo roof). To precisely compare and evaluate the solution accuracy of the shell elements, different triangular mesh patterns and distorted element mesh are adopted in the benchmark problems. All shell finite elements considered pass the basic tests; namely, the isotropy, the patch, and the zero energy mode tests.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1709-1714
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• 2004

Pressurization system of a 50m unmanned airship was manufactured according to the detailed design. In this paper. the whole procedures including system design. simulation and fabrication were described. The fabricated part were ground tested to check compliances with design requirements. Ground tests include operational tests, leakage tests, endurace tests and low temperature environmental tests. Results shows pressurization system of a 50m unmanned airship meets design requirements. Currently. pressurization system is installed to the KARI airship, Via 50m and performance verification through the flight tests are being conducted.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1192-1202
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• 1994

Fatigue behavior and life prediction were presented for thermal-mechanical and isothermal low cycle fatigue of 12Cr forged steel used for high temperature applications. In-phase and out-of-phase thermal-mechanical fatigue test at 350 to 600.deg. C and isothermal low cycle fatigue test at 600.deg. C were conducted using smooth cylindrical hollow specimen under strain-control with total strain ranges from 0.006 to 0.015. Cyclic softening behavior was observed regardless of thermal-mechanical and isothermal fatigue tests. The phase difference between temperature and strain in thermal-mechanical fatigue resulted in significantly shorter fatigue life for out-of-phase than for in-phase. The difference in fatigue lives was dependent upon the magnitudes of inelastic strain ranges and mean stresses. Increase in inelastic strain range showed a tendency of intergranular cracking and decrease in fatigue life, especially for out-of-phase thermal-mechanical fatigue. Thermal-mechanical fatigue life prediction was made by partitioning the strain ranges of the hysteresis loops and the results of isothermal low cycle fatigue tests which were performed under the combination of slow and fast strain rates. Predicted fatigue lives for out-of-phase using the strain range partitioning method showed an excellent agreement with the actual out-of-phase thermal-mechanical fatigue lives within a factor of 1.5. Conventional strain range partitioning method exhibited a poor accuracy in the prediction of in-phase thermal-mechanical fatigue lives, which was quite improved conservatively by a proposed strain range partitioning method.

• Journal of Mechanical Science and Technology
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• v.14 no.1
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• pp.11-18
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• 2000

Fracture toughness JIC and KIC tests were performed on A516 Gr70 carbon steel plate at the temperature ranging from -$160^{\circ}C$ to $600^{\circ}C$, and test results were analyzed according to ASTM E 813 and ASTM E 399. Unloading compliance J-integral tests were performed on 1TCT specimens. The relation between the $J_{IC}$ value and the test temperature was obtained. It was concluded that the temperature ranging from $-15^{\circ}C$ to $600^{\circ}C$ is the upper shelf region of ductile-brittle transition temperature, and in this temperature range, fracture toughness $J_{IC}$ values decreased with increasing temperature. The ductile brittle transition temperature of the material may be around $-30^{\circ}C$. In the region near $-30^{\circ}C$, the tendency of $J_{IC}$ to decrease with decreasing temperature was significant.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.369-370
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• 2002

To clarify the tribological properties of biodegradable lubricating oils, the four-ball tests were carried out under dip-feed lubrication using a Soda-type four-ball machine. The test balls were lubricated with soybean oil, rapeseed oil, corn oil and turbine oil. From the tests, the coefficient of friction for all the test balls lubricated with biodegradable lubricating oils was lower than that for the test ball lubricated with turbine oil. Further, from the calculation of the pV value, it was clear that the seizure resistance for all the test balls lubricated with biodegradable lubricating oils was higher than that for the test ball lubricated with turbine oil.