• Tribology and Lubricants
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• v.16 no.5
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• pp.324-331
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• 2000

Wear characteristics of Plastic and Nylon pinions against steel gear were studied to gain a better understanding of their tribological behaviors. Wear tests were conducted with power circulating gear test rig under dry contact conditions. Specific wear rates were measured as a function of applied load and the number of revolution. The worn teeth surfaces were examined with a profile projector and a camera. Nylon pinion showed lower specific wear rates than acetal pinion, but suffered teeth breakage under high load per unit tooth width. The dominant wear mechanisms found were adhesion and abrasion.

• Advances in nano research
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• v.8 no.4
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• pp.323-333
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• 2020

In recent years, there has been an upsurge for the usage of buckling restrained braces (BRB) rather than ordinary braces, as they have evidently performed better. If the overall brace buckling is ignored, BRBs are proven to have higher energy absorption capacity and flexibility. This article aims to deliberate an economically efficient yet adequate type of all-steel BRB, comprised of the main components as in traditional ones, such as : (1) a steel core that holds all axial forces and (2) a steel restrainer tube that hinders buckling to occurr in the core; there is a more practical detailing in the BRB system due to the elimination of a filling mortar. An investigation has been conducted for the proposed rectangular-tube core BRB and it is hysteric behavioral results have been compared to previous researches conducted on a structure containing a similar plate core profile that has the same cross-sectional area in its core. A loss of strength is known to occur in the BRB when the limiting condition of local buckling is not satisfied, thus causing instability. This typically occurs when the thickness of the restrainer tube's wall is smaller than the cross-sectional area of the core plate or its width. In this study, a parametric investigation for BRBs with different formations has been performed to verify the effect of the design parameters such as different core section profiles, restraining member width to thickness ratio and relative cross-sectional area of the core to restrainer, on buckling load evaluation. The proposed BRB investigation results have also been presented and compared to past BRB researches with a plate profile as the core section, and the advantages and disadvantages of this configuration have been discussed, and it is concluded that BRBs with tubular core section exhibit a better seismic performance than the ones with a plate core profile.

• Steel and Composite Structures
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• v.24 no.2
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• pp.201-211
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• 2017

This study evaluates the reliability of present European codes in predicting the collapse load of columns made with perforated cold-formed steel (CFS) profiles under combined axial load and bending. To this aim, a series of experimental tests on slender open-section specimens have been performed at varying load eccentricity. Preliminarily, stub column tests have also been performed to calculate the effective section properties of the investigated profile. By comparison of experimental data with code-specified M-N strength domains, the authors demonstrate that present code formulations may underestimate the collapse load of thin-walled perforated open sections. The study is the first step of a wider experimental and numerical study aimed at better describing strength domains of perforated CFS open sections.

• Tribology and Lubricants
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• v.18 no.3
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• pp.187-193
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• 2002

The half-value breadth off-ray diffraction profile line is generally used for a factor in nondestructive hardness measuring method of steel. In this paper, the problem in using the half-value breadth for the hardness measuring method is evaluated in strain hardened steel. And new hardness measuring method using residual stress is proposed X-ray diffraction test after rolling contact fatigue test of ball bearing with inner race of various hardness are carried out to measure the distribution of residual stress and half-value breadth from surface. The result of this study shows that there is little correlation between half-value breadth and hardness in the higher strength region and in the region increasing the hardness by strain hardening. But the magnitude of residual stress on/under race after rolling contact fatigue test becomes clearly to be correlative with hardness. Thus, it is concluded that the hardness of strain hardened steel can be estimated by this relationship between residual stress and hardness.

• Steel and Composite Structures
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• v.9 no.6
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• pp.519-534
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• 2009

This study intends to examine the characteristics of compressive behavior and conducts comparative analysis between normal compressive strength under existing equations (LRFD, ACI 318, EC 4) and experimental the maximum compressive strength from the compression experiment for the unstiffened steel plate-concrete structures. The six specimens were made to evaluate the constraining factor (${\xi}$) and width ratio (${\beta}$) effects subjected to the compressive monotonic loading. Based on this experiments, the following conclusions could be made: first, compressive behaviors of the specimens from the finite element analysis closely agreed with the ones from the actual experiments; second, the higher the width ratio (${\beta}$) was, the lower the ductility index (DI) was; and third, the test results showed the maximum compressive strength with a margin by 7% compared to the existing codes.

• Applied Science and Convergence Technology
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• v.26 no.1
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• pp.16-19
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• 2017

A thin metal layer of molybdenum is placed between the conventional barrier layer and the stainless steel substrate for investigating the diffusion property of iron (Fe) atoms. In this study, the protection probability was confirmed by measuring the concentration of out-diffused Fe using a SIMS depth profile. The Fe concentration of chromium (Cr) barrier layer with 10 nm molybdenum (Mo) layer is 5 times lower than that of Cr barrier without the thin Mo layer. The insertion of a thin Mo metal layer between the barrier layer and the stainless steel substrate effectively protects the out-diffusion of Fe atoms.

• Laser Solutions
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• v.2 no.2
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• pp.27-33
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• 1999

Electron beam was applied on the low carbon steel in order to fabricate Metal/Metal GBM(Graded Boundary Material). Ni sheet was placed on the steel substrate. The electron beam was irradiated on the surface and produced a homogeous alloyed layer. Sequential repetition of electron beam treatments for 4 times resulted in 8mm thick graded layer. To determine each layers property, optical microscopy, XRD, microhardness tester and EDS were used. The residual stress was measured by the low angle x-ray diffraction method. The graded boundary layer was stepwise profile, but Ni content incresed up to 80 wt% and Fe content decreased 20 wt% near surface. Each layers microstructure and hardness varied by different Fe/Ni composition. The compressive residual stress was induced by martensite transformation in the 1st and End layers and the shrinkage cracks were formed in graded layer by rapid cooling.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.171-178
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• 1997

This paper describes the application of discretized continuum-type optimality criteria (DCOC) for the multispan partially prestressed concrete beams. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non-prestressing steel and formwork is minimized. The design constraints include limits on the maximum deflection, flexural and shear strengths, in addition to ductility requirements, and upper and lower bounds on design variables as stipulated by the design code. Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables-effective depth, eccentricity of prestressing steel and non-prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. The self-weight of the structure is included in the equilibrium equation of the real system, as is the secondary effect resulting from the prestressing force. Two numerical examples of multispan PPC beams with rectangular cross-section are solved to show the applicability and efficiency fo the DCOC-based technique.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.85-90
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• 2014

In this paper, the transient thermal and residual stress analysis of the welding of 9% Ni steel plates using the FEA software ABAQUS are presented. The 9% Ni steel plates are welded manually with welding consumables of 70% Ni based Inconel type super-alloys (YAWATA WELD B (M)), producing a multi-pass/multi-layer butt weld. For these materials, temperature dependant mechanical and thermal material properties are used in the analysis. The back gouging is considered in welding process simulation. The FE thermal results are validated by comparing the real fusion profile and heat affected zone (HAZ). In addition, the continuous indentation test was conducted to measure the strength of base metal, HAZ and weld metal.

• Steel and Composite Structures
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• v.10 no.2
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• pp.169-185
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• 2010

The present work describes the experimental tests on steel and lightweight concrete composite beams performed at University of Minho, Portugal. The study involves tests on simply supported composite beams of 4.5 m span, with the same geometrical disposition, supports and materials. The geometrical configuration for the cross section and supports is identical for every beam, varying the shear connectors' distribution and the loading conditions. Headed studs are used to provide the connection between the steel profile and the concrete slab. The parameters in study are the stud disposition and the load distribution. The main objective is to describe the composite beams behaviour, focused on its connection, and to analyse the contribution of the different components to the beams load and deformation capacity. All the tests explored the beams maximum load and deformation capacity and different types of failure were observed.