• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.885-891
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• 2012

In this study, some structural analysis using 3D CAD data, material properties, load conditions and boundary conditions are carried out to evaluate structural stability of the multi-aerial platform for high-rise fire fighting and rescue. We conduct structural analysis for the upper structures such as turn table, booms and basket, by using a universal structural analysis program NASTRAN. As the results, there is local stress exceeding the yield strength, but it is able to relax stress concentration in a way such as changing thickness of the structure or making larger inertia moment in cross section of booms.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.171-180
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• 2000

This study aims to present a more reasonable control value than the exiting one by comparing and analyzing control values and field instrumentation values of the whole excavation depth of the four case sites using geometric averaging as a statistical method. The range of the study is confined to three things: (1) the axial force of the braced excavation walls among a variety of items prescribed in the control values by stress deformation of walls and adjacent structures; (2) by approximation of the allowable and design value; (3) and by safety factor. As a res it is desirable to revise "(Long term allowable stress + Short term allowable stress)/2 ~ Short term allowable stress," presented in the present control values by stress deformation of walls and adjacent structures, to "(Long term allowable stress + Short term allowable stress)/5 ~ (Short term allowable stress)/3." The result also shows that since there is a difference of about 3.5%, it is not necessary to revise 70, 90, and 100 percent of LEVEL I, II, and III, prescribed in the control values by the allowable and design value approximation. In addition, modifying the control value by the safety factor, now 1.07, is unnecessary, although it varies little difference from the present value.

• Korean Journal of Occupational Health Nursing
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• v.24 no.2
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• pp.103-113
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• 2015

Purpose: This study was to construct a structural equational model for explaining and predicting job stress of intensive care unit (ICU) nurses based on the Integrated model of stress of Ivancevich and Matteson (1980). Methods: The subjects of this study were 220 nurses at ICU. The data were collected from August 5 to 30, 2013 through self-reporting questionnaire survey. Results: According to the hypothetical model of this study, perceived nursing practice environment, perceived role conflict, perceived transformational leadership and perceived self-esteem showed statistically significant effects on job stress of ICU nurses directly. Professional self-concept indirectly affect job stress of ICU nurses. In conclusion, job stress of ICU nurses was directly influenced by nursing practice environment, role conflict, transformational leadership and self-esteem. Professional self-concept of the relationships among variables did not have a direct impact on job stress. Conclusion: Based on the results of this study, it is needed to develop stress management measures and programs considering these variables in order to adequately manage job stress of ICU nurses.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.451-458
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• 2012

This study aims at the structural analysis with fatigue according to the configuration of railway vehicle wheel. Maximum equivalent stress or deformation is shown at the lower face in contact with wheel and rail. As model B has the maximum stress or deformation which becomes lower than model A, model B is shown to have more durability than model A. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^{11}$ Pa and the amplitude stress of 0 to $10^{10}$ Pa, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE Bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of railway vehicle wheel by prevention and durability against its damage.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.27-39
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• 1996

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized as average and linearly varying(through the thickness) stresses. The resulting stresses are interpreted per Section 111 of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$) and Secondary(C$_1$) stress indices for pressure, the Primary(B$_2$) and Secondary(C$_2$) stress indices for moment are developed. Several analysis were peformed on various structural geometries in order to determine empirical relationships for the stress indices as a function of dimensionless ratios.

• Steel and Composite Structures
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• v.44 no.4
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• pp.587-602
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• 2022

In this study, the classical J₂ flow theory is explicitly proved to be inappropriate to describe the plastic behaviour of structural steels under different stress states according to the reported test results. A numerical framework of the characterization of the strain hardening and ductile fracture initiation involving the effect of stress states, i.e., stress triaxiality and Lode angle parameter, is proposed based on the mechanical response of structural steels under monotonic loading. Both effects on strain hardening are determined by correction functions, which are implemented as different modules in the numerical framework. Thus, other users can easily modify them according to their test results. Besides, the ductile fracture initiation is determined by a fracture locus in the space of stress triaxiality, Lode angle parameter, and fracture strain. The numerical implementation of the proposed model and the corresponding code are provided in this paper, which are also available on GitHub. The validity of the numerical procedure is examined through single element tests and the accuracy of the proposed model is verified by existing test results.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2949-2957
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• 2020

Fatigue crack growth model has been developed for dissimilar metal weld joints of a piping component under cyclic loading, where in the crack is located at the center of the weld in the circumferential direction. The fracture parameter, Stress Intensity Factor (SIF) has been computed by using principle of superposition as K_H + K_M. K_H is evaluated by assuming that, the complete specimen is made of the material containing the notch location. In second stage, the stress field ahead of the crack tip, accounting for the strength mismatch, the applied load and geometry has been characterized to evaluate SIF (K_M). For each incremental crack depth, stress field ahead of the crack tip has been quantified by using J-integral (elastic), mismatch ratio, plastic interaction factor and stress parallel to the crack surface. The associated constants for evaluation of K_M have been computed by using the quantified stress field with respect to the distance from the crack tip. Net SIF (K_H + K_M) computed, has been used for the crack growth analysis and remaining life prediction by Paris crack growth model. To validate the model, SIF and remaining life has been predicted for a pipe made up of (i) SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1. Low alloy carbon steel (ii) welded SA312 Type 304LN austenitic stainless-steel pipe. From the studies, it is observed that the model could predict the remaining life of DMWJ piping components with a maximum difference of 15% compared to experimental observations.

• Safety and Health at Work
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• v.14 no.2
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• pp.222-228
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• 2023

Background: This study aimed to explore relationships between job stress and psychological adaptation and how they related to interpersonal needs through mood states among female migrant manufacturing workers. Methods: A cross-sectional survey was conducted in 16 factories in Shenzhen, China. Sociodemographic, job stress, psychological adaptation and other psychological information of was collected. Structural equation modeling was performed to delineate the internal relationship between variables. Results: The hypothetical structural equation model exhibited acceptable model fit among female migrant manufacturing workers (χ² = 11.635, df = 2, χ²/df = 5.82, p = 0.003, RMSEA = 0.090, CFI = 0.972, SRMR = 0.020). Job stress was directly associated with mood states and interpersonal needs; Psychological adaptation was directly associated with mood states and indirectly associated with interpersonal needs; Bootstrapping tests demonstrated mediation effect of mood states in the way from psychological adaptation to interpersonal needs. Conclusion: Female migrant manufacturing workers who suffered stress from job and the process of psychological adaptation may have worse mood states and workers with worse mood states are more likely to develop unmet interpersonal needs, a proximal factor of suicidal ideation.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.565-578
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• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

• Wind and Structures
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• v.5 no.6
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• pp.527-542
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• 2002

Wind-excited vibrations of slender structures can induce fatigue damage and cause structural failure without exceeding ultimate limit state. Unfortunately, the growing importance of this problem is coupled with an evident lack of simple calculation criteria. This paper proposes a mathematical method for evaluating the crosswind fatigue of slender vertical structures, which represents the dual formulation of a parallel method that the authors recently developed with regard to alongwind vibrations. It takes into account the probability distribution of the mean wind velocity at the structural site. The aerodynamic crosswind actions on the stationary structure are caused by the vortex shedding and by the lateral turbulence, both schematised by spectral models. The structural response in the small displacement regime is expressed in closed form by considering only the contribution of the first vibration mode. The stress cycle counting is based on a probabilistic method for narrow-band processes and leads to analytical formulae of the stress cycles histogram, of the accumulated damage and of the fatigue life. The extension of this procedure to take into account aeroelastic vibrations due to lock-in is carried out by means of ESDU method. The examples point out the great importance of vortex shedding and especially of lock-in concerning fatigue.