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Article
Publication date: 7 December 2021

Chunliang Niu, Suming Xie and Tao Zhang

In order to obtain the relationship between the geometry and stress concentration of load-bearing welded joints, the fatigue design method of welded structures based on…

Abstract

Purpose

In order to obtain the relationship between the geometry and stress concentration of load-bearing welded joints, the fatigue design method of welded structures based on stiffness coordination strategy is studied.

Design/methodology/approach

Based on the structural stress theory, a new method for anti-fatigue design of welded structures oriented to stiffness coordination strategy is proposed, and the detailed implementation process of this method is given. This method is also called the three-stage anti-fatigue design method for welded structures, which includes three stages, namely, identification, analysis and relief of stress concentration.

Findings

Through the experimental analysis of welded joints in IIW standard, the effectiveness of stiffness coordination in welded joint design is proved. The method is applied to the design of welded parts and products, and the feasibility of the method in alleviating the phenomenon of stress concentration and improving the fatigue resistance of welded structures is verified.

Originality/value

In this study, based on the principle of coordinated design of weld stiffness, a three-stage anti-fatigue design method of welded structure is proposed. The method has practical value for the optimization design and anti-fatigue performance improvement of welded structure in engineering products.

Details

International Journal of Structural Integrity, vol. 13 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 3 October 2020

Somayeh Pourbagher, Hamid Reza Azemati and Bahram Saleh Sedgh Pour

Social stress is a psychological and biological pressure that stems from one's relationship with others in social environments, which has become the most serious…

Abstract

Purpose

Social stress is a psychological and biological pressure that stems from one's relationship with others in social environments, which has become the most serious humanitarian issue today. Learning environments are one of the most important environments for reducing or increasing social stress and concentration. This study aims to investigate the effect of classroom wall color on students' stress and concentration in four common types of classrooms.

Design/methodology/approach

This research is a survey of 275 university students with an age range of 20–24. The methodology is a combination of quantitative and qualitative research. Data analysis was performed by multiple variance analysis and the internal reliability of the questionnaire was calculated based on Cronbach's alpha.

Findings

Results show that classroom wall color has a significant effect on student stress and concentration. In class type one, wall color had an effect of 10.4% on stress and concentration; in the second type, this variable had an effect of 8.8%, also in the third type it had an effect of 7.3% and 8.8% in the fourth type.

Originality/value

It can be concluded that wall color has an effective role in understanding the level of stress and concentration of users in the classrooms, and considering this factor in designing classrooms improves students' behavior and the quality of education in learning environments.

Details

International Journal of Educational Management, vol. 35 no. 1
Type: Research Article
ISSN: 0951-354X

Keywords

Article
Publication date: 5 August 2022

Vikas Goyat, Tawakol A. Enab, Gyander Ghangas, Sunil Kadiyan and Ajay Kumar

Inverse distance weighted (IDW) functions are utilized to make models of heterogenous materials such as functionally graded materials (FGM) in computer aided design (CAD)…

Abstract

Purpose

Inverse distance weighted (IDW) functions are utilized to make models of heterogenous materials such as functionally graded materials (FGM) in computer aided design (CAD). However, the use of IDW function based FGM for stress concentration reduction is scarcely available in the literature. The present work aims to analyze and reduce the stress concentration around a circular hole in IDW function-based finite FGM panel under biaxial loading.

Design/methodology/approach

Extended finite element method (XFEM) model was prepared using MATLAB to investigate the effect of geometrical and material parameters on the stress concentration factor (SCF). The obtained results of IDW FGM are compared with homogeneous material as well as two different FGMs based on the power-law function.

Findings

It was observed that the IDW function based FGM is simple in material modeling, conformal with all domain boundaries and shows lower stress concentration in comparison with the homogeneous material case. While comparing IDW FGM with power-law based FGMs, it was observed that the IDW FGM has least values of stress concentration for low d/W (diameter of the hole to panel width ratio) and is comparable with power-law based FGMs for high d/W.

Originality/value

It can be stated that IDW FGM is highly suitable for stress concentration reduction in finite panels with d/W = 0.5, which can further be intended for obtaining optimum hole and panel designs.

Details

Multidiscipline Modeling in Materials and Structures, vol. 18 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 1 March 1947

R.B. Heywood

It is well known that notches have a deleterious influence on the fatigue strength of parts. A constant, the sensitivity index, is commonly used to relate the fatigue…

Abstract

It is well known that notches have a deleterious influence on the fatigue strength of parts. A constant, the sensitivity index, is commonly used to relate the fatigue stress concentration factor to the elastic stress concentration factor. The author outlines a simpler hypothesis, which he claims to be a more reliable guide to fatigue behaviour in notches. Briefly it assumes that the elastic stress concentration factor gives the reduction in the fatigue strength due to the notch, but because of the local nature of the stress concentration, the endurance limit is increased according to a simple law. This increase in the fatigue strength depends on the smallness of the notch.

Details

Aircraft Engineering and Aerospace Technology, vol. 19 no. 3
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 23 August 2013

Keiji Houjou, Koji Takahashi and Kotoji Ando

The purpose of this study was to investigate the effect of overload (bending moment with plastic deformation: Mp) on three point bending specimen at the fatigue limit of…

Abstract

Purpose

The purpose of this study was to investigate the effect of overload (bending moment with plastic deformation: Mp) on three point bending specimen at the fatigue limit of high-tensile-strength steel containing a crack in the stress concentration zone.

Design/methodology/approach

An artificial semi-circular slit was introduced and Mp was applied after which bending fatigue tests were carried out.

Findings

The relationship between the level of Mp and the fatigue limit (σw) was proportional; the fatigue limits of specimens containing 0.2- and 0.3-mm-deep slits are improved by the Mp process as much as twice the original values; the slit size that can be rendered harmless by the Mp process is a=0.05 mm in depth; and all non-propagating cracks appeared around the artificial slit.

Originality/value

Very few studies have been conducted on the fatigue limit of materials containing crack-like surface defects after overload in the stress concentration zone. This study elucidated the effect of Mp on the fatigue limit.

Details

International Journal of Structural Integrity, vol. 4 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 13 September 2021

Jose-Gonzalo Gonzalez-Rodriguez, Andres Carmona Hernandez, E. Vázquez-Vélez, A. Contreras-Cuevas and Jorge Uruchurtu Chavarin

This paper aims to use an imidazole-based n-ionic Gemini surfactant derived from palm oil to inhibit the sulfide stress corrosion cracking of a supermartensitic stainless steel.

Abstract

Purpose

This paper aims to use an imidazole-based n-ionic Gemini surfactant derived from palm oil to inhibit the sulfide stress corrosion cracking of a supermartensitic stainless steel.

Design/methodology/approach

The slow strain rate testing technique, hydrogen permeation tests and potentiodynamic polarization curves have been used.

Findings

Addition of the inhibitor below the critical micelle concentration (CMC) decreased the corrosion current density (icorr), but not enough to avoid embrittlement due to the entry of hydrogen into the steel. Instead, the addition of the inhibitor close to the CMC decreased the icorr, suppressed the entry of hydrogen and inhibited the sulfide stress cracking of steel. Finally, the addition of inhibitor above the CMC led to a slight increase of icorr and promoted localized corrosion, however, the sulfide stress cracking of steel was inhibited.

Originality/value

A green sulfide stress corrosion cracking inhibitor of a supermartensitic stainless steel has been obtained.

Details

Anti-Corrosion Methods and Materials, vol. 68 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 5 February 2018

Ryutaro Fueki and Koji Takahashi

The purpose of this paper is to estimate the acceptable defect size amax after needle peening (NP) and predict the fatigue limit improvement through the use of NP for an…

Abstract

Purpose

The purpose of this paper is to estimate the acceptable defect size amax after needle peening (NP) and predict the fatigue limit improvement through the use of NP for an austenitic stainless steel welded joint containing an artificial semi-circular slit on a weld toe.

Design/methodology/approach

Residual stress and hardness distribution were measured. Microstructures around the weld toe were observed to clarify the cause for the change in hardness after NP. Finite element method analysis was used to analyze the change in the stress concentration following NP. Fracture mechanics was used to evaluate amax after NP. The fatigue limits before and after NP were predicted by determining amax for several levels of stress amplitude.

Findings

The tensile residual stress induced at the surface of the weld toe prior to NP changed to a compressive residual stress after NP. The residual stress near the surface layer after NP exceeded the yield stress prior to NP due to the increase in yield stress as a result of work hardening as well as the generation of a deformation-induced martensitic structure. The stress concentration was reduced due to the shape improvement caused by NP. The estimation value of amax after NP and the prediction results of fatigue limits were in good agreement with the fatigue test results.

Practical implications

The proposed method is useful in improving the reliability of welded joints used in large steel structures, transportation equipments and industrial machines.

Originality/value

From an engineering perspective, it is essential to estimate amax and the fatigue limit of welded joints with crack-like defects. However, it is unclear as to whether it is possible to predict amax and the effects of NP on the fatigue limit for stainless steel welded joints.

Details

International Journal of Structural Integrity, vol. 9 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 1 April 1945

I.G. Bowen

MUCH theoretical and experimental data are available on the strength and stiffness of tension joints with perforations. The object of the present paper is twofold…

Abstract

MUCH theoretical and experimental data are available on the strength and stiffness of tension joints with perforations. The object of the present paper is twofold: firstly, to summarize some relevant parts of existing data, and secondly, to present the results of recent tests which serve to illustrate some outstanding features of members tested to destruction.

Details

Aircraft Engineering and Aerospace Technology, vol. 17 no. 4
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 January 2006

Dragan D. Milasinovic

This paper is concerned with a new proposal regarding the analysis of visco‐elastoplasticity and fatigue and is based on rheological‐dynamical theory. Due to the analogy…

Abstract

This paper is concerned with a new proposal regarding the analysis of visco‐elastoplasticity and fatigue and is based on rheological‐dynamical theory. Due to the analogy between rheological model and dynamical model with viscous damping, it becomes obvious that inelastic response of members is essentially a dynamical problem. An analytical rheological‐dynamical viscoelasto‐ plastic solution of one‐dimensional longitudinal continuous vibration under loading and solution for the stress relaxation as unloading have been developed and used to obtain the fatigue limit of thin long bars. Rheologic behavior of the bar can be characterized by one parameter, like in a single‐degree‐of‐freedom spring mass system. In all inelastic strains time rate effects are always present to some degree. Whether or not their exclusion has a significant influence on the prediction of the material fatigue behavior depends upon several factors like: maximum absolute stress in the cycle, coefficient of asymmetry of cycle, creep coefficient, slope of the strain hardening portion of the stress‐strain curve, relative frequency and uniaxial yield stress. This paper provides description of dynamic magnification factor, relaxation of stress, stress concentration and the fatigue limit of thin long symmetrical bars.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 13 April 2015

Ismail Bensaid, Bachir Kerboua and Cheikh Abdelmajid

The purpose of this paper is to develop a new improved solution and a new model to predict both shear and normal interfacial stress in simply supported beams strengthened…

Abstract

Purpose

The purpose of this paper is to develop a new improved solution and a new model to predict both shear and normal interfacial stress in simply supported beams strengthened with bonded prestressed FRP laminates by taking into account the fiber volume fraction spacing that play an important role on the interfacial stresses concentration.

Design/methodology/approach

The study has been conducted by using analytical approaches for interfacial stresses in plated beams. The analysis is based on the deformation compatibility approach where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In addition, an unrealistic restriction of the same curvatures in the RC beam and FRP panel commonly used in most of the existing studies is released in the present theoretical formulation.

Findings

To verify the analytical model, the present predictions are compared first with those of (Malek et al., 1998; Smith and Teng, 2001) in the case of the absence of the prestressing force; for the second time, the present method is compared with that developed by (Al-Emrani and Kliger, 2006; Benachour et al., 2008) in the case where only the prestressing force is applied. From the presented results, it can be seen that the present solution agree closely with the other methods in the literature.

Originality/value

The paper puts in evidence a new originality approach theory, taking into account the mechanical load, and the prestressed FRP plate model having variable fiber spacing which considers a strength rigidity and resistance of the damaged structures, which is one aspect that has not been taken into account by the previous studies.

Details

International Journal of Structural Integrity, vol. 6 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

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