Residual Stress Analysis Based on Acoustic and Optical Methods
Directory of Open Access Journals (Sweden)
Sanichiro Yoshida
2016-02-01
Full Text Available Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.
Analysis of Stress Updates in the Material-point Method
DEFF Research Database (Denmark)
Andersen, Søren; Andersen, Lars
2009-01-01
The material-point method (MPM) is a new numerical method for analysis of large strain engineering problems. The MPM applies a dual formulation, where the state of the problem (mass, stress, strain, velocity etc.) is tracked using a finite set of material points while the governing equations...... are solved on a background computational grid. Several references state, that one of the main advantages of the material-point method is the easy application of complicated material behaviour as the constitutive response is updated individually for each material point. However, as discussed here, the MPM way...
The stress analysis method for three-dimensional composite materials
Nagai, Kanehiro; Yokoyama, Atsushi; Maekawa, Zen'ichiro; Hamada, Hiroyuki
1994-05-01
This study proposes a stress analysis method for three-dimensionally fiber reinforced composite materials. In this method, the rule-of mixture for composites is successfully applied to 3-D space in which material properties would change 3-dimensionally. The fundamental formulas for Young's modulus, shear modulus, and Poisson's ratio are derived. Also, we discuss a strength estimation and an optimum material design technique for 3-D composite materials. The analysis is executed for a triaxial orthogonally woven fabric, and their results are compared to the experimental data in order to verify the accuracy of this method. The present methodology can be easily understood with basic material mechanics and elementary mathematics, so it enables us to write a computer program of this theory without difficulty. Furthermore, this method can be applied to various types of 3-D composites because of its general-purpose characteristics.
Analytical method for thermal stress analysis of plasma facing materials
You, J. H.; Bolt, H.
2001-10-01
The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed.
Analytical method for thermal stress analysis of plasma facing materials
International Nuclear Information System (INIS)
You, J.H.; Bolt, H.
2001-01-01
The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed
Social Support and Work Stress: A Mixed Method Analysis
Directory of Open Access Journals (Sweden)
Vânia Lúcia Pereira de Andrade
2017-12-01
Full Text Available Occupational stress and coping strategies have increasingly become the focus of research for their applied feature. The aim of this study was to investigate how social support has helped people deal with stressful situations in the workplace. In order to reach this aim an exploratory mixed method embedded research design was conducted. Study 1, quantitative, described the level of satisfaction with social support and perceived organizational support by employing a scale that summarized factors of the perceived organizational support. Study 2, a qualitative one, sought to describe the stressors in the workplace environment, to whom the workers resorted to, and the kind of perceived social support. The group interview script was based on the dimensions proposed by Folkman e Lazarus (1985 model. Fifty-one volunteer workers participated in the study. Results showed a lack of social support in the workplace: incivility of colleagues and managers, psychological contract breach and conflict of values. Investments in personal development that stimulate urbanity in organizations and a listening space for employees are suggested actions that can benefit affective dimensions of work.
Effect of abiotic and biotic stress factors analysis using machine learning methods in zebrafish.
Gutha, Rajasekar; Yarrappagaari, Suresh; Thopireddy, Lavanya; Reddy, Kesireddy Sathyavelu; Saddala, Rajeswara Reddy
2018-03-01
In order to understand the mechanisms underlying stress responses, meta-analysis of transcriptome is made to identify differentially expressed genes (DEGs) and their biological, molecular and cellular mechanisms in response to stressors. The present study is aimed at identifying the effect of abiotic and biotic stress factors, and it is found that several stress responsive genes are common for both abiotic and biotic stress factors in zebrafish. The meta-analysis of micro-array studies revealed that almost 4.7% i.e., 108 common DEGs are differentially regulated between abiotic and biotic stresses. This shows that there is a global coordination and fine-tuning of gene regulation in response to these two types of challenges. We also performed dimension reduction methods, principal component analysis, and partial least squares discriminant analysis which are able to segregate abiotic and biotic stresses into separate entities. The supervised machine learning model, recursive-support vector machine, could classify abiotic and biotic stresses with 100% accuracy using a subset of DEGs. Beside these methods, the random forests decision tree model classified five out of 8 stress conditions with high accuracy. Finally, Functional enrichment analysis revealed the different gene ontology terms, transcription factors and miRNAs factors in the regulation of stress responses. Copyright © 2017 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Imafuku, Muneyuki; Suzuki, Hiroshi; Sueyoshi, Kazuyuki; Akita, Koichi; Ohya, Shin-ichi
2008-01-01
Generalized formula of the x-ray stress analysis for a single crystal with unknown stress-free lattice parameter was proposed. This method enables us to evaluate the plane stress states with any combination of diffraction planes. We can choose and combine the appropriate x-ray sources and diffraction plane families, depending on the sample orientation and the apparatus, whenever diffraction condition is satisfied. The analysis of plane stress distributions in an iron single crystal was demonstrated combining with the diffraction data for Fe{211} and Fe{310} plane families
Mitigation method of thermal transient stress by thermalhydraulic-structure total analysis
International Nuclear Information System (INIS)
Kasahara, Naoto; Jinbo, Masakazu; Hosogai, Hiromi
2003-01-01
This study proposes a rational evaluation and mitigation method of thermal transient loads in fast reactor components by utilizing relationships among plant system parameters and stresses induced by thermal transients of plants. A thermalhydraulic-structure total analysis procedure helps us to grasp relationship among system parameters and thermal stresses. Furthermore, it enables mitigation of thermal transient loads by adjusting system parameters. In order to overcome huge computations, a thermalhydraulic-structure total analysis code and the Design of Experiments methodology are utilized. The efficiency of the proposed mitigation method is validated through thermal stress evaluation of an intermediate heat exchanger in Japanese demonstration fast reactor. (author)
Calculation method for residual stress analysis of filament-wound spherical pressure vessels
International Nuclear Information System (INIS)
Knight, C.E. Jr.
1976-01-01
Filament wound spherical pressure vessels may be produced with very high performance factors. These performance factors are a calculation of contained pressure times enclosed volume divided by structure weight. A number of parameters are important in determining the level of performance achieved. One of these is the residual stress state in the fabricated unit. A significant level of an unfavorable residual stress state could seriously impair the performance of the vessel. Residual stresses are of more concern for vessels with relatively thick walls and/or vessels constructed with the highly anisotropic graphite or aramid fibers. A method is established for measuring these stresses. A theoretical model of the composite structure is required. Data collection procedures and techniques are developed. The data are reduced by means of the model and result in the residual stress analysis. The analysis method can be used in process parameter studies to establish the best fabrication procedures
International Nuclear Information System (INIS)
Aihara, S.; Atsumi, K.; Ujiie, K.; Satoh, S.
1981-01-01
Self-restraining stresses generate not only moments but also axial forces. Therefore the moment and force equilibriums of cross section are considered simultaneously, in combination with other external forces. Thus, under this theory, two computer programs are prepared for. Using these programs, the design procedures which considered the reduction of self-restraining stress, become easy if the elastic design stresses, which are separated normal stresses and self-restraining stresses, are given. Numerical examples are given to illustrate the application of the simplified elastic-plastic analysis and to study its effectiveness. First this method is applied to analyze an upper shielding wall in MARK-2 type's Reactor building. The results are compared with those obtained by the elastic-plastic analysis of Finite Element Method. From this comparison it was confirmed that the method described, had adequate accuracy for re-bar design. As a second example, Mat slab of Reactor building is analyzed. The quantity of re-bars calculated by this method, comes to about two third of re-bars less than those required when self-restraining stress is considered as normal stress. Also, the self-restraining stress reduction factor is about 0.5. (orig./HP)
Directory of Open Access Journals (Sweden)
Mohammad Hadi Jalali
2018-01-01
Full Text Available Elastic stress analysis of rotating variable thickness annular disk made of functionally graded material (FGM is presented. Elasticity modulus, density, and thickness of the disk are assumed to vary radially according to a power-law function. Radial stress, circumferential stress, and radial deformation of the rotating FG annular disk of variable thickness with clamped-clamped (C-C, clamped-free (C-F, and free-free (F-F boundary conditions are obtained using the numerical finite difference method, and the effects of the graded index, thickness variation, and rotating speed on the stresses and deformation are evaluated. It is shown that using FG material could decrease the value of radial stress and increase the radial displacement in a rotating thin disk. It is also demonstrated that increasing the rotating speed can strongly increase the stress in the FG annular disk.
Analysis of a plane stress wave by the moving least squares method
Directory of Open Access Journals (Sweden)
Wojciech Dornowski
2014-08-01
Full Text Available A meshless method based on the moving least squares approximation is applied to stress wave propagation analysis. Two kinds of node meshes, the randomly generated mesh and the regular mesh are used. The nearest neighbours’ problem is developed from a triangulation that satisfies minimum edges length conditions. It is found that this method of neighbours’ choice significantly improves the solution accuracy. The reflection of stress waves from the free edge is modelled using fictitious nodes (outside the plate. The comparison with the finite difference results also demonstrated the accuracy of the proposed approach.[b]Keywords[/b]: civil engineering, meshless method, moving least squares method, elastic waves
Numerical stress analysis of toroidal coil by three-dimensional finite element method
International Nuclear Information System (INIS)
Nishimura, Hidetomo; Shimamoto, Susumu
1977-10-01
A structure analysis program based on finite element method for toroidal coils, developed in JAERI, and its example application to a medium-size tokamak are described. In this application, the effects of material anisotropy, poloidal field and spring constant value were studied, and also the influence of toroidal coil failure on the peak stress. The following were revealed. The effect of anisotropy on the peak stress in reinforcement must be considered. The effect of poloidal field on the peak stress is small compared with that of toroidal field. The spring constant value between coil and support does not much influence the peak stress value, The peak stress in reinforcement rises with increasing number of failed coils. In the case of 2000 nodes on the structure, CPU time with the program is about 40 min. (auth.)
A numerical analysis method on thermal and shrinkage stress of concrete
International Nuclear Information System (INIS)
Takiguchi, Katsuki; Hotta, Hisato
1991-01-01
Thermal stress often causes cracks in large scale concrete such as that for dam construction. The drying shrinkage of concrete causes cracks in concrete structures. These thermal stress and drying shrinkage stress may be the main reasons cracks occur in concrete, however there is few research which dealt with both stresses together. The problems on the thermal stress and the drying shrinkage are not independent, and should be dealt with together, because both temperature and water content of concrete affect hydration reaction, and the degree of hydration determines all the characteristics of concrete at early age. In this study, the degree of hydration is formulated experimentally, and a numerical stress analysis method taking the hydration reaction in consideration is presented. The formulation of the rate of hydration reaction, the method of analyzing thermal and drying shrinkage stresses, the analytical results for a concrete column and the influence that continuous load exerted to the tensile strength of concrete are reported. The relatively high stress nearly equal to the tensile strength of concrete arises near the surface. (K.I.)
Development of a micrometre-scale radiographic measuring method for residual stress analysis
International Nuclear Information System (INIS)
Moeller, D.
1999-01-01
The radiographic method described uses micrometre X-ray diffraction for high-resolution residual stress analysis in single crystals. The focus is on application of two x-ray optics (glass capillaries) for shaping a sufficiently fine and intensive primary beam. Due to application of a proper one-grain measuring and analysis method, the resolution results are applicable to the characteristic grain sizes of many materials. (orig.) [de
Analysis of Simple Creep Stress Calculation Methods for Creep Life Assessment
Energy Technology Data Exchange (ETDEWEB)
Seo, Jun Min; Lee, Han Sang; Kim, Yun Jae [Korea Univ., Daejeon (Korea, Republic of)
2017-08-15
Creep analysis takes much more time than elastic or elastic-plastic analysis. In this study, we conducted elastic and elastic-plastic analysis and compared the results with creep analysis results. In the elastic analysis, we used primary stress, which can be classified by the Mα-tangent method and stress intensities recommended in the ASME code. In the elastic-plastic analysis, we calculated the parameters recommended in the R5 code. For the FE models, a bending load, uniaxial load, and biaxial load were applied to the cross shaped welded plate, and a bending load and internal pressure were applied to the elbow pipe. To investigate the element size sensitivity, we conducted FE analysis for various element sizes for the cases where bending load was applied to the cross shaped welded plate. There was no significant difference between the creep.
Contact Stress Analysis for Gears of Different Helix Angle Using Finite Element Method
Directory of Open Access Journals (Sweden)
Patil Santosh
2014-07-01
Full Text Available The gear contact stress problem has been a great point of interest for many years, but still an extensive research is required to understand the various parameters affecting this stress. Among such parameters, helix angle is one which has played a crucial role in variation of contact stress. Numerous studies have been carried out on spur gear for contact stress variation. Hence, the present work is an attempt to study the contact stresses among the helical gear pairs, under static conditions, by using a 3D finite element method. The helical gear pairs on which the analysis is carried are 0, 5, 15, 25 degree helical gear sets. The Lagrange multiplier algorithm has been used between the contacting pairs to determine the stresses. The helical gear contact stress is evaluated using FE model and results have also been found at different coefficient of friction, varying from 0.0 to 0.3. The FE results have been further compared with the analytical calculations. The analytical calculations are based upon Hertz and AGMA equations, which are modified to include helix angle. The commercial finite element software was used in the study and it was shown that this approach can be applied to gear design efficiently. The contact stress results have shown a decreasing trend, with increase in helix angle.
Frequency spectrum method-based stress analysis for oil pipelines in earthquake disaster areas.
Directory of Open Access Journals (Sweden)
Xiaonan Wu
Full Text Available When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure. To date, researchers have performed limited safety analyses of oil pipelines in earthquake disaster areas that include stress analysis. Therefore, using the spectrum method and theory of one-dimensional beam units, CAESAR II is used to perform a dynamic earthquake analysis for an oil pipeline in the XX earthquake disaster area. This software is used to determine if the displacement and stress of the pipeline meet the standards when subjected to a strong earthquake. After performing the numerical analysis, the primary seismic action axial, longitudinal and horizontal displacement directions and the critical section of the pipeline can be located. Feasible project enhancement suggestions based on the analysis results are proposed. The designer is able to utilize this stress analysis method to perform an ultimate design for an oil pipeline in earthquake disaster areas; therefore, improving the safe operation of the pipeline.
Frequency spectrum method-based stress analysis for oil pipelines in earthquake disaster areas.
Wu, Xiaonan; Lu, Hongfang; Huang, Kun; Wu, Shijuan; Qiao, Weibiao
2015-01-01
When a long distance oil pipeline crosses an earthquake disaster area, inertial force and strong ground motion can cause the pipeline stress to exceed the failure limit, resulting in bending and deformation failure. To date, researchers have performed limited safety analyses of oil pipelines in earthquake disaster areas that include stress analysis. Therefore, using the spectrum method and theory of one-dimensional beam units, CAESAR II is used to perform a dynamic earthquake analysis for an oil pipeline in the XX earthquake disaster area. This software is used to determine if the displacement and stress of the pipeline meet the standards when subjected to a strong earthquake. After performing the numerical analysis, the primary seismic action axial, longitudinal and horizontal displacement directions and the critical section of the pipeline can be located. Feasible project enhancement suggestions based on the analysis results are proposed. The designer is able to utilize this stress analysis method to perform an ultimate design for an oil pipeline in earthquake disaster areas; therefore, improving the safe operation of the pipeline.
A test case of the deformation rate analysis (DRA) stress measurement method
Energy Technology Data Exchange (ETDEWEB)
Dight, P.; Hsieh, A. [Australian Centre for Geomechanics, Univ. of WA, Crawley (Australia); Johansson, E. [Saanio and Riekkola Oy, Helsinki (Finland); Hudson, J.A. [Rock Engineering Consultants (United Kingdom); Kemppainen, K.
2012-01-15
As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the {approx} 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely
A test case of the deformation rate analysis (DRA) stress measurement method
International Nuclear Information System (INIS)
Dight, P.; Hsieh, A.; Johansson, E.; Hudson, J.A.; Kemppainen, K.
2012-01-01
As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the ∼ 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely different to the NW-SE regional
Application of photostress method in stress analysis of a rotating disc
Frankovský, P.; Trebuňa, F.
2014-01-01
The presented article demonstrates the application of PhotoStressR method in stress analysis of a rotating disc of a constant thickness, which was made of a photoelastic material PS-1A. Isoclinic fringes were observed on the rotating disc using linear polarized light at revolutions 5 000 RPM. Observations were carried out under angle parameter 0 o to 90 o with 10 o increase. A set of isostatic lines of I and II set was made from the set of obtained isoclinic lines. During gradual increase of ...
Bednarek, Piotr T; Orłowska, Renata; Niedziela, Agnieszka
2017-04-21
We present a new methylation-sensitive amplified polymorphism (MSAP) approach for the evaluation of relative quantitative characteristics such as demethylation, de novo methylation, and preservation of methylation status of CCGG sequences, which are recognized by the isoschizomers HpaII and MspI. We applied the technique to analyze aluminum (Al)-tolerant and non-tolerant control and Al-stressed inbred triticale lines. The approach is based on detailed analysis of events affecting HpaII and MspI restriction sites in control and stressed samples, and takes advantage of molecular marker profiles generated by EcoRI/HpaII and EcoRI/MspI MSAP platforms. Five Al-tolerant and five non-tolerant triticale lines were exposed to aluminum stress using the physiologicaltest. Total genomic DNA was isolated from root tips of all tolerant and non-tolerant lines before and after Al stress following metAFLP and MSAP approaches. Based on codes reflecting events affecting cytosines within a given restriction site recognized by HpaII and MspI in control and stressed samples demethylation (DM), de novo methylation (DNM), preservation of methylated sites (MSP), and preservation of nonmethylatedsites (NMSP) were evaluated. MSAP profiles were used for Agglomerative hierarchicalclustering (AHC) based on Squared Euclidean distance and Ward's Agglomeration method whereas MSAP characteristics for ANOVA. Relative quantitative MSAP analysis revealed that both Al-tolerant and non-tolerant triticale lines subjected to Al stress underwent demethylation, with demethylation of CG predominating over CHG. The rate of de novo methylation in the CG context was ~3-fold lower than demethylation, whereas de novo methylation of CHG was observed only in Al-tolerant lines. Our relative quantitative MSAP approach, based on methylation events affecting cytosines within HpaII-MspI recognition sequences, was capable of quantifying de novo methylation, demethylation, methylation, and non-methylated status in control
contact stress analysis of involute spur gear by finite element method
African Journals Online (AJOL)
USER
section using C- programming. Bending stress analysis has been performed using finite element analysis with ANSYS software. Comparison of bending stress analysis has been performed for symmetric and asymmetric spur gear tooth at critical section. Mushin J. Jweeg, et.al. [7] used 2D contact stress FEA model to ...
Botelho, M; Gao, X; Bhuyan, S Y
2018-04-17
Stress in dental students is well established with potential psychological distress, emotional exhaustion and burnout-related symptoms. Little attention has been given to the problems encountered by dental students during the transition from theoretical or paraclinical training to the clinical environment. The aim of this study was to adopt a qualitative research methods approach to understand the perceived stressors during students' clinical transition and provide insights for curriculum planners to enhance learning. This study analysed four groups of 2nd- and 3rd-year BDS students' experiences in focus group interviews relating to their pre-clinical and clinical transitions. The interviews were recorded and transcribed verbatim, and a thematic analysis was performed using an inductive qualitative approach. Key overlapping domains identified were the transition gap and stresses. The transition gap was subclassified into knowledge and skill (hard and soft), and stresses was subcategorised into internal and external stresses. On first coming to clinics, students experienced knowledge gaps of unfamiliar clinical treatments with mismatches between knowledge acquisition and clinical exposure. Students felt incompetent owing to the stresses attributable to curriculum design, staff and the patient. This negatively affected their confidence and clinical performance. A range of challenges have been identified that will allow curriculum designer's to plan a more supportive learning experience to help students during their transition to clinical practice giving them timely knowledge, confidence and clinical performance to better prepare them for entering clinics. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Application of photostress method in stress analysis of a rotating disc
Directory of Open Access Journals (Sweden)
P. Frankovský
2014-10-01
Full Text Available The presented article demonstrates the application of PhotoStressR method in stress analysis of a rotating disc of a constant thickness, which was made of a photoelastic material PS-1A. Isoclinic fringes were observed on the rotating disc using linear polarized light at revolutions 5 000 RPM. Observations were carried out under angle parameter 0 o to 90 o with 10 o increase. A set of isostatic lines of I and II set was made from the set of obtained isoclinic lines. During gradual increase of rotations of the rotating disc up to 17 000 RPM, and with circular polarized light, we observed the distribution of colourful isochromatic fringes on the rotating disc. The field of isochromatic fringes, gained experimentally, at 15 000 RPM was compared with the field which was gained by means of a numerical analysis.
Directory of Open Access Journals (Sweden)
Zhao Fang
2017-01-01
Full Text Available Welded beam-to-column connections of high-rise steel structures are susceptive to fatigue damage under wind loading. However, most fatigue assessments in the field of civil engineering are mainly based on nominal stress or hot spot stress theories, which has the disadvantage of dependence on the meshing styles and massive curves selected. To address this problem, in this paper, the equivalent structural stress method with advantages of mesh-insensitive quality and capability of unifying different stress-life curves (S-N curves into one is introduced to the wind-induced fatigue assessment of a large-scale complicated high-rise steel structure. The multi-scale finite element model is established and the corresponding wind loading is simulated. Fatigue life assessments using equivalent structural stress method, hot spot stress method and nominal stress method are performed, and the results are verified and comparisons are made. The mesh-insensitive quality is also verified. The results show that the lateral weld toe of the butt weld connecting the beam flange plate and the column is the location where fatigue damage most likely happens. Nominal stress method considers fatigue assessment of welds in a more global way by averaging all the stress on the weld section while in equivalent structural stress method and hot spot method local stress concentration can be taken into account more precisely.
Czech Academy of Sciences Publication Activity Database
Berezovski, A.; Kolman, Radek; Blažek, Jiří; Kopačka, Ján; Gabriel, Dušan; Plešek, Jiří
2014-01-01
Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] R&D Projects: GA ČR(CZ) GAP101/11/0288; GA ČR(CZ) GAP101/12/2315 Institutional support: RVO:61388998 Keywords : elastic wave propagation * finite element method * isogeometric analysis * finite volume method * stress discontinuities * spurious oscillations Subject RIV: JR - Other Machinery http://www.ndt.net/events/ECNDT2014/app/content/Paper/25_Berezovski_Rev1.pdf
Stress Analysis of an Edge-Cracked Plate by using Photoelastic Fringe Phase Shifting Method
International Nuclear Information System (INIS)
Baek, Tae Hyun; Kim, Myung Soo; Cho, Sung Ho
2000-01-01
The method of photoelasticity allows one to obtain principal stress differences and principal stress directions in a photoelastic model. In the classical approach, the photoelastic parameters are measured manually point by point. The previous methods require much time and skill in the identification and measurement of photoelastic data. Fringe phase shifting method has been recently developed and widely used to measure and analyze fringe data in photo-mechanics. This paper presents the test results of photoelastic fringe phase shifting technique for the stress analysis of a circular disk under compression and an edge-cracked plate subjected to tensile load. The technique used here requires four phase stepped photoelastic images obtained from a circular polariscope by rotating the analyzer at 0 .deg. ,45 .deg. ,90 .deg. ,and 135 .deg. . Experimental results are compared with those or FEM. Good agreement between the results can be observed. However, some error may be included if the technique is used to general direction which is not parallel to isoclinic fringe
International Nuclear Information System (INIS)
Sinkovits, Theo; Zhao, Yue; O'Brien, Rebecca; Dowey, Steve
2014-01-01
Interruptions during film growth have been discussed by researchers to assist in understanding the evolution of stress in physical vapour deposition films. A change in intrinsic stress is directly related to microstructure, hence careful analysis of stress in films can provide valuable structure–stress correlated information. In this study we discuss the use of combining two X-ray diffraction (XRD) stress analysis methods to elucidate the effect of interruptions during growth on the residual stress of TiN films. The sin 2 ψ and crystallite group method (CGM), scanning the (220) peaks from all grains in the film and only (111) oriented crystallites respectively, were used to analyse residual stress in standard and interrupted cathodic arc TiN films 1.5, 3.5 and 6.5 μm thick, grown on high-speed steel substrates. The sin 2 ψ method does not reveal any changes in stress with interruptions, however, measurements using the CGM show increased compressive stress and increased a 0 in the resultant TiN films. A comparison of results from both XRD methods indicates that an increased compressive stress from interruptions could be due to an increased number of defects in (111) oriented grains during the interruptions which would also affect a 0 as evident. In both methods, compressive stresses are found to decrease with increased thickness of films. - Highlights: • Interrupting TiN film growth increases compressive stress in (111) grains. • Increased stress is believed to be caused by defects incorporated into or not annealed out of (111) grains. • A comparison of sin 2 ψ and CGM results reveals differences in stress. • Compressive stress decreases as TiN films increase in thickness from 1.5 μm to 6.5 μm
SAFE-3D, Stress Analysis of 3-D Composite Structure by Finite Elements Method
International Nuclear Information System (INIS)
Cornell, D.C.; Jadhav, K.; Crowell, J.S.
1969-01-01
1 - Description of problem or function: SAFE-3D is a finite-element program for the three-dimensional elastic analysis of heterogeneous composite structures. The program uses the following types of finite elements - (1) tetrahedral elements to represent the continuum, (2) triangular plane stress membrane elements to represent inner liner or outer case, and (3) uniaxial tension-compression elements to represent internal reinforcement. The structure can be of arbitrary geometry and have any distribution of material properties, temperatures, surface loadings, and boundary conditions. 2 - Method of solution: The finite-element variational method is used. Equilibrium equations are solved by the alternating component iterative method. 3 - Restrictions on the complexity of the problem - Maxima of: 5000 nodes; 16000 elements. The program cannot be applied to incompressible solids and is not recommended for Poisson's ratio in the range of nu between 0.495 and 0.5
A new method of residual stress distribution analysis for corroded Zircaloy-4 cladding
International Nuclear Information System (INIS)
Godlewski, J.; Cadalbert, R.
1992-01-01
An X-ray diffraction method of residual stress measurement is developed to determine the stress level in the metal near the metal/oxide interface of Zircaloy-4 cladding samples oxidized in steam water at 400degC under a pressure of 10.3 MPa. The stress gradient is obtained and the evolution of the average stress is determined as function of the oxidation time. The presence of tetragonal zirconia phase in quite large quantity near the metal/oxide interface could be correlated to the high stress level in the base metal, adjacent to the interface. (author)
A new method for residual stress distribution - analysis of corroded zircaloy-4 cladding
International Nuclear Information System (INIS)
Godlewski, J.; Cadalbert, R.
1992-01-01
An X-ray diffraction method for residual stress measurement is developed to determine the stress level in the metal near the metal/oxide interface of Zircaloy-4 cladding samples oxidized in steam water at 400 deg C under a pressure of 10.3 MPa. The stress gradient is obtained and the evolution of the average stress is determined as a function of the oxidation time. The presence of tetragonal zirconia phase in quite large quantity near the metal/oxide interface could be correlated to the high stress level in the base metal, adjacent to the interface. 12 refs., 5 figs., 1 tab
DEFF Research Database (Denmark)
Burcharth, Hans F.
The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)......The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)...
International Nuclear Information System (INIS)
Yi, Won; Yu, Yeong Chul; Jeong, Eui Seob; Lee, Chang Ho
1995-01-01
It is very important to evaluate the bonding residual thermal stress in dissimilar materials such as LSI package. In this study, the bonding residual thermal stress was calculated using the boundary element method, varing with the sub-element, geometry of specimen and adhesive thickness. The present results reveal a stress singularity at the edge of the interface, therefore the bonding strength of metal/resin interface can be estimated by taking into account it.
International Nuclear Information System (INIS)
Dolhof, V.; Musil, J.; Cepera, M.; Zeman, J.
1995-01-01
Residual stress is an important parameter in coating technology since it often relates to the maximum coating thickness which can be deposited without spallation, and this applies to coatings produced by different thermal spray and thin film technologies. Indeed, the mechanisms by which residual stress is built up or locked into a coating depends markedly on the deposition process and coating structure (growth structure, phase composition) in the same way too. Methods for determining residual stresses in materials include both destructive and non-destructive methods. This contribution describes semi-destructive hole-drilling strain gauge method modified for measurement of residual stresses in thermal sprayed coatings. This method of stress analysis was used for determination of stress levels in thermal sprayed WC-17% Co coatings onto 13% Cr steel substrates. Results show that deposition conditions and final coating structure influence directly the residual stress level in the coatings. It is proved that semi-destructive hole-tube drilling measurement is effective reproducible method of coating stress analysis and good solution for optimization of deposition process
Energy Technology Data Exchange (ETDEWEB)
Smith, M. [University of British Columbia – Okanagan, School of Engineering, 3333 University Way, Kelowna, Canada V1V 1V7 (Canada); Levesque, J.-B. [Institut de recherche d' Hydro-Québec (IREQ), 1800 Lionel-Boulet Blvd., Varennes, Canada J3X 1S1 (Canada); Bichler, L., E-mail: lukas.bichler@ubc.ca [University of British Columbia – Okanagan, School of Engineering, 3333 University Way, Kelowna, Canada V1V 1V7 (Canada); Sediako, D. [Canadian Nuclear Laboratories, Building 459, Station 18, Chalk River, Canada K0J 1J0 (Canada); Gholipour, J.; Wanjara, P. [National Research Council of Canada, Aerospace 5145 Decelles Ave., Montreal, Canada H3T 2B2 (Canada)
2017-04-13
In this study, an analysis of elastic residual stress in Inconel{sup ®} 718 (IN 718) linear friction welds (LFWs) was carried out. In particular, the suitability of LFW for manufacturing and repair of aero engine components was emulated by joining virgin and in-service (extracted from a turbine disk) materials. The evolution in the residual strains and stresses in the heat-affected zone (HAZ), thermomechanically affected zone (TMAZ) and dynamically recrystallized zone (DRX) of the weld was characterized using the neutron diffraction and contour methods. The results provided insight into diverse challenges in quantitative analysis of residual stresses in welded IN 718 using diffraction techniques. Specifically, judicious selection of the beam width, height and stress-free lattice spacing were seen to be crucial to minimize measurement error and increase accuracy. Further, the contour method – a destructive technique relying on capturing the stress relaxation after electrical discharge machining – was used to characterize the residual stress distribution on two-dimensional plane sections of the welds. Both techniques suggested an increasing magnitude of residual stress originating from the base metal that reached a peak at the weld interface. Both methods indicated that the peak magnitude of residual stresses were below the yield stress of IN 718.
Dantz, D; Reimers, W
1999-01-01
The residual stress state in microwave sintered metal-ceramic functionally graded materials (FGM) consisting of 8Y-ZrO/sub 2//Ni and 8Y-ZrO/sub 2//NiCr8020, respectively, was analysed by non- destructive diffraction methods. In $9 order to get knowledge of the complete residual stress state in the near surface region as well as in the interior of the material, complementary methods were applied. Whereas the surface was characterised by X-ray techniques using $9 conventional sources, the stresses within the bulk of the material were investigated by means of high energy synchrotron radiation. The stress state was found to obey the differences in the coefficients of thermal expansion $9 (micro-stresses) on the one hand and the inhomogeneous cooling conditions (macrostresses) on the other hand. (7 refs).
Statistical analysis of x-ray stress measurement by centroid method
International Nuclear Information System (INIS)
Kurita, Masanori; Amano, Jun; Sakamoto, Isao
1982-01-01
The X-ray technique allows a nondestructive and rapid measurement of residual stresses in metallic materials. The centroid method has an advantage over other X-ray methods in that it can determine the angular position of a diffraction line, from which the stress is calculated, even with an asymmetrical line profile. An equation for the standard deviation of the angular position of a diffraction line, σsub(p), caused by statistical fluctuation was derived, which is a fundamental source of scatter in X-ray stress measurements. This equation shows that an increase of X-ray counts by a factor of k results in a decrease of σsub(p) by a factor of 1/√k. It also shows that σsub(p) increases rapidly as the angular range used in calculating the centroid increases. It is therefore important to calculate the centroid using the narrow angular range between the two ends of the diffraction line where it starts to deviate from the straight background line. By using quenched structural steels JIS S35C and S45C, the residual stresses and their standard deviations were calculated by the centroid, parabola, Gaussian curve, and half-width methods, and the results were compared. The centroid of a diffraction line was affected greatly by the background line used. The standard deviation of the stress measured by the centroid method was found to be the largest among the four methods. (author)
International Nuclear Information System (INIS)
Shimooka, Hiroshi
1982-01-01
The disposal of high-level radioactive waste should result in temperature rises and thermal stresses which change the hydraulic conductivity of the rock around the repository. For safety analysis on disposal of high-level radioactive waste into hard rock, it is necessary to find the temperature rises and thermal stresses distributions around the repository. In this paper, these distribution changes are analyzed by the use of the finite difference method. In advance of numerical analysis, it is required to simplify the shapes and properties of the repository and the rock. Several kinds of numerical models are prepared, and the results of this analysis are examined. And, the waste disposal methods are discussed from the stand-points of the temperature rise and thermal stress analysis. (author)
Analysis of residual stresses on the transverse beam of a casting stand by means of drilling method
Directory of Open Access Journals (Sweden)
P. Frankovský
2014-10-01
Full Text Available The presented paper demonstrates the application of drilling method in the analysis of residual stresses on the transverse beam of a casting stand. In the initial stage of the analysis the determination of strains was done for individual steps of drilling in the area which was determined by means of numerical analysis. The drilling was carried out gradually by 0,5 mm up to the depth of 5 mm, while the diameter of the drilled hole was 3,2 mm. During the analysis we used the drilling device RS-200, strain indicator P3 and SGD 1-RY21-3/120. The paper presents the development of residual stresses throughout the depth of the drilled hole which were determined according to standard ASTM E837-01, by means of integral method, power series method and by means of Power Series method.
Direct method of design and stress analysis of rotating disks with temperature gradient
Manson, S S
1950-01-01
A method is presented for the determination of the contour of disks, typified by those of aircraft gas turbines, to incorporate arbitrary elastic-stress distributions resulting from either centrifugal or combined centrifugal and thermal effects. The specified stress may be radial, tangential, or any combination of the two. Use is made of the finite-difference approach in solving the stress equations, the amount of computation necessary in the evolution of a design being greatly reduced by the judicious selection of point stations by the aid of a design chart. Use of the charts and of a preselected schedule of point stations is also applied to the direct problem of finding the elastic and plastic stress distribution in disks of a given design, thereby effecting a great reduction in the amount of calculation. Illustrative examples are presented to show computational procedures in the determination of a new design and in analyzing an existing design for elastic stress and for stresses resulting from plastic flow.
Townsend, Kevin C; Thomas-Aitken, Holly D; Rudert, M James; Kern, Andrew M; Willey, Michael C; Anderson, Donald D; Goetz, Jessica E
2018-01-23
Evaluation of abnormalities in joint contact stress that develop after inaccurate reduction of an acetabular fracture may provide a potential means for predicting the risk of developing post-traumatic osteoarthritis. Discrete element analysis (DEA) is a computational technique for calculating intra-articular contact stress distributions in a fraction of the time required to obtain the same information using the more commonly employed finite element analysis technique. The goal of this work was to validate the accuracy of DEA-computed contact stress against physical measurements of contact stress made in cadaveric hips using Tekscan sensors. Four static loading tests in a variety of poses from heel-strike to toe-off were performed in two different cadaveric hip specimens with the acetabulum intact and again with an intentionally malreduced posterior wall acetabular fracture. DEA-computed contact stress was compared on a point-by-point basis to stress measured from the physical experiments. There was good agreement between computed and measured contact stress over the entire contact area (correlation coefficients ranged from 0.88 to 0.99). DEA-computed peak contact stress was within an average of 0.5 MPa (range 0.2-0.8 MPa) of the Tekscan peak stress for intact hips, and within an average of 0.6 MPa (range 0-1.6 MPa) for fractured cases. DEA-computed contact areas were within an average of 33% of the Tekscan-measured areas (range: 1.4-60%). These results indicate that the DEA methodology is a valid method for accurately estimating contact stress in both intact and fractured hips. Copyright © 2017 Elsevier Ltd. All rights reserved.
Stress and displacement analysis of a modern design lathe body by the fi nite element method (FEM
Directory of Open Access Journals (Sweden)
R. Staniek
2012-01-01
Full Text Available The Finite element method (FEM was used in this study for the analysis of the strain and stress of a turning machine body. The fi nal design decisions were made on the basis of stress and displacement fi eld analysis of various design versions related to the structure of the considered machine tool. The results presented in this paper will be helpful for practical static and dynamic strength evaluation as well as for the appropriate design of machine tools using the FEM.
Bednarek, Piotr T.; Or?owska, Renata; Niedziela, Agnieszka
2017-01-01
Background We present a new methylation-sensitive amplified polymorphism (MSAP) approach for the evaluation of relative quantitative characteristics such as demethylation, de novo methylation, and preservation of methylation status of CCGG sequences, which are recognized by the isoschizomers HpaII and MspI. We applied the technique to analyze aluminum (Al)-tolerant and non-tolerant control and Al-stressed inbred triticale lines. The approach is based on detailed analysis of events affecting H...
Serata, S.
2006-12-01
The Serata Stressmeter has been developed to measure and monitor earthquake shear stress build-up along shallow active faults. The development work made in the past 25 years has established the Stressmeter as an automatic stress measurement system to study timing of forthcoming major earthquakes in support of the current earthquake prediction studies based on statistical analysis of seismological observations. In early 1982, a series of major Man-made earthquakes (magnitude 4.5-5.0) suddenly occurred in an area over deep underground potash mine in Saskatchewan, Canada. By measuring underground stress condition of the mine, the direct cause of the earthquake was disclosed. The cause was successfully eliminated by controlling the stress condition of the mine. The Japanese government was interested in this development and the Stressmeter was introduced to the Japanese government research program for earthquake stress studies. In Japan the Stressmeter was first utilized for direct measurement of the intrinsic lateral tectonic stress gradient G. The measurement, conducted at the Mt. Fuji Underground Research Center of the Japanese government, disclosed the constant natural gradients of maximum and minimum lateral stresses in an excellent agreement with the theoretical value, i.e., G = 0.25. All the conventional methods of overcoring, hydrofracturing and deformation, which were introduced to compete with the Serata method, failed demonstrating the fundamental difficulties of the conventional methods. The intrinsic lateral stress gradient determined by the Stressmeter for the Japanese government was found to be the same with all the other measurements made by the Stressmeter in Japan. The stress measurement results obtained by the major international stress measurement work in the Hot Dry Rock Projects conducted in USA, England and Germany are found to be in good agreement with the Stressmeter results obtained in Japan. Based on this broad agreement, a solid geomechanical
SAFE-PLANE, Stress Analysis of Planar Structure by Finite Elements Method
International Nuclear Information System (INIS)
Cornell, D.C.; Reich, Morris
1967-01-01
1 - Description of problem or function: SAFE-PLANE is applied to two- dimensional structures of arbitrary geometry under in-plane loads. Either plane stress or plane strain conditions may be imposed. Mechanical and thermal loads are permitted. 2 - Method of solution: The finite-element method is used to construct a mathematical model by assembling discrete elements. The total potential energy of the structure is determined and subsequently minimized by iteration on components of the displacement field until static equilibrium of the structure is attained. Strains and stresses are computed from the resulting displacements. 3 - Restrictions on the complexity of the problem: Multi-material structures with varying rigidities converge very slowly. Not valid for incompressible materials. Maximum number of nodal points = 675. Maximum number of elements = 1350
Stress analysis of composite wind turbine blade by finite element method
Yeh, Meng-Kao; Wang, Chen-Hsu
2017-10-01
In this study, the finite element analysis software ANSYS was used to analyze the composite wind turbine blade. The wind turbine blade model used is adopted from the 5 MW model of US National Renewable Energy Laboratory (NREL). The wind turbine blade is a sandwich structure, comprising outermost carbon fiber cloth/epoxy composites, the inner glass fiber/vinylester layers, and PVC foam core, together with stiffeners. The wind pressure is converted into the load on the blade structure. The stress distribution and deformation of wind turbine blade were obtained by considering different pitch angles and at different angular positions. The Tsai-Hill criterion was used to determine the failure of wind turbine blade. The results show that at the 0° pitch angle, the wind turbine blade is subjected to the largest combined load and therefore the stress is the largest; with the increasing pitch angle, the load gradually decreases and the stress is also smaller. The stress and displacement are the greatest when the wind blade is located at 120° angular position from its highest vertex.
International Nuclear Information System (INIS)
Linjun, Xie; Guohong, Xue; Ming, Zhang
2016-01-01
Graphical abstract: HDS stress coefficient test apparatus. - Highlights: • This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. • The mathematical relation between the load and the strain is obtained about the HDS, and the mathematical model of the stress coefficient and the friction coefficient is established. So, a set of test apparatuses for obtaining the stress coefficient is designed according to the model scaling criterion and the friction coefficient of the K1000 HDS is calculated to be 0.336 through the obtained stress coefficient. • The relation curve between the theoretical load and the friction coefficient is obtained through analysis and indicates that the change of the friction coefficient f would influence the pretightening load under the condition of designed stress. The necessary pretightening load in the design process is calculated to be 5469 kN according to the obtained friction coefficient. Therefore, the friction coefficient and the pretightening load under the design conditions can provide accurate pretightening data for the analysis and design of the reactor HDS according to the operations. - Abstract: This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. By carrying out tests and researches through a stress testing technique, P–σ curves in loading and unloading processes of the HDS are obtained and the stress coefficient k f of the HDS is obtained. So, the
Energy Technology Data Exchange (ETDEWEB)
Linjun, Xie, E-mail: linjunx@zjut.edu.cn [College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Guohong, Xue; Ming, Zhang [Shanghai Nuclear Engineering Research & Design Institute, Shanghai 200233 (China)
2016-08-01
Graphical abstract: HDS stress coefficient test apparatus. - Highlights: • This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. • The mathematical relation between the load and the strain is obtained about the HDS, and the mathematical model of the stress coefficient and the friction coefficient is established. So, a set of test apparatuses for obtaining the stress coefficient is designed according to the model scaling criterion and the friction coefficient of the K1000 HDS is calculated to be 0.336 through the obtained stress coefficient. • The relation curve between the theoretical load and the friction coefficient is obtained through analysis and indicates that the change of the friction coefficient f would influence the pretightening load under the condition of designed stress. The necessary pretightening load in the design process is calculated to be 5469 kN according to the obtained friction coefficient. Therefore, the friction coefficient and the pretightening load under the design conditions can provide accurate pretightening data for the analysis and design of the reactor HDS according to the operations. - Abstract: This paper performs mathematic deduction to the physical model of Hold Down Spring (HDS), establishes a mathematic model of axial load P and stress, stress coefficient and friction coefficient and designs a set of test apparatuses for simulating the pretightening process of the HDS for the first time according to a model similarity criterion. By carrying out tests and researches through a stress testing technique, P–σ curves in loading and unloading processes of the HDS are obtained and the stress coefficient k{sub f} of the HDS is obtained. So, the
A method for the dynamic and thermal stress analysis of space shuttle surface insulation
Ojalvo, I. U.; Levy, A.; Austin, F.
1975-01-01
The thermal protection system of the space shuttle consists of thousands of separate insulation tiles bonded to the orbiter's surface through a soft strain-isolation layer. The individual tiles are relatively thick and possess nonuniform properties. Therefore, each is idealized by finite-element assemblages containing up to 2500 degrees of freedom. Since the tiles affixed to a given structural panel will, in general, interact with one another, application of the standard direct-stiffness method would require equation systems involving excessive numbers of unknowns. This paper presents a method which overcomes this problem through an efficient iterative procedure which requires treatment of only a single tile at any given time. Results of associated static, dynamic, and thermal stress analyses and sufficient conditions for convergence of the iterative solution method are given.
Goodnite, Patricia M
2014-01-01
To analyze the concept of stress and provide an operational definition of stress. Literature review revealed that stress is a commonly used, but often ambiguous, term. Findings supported a definition of stress entailing an individual's perception of a stimulus as overwhelming, which in turn elicits a measurable response resulting in a transformed state. This analysis adopts a dynamic definition of stress that may serve to encourage communication, promote reflection, and enhance concept understanding. This definition may provide direction for future work, as well as enhance efforts to serve patients affected by stress. © 2013 Wiley Periodicals, Inc.
Dynamic, large-deflection, inelastic and thermal stress analysis by the finite element method
International Nuclear Information System (INIS)
Haisler, W.E.; Stricklin, J.A.
1975-01-01
A finite element theory and computer program have been developed for predicting the dynamic, large displacement, inelastic and thermal response of stiffened and layered structures. The dependence of material properties on temperature is explicitly accounted for and any arbitrary, transient mechanical or thermal load history is allowed. The shell may have internal or external stiffeners and be constructed with up to three layers. The equations of motion are developed by using the pseudo force approach to represent all nonlinearities and are then solved by using either the Houbolt method or central differences. Moderately large rotations are allowed. The program is based on an incremental theory of plasticity using the Von Mises yield condition and associated flow rule. The post yield or work-hardening behavior is idealized with either the isotropic hardening or mechanical sublayer models. Two models are utilized since it has been found through comparison with experimental results that isotropic hardening is best for simple loading conditions while the mechanical sublayer model is better for reverse and cyclic loading. Strain-rate effects are also accounted for in the program by using a power-law type model based on the strain rate. The dependence of material properties on temperature is taken into account in the pseudo forces. Young's modulus, Poisson's ratio, thermal coefficient of expansion, the yield stress, and the entire stress strain curve are treated as functions of the applied temperature. Containment vessels subjected to transient and shock-type mechanical and thermal loads have been analyzed
International Nuclear Information System (INIS)
Kang, Mi Hyun; Seong, Back Suck; Kim, Hyoung Seop
2009-01-01
Severe plastic deformation (SPD) is one of the most promising top-down techniques, moving towards industrialization to fabricate bulk ultrafine grain materials. The strain distribution and deformation behavior during the ECAP (equal channel angular pressing), influenced by tool angles, friction and material behavior, was studied through experimental and numerical analyses. The residual stress of work piece which was straight before ECAP produces many serious problems in the next processing e.g. input of the work piece for the next ECAP. The bent work piece needs additional straightening or surface polishing even if the amount of bending is small, and residual stress need to be released before service applications. Residual stress, particularly tensile residual stress can be a very important factor in affecting the reliability and integrity of working parts. The formation of tensile residual stress may result in initiation of fatigue cracks, stress corrosion cracking, or other types of fracture. Hence, residual stress and resulting bending need to be controlled during ECAP. Thus, in current study the bending behavior and the residual stress of the work piece in ECAP are analyzed through experimental and finite element analyses by considering the effects of material, geometric, and processing parameters individually. The stress states in the ECAP processed work piece were measured by the non-destructive way using neutron diffraction. Efforts were made to suggest the alternate routes to reduce the residual stress and bending of work piece in ECAP
Iremonger, M J
1982-01-01
BASIC Stress Analysis aims to help students to become proficient at BASIC programming by actually using it in an important engineering subject. It also enables the student to use computing as a means of learning stress analysis because writing a program is analogous to teaching-it is necessary to understand the subject matter. The book begins by introducing the BASIC approach and the concept of stress analysis at first- and second-year undergraduate level. Subsequent chapters contain a summary of relevant theory, worked examples containing computer programs, and a set of problems. Topics c
International Nuclear Information System (INIS)
Yuuki, R.; Ejima, K.
1991-01-01
In this study, three-dimensional boundary element elastostatic analysis is carried out on various surface crack problems. The present BEM uses a Mindlin's solution as well as a Kelvin's solution as a fundamental solution. So we can obtain accurate solutions for a surface crack just before or after a penetration. The obtained solutions for various shapes of surface cracks are stored as the data base, based on the influence function method. We develop the surface crack extension analysis system using the stress intensity factor data base and also the fatigue crack growth law. Our system seems to be useful especially for the analysis of the surface crack just before or after the penetration and also under the residual stresses
SAFE-AXISYM, Stress Analysis of Axisymmetric Composite Structure by Finite Elements Method
International Nuclear Information System (INIS)
Cornell, D.C.
1967-01-01
1 - Nature of physical problem solved: SAFE-AXISYM is a program for the analysis of multi-material axisymmetric composite structures. It is designed for the analysis of heterogeneous structures such as reinforced and/or prestressed concrete vessels. The structure is assumed to be linearly elastic, and only bodies of revolution subjected to axisymmetric loading can be treated. 2 - Method of solution: SAFE-AXISYM uses a finite element method with a modified Gauss-Seidel iteration scheme. A reference grid subdivides the structure into ring-like small, finite elements, the vertices of which are called nodes. The grid may be generated by hand, by the computer or by a combination of the two methods. Each node has two degrees of freedom, translation in the and in the axial direction. Both zero and non-zero fixed displacement constraints may be assumed, and the loading condition may be mechanical and/or thermal. 3 - Restrictions on the complexity of the problem: Multi-material structures with varying rigidities converge very slowly. Not valid for incompressible materials. Maximum number of nodes = 475. Maximum number of elements = 1100
Stress analysis of two methods of ceramic inlay preparation by finite element
Directory of Open Access Journals (Sweden)
Leila Pishevar
2014-01-01
Conclusion: Cements with minimum shrinkage and as thin layer as possible should be used. Filling the undercut with glass ionomer cement decreases the stress. Other experimental and clinical studies must follow this research.
Göbel, M; Springer, J; Scherff, J
1998-05-01
Psychophysiological measures offer objective information for workplace design according to user requirements. They are, however, rarely applied in industrial practice due to weak points from the designer's point of view, such as the differentiation of various superimposed stressors, inter-individual differences, and the effort required for data acquisition and handling. In this study a set of psychophysiological methods was used to analyse bus driver workplaces as a basis for redesign, and afterwards to evaluate design improvements. During inner-city operation bus drivers are exposed to a particular workload situation, especially due to the high density of traffic and bus stops. Their job is characterized by highly frequent and often simultaneous task execution, performed with a compulsory body posture and under exposure to vibration and noise. To reduce the workload related to the equipment and tasks of bus driving, a research project was initiated to design a new driver workplace that meets the specific ergonomic requirements of the drivers. A detailed workload analysis, consisting of a task analysis, a strain analysis derived from ECG measures and an eye movement analysis was performed during public bus driving in different cities and with different drivers and bus types. Although the results have to be considered as somewhat limited owing to the methodological restraints and conditions of a field study, they provided valuable guidance for design. A new concept for the driver cabin was created based on this database. After installation, this design was evaluated by similar psychophysiological measures. Comparison of the pre- and post results indicates that the redesigned work station reduced workload levels.
Leem, Dohyun; Kim, Jin-Hwan; Barlat, Frédéric; Song, Jung Han; Lee, Myoung-Gyu
2018-03-01
An inverse approach based on the virtual fields method (VFM) is presented to identify the material hardening parameters under dynamic deformation. This dynamic-VFM (D-VFM) method does not require load information for the parameter identification. Instead, it utilizes acceleration fields in a specimen's gage region. To investigate the feasibility of the proposed inverse approach for dynamic deformation, the virtual experiments using dynamic finite element simulations were conducted. The simulation could provide all the necessary data for the identification such as displacement, strain, and acceleration fields. The accuracy of the identification results was evaluated by changing several parameters such as specimen geometry, velocity, and traction boundary conditions. The analysis clearly shows that the D-VFM which utilizes acceleration fields can be a good alternative to the conventional identification procedure that uses load information. Also, it was found that proper deformation conditions are required for generating sufficient acceleration fields during dynamic deformation to enhance the identification accuracy with the D-VFM.
International Nuclear Information System (INIS)
Shiraishi, Haruki; Tabuchi, Masaaki
2000-01-01
Applying the finite element method in two dimensions, an analysis is performed to derive the stress-strain relationship of material containing voids in matrix, and which is subjected to large deformation. The conditions assumed for the analysis are applicability of continuum body mechanics, Mises yield criterion, J2 flow theory, power work-hardening, plane stress in two-dimensional system and uniform cyclically recurring void distribution. Taking as example a case of material presenting 0.3 work-hardening, it is indicated from the analysis that: With voids arrayed in square lattice, total elongation would be little affected by change in void size; With a void spacing in lattice of 10 μ m, a uniform elongation 12-14% should be obtained in a wide range of void sizes from 0.01 to 8.0 μm; Tensile strength should start to lower at a void areal fraction of around 1%; A sharply lowered uniform elongation of a level far below 1% should be presented by material of low work-hardening exponent. The severe decline of ductility seen with 316 stainless steel upon neutron irradiation at temperatures around 600 K is interpreted as resulting from a combination of low work-hardening and the presence of voids in matrix. (author)
Directory of Open Access Journals (Sweden)
Fernando Bevilacqua
2018-01-01
Full Text Available Facial analysis is a promising approach to detect emotions of players unobtrusively; however approaches are commonly evaluated in contexts not related to games or facial cues are derived from models not designed for analysis of emotions during interactions with games. We present a method for automated analysis of facial cues from videos as a potential tool for detecting stress and boredom of players behaving naturally while playing games. Computer vision is used to automatically and unobtrusively extract 7 facial features aimed at detecting the activity of a set of facial muscles. Features are mainly based on the Euclidean distance of facial landmarks and do not rely on predefined facial expressions, training of a model, or the use of facial standards. An empirical evaluation was conducted on video recordings of an experiment involving games as emotion elicitation sources. Results show statistically significant differences in the values of facial features during boring and stressful periods of gameplay for 5 of the 7 features. We believe our approach is more user-tailored, convenient, and better suited for contexts involving games.
International Nuclear Information System (INIS)
Romppanen, A.-J.; Immonen, E.
2013-12-01
The residual stresses formed as a result of Electronic Beam welding (EB-welding) in copper are investigated by Posiva. In the present study, residual stresses of EB-welded copper plates were studied with contour method. In the method eleven copper plates (X436 - X440 and X453 - X458) were cut in half with wire electric discharge machining (EDM) after which the deformation due to stress relaxation was measured with coordinate measurement system. The measured data was then used as boundary displacement data for the FEM analyses, in which the corresponding residual stresses were calculated. Before giving the corresponding displacement boundary conditions to the FE models, the deformation data was processed and smoothed appropriately. The residual stress levels of the copper plates were found to be around 40 - 55 MPa at maximum. This corresponds to other reported residual stress measurements and current state of knowledge with this material in Posiva. (orig.)
PDX vacuum vessel stress analysis
International Nuclear Information System (INIS)
Nikodem, Z.D.
1975-01-01
A stress analysis of PDX vacuum vessel is described and the summary of results is presented. The vacuum vessel is treated as a toroidal shell of revolution subjected to an internal vacuum. The critical buckling pressure is calculated. The effects of the geometrical discontinuity at the juncture of toroidal shell head and cylindrical outside wall, and the concavity of the cylindrical wall are examined. An effect of the poloidal field coil supports and the vessel outside supports on the stress distribution in the vacuum vessel is determined. A method evaluating the influence of circular ports in the vessel wall on the stress level in the vessel is outlined
International Nuclear Information System (INIS)
Franca, L.P.; Toledo, E.M.; Loula, A.F.D.; Garcia, E.L.M.
1988-12-01
A new finite element method is employed to approximate axisymmetric shell problems. This formulation enhances stability and accuracy, from thin to moderately thick shells, compared to the correspondent Galerkin finite element approximations. Numerical results illustrate the good performance of the present method on some typical pressure vessels aplications. (author) [pt
Concept Analysis: Alzheimer's Caregiver Stress.
Llanque, Sarah; Savage, Lynette; Rosenburg, Neal; Caserta, Michael
2016-01-01
The aim of this article was to analyze the concept of caregiver stress in the context of caring for a person with Alzheimer's disease and related dementias. Currently, there are more than 15 million unpaid caregivers for persons suffering from Alzheimer's disease and related dementias. This unpaid care can be stressful for caregivers due to the chronic nature of the disease process, as well as other factors. The paper incorporates the modified method of Wilson's concept analysis procedure to analyze the concept of caregiver stress. A review of the literature was undertaken using the Cumulative Index to Nursing and Allied Health Literature, Google Scholar, and PubMed. A theoretical definition of caregiver stress is provided, and the defining attributes, related concepts, antecedents, and consequences of caregiver stress are proposed, and case studies are presented. The analysis demonstrates that caregiver stress is the unequal exchange of assistance among people who stand in close relationship to one another, which results in emotional and physical stress on the caregiver. Implications for future nursing research and practice conclude the paper. © 2014 Wiley Periodicals, Inc.
Stress Analysis of Composites.
1981-01-01
8217, Finite Elements in Nonlinear Mechanics, 1., 109-130, Tapir Publishers, Norway (1978). 9. A.J. Barnard and P.W. Sharman, ’Elastic-Plastic Analysis Using...Hybrid Stress Finite Elements,’ Finite Elements in Nonlinear Mechanics, 1, 131-148, Tapir Publishers Norway, (1978). ’.........Pian, ’Variational
Directory of Open Access Journals (Sweden)
Pedram Iranmanesh
2014-01-01
Full Text Available Introduction: In the present study, the finite element method (FEM was used to investigate the effects of prosthesis material types on stress distribution of the bone surrounding implants and to evaluate stress distribution in three-unit implant-supported fixed dental prosthesis (FDP. Materials and Methods: A three-dimensional (3D finite element FDP model of the maxillary second premolar to the second molar was designed. Three load conditions were statically applied on the functional cusps in horizontal (57.0 N, vertical (200.0 N, and oblique (400.0 N, θ = 120° directions. Four standard framework materials were evaluated: Polymethyl methacrylate (PMMA, base-metal, porcelain fused to metal, andporcelain. Results: The maximum of von Mises stress in the oblique direction was higher than the vertical and horizontal directions in all conditions. In the bone-crestal section, the maximum von Mises stress (53.78 MPa was observed in PMMA within oblique load. In FDPs, the maximum stress was generated at the connector region in all conditions. Conclusion: A noticeable difference was not observed in the bone stress distribution pattern with different prosthetic materials. Although, higher stress value could be seen in polymethyl methacrylate, all types of prosthesis yielded the same stress distribution pattern in FDP. More clinical studies are needed to evaluate the survival rate of these materials.
Stress analysis for shells with double curvature by finite element method
International Nuclear Information System (INIS)
Mueller, A.
1981-08-01
A simple triangular finite element for plates and shells, is presented. Since the rotation fields are assumed independent of the displacement fields, simple shape functions of second and third degree were used. An implicit penalty method allows one to solve thin shell problems since the Kirchoff-Love hypothesis are automatically satisfied. (Author) [pt
Stress and Deformation Analysis in Base Isolation Elements Using the Finite Element Method
Directory of Open Access Journals (Sweden)
Claudiu Iavornic
2011-01-01
Full Text Available In Modern tools as Finite Element Method can be used to study the behavior of elastomeric isolation systems. The simulation results obtained in this way provide a large series of data about the behavior of elastomeric isolation bearings under different types of loads and help in taking right decisions regarding geometrical optimizations needed for improve such kind of devices.
International Nuclear Information System (INIS)
Shim, Do Jun; Son, Beom Goo; Kim, Young Jin; Kim, Yun Jae
2004-01-01
To investigate relevance of the definition of the reference stress to estimate J and C * for surface crack problems, this paper compares FE J and C * results for surface cracked pipes with those estimated according to the reference stress approach using various definitions of the reference stress. Pipes with part circumferential inner surface crack and finite internal axial crack are considered, subject to internal pressure and global bending. The crack depth and aspect ratio are systematically varied. The reference stress is defined in four different ways using (I) the local limit load, (II) the global limit load, (III) the global limit load determined from the FE limit analysis, and (IV) the optimised reference load. It is found that the reference stress based on the local limit load gives overall excessively conservative estimates of J and C * . Use of the global limit load clearly reduces the conservatism, compared to that of the local limit load, although it can provide sometimes non-conservative estimates of J and C * . The use of the FE global limit load gives overall non-conservative estimates of J and C * . The reference stress based on the optimised reference load gives overall accurate estimates of J and C * , compared to other definitions of the reference stress. Based on the present finding, general guidance on the choice of the reference stress for surface crack problems is given
Mergny, Elke; Ansriou, M.; Lespagnard, A.; Ouaar, Amine; Latteur, Pierre; International Association for Shell and Spatial Structures (IASS) Symposium 2015
2015-01-01
- The wide majority of reinforced concrete structures are made of structural 1D or 2D elements such as beams, columns, slabs or walls, for which design methods are well known since decades, largely detailed in the literature such as EC2 or FIB Model Code [1, 2], and based on the fact that the knowledge of internal forces (moments, axial and shear forces) naturally lead to the values of the reinforcement. However, a minority of structures is characterized by a more or less complex three-dim...
International Nuclear Information System (INIS)
Fassmann, Werner
2014-06-01
According to the current theoretical and empirical state-of-the-art, stress has to be understood as the emotional and cognitive reaction by which humans adapt to situations which imply real or imagined danger, threat, or frustration of important personal goals or needs. The emotional reaction to such situations can be so extreme that rational coping with the situation will be precluded. In less extreme cases, changes of cognitive processes underlying human action will occur, which may systematically affect the reliability of tasks personnel has to perform in a stressful situation. Reliable task performance by personnel of nuclear power plants and other risk technologies is also affected by such effects. The method developed in the frame of the research and development project RS1198 sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi) addresses both aspects of emotional and cognitive coping with stressful situations. Analytical and evaluation steps of the approach provide guidance to the end users on how to capture and quantify the contribution of stress-related emotional and cognitive factors to the reliable performance of knowledge-based actions. For this purpose, a suitable guideline has been developed. Further research for clarifying open questions has been identified. A case study application illustrates how to use the method. Part of the work performed in this project was dedicated to a review addressing the question to which extent Swain's approach to the analysis and evaluation of stress is in line with current scientific knowledge. Suitable suggestions for updates have been developed.
International Nuclear Information System (INIS)
Fujihara, Hirohiko; Ueda, Masahiro
1975-01-01
In the design of chemical reactors or nuclear pressure vessels it is often important to evaluate the stress distribution in nozzle-to-shell intersections. The finite element method is a powerful tool for stress analysis, but it has a defects to require troublesome work in preparing input data. Specially, the mesh data of oblique nozzles and tangential nozzles, in which stress concentration is very high, are very difficult to be prepared. The authors made a mesh generation program which can be used to any nozzle-to-shell intersections, and combining this program with a three dimensional stress analysis program by the finite element method they made the stress analysis of nozzle-to-shell intersections under internal pressure. Consequently, stresses, strains and deformations of nozzles nonsymmetrical to spherical shells and nozzles tangential to cylindrical shells were made clear and it was shown that the curvature of the inner surface of the nozzle corner was a controlling factor in reducing stress concentration. (auth.)
DEFF Research Database (Denmark)
Vallejo, R L; Rexroad III, C E; Silverstein, J T
2009-01-01
As a first step toward the genetic mapping of QTL affecting stress response variation in rainbow trout, we performed complex segregation analyses (CSA) fitting mixed inheritance models of plasma cortisol by using Bayesian methods in large full-sib families of rainbow trout. To date, no studies have...... been conducted to determine the mode of inheritance of stress response as measured by plasma cortisol response when using a crowding stress paradigm and CSA in rainbow trout. The main objective of this study was to determine the mode of inheritance of plasma cortisol after a crowding stress....... The results from fitting mixed inheritance models with Bayesian CSA suggest that 1 or more major genes with dominant cortisol-decreasing alleles and small additive genetic effects of a large number of independent genes likely underlie the genetic variation of plasma cortisol in the rainbow trout families...
Yin, Yuanjie; Fan, Bozhao; He, Wei; Dai, Xianglu; Guo, Baoqiao; Xie, Huimin
2018-03-01
Diffraction grating strain gauge (DGSG) is an optical strain measurement method. Based on this method, a six-spot diffraction grating strain gauge (S-DGSG) system has been developed with the advantages of high and adjustable sensitivity, compact structure, and non-contact measurement. In this study, this system is applied for the residual stress measurement in thermal barrier coatings (TBCs) combining the hole-drilling method. During the experiment, the specimen’s location is supposed to be reset accurately before and after the hole-drilling, however, it is found that the rigid body displacements from the resetting process could seriously influence the measurement accuracy. In order to understand and eliminate the effects from the rigid body displacements, such as the three-dimensional (3D) rotations and the out-of-plane displacement of the grating, the measurement error of this system is systematically analyzed, and an optimized method is proposed. Moreover, a numerical experiment and a verified tensile test are conducted, and the results verify the applicability of this optimized method successfully. Finally, combining this optimized method, a residual stress measurement experiment is conducted, and the results show that this method can be applied to measure the residual stress in TBCs.
Stress analysis of shear/compression test
International Nuclear Information System (INIS)
Nishijima, S.; Okada, T.; Ueno, S.
1997-01-01
Stress analysis has been made on the glass fiber reinforced plastics (GFRP) subjected to the combined shear and compression stresses by means of finite element method. The two types of experimental set up were analyzed, that is parallel and series method where the specimen were compressed by tilted jigs which enable to apply the combined stresses, to the specimen. Modified Tsai-Hill criterion was employed to judge the failure under the combined stresses that is the shear strength under the compressive stress. The different failure envelopes were obtained between the two set ups. In the parallel system the shear strength once increased with compressive stress then decreased. On the contrary in the series system the shear strength decreased monotonicly with compressive stress. The difference is caused by the different stress distribution due to the different constraint conditions. The basic parameters which control the failure under the combined stresses will be discussed
International Nuclear Information System (INIS)
Nau, Andreas; Scholtes, B.
2014-01-01
Residual stresses can be result in both detrimental as well as beneficial consequences on the component's strength and lifetime. A most detailed knowledge of the residual stress state is a pre-requisite for the assessment of the component's performance. The mechanical methods for residual stress measurements are classified in non-destructive, destructive and semi-destructive methods. The two commonly used (semi-destructive) mechanical methods are the hole drilling and the ring core method. In the context of reactor safety research of the Federal Ministry of Economic Affairs and Energy (BMWi), two fundamental and interacting weak points of the hole drilling as well as of the ring core method are investigated. On the one hand, there are effects concerning geometrical boundary conditions of the components and on the other hand, there are influences of plasticity due to notch effects. Both aspects affect the released strain field, when the material is removed and finally, the calculated residual stresses. The first issue mentioned above is under the responsibility of Institute of Materials Engineering - Metallic Materials (Kassel University) and the last one will be investigated by University of Stuttgart-Otto-Graf-Institut - materials testing institute. Within the framework of this project it could be demonstrated that updated calibration coefficients lead to more reliable residual stress calculation in contrast to existing ones. These findings are valid for points of measurements on components without geometrical boundary effects like edges or shoulders. Reasons are high developed Finite-Element software packages and the opportunity of modelling the point of measurement (hole geometry, layout of the strain gauges) and its vicinity more in detail. Special challenges are multi-axial residual stress depth distributions and the geometry of components composing edges and claddings. Unlike existing analyses considering uni-axial and homogeneous stress states, bi
Isaacson, Eugene
1994-01-01
This excellent text for advanced undergraduates and graduate students covers norms, numerical solution of linear systems and matrix factoring, iterative solutions of nonlinear equations, eigenvalues and eigenvectors, polynomial approximation, and other topics. It offers a careful analysis and stresses techniques for developing new methods, plus many examples and problems. 1966 edition.
International Nuclear Information System (INIS)
Xu, Wujiao; Zou, Mingping; Zhang, Lei
2014-01-01
The hot deformation behaviors of steel 34CrMo4 is investigated by hot compression test with the temperature range of 1073–1373 K and the strain rate range of 0.01–10 s −1 . The flow behaviors of 34CrMo4 steel were characterized based on the true stress–true strain curves. The hyperbolic sine law in Arrhenius type is adopted in the constitutive modeling for 34CrMo4. Solving algorithm of the stress multiplier α in hyperbolic sine law is a key factor to guarantee the constitutive model accuracy. How to solve the stress multiplier α is investigated and an optimum solution method for α is proposed. Meanwhile, the influence of strain is incorporated in constitutive analysis by considering the effect of strain on material constants α, n, Q and A. With the optimum solution method for stress multiplier α proposed, the stress prediction is satisfactory with the higher correlation coefficient, R = 0.988 and the lower average absolute relative error, AARE = 3.44% for the entire strain rate-temperature domain. The optimum solution method for stress multiplier α can also be applied for other materials to predict the flow behavior more accurately. - Highlights: • Isothermal compression tests were conducted to study the flow behavior of 34CrMo4. • The influence of strain is incorporated in constitutive model. • An optimum solution method for stress multiplier α is proposed
International Nuclear Information System (INIS)
Mirbach, David von
2014-01-01
Residual stresses in mechanical components can result in both detrimental but also beneficial effects on the strength and lifetime of the components. The most detailed knowledge of the residual stress state is of advantage or a pre-requisite for the assessment of the component performance. The mechanical methods for residual stress measurement are divided into the groups of non-destructive and destructive methods. Two commonly used mechanical methods for determination of residual stresses are the hole drilling method and the ring core method which can be regarded as semi-destructive methods. In the context of reactor safety research of the German Federal Ministry of Economic and Technology (BMWi) two fundamental and interacting weak points of the hole drilling method as well as of the ring core method, respectively, in order to determine residual stresses are going to be investigated. As a consequence reliability of the methods will be improved in this joint research project. On the one hand there are effects of geometrical boundary conditions of the components and on the other hand there is the influence of plasticity due to notch effects both affecting the released strain field after removing material and after all the calculated residual stresses. The first issue mentioned above is under the responsibility of the Institute of Materials Engineering (Kassel University) and the last one is investigated by Universitaet of Stuttgart-Otto-Graf-Institut - materials testing institute. As a consequence of a successful project the knowledge base will be considerably improved resulting in benefits for various engineering fields. Especially the quantitative consideration of real residual stress states for optimized component designs will be possible and after all the consequences of residual stresses on safety of components which are used in nuclear facilities can be evaluated. The state of art was reground in the first research chapter and the analysed strain gauges where
Energy Technology Data Exchange (ETDEWEB)
Anno, N; Sugita, J [Honda R and D, Co. Ltd., Saitama (Japan)
1993-03-01
Piston troubles are mostly caused by cracks generating in each part of a piston. The finite element method (FEM) has been used for stress analysis of the piston, but has not been applied enough to design optimum configurations due to too much time for making models. In this study, stress analysis was carried out by the boundary element method (BEM), with which it is easy to make models and to change configurations, with various improvements. In addition, methods to execute a thermal load fatigue test and an actual running test to confirm analytical results were also improved. BEASY was used as basic software for analysis by BEM, and some improvements such as reduction of CPU time and optimization of memory using methods were carried out. It was easy to change configurations of the models by BEM, and the effect of the change in the piston boss configuration upon the stress agreed well with the actual test result. Design and evaluation of the optimum configuration has become easier by feedback of the results of the newly developed thermal load fatigue test to the analysis by BEM. 5 refs., 12 figs., 2 tabs.
International Nuclear Information System (INIS)
McCoy, Michael L.; Moradi, Rasoul; Lankarani, Hamid M.
2011-01-01
This paper examines the effectiveness of analyzing impact events in mechanical systems for design purposes using simple or low ordered finite elements. Traditional impact dynamics analyses of mechanical systems namely stereomechanics, energy method, stress-wave propagation and contact mechanics approaches are limited to very simplified geometries and provide basic analyses in making predictions and understanding the dominant features of the impact in a mechanical system. In engineering practice, impacted systems present a complexity of geometry, stiffness, mass distributions, contact areas and impact angles that are impossible to analyze and design with the traditional impact dynamics methods. In real cases, the effective tool is the finite element (FE) method. The high-end FEA codes though may be not available for typical engineer/designer. This paper provides information on whether impact events of mechanical systems can be successfully modeled using simple or low-order finite elements. FEA models using simple elements are benchmarked against theoretical impact problems and published experimental impact results. As a case study, an FE model using simple plastic beam elements is further tested to predict stresses and deflections in an experimental structural impact
Advanced Techniques of Stress Analysis
Directory of Open Access Journals (Sweden)
Simion TATARU
2013-12-01
Full Text Available This article aims to check the stress analysis technique based on 3D models also making a comparison with the traditional technique which utilizes a model built directly into the stress analysis program. This comparison of the two methods will be made with reference to the rear fuselage of IAR-99 aircraft, structure with a high degree of complexity which allows a meaningful evaluation of both approaches. Three updated databases are envisaged: the database having the idealized model obtained using ANSYS and working directly on documentation, without automatic generation of nodes and elements (with few exceptions, the rear fuselage database (performed at this stage obtained with Pro/ ENGINEER and the one obtained by using ANSYS with the second database. Then, each of the three databases will be used according to arising necessities.The main objective is to develop the parameterized model of the rear fuselage using the computer aided design software Pro/ ENGINEER. A review of research regarding the use of virtual reality with the interactive analysis performed by the finite element method is made to show the state- of- the-art achieved in this field.
Clinical experimental stress studies: methods and assessment.
Bali, Anjana; Jaggi, Amteshwar Singh
2015-01-01
Stress is a state of threatened homeostasis during which a variety of adaptive processes are activated to produce physiological and behavioral changes. Stress induction methods are pivotal for understanding these physiological or pathophysiological changes in the body in response to stress. Furthermore, these methods are also important for the development of novel pharmacological agents for stress management. The well-described methods to induce stress in humans include the cold pressor test, Trier Social Stress Test, Montreal Imaging Stress Task, Maastricht Acute Stress Test, CO2 challenge test, Stroop test, Paced Auditory Serial Addition Task, noise stress, and Mannheim Multicomponent Stress Test. Stress assessment in humans is done by measuring biochemical markers such as cortisol, cortisol awakening response, dexamethasone suppression test, salivary α-amylase, plasma/urinary norepinephrine, norepinephrine spillover rate, and interleukins. Physiological and behavioral changes such as galvanic skin response, heart rate variability, pupil size, and muscle and/or skin sympathetic nerve activity (microneurography) and cardiovascular parameters such as heart rate, blood pressure, and self-reported anxiety are also monitored to assess stress response. This present review describes these commonly employed methods to induce stress in humans along with stress assessment methods.
Oomori, H; Imura, S; Gesso, H
1992-04-01
To develop stem design achieving primary fixation of stems and effective load transfer to the femur, we studied stress analysis of stems in cementless total hip arthroplasty by two-dimensional finite element method using boundary friction layer in stem-bone interface. The results of analyses of stem-bone interface stresses and von Mises stresses at the cortical bones indicated that ideal stem design features would be as follows: 1) Sufficient length, with the distal end extending beyond the isthmus region. 2) Maximum possible width, to contact the cortical bones in the isthmus region. 3) No collars but a lateral shoulder at the proximal portion. 4) A distal tip, to contact the cortical bones at the distal portion.
Ichihashi, K; Imura, S; Oomori, H; Gesso, H
1994-11-01
We compared the biomechanical characteristics of bipolar and unipolar hemiarthroplasty on the proximal migration of the outer head by determining the von Mises stress distribution and acetabular (outer head) displacement with clinical assessment of hemiarthroplasty in 75 patients. This analysis used the two-dimensional finite element method, which incorporated boundary friction layers on both the inner and outer bearings of the prosthesis. Acetabular reaming increased stress within the pelvic bone and migration of the outer head. A combination of the acetabular reaming and bone transplantation increased the stress within the pelvic bone and grafted bone, and caused outer head migration. These findings were supported by clinical results. Although the bipolar endoprosthesis was biomechanically superior to the unipolar endoprosthesis, migration of the outer head still occurred. The bipolar endoprosthesis appeared to be indicated in cases of a femoral neck fracture or of avascular necrosis in the femoral head, but its use in cases of osteoarthritis in the hip required caution.
Photoelastic stress analysis in mitred bend under internal pressure
International Nuclear Information System (INIS)
Sawa, Yoshiaki
1987-01-01
The stress analysis and stress relaxation in mitred bend subjected to internal pressure have been studied by means of the photoelastic stress freezing method. The experimental results show that stress concentration occurs in the wedge tip of the intersectional plane and it is considerably influenced by the bent angle. Then, the stress relaxation was obtained by planing the wedge tip. (author)
Rotors stress analysis and design
Vullo, Vincenzo
2013-01-01
Stress and strain analysis of rotors subjected to surface and body loads, as well as to thermal loads deriving from temperature variation along the radius, constitutes a classic subject of machine design. Nevertheless attention is limited to rotor profiles for which governing equations are solvable in closed form. Furthermore very few actual engineering issues may relate to structures for which stress and strain analysis in the linear elastic field and, even more, under non-linear conditions (i.e. plastic or viscoelastic conditions) produces equations to be solved in closed form. Moreover, when a product is still in its design stage, an analytical formulation with closed-form solution is of course simpler and more versatile than numerical methods, and it allows to quickly define a general configuration, which may then be fine-tuned using such numerical methods. In this view, all subjects are based on analytical-methodological approach, and some new solutions in closed form are presented. The analytical formul...
Sugiura, M.; Seika, M.
1994-02-01
In this study, a new technique to measure the density of slip-bands automatically is developed, namely, a TV image of the slip-bands observed through a microscope is directly processed by an image-processing system using a personal computer and an accurate value of the density of slip-bands is measured quickly. In the case of measuring the local stresses in machine parts of large size with the copper plating foil, the direct observation of slip-bands through an optical microscope is difficult. In this study, to facilitate a technique close to the direct microscopic observation of slip-bands in the foil attached to a large-sized specimen, the replica method using a platic film of acetyl cellulose is applied to replicate the slip-bands in the attached foil.
Directory of Open Access Journals (Sweden)
mossayeb dalvand
2017-08-01
Full Text Available In this study 3D stress-strain distribution of dowel and glue line on L-type joints made of plywood doweled was investigated. Members of joints made of 11-ply hardwood plywood (Hornbeam, Beech and Alder that were 19 mm in thickness. In this study effect of beech dowels in three levels diameters (6, 8 and 10 mm and penetration of depth (9, 13 and 17 mm on bending moment capacity of L-type joints under compression loading was investigated as experimental test, then stress-strain distribution of wood dowel and glue line in specimens were simulated by means of ANSYS 15 software with finite element method (FEM.Results have shown that bending moment resistance increased with increasing dowel diameter from 6 to 8 mm, but downward trend was observed with increasing 8 to 10 mm in dowel diameter. Bending moment resistance increased with increasing penetration depth. Also, result obtained of simulation by means of ANSYS software have shown that stress-strain in dowel and glue line increased with increasing diameter of dowel and Increasing stress in joints made of diameter dowel 10 mm due to fracture in joints and decrease in resistance once. According to results obtained of model analysis, the ultimate stress of dowel and glue line occurred in the area that joints were contacted.
International Nuclear Information System (INIS)
Moulin, Didier.
1981-02-01
An empirical rule usable for design by analysis against progressive distorsion has been set up from experiments conducted in C.E.N. Saclay. This rule is checked with experimental data obtained by W.F. ANDERSON, this experiment is sufficiently different from the Saclay one to evaluate the merits of the rule. The satisfactory results achieved, are another validation of the efficiency diagram on which the method is based [fr
International Nuclear Information System (INIS)
Dearien, J.A.; Uldrich, E.D.
1975-01-01
1 - Description of problem or function: The code STRAP (Structural Analysis Package) was developed to analyze the response of structural systems to static and dynamic loading conditions. STRAP-S solves for the displacements and member forces of structural systems under static loads and temperature gradients. STRAP-D will solve numerically a given structural dynamics problem. 2 - Method of solution: STRAP-S generates the stiffness matrix of a structure by the finite element method and solves the resulting equations for structural displacements and member forces. STRAP-D generates the stiffness matrix, solves for eigenvalues and eigenvectors, uncouples and solves the series of second-order ordinary differential equations, and then calculates and plots the requested member forces. 3 - Restrictions on the complexity of the problem: STRAP-S maxima: 250 degrees of freedom, 100 members; STRAP-D maxima: 100 degrees of freedom, 80 time-steps in the forcing function input
Voice stress analysis and evaluation
Haddad, Darren M.; Ratley, Roy J.
2001-02-01
Voice Stress Analysis (VSA) systems are marketed as computer-based systems capable of measuring stress in a person's voice as an indicator of deception. They are advertised as being less expensive, easier to use, less invasive in use, and less constrained in their operation then polygraph technology. The National Institute of Justice have asked the Air Force Research Laboratory for assistance in evaluating voice stress analysis technology. Law enforcement officials have also been asking questions about this technology. If VSA technology proves to be effective, its value for military and law enforcement application is tremendous.
Stress analysis of pressure vessels
International Nuclear Information System (INIS)
Kim, B.K.; Song, D.H.; Son, K.H.; Kim, K.S.; Park, K.B.; Song, H.K.; So, J.Y.
1979-01-01
This interim report contains the results of the effort to establish the stress report preparation capability under the research project ''Stress analysis of pressure vessels.'' 1978 was the first year in this effort to lay the foundation through the acquisition of SAP V structural analysis code and a graphic terminal system for improved efficiency of using such code. Software programming work was developed in pre- and post processing, such as graphic presentation of input FEM mesh geometry and output deformation or mode shope patterns, which was proven to be useful when using the FEM computer code. Also, a scheme to apply fracture mechanics concept was developed in fatigue analysis of pressure vessels. (author)
Concept Analysis: Alzheimer’s Caregiver Stress
Llanque, Sarah; Savage, Lynette; Rosenburg, Neal; Honor’s, BA; Caserta, Michael
2015-01-01
AIM The aim of this article was to analyze the concept of caregiver stress in the context of caring for a person with Alzheimer’s disease and related dementias. BACKGROUND Currently, there are more than 15 million unpaid care-givers for persons suffering from Alzheimer’s disease and related dementias. This unpaid care can be stressful for caregivers due to the chronic nature of the disease process, as well as other factors. METHOD The paper incorporates the modified method of Wilson’s concept analysis procedure to analyze the concept of caregiver stress. DATA SOURCES A review of the literature was undertaken using the Cumulative Index to Nursing and Allied Health Literature, Google Scholar, and PubMed. RESULTS A theoretical definition of caregiver stress is provided, and the defining attributes, related concepts, antecedents, and consequences of caregiver stress are proposed, and case studies are presented. CONCLUSIONS The analysis demonstrates that caregiver stress is the unequal exchange of assistance among people who stand in close relationship to one another, which results in emotional and physical stress on the caregiver. Implications for future nursing research and practice conclude the paper. PMID:24787468
Stress analysis of PCV nozzle junction
International Nuclear Information System (INIS)
Uchiyama, Shoichi; Oikawa, Tsuneo; Hoshino, Seizo
1976-01-01
Most of various pressure vessels comprise each one cylindrical shell and one or more nozzles. In this study, in order to analyze the stress in the structures of this type as minutely and exactly as possible, the program for stress analysis by the finite element method was made, which is required for the strength analysis for three-dimensional structures. Especially, the problem of the stress distribution around nozzle junctions was solved theoretically with the program. The program for the analysis developed in this study is provided with various functions, such as the input generator for cylindrical, conical and spherical shells, and plotter, and is very covenient. The accuracy of analysis is very good. The method of analysis and the calculation of the rigidity matrices for the deformation in plane and bending are explained. The result of the stress analysis around the nozzle junctions of a containment vessel with this program was in good agreement with experimental data and the result with SAP-4 code, therefore the propriety of the calculated result with this program was proved. Also calculations were carried out on three cases, namely a flat plate fixed at one end with distributed load, a cylinder fixed at one end with internal pressure, and an I-beam fixed at one end with concentrated load. The calculated results agreed well with theoretical solutions in all cases. (Kako, I.)
Methods of measuring residual stresses in components
International Nuclear Information System (INIS)
Rossini, N.S.; Dassisti, M.; Benyounis, K.Y.; Olabi, A.G.
2012-01-01
Highlights: ► Defining the different methods of measuring residual stresses in manufactured components. ► Comprehensive study on the hole drilling, neutron diffraction and other techniques. ► Evaluating advantage and disadvantage of each method. ► Advising the reader with the appropriate method to use. -- Abstract: Residual stresses occur in many manufactured structures and components. Large number of investigations have been carried out to study this phenomenon and its effect on the mechanical characteristics of these components. Over the years, different methods have been developed to measure residual stress for different types of components in order to obtain reliable assessment. The various specific methods have evolved over several decades and their practical applications have greatly benefited from the development of complementary technologies, notably in material cutting, full-field deformation measurement techniques, numerical methods and computing power. These complementary technologies have stimulated advances not only in measurement accuracy and reliability, but also in range of application; much greater detail in residual stresses measurement is now available. This paper aims to classify the different residual stresses measurement methods and to provide an overview of some of the recent advances in this area to help researchers on selecting their techniques among destructive, semi destructive and non-destructive techniques depends on their application and the availabilities of those techniques. For each method scope, physical limitation, advantages and disadvantages are summarized. In the end this paper indicates some promising directions for future developments.
Energy Technology Data Exchange (ETDEWEB)
Lee, Chun Bae; Jung, Girl; Park, Tae Geun; Yang, Min Bok; Kim, Myung Soo; Baek, Tae Hyun [Kunsan National University, Kunsan (Korea, Republic of)
2005-05-15
This paper presents the experimental distributions of isochromatic fringes obtained in a quadrate plate which has a hole at its center. Isochromatic fringe are measured by the use of Tardy compensation method and phase shifting technique, and they are compared with those obtained from finite element method. Tardy compensation method is a conventional method and widely used but it is time-costing and inaccurate to obtain the movement of isoclinic fringe on a given point. Therefore, the 8-step phase shifting methodology is introduced and applied in this paper.
International Nuclear Information System (INIS)
Lee, Chun Bae; Jung, Girl; Park, Tae Geun; Yang, Min Bok; Kim, Myung Soo; Baek, Tae Hyun
2005-01-01
This paper presents the experimental distributions of isochromatic fringes obtained in a quadrate plate which has a hole at its center. Isochromatic fringe are measured by the use of Tardy compensation method and phase shifting technique, and they are compared with those obtained from finite element method. Tardy compensation method is a conventional method and widely used but it is time-costing and inaccurate to obtain the movement of isoclinic fringe on a given point. Therefore, the 8-step phase shifting methodology is introduced and applied in this paper.
Çelik Köycü, Berrak; İmirzalıoğlu, Pervin
2017-07-01
Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA). A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period. The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions. The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations. © 2015 by the American College of Prosthodontists.
Energy Technology Data Exchange (ETDEWEB)
Lostado, Ruben [University of La Rioja, Logroño (Spain); Martinez, Roberto Fernandez [University of Basque Country UPV/EHU, Bilbao (Spain); MacDonald, Bryan J. [Dublin City University, Dublin (Ireland)
2015-11-15
Double-row Tapered roller bearings (TRBs) are mechanical devices that are designed to support high axial, radial and torque loads. This combination of loads produces high contact stresses on the bearing raceways that are difficult to predict and validate experimentally, and can cause defects like pitting and fatigue spalling. In response, theoretical models have been proposed by many researchers to calculate the approximate distribution of contact stresses over the bearing raceways. More recently, numerical methods that are based on the Finite element method (FEM) have been used to obtain the contact stresses, although this method requires that the mesh size first be adjusted. This paper shows a process for adjusting a double-row TRB Finite element (FE) model. It is based on generating successive nonlinear FE submodels to calculate the distribution of contact stresses. A theoretical model and contact pressure sensors were used to adjust and validate the Finite element (FE) model.
PDX toroidal field coils stress analysis
International Nuclear Information System (INIS)
Nikodem, Z.D.; Smith, R.A.
1975-01-01
A method used in the stress analysis of the PDX toroidal field coil is developed. A multilayer coil design of arbitrary dimensions in the shape of either a circle or an oval is considered. The analytical model of the coil and the supporting coil case with connections to the main support structure is analyzed using the finite element technique. The three dimensional magnetic fields and the non-uniform body forces which are a loading condition on a coil due to toroidal and poloidal fields are calculated. The method of analysis permits rapid and economic evaluations of design changes in coil geometry as well as in coil support structures. Some results pertinent to the design evolution and their comparison are discussed. The results of the detailed stress analysis of the final coil design due to toroidal field, poloidal field and temperature loads are presented
Finite element stress analysis of brick-mortar masonry under ...
African Journals Online (AJOL)
Stress analysis of a brick-mortar couplet as a substitute for brick wall structure has been performed by finite element method, and algorithm for determining the element stiffness matrix for a plane stress problem using the displacement approach was developed. The nodal displacements were derived for the stress in each ...
Cheung, C Y Maurice; Williams, Thomas C R; Poolman, Mark G; Fell, David A; Ratcliffe, R George; Sweetlove, Lee J
2013-09-01
Flux balance models of metabolism generally utilize synthesis of biomass as the main determinant of intracellular fluxes. However, the biomass constraint alone is not sufficient to predict realistic fluxes in central heterotrophic metabolism of plant cells because of the major demand on the energy budget due to transport costs and cell maintenance. This major limitation can be addressed by incorporating transport steps into the metabolic model and by implementing a procedure that uses Pareto optimality analysis to explore the trade-off between ATP and NADPH production for maintenance. This leads to a method for predicting cell maintenance costs on the basis of the measured flux ratio between the oxidative steps of the oxidative pentose phosphate pathway and glycolysis. We show that accounting for transport and maintenance costs substantially improves the accuracy of fluxes predicted from a flux balance model of heterotrophic Arabidopsis cells in culture, irrespective of the objective function used in the analysis. Moreover, when the new method was applied to cells under control, elevated temperature and hyper-osmotic conditions, only elevated temperature led to a substantial increase in cell maintenance costs. It is concluded that the hyper-osmotic conditions tested did not impose a metabolic stress, in as much as the metabolic network is not forced to devote more resources to cell maintenance. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.
Energy Technology Data Exchange (ETDEWEB)
Fassmann, Werner
2014-06-15
According to the current theoretical and empirical state-of-the-art, stress has to be understood as the emotional and cognitive reaction by which humans adapt to situations which imply real or imagined danger, threat, or frustration of important personal goals or needs. The emotional reaction to such situations can be so extreme that rational coping with the situation will be precluded. In less extreme cases, changes of cognitive processes underlying human action will occur, which may systematically affect the reliability of tasks personnel has to perform in a stressful situation. Reliable task performance by personnel of nuclear power plants and other risk technologies is also affected by such effects. The method developed in the frame of the research and development project RS1198 sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi) addresses both aspects of emotional and cognitive coping with stressful situations. Analytical and evaluation steps of the approach provide guidance to the end users on how to capture and quantify the contribution of stress-related emotional and cognitive factors to the reliable performance of knowledge-based actions. For this purpose, a suitable guideline has been developed. Further research for clarifying open questions has been identified. A case study application illustrates how to use the method. Part of the work performed in this project was dedicated to a review addressing the question to which extent Swain's approach to the analysis and evaluation of stress is in line with current scientific knowledge. Suitable suggestions for updates have been developed.
International Nuclear Information System (INIS)
Chen, P.C.; Oshida, Y.
1989-01-01
Multi-layer thin film which has structure of Cu/Cr/K/Cr/Cu prepared by sputtering process was analyzed for interfacial stresses for as-deposited conditions. This structure was also annealed at 150 degrees C, and 350 degrees C for around 15 min. in a vacuum and cooled slowly down for stress analyses. Equations for residual stress estimations for homogeneous material system using layer removal technique (stress relief) is now applied for inhomogeneous system (multi-layer structure). The results are compared with the data obtained from x-ray diffraction technique by using sin 2 Ψ - 2 θ method, for Cu layer. From the present analyses, the data obtained using layer removal seem to be qualitatively consistent with but not quantitatively in agreement with x-ray method
14 CFR 33.62 - Stress analysis.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Stress analysis. 33.62 Section 33.62... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.62 Stress analysis. A stress analysis must be performed on each turbine engine showing the design safety margin of each turbine...
The stress and strain analysis research of class 1 eqnipments
International Nuclear Information System (INIS)
Ye Yuanwu; Tang Long; Wang Yueying; Qi Min; Yu Huajin
2008-01-01
The class 1 equipment is very important in the nuclear device, in the design and testing process required to carry out their stress and strain analysis, so as to ensure their safety. There are two ways to get stress and strain analysis of the class 1 equipment, the theoretical and experimental methods. Through theoretical method can get the stress and strain of the class 1 equipment, so as to provide a basis for the design of the equipment; through the experimental method to verify the accuracy of the theoretical methods and provide a basis for the safety assessment of the equipment. The main ressel of CEFR (China Experimental Fast Reactor) is the class 1 equipment. In this paper, according to the stress and strain analysis research of CEFR main vessel, the theories and expperimental methods of nuclear class 1 equipments stress and strain analysis has been described. (authors)
Measurement of residual stresses by the moire method
Sciammarella, C. A.; Albertazzi, A., Jr.
Three different applications of the moire method to the determination of residual stresses and strains are presented. The three applications take advantage of the property of ratings to record the changes of the surface they are printed on. One of the applications deals with thermal residual stresses, another with contact residual stress and the third one is a generalization of the blind hole technique. This last application is based on a computer assisted moire technique and on the generalization of the quasi-heterodyne techniques of fringe pattern analysis.
International Nuclear Information System (INIS)
Mirbach, David von
2015-01-01
Residual stresses in mechanical components can result in both detrimental but also beneficial effects on the strength and lifetime of the components. The most detailed knowledge of the residual stress state is of advantage or a pre-requisite for the assessment of the component performance. Two commonly used methods for determination of residual stresses are the hole drilling method and the ring core method which can be regarded to the mechanical methods. In the context of reactor safety research of the German Federal Ministry of Economic and Energy (BMWi) two fundamental and interacting weak points of the hole drilling method as well as of the ring core method, respectively, in order to determine residual stresses are going to be investigated. As a consequence reliability of the methods will be improved in this joint research project. On the one hand there are effects of geometrical boundary conditions of the components and on the other hand there is the influence of plasticity due to notch effects both affecting the released strain field after removing material and after all the calculated residual stresses. The first issue mentioned above is under the responsibility of the Institute of Materials Engineering (Kassel University) and the last one is investigated by materials testing institute university Stuttgart. As a consequence of a successful project the knowledge base will be considerably improved resulting in benefits for various engineering fields. Especially the quantitative consideration of real residual stress states for optimized component designs will be possible and after all the consequences of residual stresses on safety of components which are used in nuclear facilities can be evaluated. In this second experimental research chapter (phase 2) the findings of the first numerical and theoretical research chapter (phase 1) where proofed. The developed differential calculation method with the method of adaptive calibration functions were compared with the
Complete stress tensor determination by microearthquake analysis
Slunga, R.
2010-12-01
the depth based on the assumptions of a fractured crust, widely vary ing stress field, and a general closeness to instability as found by stress measurements (Jamison and Cook 1976). Wheather this approach is working or not is best answered by applying it to real data. This was provided by the IMO network in Iceland. Along Southern Iceland Seismic Zone (SISZ) more than 200,000 microearthquakes and a few M 5 EQs and 2 M=6.6 EQs have been recorded. The results will be presented it is obvious that the use of the stresses determined from the microearthquake recordings may significa ntly improve earthquake warnings and will make it possible to use the absolute C FS method for more deterministic predictions. Note that the microearthquake meth od only shows the part of the stress field that has caused slip. Volumes with st able stress will not show up. However stress measurements (Brown and Hoek 1978, Slunga 1988) have shown that the crustal stresses in general are close to instabi lity and microearthquake source analysis has shown that a large number of differ ent fractures become unstable within longer time windows. This may explain the e xcellent results given by the Icelandic tests of the absolute stress tensor fiel d as given by the microearthquakes. However I prefer to call this stress apparen t.
Practical stress analysis in engineering design
Huston, Ronald
2008-01-01
Presents the application of engineering design and analysis based on the approach of understanding the physical characteristics of a given problem and then modeling the important aspects of the physical system. This book covers such topics as contact stress analysis, singularity functions, gear stresses, fasteners, shafts, and shaft stresses.
Asymptotic Method for Cladding Stress Evaluation in PCMI
International Nuclear Information System (INIS)
Kim, Hyungkyu; Kim, Jaeyong; Yoon, Kyungho; Lee, Kanghee; Kang, Heungseok
2014-01-01
A PCMI (Pellet Cladding Mechanical Interaction) failure was first reported in the GETR (General Electric Test Reactor) at Vacellitos in 1963, and such failures are still occurring. Since the high stress values in the cladding tube has been of a crucial concern in PCMI studies, there have been many researches on the stress analysis of a cladding tube pressed by a pellet. Typical works can be found in some references. It has often been assumed, however, that the cracks in the pellet were equally spaced and the pellet was a rigid body. In addition, the friction coefficient was arbitrarily chosen so that a slipping between the pellets and cladding tube could not be logically defined. Moreover, the stress intensification due to the sharp edge of a pellet fragment has never been realistically considered. These problems above drove us to launch a framework of a PCMI study particularly on stress analysis technology to improve the present analysis method incorporating the actual PCMI conditions such as the stress intensification, arbitrary distribution of the pellet cracks, material properties (esp. pellet) and slipping behavior of the pellet/cladding interface. As a first step of this work, this paper introduces an asymptotic method that was originally developed for a stress analysis in the vicinity of a sharp notch of a homogeneous body. The intrinsic reason for applying this method is to simulate the stress singularity that is expected to take place at the sharp edge of a pellet fragment due to cracking during irradiation. As a first attempt of this work, an eigenvalue problem is formulated in the case of adhered contact, and the generalized stress intensity factors are defined and evaluated. Although some works obviously remain to be accomplished, for the present framework on the PCMI analysis (e. g., slipping behaviour, contact force etc.), it was addressed that the asymptotic method can produce the stress values that cause the cladding tube failure in PCMI more
DEFF Research Database (Denmark)
Spataru, Sergiu; Hacke, Peter; Sera, Dezso
2015-01-01
We propose a method of in-situ characterization of the photovoltaic module power at standard test conditions using superposition of the dark current-voltage (I-V) curve measured at elevated stress temperature during potential-induced degradation (PID) testing. PID chamber studies were performed o...
Wu, Y. H.; Nakakita, E.
2017-12-01
Hillslope stability is highly related to stress equilibrium near the top surface of soil-mantled hillslopes. Stress field in a hillslope can also be significantly altered by variable groundwater motion under the rainfall influence as well as by different vegetation above and below the slope. The topographic irregularity, biological effects from vegetation and variable rainfall patterns couple with others to make the prediction of shallow landslide complicated and difficult. In an increasing tendency of extreme rainfall, the mountainous area in Japan has suffered more and more shallow landslides. To better assess shallow landslide hazards, we would like to develop a new mechanically-based method to estimate the fully three-dimensional stress field in hillslopes. The surface soil-layer of hillslope is modelled as a poroelastic medium, and the tree surcharge on the slope surface is considered as a boundary input of stress forcing. The modelling of groundwater motion is involved to alter effective stress state in the soil layer, and the tree root-reinforcement estimated by allometric equations is taken into account for influencing the soil strength. The Mohr-Coulomb failure theory is then used for locating possible yielding surfaces, or says for identifying failure zones. This model is implemented by using the finite element method. Finally, we performed a case study of the real event of massive shallow landslides occurred in Hiroshima in August, 2014. The result shows good agreement with the field condition.
Measurement of edge residual stresses in glass by the phase-shifting method
Ajovalasit, A.; Petrucci, G.; Scafidi, M.
2011-05-01
Control and measurement of residual stress in glass is of great importance in the industrial field. Since glass is a birefringent material, the residual stress analysis is based mainly on the photoelastic method. This paper considers two methods of automated analysis of membrane residual stress in glass sheets, based on the phase-shifting concept in monochromatic light. In particular these methods are the automated versions of goniometric compensation methods of Tardy and Sénarmont. The proposed methods can effectively replace manual methods of compensation (goniometric compensation of Tardy and Sénarmont, Babinet and Babinet-Soleil compensators) provided by current standards on the analysis of residual stresses in glasses.
Stress description model by non destructive magnetic methods
International Nuclear Information System (INIS)
Flambard, C.; Grossiord, J.L.; Tourrenc, P.
1983-01-01
Since a few years, CETIM investigates analysis possibilities of materials, by developing a method founded on observation of ferromagnetic noise. By experiments, correlations have become obvious between state of the material and recorded signal. These correlations open to industrial applications to measure stresses and strains in elastic and plastic ranges. This article starts with a brief historical account and theoretical backgrounds of the method. The experimental frame of this research is described, and the main results are analyzed. Theoretically, a model was built up, and we present it. It seems in agreement with some experimental observations. The main results concerning stress application, thermal and surface treatments (decarbonizing) are presented [fr
Residual stress analysis in thick uranium films
International Nuclear Information System (INIS)
Hodge, A.M.; Foreman, R.J.; Gallegos, G.F.
2005-01-01
Residual stress analysis was performed on thick, 1-25 μm, depleted uranium (DU) films deposited on an Al substrate by magnetron sputtering. Two distinct characterization techniques were used to measure substrate curvature before and after deposition. Stress evaluation was performed using the Benabdi/Roche equation, which is based on beam theory of a bi-layer material. The residual stress evolution was studied as a function of coating thickness and applied negative bias voltage (0, -200, -300 V). The stresses developed were always compressive; however, increasing the coating thickness and applying a bias voltage presented a trend towards more tensile stresses and thus an overall reduction of residual stresses
Stress Analysis in Polymeric Coating Layer Deposited on Rigid Substrate
Energy Technology Data Exchange (ETDEWEB)
Lee, Sang Soon Lee [Korea University of Technology and Education, School of Mechatronics Engineering, Chonan (Korea, Republic of)
2015-08-15
This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.
Finite element analysis of thermal stress distribution in different ...
African Journals Online (AJOL)
Nigerian Journal of Clinical Practice • Jan-Feb 2016 • Vol 19 • Issue 1. Abstract ... Key words: Amalgam, finite element method, glass ionomer cement, resin composite, thermal stress ... applications for force analysis and assessment of different.
The method for measuring residual stress in stainless steel pipes
International Nuclear Information System (INIS)
Shimov, Georgy; Rozenbaum, Mikhail; Serebryakov, Alexandr; Serebryakov, Andrey
2016-01-01
The main reason of appearance and growth of corrosion damages of the nuclear steam generator heat exchanger tubes is the process of stress-corrosion cracking of metal under the influence of residual tensile stress. Methods used in the production for estimating residual stresses (such as a method of ring samples) allow measuring only the average tangential stress of the pipe wall. The method of ring samples does not allow to assess the level of residual stress in the surface layer of the pipe. This paper describes an experimental method for measuring the residual stresses on the pipe surface by etching a thin surface layer of the metal. The construction and working principle of a trial installation are described. The residual stresses in the wall of the tubes 16 × 1.5 mm (steel AISI 321) for nuclear steam generators is calculated. Keywords: heat exchange pipes, stress corrosion cracking, residual stresses, stress distribution, stress measurement.
Finite Element Residual Stress Analysis of Planetary Gear Tooth
Directory of Open Access Journals (Sweden)
Jungang Wang
2013-01-01
Full Text Available A method to simulate residual stress field of planetary gear is proposed. In this method, the finite element model of planetary gear is established and divided to tooth zone and profile zone, whose different temperature field is set. The gear's residual stress simulation is realized by the thermal compression stress generated by the temperature difference. Based on the simulation, the finite element model of planetary gear train is established, the dynamic meshing process is simulated, and influence of residual stress on equivalent stress of addendum, pitch circle, and dedendum of internal and external meshing planetary gear tooth profile is analyzed, according to non-linear contact theory, thermodynamic theory, and finite element theory. The results show that the equivalent stresses of planetary gear at both meshing and nonmeshing surface are significantly and differently reduced by residual stress. The study benefits fatigue cracking analysis and dynamic optimization design of planetary gear train.
Assessment of residual stress of 7050-T7452 aluminum alloy forging using the contour method
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zheng [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Yang, Yinfei, E-mail: yyfgoat@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Li, Liang [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Bo; Tian, Hui [Xi’an Aircraft Industrial (Group) Co. Ltd., Xi’an 710000 (China)
2015-09-17
The cold-compression stress relief process has been used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings. However, this method does not completely relieve the stress. Longitudinal residual stresses in 7050-T7452 aluminum alloy forging were measured with contour method. The measuring procedure of the contour method including specimen cutting under clamps with a wire electrical discharge machine, contour measurement of the cut surface with a laser scanner, careful data processing and elastic finite element analysis was introduced in detail. In addition, multiple cuts were used to map cross sectional stress at different cut surfaces. Finally, the longitudinal residual stress throughout the cut plane was mapped, and through thickness longitudinal stress profiles were also analyzed. Investigated results suggest that spatial variation of stress distribution can be attributed to the non-uniform plastic deformation of the cold-compression stress relief process. The overall reduction of peak stress magnitudes is approximately 43–79%.
Assessment of residual stress of 7050-T7452 aluminum alloy forging using the contour method
International Nuclear Information System (INIS)
Zhang, Zheng; Yang, Yinfei; Li, Liang; Chen, Bo; Tian, Hui
2015-01-01
The cold-compression stress relief process has been used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings. However, this method does not completely relieve the stress. Longitudinal residual stresses in 7050-T7452 aluminum alloy forging were measured with contour method. The measuring procedure of the contour method including specimen cutting under clamps with a wire electrical discharge machine, contour measurement of the cut surface with a laser scanner, careful data processing and elastic finite element analysis was introduced in detail. In addition, multiple cuts were used to map cross sectional stress at different cut surfaces. Finally, the longitudinal residual stress throughout the cut plane was mapped, and through thickness longitudinal stress profiles were also analyzed. Investigated results suggest that spatial variation of stress distribution can be attributed to the non-uniform plastic deformation of the cold-compression stress relief process. The overall reduction of peak stress magnitudes is approximately 43–79%
Stress determination and geomechanical stability analysis of an oil ...
Indian Academy of Sciences (India)
Practical data including geomechanical parameters along with drilling data from one of Iranian oilfields, Mansouri-54 well have been utilized in this analysis. in situ stress was determined using stress polygon method and conducting hydraulic fracturing data in the field. Analytical solution using the Mogi–Coulomb and the ...
Thermal stresses in the space shuttle orbiter: Analysis versus test
International Nuclear Information System (INIS)
Grooms, H.R.; Gibson, W.F. Jr.; Benson, P.L.
1984-01-01
Significant temperature differences occur between the internal structure and the outer skin of the Space Shuttle Orbiter as it returns from space. These temperature differences cause important thermal stresses. A finite element model containing thousands of degrees of freedom is used to predict these stresses. A ground test was performed to verify the prediction method. The analysis and test results compare favorably. (orig.)
Stress analysis in FRP composites
Directory of Open Access Journals (Sweden)
Nitin Jauhari
2016-09-01
Full Text Available A composite material, in mechanics sense, is a structure with the ingredients as element transferring forces to adjacent members. The issue of defects and their effect on the mechanical properties of composites is of great concern among high end users. Experimental investigation of failure modes of composite materials requires correlating the fundamentals of composite materials, their mechanical properties as well as their failure characteristics in the presence of defects. In this paper, three formats of defects of hole (single, double and quadruple as a discontinuity were incorporated along with tensile testing. Unique failure modes of these specimens provided overview regarding mechanical behaviour of composite materials containing defects. Certain correlations were observed between defects and resulting properties. Results are in agreement with general behaviour of FRP composite laminates and it can be concluded that for low deformation in composite laminates, number of layers must be increased, which at the same time results in increase of von-Mises stress. Fibres are the main constituents which are responsible for strength of a composite laminate and they along with fibre orientation, play an important role on its load bearing capacity. It can be inferred based on the analysis that cross-ply configuration [0°/90°] has good load bearing capacity as well as least deflection emphasizing more strength.
[Methods and Applications of Psychological Stress State Assessment].
Li, Xin; Yang, Yadan; Hou, Yongjie; Chen, Zetao
2015-08-01
In this paper, the response of individual's physiological system under psychological stress state is discussed, and the theoretical support for psychological stress assessment research is provided. The two methods, i.e., the psychological stress assessment of questionnaire and physiological parameter assessment used for current psychological stress assessment are summarized. Then, the future trend of development of psychological stress assessment research is pointed out. We hope that this work could do and provide further support and help to psychological stress assessment studies.
Nuclear class 1 piping stress analysis
International Nuclear Information System (INIS)
Lucas, J.C.R.; Maneschy, J.E.; Mariano, L.A.; Tamura, M.
1981-01-01
A nuclear class 1 piping stress analysis, according to the ASME code, is presented. The TRHEAT computer code has been used to determine the piping wall thermal gradient. The Nupipe computer code was employed for the piping stress analysis. Computer results were compared with the allowable criteria from the ASME code. (Author) [pt
Evaluation of Residual Stresses using Ring Core Method
Directory of Open Access Journals (Sweden)
Holý S.
2010-06-01
Full Text Available The method for measuring residual stresses using ring-core method is described. Basic relations are given for residual stress measurement along the specimen depth and simplified method is described for average residual stress estimation in the drilled layer for known principal stress directions. The estimation of calculated coefficients using FEM is described. Comparison of method sensitivity is made with hole-drilling method. The device for method application is described and an example of experiment is introduced. The accuracy of method is discussed. The influence of strain gauge rosette misalignment to the evaluated residual stresses is performed using FEM.
International Nuclear Information System (INIS)
Deville, J.P.
1998-01-01
Nowadays, there are a lot of surfaces analysis methods, each having its specificity, its qualities, its constraints (for instance vacuum) and its limits. Expensive in time and in investment, these methods have to be used deliberately. This article appeals to non specialists. It gives some elements of choice according to the studied information, the sensitivity, the use constraints or the answer to a precise question. After having recalled the fundamental principles which govern these analysis methods, based on the interaction between radiations (ultraviolet, X) or particles (ions, electrons) with matter, two methods will be more particularly described: the Auger electron spectroscopy (AES) and x-rays photoemission spectroscopy (ESCA or XPS). Indeed, they are the most widespread methods in laboratories, the easier for use and probably the most productive for the analysis of surface of industrial materials or samples submitted to treatments in aggressive media. (O.M.)
Methods of Multivariate Analysis
Rencher, Alvin C
2012-01-01
Praise for the Second Edition "This book is a systematic, well-written, well-organized text on multivariate analysis packed with intuition and insight . . . There is much practical wisdom in this book that is hard to find elsewhere."-IIE Transactions Filled with new and timely content, Methods of Multivariate Analysis, Third Edition provides examples and exercises based on more than sixty real data sets from a wide variety of scientific fields. It takes a "methods" approach to the subject, placing an emphasis on how students and practitioners can employ multivariate analysis in real-life sit
Prediction of residual stress using explicit finite element method
Directory of Open Access Journals (Sweden)
W.A. Siswanto
2015-12-01
Full Text Available This paper presents the residual stress behaviour under various values of friction coefficients and scratching displacement amplitudes. The investigation is based on numerical solution using explicit finite element method in quasi-static condition. Two different aeroengine materials, i.e. Super CMV (Cr-Mo-V and Titanium alloys (Ti-6Al-4V, are examined. The usage of FEM analysis in plate under normal contact is validated with Hertzian theoretical solution in terms of contact pressure distributions. The residual stress distributions along with normal and shear stresses on elastic and plastic regimes of the materials are studied for a simple cylinder-on-flat contact configuration model subjected to normal loading, scratching and followed by unloading. The investigated friction coefficients are 0.3, 0.6 and 0.9, while scratching displacement amplitudes are 0.05 mm, 0.10 mm and 0.20 mm respectively. It is found that friction coefficient of 0.6 results in higher residual stress for both materials. Meanwhile, the predicted residual stress is proportional to the scratching displacement amplitude, higher displacement amplitude, resulting in higher residual stress. It is found that less residual stress is predicted on Super CMV material compared to Ti-6Al-4V material because of its high yield stress and ultimate strength. Super CMV material with friction coefficient of 0.3 and scratching displacement amplitude of 0.10 mm is recommended to be used in contact engineering applications due to its minimum possibility of fatigue.
The study on evaluation method for primary stress of 3-D structure
International Nuclear Information System (INIS)
Sadahiro, Daisuke; Shibamoto, Hiroshi; Nagashima, Hideaki; Inoue, Kazuhiko; Kasahara, Naoto
2005-01-01
This paper describes an evaluation method of primary stress in 3-D structures. In 'Design by Analysis' for nuclear components, the stresses in structures are classified into the primary and the secondary stresses. The primary stress in axisymmetric structures can be evaluated by linearization of stress distribution in the specified section, but it is difficult to define the evaluation section in the 3-D structures, and to evaluate the primary stress with the conventional procedure. From this reason, the alternative evaluation method is needed. In this paper, the evaluation method of primary stress in 3-D structures is presented utilizing the feature of primary stress that is independent from stress re-distribution. (author)
International Nuclear Information System (INIS)
Sasaki, Toshihiko; Takago, Shigeki
2016-01-01
This paper outlined a stress measurement method using neutrons, and introduced the application examples to stress measurement for metal-based composite materials. In the angular dispersion type measurement using a steady-state reactor type neutron source, the white beams taken out from a nuclear reactor are monochromatized (wavelength λ is a constant value) with a single crystal monochromator and utilized. As an example of measurement, there was the case as follows: the stress of a sintered material which has been put to practical use as valve seat part for automobiles was measured by the neutron method, and the deformation behavior during load was studied. This study performed neutron diffraction measurement using a residual stress analyzer (RESA: Diffractometer for Residual Stress Analysis) installed at JAEA's experimental reactor JRR-3. As a result, it was found that the stress state of the sintered composite material of Fe-Cr and TiN can be predicted with a micromechanics model. A neutron diffraction ring can be obtained using a neutron image plate (IP), where fine powder of gadolinium (Gd) was incorporated into IP for X-rays, and it can be used as an IP reader in the same way as the case of X-rays. A report has been introduced on the examination results of the highly accurate stress measurement by applying the cos α method devised for X-ray stress measurement to neutron diffraction ring. (A.O.)
Analysis of residual stresses in a long hollow cylinder
International Nuclear Information System (INIS)
Tokovyy, Yuriy V.; Ma, Chien-Ching
2011-01-01
This paper presents an analytical method for solving the axisymmetric stress problem for a long hollow cylinder subjected to locally-distributed residual (incompatible) strains. This method is based on direct integration of the equilibrium and compatibility equations, which thereby have been reduced to the set of two governing equations for two key functions with corresponding boundary and integral conditions. The governing equations were solved by making use of the Fourier integral transformation. Application of the method is illustrated with an analysis of the welding residual stresses in a butt-welded thick-walled pipe. - Highlights: → A solution to the axisymmetric stress problem for a hollow cylinder is constructed. → The cylinder is subjected to a field of locally-distributed residual strains. → The method is based on direct integration of the equilibrium equations. → An application of our solution to analysis of welding residual stresses is considered.
International Nuclear Information System (INIS)
Maekawa, Akira; Serizawa, Hisashi; Murakawa, Hidekazu
2012-01-01
It is necessary to establish properly reliable weld residual stress analysis methods for accurate crack initiation and growth assessment of primary water stress corrosion cracking (PWSCC), which may occur in nickel-based dissimilar metal welds in pressurized water reactors. The U.S. Nuclear Regulatory Commission conducted an international round robin for weld residual stress analysis to improve stress analysis methods and to examine the uncertainties involved in the calculated stress values. In this paper, the results from the authors' participation in the round robin were reported. In the round robin, the weld residual stress in a nickel-based dissimilar metal weld of a pressurizer surge nozzle mock-up was computed under various analysis conditions. Based on these residual stress analysis results, a welding simulation code currently being developed that uses the iterative substructure method was validated and affecting factors on the analysis results were identified. (author)
Thermographic Analysis of Stress Distribution in Welded Joints
Directory of Open Access Journals (Sweden)
Domazet Ž.
2010-06-01
Full Text Available The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.
Thermographic Analysis of Stress Distribution in Welded Joints
Piršić, T.; Krstulović Opara, L.; Domazet, Ž.
2010-06-01
The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural) stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis) in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.
Rock stress measurements using the LUT-Gauge overcoring method
International Nuclear Information System (INIS)
Leijon, B.
1988-04-01
With overcoring techniques, rock stresses are determined indirectly from measurements of the dimensional changes of a borehole, occurring when the rock volume surrounding the hole is isolated from the stresses in the host rock. This thesis describes the development and application of an overcoring technique. The key-component of the instrumentation that has been developed is a triaxial borehole strain cell, referred to as the LUT-Gauge. Laboratory tests were conducted to evaluate the performance of the instrumentation. Special emphasis was given to determining temperature sensitivity of the measuring system since this was identified as a potential source of measurement error. Results indicated good instrument reliability and that the measurement error due to temperature variations typically experienced under field conditions is ± 1 MPa or less. The technique was also evaluated by a series of field tests. Comparison of the results obtained by the different methods showed satisfactory agreement. Analysis of the comprehensive field data collected showed that the confidence that can be attached to an overcoring test is largely governed by the mechanical characteristics of the overcored specimen. Expressed as the standard deviation of the mean stress magnitude, the scatter obtained from repeated testing within a borehole section of about 10 m in length, is found to be ± 4 MPa or less. Rock engineering investigations typically refer to a scale of hundreds of metres or more. This study has demonstrated the existence of significant variations of the stress field on this scale. These variations thus impose difficulties in the application of stress data to the analysis of problems in rock engineering, since the pointwise results obtained from stress measurements cannot be extrapolated with good confidence. (30 refs.) (author)
Personality and methods of coping with stress
Directory of Open Access Journals (Sweden)
Aleksandra Cieślik
2014-04-01
Full Text Available Good health and well-being are the natural desires of every human being. However, people have to cope with various kinds of stress in everyday life. Most people are under stress due to: the situation in the world, unemployment, traffic jam, their manager’s opinion, illness, divorce, etc. The level of stress increases particularly in situ ations when people sense danger of physical, social or psychological risks. This phenomenon is very common, and many people have come to think that this is something normal in modern life. Stress can cause depression and frustration, and it does not help in achieving goals and being successful. Ordinary people have a negative concept of stress, but stress response also helps one to rise to meet challenges. Some level of stress is recommended because it helps people to solve problems. While under stress one can function better and work faster, it sharpens concentration and increases brain efficiency. At the beginning of the third millennium, stress has become the people’s enemy, so they should learn how to cope with it. It is common knowledge that one cannot avoid stress, so it is important to learn how to control and deal with it.
DEFF Research Database (Denmark)
Olivarius, Signe
of the transcriptome, 5’ end capture of RNA is combined with next-generation sequencing for high-throughput quantitative assessment of transcription start sites by two different methods. The methods presented here allow for functional investigation of coding as well as noncoding RNA and contribute to future...... RNAs rely on interactions with proteins, the establishment of protein-binding profiles is essential for the characterization of RNAs. Aiming to facilitate RNA analysis, this thesis introduces proteomics- as well as transcriptomics-based methods for the functional characterization of RNA. First, RNA...
Whealin, Julia M; Jenchura, Emily C; Wong, Ava C; Zulman, Donna M
2016-10-26
Mental health conditions are prevalent among US veterans and pose a number of self-management and health care navigation challenges. Post-Traumatic Stress Disorder (PTSD) with comorbid chronic medical conditions (CMCs) is especially common, in both returning Iraq or Afghanistan and earlier war-era veterans. Patient-facing electronic health (eHealth) technology may offer innovative strategies to support these individuals' needs. This study was designed to identify the types of eHealth tools that veterans with PTSD and comorbid CMCs use, understand how they currently use eHealth technology to self-manage their unique health care needs, and identify new eHealth resources that veterans feel would empower them to better manage their health care. A total of 119 veterans with PTSD and at least one CMC who have used the electronic personal health record system of the US Department of Veterans Affairs (VA) responded to a mailed survey about their chronic conditions and preferences related to the use of technology. After the survey, 2 focus groups, stratified by sex, were conducted with a subgroup of patients to explore how veterans with PTSD and comorbid CMCs use eHealth technology to support their complex health care needs. Focus groups were transcribed verbatim and analyzed using standard content analysis methods for coding textual data, guided by the "Fit between Individual, Task, and Technology" framework. Survey respondents had a mean age of 64.0 (SD 12.0) years, 85.1% (97/114) were male, 72.4% (84/116) were white, and 63.1% (70/111) had an annual household income of eHealth literacy was 27.7 (SD 9.8). Of the respondents, 44.6% (50/112) used health-related technology 1 to 3 times per month and 21.4% (24/112) used technology less than once per month. Veterans reported using technology most often to search for health information (78.9%, 90/114), communicate with providers (71.1%, 81/114), and track medications (64.9%, 74/114). Five major themes emerged that describe how
Energy Technology Data Exchange (ETDEWEB)
Genzel, C.
2000-11-01
The topic of the habilitation thesis is the development of an X-ray diffraction method for measurement and depth-resolved analysis of internal stresses in the surface region of polycrystalline materials. The method relies on the basic approach of varying {tau}, the penetration depth of the X-rays in the materials, by the scattering vector g{sub theta{psi}} via stepwise specimen rotation. Thus, depth profiles of the interlattice plane distances d(hkl) in the specimen system can be derived for given direction and inclination angles {theta} and {psi} of the scattering vector. This offers the possibility to identify individual components of the stress tensors of the basic equation of the X-ray diffraction analysis, and to perform separate analyses of those components. For calculation of the relevant internal stress distributions {sigma}{sub ij}({tau}) using the interlattice plane distance profiles, a self-consistent method is established which takes into account the high sensitivity of the derived internal stresses in relation to the interlattice plane distance d{sub 0}(hkl) in the stress-free crystal lattice. The evaluation yields results describing the depth profiles as well as the strain-free interlattice plane distance d{sub 0}(hkl), so that a quantitative analysis is possible of tri-axial internal stress states in the surface region of the materials. (orig./CB) [German] Den Gegenstand der vorliegenden Arbeit bildet die Entwicklung eines roentgenographischen Mess- und Auswerteverfahrens zur tiefenaufgeloesten Analyse des oberflaechennahen Eigenspannungszustandes in vielkristallinen Werkstoffen. Der Grundgedanke der Methode besteht darin, die Eindringtiefe {tau} der Roentgenstrahlung in den Werkstoff durch schrittweise Drehung der Probe um den Streuvektor g{sub {theta}}{sub {psi}} zu variieren. Damit koennen Tiefenprofile der Netzebenenabstaende d(hkl) fuer fest vorgegebene Azimut- und Neigungswinkel {theta} und {psi} des Streuvektors im Probensystem ermittelt
Fillet Weld Stress Using Finite Element Methods
Lehnhoff, T. F.; Green, G. W.
1985-01-01
Average elastic Von Mises equivalent stresses were calculated along the throat of a single lap fillet weld. The average elastic stresses were compared to initial yield and to plastic instability conditions to modify conventional design formulas is presented. The factor is a linear function of the thicknesses of the parent plates attached by the fillet weld.
Residual stress concerns in containment analysis
International Nuclear Information System (INIS)
Costantini, F.; Kulak, R. F.; Pfeiffer, P. A.
1997-01-01
The manufacturing of steel containment vessels starts with the forming of flat plates into curved plates. A steel containment structure is made by welding individual plates together to form the sections that make up the complex shaped vessels. The metal forming and welding process leaves residual stresses in the vessel walls. Generally, the effect of metal forming residual stresses can be reduced or virtually eliminated by thermally stress relieving the vesseL In large containment vessels this may not be practical and thus the residual stresses due to manufacturing may become important. The residual stresses could possibly tiect the response of the vessel to internal pressurization. When the level of residual stresses is significant it will affect the vessel's response, for instance the yielding pressure and possibly the failure pressure. The paper will address the effect of metal forming residual stresses on the response of a generic pressure vessel to internal pressurization. A scoping analysis investigated the effect of residual forming stresses on the response of an internally pressurized vessel. A simple model was developed to gain understanding of the mechanics of the problem. Residual stresses due to the welding process were not considered in this investigation
Analysis of residual stresses in welded joints
International Nuclear Information System (INIS)
Lemos, F.L. de.
1984-01-01
The study of two stress measurements techniques is presented showing experimental results that allows to evaluate its reliability. These two methods are 'The Center Hole Drilling Method' and 'The Overcoring' and they are considered semi-destructive methods. (E.G.) [pt
Role stress amongst nurses at the workplace: concept analysis.
Riahi, Sanaz
2011-09-01
The present study explicates the concept of role stress amongst nurses through an analysis adopted from Walker and Avant; Strategies for Theory Construction in Nursing, 4th edn, Prentice Hall, New Jersey, NY. Role stress has become a significant problem amongst nurses and has created much distress leading to burnout among many in the nursing profession. It is significant to analyse the concept of role stress and its relative attributes and consequences, in order to recognize the necessary antecedents needed to create better conditions for nurses at the workplace. A modified method developed by Walker and Avant was used for this concept analysis. A model representing the concept of role stress was developed through careful consideration of the attributes, consequences, antecedents and empirical referents of role stress. The concept analysis of role stress among nurses at the workplace recognized the vulnerability of the nursing discipline towards burnout and distress in general. It is critical to be aware of the current state of health care and note the increased workload created for nurses. Nurses are at a greater vulnerability for role stress, making it imperative for health care organizations to critically evaluate and establish preventative measures for the concept of role stress. 2011 Blackwell Publishing Ltd.
Stresses, fatigue and fracture analysis in the tube sheets
International Nuclear Information System (INIS)
Billon, F.
1986-05-01
The purpose of the present work is to study the behaviour of the nuclear PWR steam generator tube sheet. But the methods developed in this field can easily be generalized in order to study tube sheets from any other type of heat exchangers. The aim of the stress analysis of these sheets is to verify their correct design, to quantify the risk of fatigue damage in the areas submitted to a high stress concentration and through the fracture mechanic, to make sure there is no risk of fast fracture resulting from initiated or pre-existing defects. This analysis necessarily relates to the calculation of stresses in all parts of the multidrilled area, mainly around the holes where they are concentrated. However the tube sheets are so complexe structures that their direct modelization cannot be envisaged within the context of the finite element method. We then must refer to the concept of equivalent medium in order to calculate the nominal stresses. Then using the stresses multiple fonctions appropriate to the net geometry, we can calculate the actual stresses concentrated around the holes. The method depends on the behaviour of the elementary volume which represents the behaviour of the multidrilled medium. This approach must allow to correctly take account of the ''thermal skin effect'', which is a phenomenon particular to the tube sheets with thermal loads. It must as well be generalized in order to analyse the irregular ligaments which affect the periodical stresses distribution and locally overconcentrate them [fr
International Nuclear Information System (INIS)
Alverbro, Karin
2010-01-01
Many decision-making situations today affect humans and the environment. In practice, many such decisions are made without an overall view and prioritise one or other of the two areas. Now and then these two areas of regulation come into conflict, e.g. the best alternative as regards environmental considerations is not always the best from a human safety perspective and vice versa. This report was prepared within a major project with the aim of developing a framework in which both the environmental aspects and the human safety aspects are integrated, and decisions can be made taking both fields into consideration. The safety risks have to be analysed in order to be successfully avoided and one way of doing this is to use different kinds of risk analysis methods. There is an abundance of existing methods to choose from and new methods are constantly being developed. This report describes some of the risk analysis methods currently available for analysing safety and examines the relationships between them. The focus here is mainly on human safety aspects
Khan, Muhammad Saleem; Qureshi, Naureen Aziz; Jabeen, Farhat; Asghar, Muhammad Saleem; Shakeel, Muhammad; Fakhar-E-Alam, Muhammad
2017-04-01
The physicochemical and biological properties of metals change as the particles are reduced to nanoscale. This ability increases the application of nanoparticles in commercial and medical industry. Keeping in view this importance, Silver nanoparticles (Ag-NPs) were synthesized by reduction methods using formaldehyde as reducing agent in the chemical route and lemon extracts in the biological route. The scanning electron microscope (SEM) images of nanoparticles suggested that the particles were either agglomerated or spherical in shape with mean diameter of 16.59 nm in the chemical route and 42.93 nm in the biological route. The particles were between 5 and 80 nm with maximum frequency between 5 and 20 nm in the chemical route and between 5 and 100 nm with maximum frequency between 15 and 50 nm in the biological method. In the second phase of the study, the effect of Ag-NPs on the oxidative stress was studied. For this purpose, Labeo rohita (20 ± 2.5 g in weight and 12 ± 1.4 cm in length) were involved. Six treatments were applied in three replicates having five fishes in each replicate. The first treatment was used as control group, and the other five treatments were exposed to either 10 or 20 or 30 or 45 or 55 mg L -1 of Ag-NPs for 28 days. The treatment of Ag-NPs caused oxidative stress in the liver and gill tissues, which induced alterations in the activities of antioxidant enzymes. The level of catalase (CAT) was decreased in response to Ag-NPs concentration in dose-dependent manner. Ag-NPs treatment stimulated the liver and gill tissues to significantly increase the level of superoxide dismutase (SOD), which might be due to synthesis of SOD and addition in the pre-existing SOD level. The level decreases again due to depletion of SOD level. There was a sharp decline in the activities of glutathione S-transferase (GST) in both gills and liver tissues even at lower concentration, and this decrease in the GST activity was significantly
International Nuclear Information System (INIS)
1993-01-01
For an analysis of the safety-related significance of residual stresses, mechanical, magnetic as well as ultrasonic and diffraction methods can be applied as testing methods. The results of an interlaboratory test concerning the experimental determination of residual stresses in a railway track are included. Further, questions are analyzed concerning the in-service inspections of components and systems with regard to their operational safety and life. Measurement methods are explained by examples from power plant engineering, nuclear power plant engineering, construction and traffic engineering as well as aeronautics. (DG) [de
Stress analysis for robot arm version 2
International Nuclear Information System (INIS)
Anwar Abdul Rahman; Fikri, A.; Salleh, M. S.; Mohd Arif Hamzah; Azraf Azman; Rosli Darmawan; Mohd Rizal Mamat
2010-01-01
The design of a robot needs to be analyzed to ensure the specification and requirement by the user is full filled. Therefore, stress analysis has been performed on the robot arm version 2 after its complete fabrication. This paper discusses the result of the analysis and proposed measures to improve the future design of robot arm. (author)
International Nuclear Information System (INIS)
Yoshioka, Yasuo; Sasaki, Toshihiko; Kuramoto, Makoto.
1984-01-01
A new polynomial approximation method was proposed for the X-ray multiaxial stress analysis, in which the effect of stress gradient along the penetration depth of X-rays was taken into account. Three basic assumptions were made; (1) the stress gradient is linear in respect to the depth from the specimen surface, (2) the ponetration depth of X-rays is a function of Sin 2 phi and (3) the strain measured by X-rays corresponds to the weighted average strain on the intensity of the diffracted X-rays. Consequently, the stress state within the thin layer near the surface was expressed by making use of three surface stresses and six stress gradients in the present method. The average strains by X-rays were approximated by the third order polynomial equations of sin 2 phi using a least square method at several phi angles on the coordinate system of specimen. Since the coefficients of these polynomials include these nine stress components mentioned above, it is possible to solve them as simultaneous equations. The calculating process of this method is simpler than that of the integral method. An X-ray plane stress problem was analyzed as an application of the present method, and the residual stress distribution on a shot-peened steel plate was actually measured by use of Cr-Kα X-rays to verify the analysis. The result showed that the compressive residual stress near the surface determined by the present method was smaller than the weighted average stress by the Sin 2 phi method because of the steep stress gradient. The present method is useful to obtain a reasonable value of stress for such a specimen with steep stress gradients near the surface. (author)
Internal stress analysis by acoustic polarimetry
International Nuclear Information System (INIS)
Rouge, Jean; Robert, Andre
The associated improvements of acoustics and electronics allow the field of applications relative to the ultrasonic methods to be extended to the non destructive control of materials and structures. Thus, the acoustical polarimetry is a new method allowing the measurement in orientation and intensity of residual or induced internal stresses in metals or other materials [fr
Numerical analysis of interacting cracks in biaxial stress field
International Nuclear Information System (INIS)
Kovac, M.; Cizelj, L.
1999-01-01
The stress corrosion cracks as seen for example in PWR steam generator tubing made of Inconel 600 usually produce highly irregular kinked and branched crack patterns. Crack initialization and propagation depends on stress state underlying the crack pattern. Numerical analysis (such as finite element method) of interacting kinked and branched cracks can provide accurate solutions. This paper discusses the use of general-purpose finite element code ABAQUS for evaluating stress fields at crack tips of interacting complex cracks. The results obtained showed reasonable agreement with the reference solutions and confirmed use of finite elements in such class of problems.(author)
International Nuclear Information System (INIS)
Berthomier, Charles
1975-01-01
A method capable of handling the amplitude and the frequency time laws of a certain kind of geophysical signals is described here. This method is based upon the analytical signal idea of Gabor and Ville, which is constructed either in the time domain by adding an imaginary part to the real signal (in-quadrature signal), or in the frequency domain by suppressing negative frequency components. The instantaneous frequency of the initial signal is then defined as the time derivative of the phase of the analytical signal, and his amplitude, or envelope, as the modulus of this complex signal. The method is applied to three types of magnetospheric signals: chorus, whistlers and pearls. The results obtained by analog and numerical calculations are compared to results obtained by classical systems using filters, i.e. based upon a different definition of the concept of frequency. The precision with which the frequency-time laws are determined leads then to the examination of the principle of the method and to a definition of instantaneous power density spectrum attached to the signal, and to the first consequences of this definition. In this way, a two-dimensional representation of the signal is introduced which is less deformed by the analysis system properties than the usual representation, and which moreover has the advantage of being obtainable practically in real time [fr
Creep analysis by the path function method
International Nuclear Information System (INIS)
Akin, J.E.; Pardue, R.M.
1977-01-01
The finite element method has become a common analysis procedure for the creep analysis of structures. The most recent programs are designed to handle a general class of material properties and are able to calculate elastic, plastic, and creep components of strain under general loading histories. The constant stress approach is too crude a model to accurately represent the actual behaviour of the stress for large time steps. The true path of a point in the effective stress-effective strain (sigmasup(e)-epsilonsup(c)) plane is often one in which the slope is rapidly changing. Thus the stress level quickly moves away from the initial stress level and then gradually approaches the final one. The result is that the assumed constant stress level quickly becomes inaccurate. What is required is a better method of approximation of the true path in the sigmasup(e)-epsilonsup(c) space. The method described here is called the path function approach because it employs an assumed function to estimate the motion of points in the sigmasup(e)-epsilonsup(c) space. (Auth.)
Implications of stress range for inelastic analysis
International Nuclear Information System (INIS)
Karabin, M.E.; Dhalla, A.K.
1981-01-01
The elastic stress range over a complete load cycle is routinely used to formulate simplified rules regarding the inelastic behavior of structures operating at elevated temperature. For example, a 300 series stainless steel structure operating at elevated temperature, in all probability, would satisfy the ASME Boiler and Pressure Vessel Code criteria if the linearized elastic stress range is less than three times the material yield strength. However, at higher elastic stress ranges it is difficult to judge, a priori, that a structural component would comply with inelastic Code criteria after a detailed inelastic analysis. The purpose of this paper is to illustrate that it is not the elastic stress range but the stress intensities at specific times during a thermal transient which provide a better insight into the inelastic response of the structure. The specific example of the CRBRP flued head design demonstrates that the temperature differential between various parts of the structure can be changed by modifying the insulation pattern and heat flow path in the structure, without significantly altering the elastic stress range over a complete load cycle. However, the modified design did reduce the stress intensity during steady state elevated temperature operation. This modified design satisfied the inelastic Code criteria whereas the initial design failed to comply with the strain accumulation criterion
Methods for geochemical analysis
Baedecker, Philip A.
1987-01-01
The laboratories for analytical chemistry within the Geologic Division of the U.S. Geological Survey are administered by the Office of Mineral Resources. The laboratory analysts provide analytical support to those programs of the Geologic Division that require chemical information and conduct basic research in analytical and geochemical areas vital to the furtherance of Division program goals. Laboratories for research and geochemical analysis are maintained at the three major centers in Reston, Virginia, Denver, Colorado, and Menlo Park, California. The Division has an expertise in a broad spectrum of analytical techniques, and the analytical research is designed to advance the state of the art of existing techniques and to develop new methods of analysis in response to special problems in geochemical analysis. The geochemical research and analytical results are applied to the solution of fundamental geochemical problems relating to the origin of mineral deposits and fossil fuels, as well as to studies relating to the distribution of elements in varied geologic systems, the mechanisms by which they are transported, and their impact on the environment.
Blade dynamic stress analysis of rotating bladed disks
Directory of Open Access Journals (Sweden)
Kellner J.
2007-10-01
Full Text Available The paper deals with mathematical modelling of steady forced bladed disk vibrations and with dynamic stress calculation of the blades. The blades are considered as 1D kontinuum elastic coupled with three-dimensional elastic disk centrally clamped into rotor rotating with constant angular speed. The steady forced vibrations are generated by the aerodynamic forces acting along the blade length. By using modal synthesis method the mathematical model of the rotating bladed disk is condensed to calculate steady vibrations. Dynamic stress analysis of the blades is based on calculation of the time dependent reduced stress in blade cross-sections by using Hubert-Misses-Hencky stress hypothesis. The presented method is applied to real turbomachinery rotor with blades connected on the top with shroud.
Methods for evaluation of mechanical stress condition of materials
Directory of Open Access Journals (Sweden)
Mirchev Yordan
2018-01-01
Full Text Available Primary attention is given to the following methods: method by drilling cylindrical holes (drill method and integrated ultrasonic method using volume (longitudinal and transverse, surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.
COMPUTER METHODS OF GENETIC ANALYSIS.
Directory of Open Access Journals (Sweden)
A. L. Osipov
2017-02-01
Full Text Available The basic statistical methods used in conducting the genetic analysis of human traits. We studied by segregation analysis, linkage analysis and allelic associations. Developed software for the implementation of these methods support.
Plant stress analysis technology deployment
Energy Technology Data Exchange (ETDEWEB)
Ebadian, M.A.
1998-01-01
Monitoring vegetation is an active area of laser-induced fluorescence imaging (LIFI) research. The Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU) is assisting in the transfer of the LIFI technology to the agricultural private sector through a market survey. The market survey will help identify the key eco-agricultural issues of the nations that could benefit from the use of sensor technologies developed by the Office of Science and Technology (OST). The principal region of interest is the Western Hemisphere, particularly, the rapidly growing countries of Latin America and the Caribbean. The analysis of needs will assure that the focus of present and future research will center on economically important issues facing both hemispheres. The application of the technology will be useful to the agriculture industry for airborne crop analysis as well as in the detection and characterization of contaminated sites by monitoring vegetation. LIFI airborne and close-proximity systems will be evaluated as stand-alone technologies and additions to existing sensor technologies that have been used to monitor crops in the field and in storage.
Electromagnetic field and mechanical stress analysis code
International Nuclear Information System (INIS)
1978-01-01
Analysis TEXMAGST is a two stage linear finite element code for the analysis of static magnetic fields in three dimensional structures and associated mechanical stresses produced by the anti J x anti B forces within these structures. The electromagnetic problem is solved in terms of magnetic vector potential A for a given current density anti J as curl 1/μ curl anti A = anti J considering the magnetic permeability as constant. The Coulombian gauge (div anti A = o) was chosen and was implemented through the use of Lagrange multipliers. The second stage of the problem - the calculation of mechanical stresses in the same three dimensional structure is solved by using the same code with few modifications - through a restart card. Body forces anti J x anti B within each element are calculated from the solution of the first stage run and represent the input to the second stage run which will give the solution for the stress problem
Thermal stresses in long prisms by relaxation methods
Energy Technology Data Exchange (ETDEWEB)
Cummins, J D [Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)
1959-07-15
A general method is presented for calculating the elastic thermal stresses in long prisms which are producing heat and are not solvable by simple analytical methods. The problem of an inverted lattice i.e. an hexagonal coolant passage surrounded by hexagonal fuel elements is considered and the temperature and principal thermal stress distributions evaluated for the particular case of 20% coolant. The maximum thermal stress for this type of fuel element is about the same as the maximum thermal stress in a cylindrical fuel element surrounded by a sea of coolant assuming the existence of the same maximum temperature drop and material properties. (author)
Evaluation of Stress Loaded Steel Samples Using Selected Electromagnetic Methods
International Nuclear Information System (INIS)
Chady, T.
2004-01-01
In this paper the magnetic leakage flux and eddy current method were used to evaluate changes of materials' properties caused by stress. Seven samples made of ferromagnetic material with different level of applied stress were prepared. First, the leakage magnetic fields were measured by scanning the surface of the specimens with GMR gradiometer. Next, the same samples were evaluated using an eddy current sensor. A comparison between results obtained from both methods was carried out. Finally, selected parameters of the measured signal were calculated and utilized to evaluate level of the applied stress. A strong coincidence between amount of the applied stress and the maximum amplitude of the derivative was confirmed
Thermal stresses in long prisms by relaxation methods
International Nuclear Information System (INIS)
Cummins, J.D.
1959-07-01
A general method is presented for calculating the elastic thermal stresses in long prisms which are producing heat and are not solvable by simple analytical methods. The problem of an inverted lattice i.e. an hexagonal coolant passage surrounded by hexagonal fuel elements is considered and the temperature and principal thermal stress distributions evaluated for the particular case of 20% coolant. The maximum thermal stress for this type of fuel element is about the same as the maximum thermal stress in a cylindrical fuel element surrounded by a sea of coolant assuming the existence of the same maximum temperature drop and material properties. (author)
Analysis of stress and deformation in non-stationary creep
International Nuclear Information System (INIS)
Feijoo, R.A.; Taroco, E.; Guerreiro, J.N.C.
1980-12-01
A variational method and its algorithm are presented; they permit the analysis of stress and deformation in non-stationary creep. This algorithm is applied to an infinite cylinder submitted to an internal pressure. The solution obtained is compared with the solution of non-stationary creep problems [pt
Analysis of Biaxially Stressed Bridge Deck Plates
DEFF Research Database (Denmark)
Jönsson, Jeppe; Bondum, Tommi Højer
2012-01-01
The ultimate state analysis of bridge deck plates at the intersection zone between main girders and transverse beams is complicated by biaxial membrane stresses, which may be in compression or tension in either direction depending on the bridge configuration and the specific location. This paper...
A study on the stress history condensation method for a fatigue monitoring system
International Nuclear Information System (INIS)
Ko, Hanok; Jhung, Myungjo; Lee, Kihyoung
2014-01-01
Fatigue damage is the one of important aging mechanisms. Time-varying thermal, pressure and mechanical loads produce perturbations of stress cycles primarily at the surface of a component. Stress cycles of sufficient magnitude cause fatigue damage, which can ultimately lead to cracking of the component. According to NUREG-1801, fatigue monitoring systems identify acceptable aging management programs, including programs for fatigue and cyclic operation. In a monitoring system, the rainflow counting method is mainly used as the stress cycle counting method. Before determining the stress cycles using rainflow counting method, stress extremum (or peak/valley) must be identified. Because real stress history contains large numbers of very small cycles, which may be a result of digitization noise, these cycles will slow down the analysis and distort the scaling of graphical displays. As a result, it is found that stress cycles smaller than a threshold value are discarded by using the proposed method. In this paper, an engineering methodology which extracts extremum from the real-time transient data, so-called SEE, has been developed. The proposed method is very simple and so fast because it only uses the difference between the input value and local peak/valley. The stress cycles counted by two methods are compared with those counted by only rainflow counting method and it is found that stress cycles smaller than a threshold value were eliminated
Stress analysis of a rupture disk
International Nuclear Information System (INIS)
Werne, R.W.
1975-04-01
The results of an elastic stress analysis of the rupture disk for an internal pressure of 45.5 MPa (6600 psi) indicate that the maximum von Mises stresses occur in the membrane and are on the order of 483 to 690 MPa (70,000 psi). This far exceeds the yield of the membrane material of 207 MPa (30,000 psi). These high stresses are expected since the membrane is designed to burst at that design pressure. The von Mises stresses in the rest of the body are less than 138 MPa (20,000 psi). An elastic-plastic analysis of the membrane alone subjected to the 45.5 MPa (6600 psi) pressure indicates that it becomes plastically unstable, i.e., it continues to deform under constant load. A second load case with a constant 6.9 MPa (1000 psi) pressure throughout the entire body (i.e., after release of pressure by burst of the membrane) was analyzed. The results indicate that the elastic von Mises stresses are less than 26.7 MPa (3880 psi) throughout the body. (U.S.)
Critical wall shear stress for the EHEDG test method
DEFF Research Database (Denmark)
Jensen, Bo Boye Busk; Friis, Alan
2004-01-01
In order to simulate the results of practical cleaning tests on closed processing equipment, based on wall shear stress predicted by computational fluid dynamics, a critical wall shear stress is required for that particular cleaning method. This work presents investigations that provide a critical...... wall shear stress of 3 Pa for the standardised EHEDG cleaning test method. The cleaning tests were performed on a test disc placed in a radial flowcell assay. Turbulent flow conditions were generated and the corresponding wall shear stresses were predicted from CFD simulations. Combining wall shear...... stress predictions from a simulation using the low Re k-epsilon and one using the two-layer model of Norris and Reynolds were found to produce reliable predictions compared to empirical solutions for the ideal flow case. The comparison of wall shear stress curves predicted for the real RFC...
International Nuclear Information System (INIS)
Hawong, Jai Sug; Lee, Dong Hun; Lee, Dong Ha; Tche, Konstantin
2004-01-01
In this research, the photoelastic experimental hybrid method with Hook-Jeeves numerical method has been developed: This method is more precise and stable than the photoelastic experimental hybrid method with Newton-Rapson numerical method with Gaussian elimination method. Using the photoelastic experimental hybrid method with Hook-Jeeves numerical method, we can separate stress components from isochromatics only and stress intensity factors and stress concentration factors can be determined. The photoelastic experimental hybrid method with Hook-Jeeves had better be used in the full field experiment than the photoelastic experimental hybrid method with Newton-Rapson with Gaussian elimination method
International Nuclear Information System (INIS)
Ohya, Shin-ichi; Yoshioka, Yasuo; Maeno, Shigeki
1996-01-01
X-ray stress measurements for isotropic polycrystalline are materials are usually carried out by the sin 2 ψ method under the assumption of no stress gradient in X-ray penetration depth. When a steep stress gradient exists in the vicinity of surface layer, however, non-linear sin 2 ψ relation is observed and the sin 2 ψ method cannot be applied on such cases. Although several X-ray stress analyzers have been developed for materials with steep stress gradient in the surface layer, it is desirable to use diffraction data at higher incident angles of ψ 0 as possible as close on 90 degrees in order to determine the both values of surface stress and stress gradient with high accuracy. In the present study, an X-ray stress analyzer based on Ω geometry was fabricated to enable X-ray incidence at higher angle of ψ 0 . The X-ray detector was positioned on -η side against X-ray incident beam. Both of the residual surface stress and stress gradient were determined by use of the COSψ method on shot-peened steel and silicon nitride specimens. This prototype stress analyzer was found effective to perform a biaxial or triaxial stress analysis. (author)
Syahroni, N.; Hartono, A. B. W.; Murtedjo, M.
2018-03-01
In the ship fabrication industry, welding is the most critical stage. If the quality of welding on ship fabrication is not good, then it will affect the strength and overall appearance of the structure. One of the factors that affect the quality of welding is residual stress and distortion. In this research welding simulation is performed on the inner bottom construction of Geomarin IV Ship Survey using shell element and has variation to welding sequence. In this study, welding simulations produced peak temperatures at 2490 K at variation 4. While the lowest peak temperature was produced by variation 2 with a temperature of 2339 K. After welding simulation, it continued simulating residual stresses and distortion. The smallest maximum tensile residual stress found in the inner bottom construction is 375.23 MPa, and the maximum tensile pressure is -20.18 MPa. The residual stress is obtained from variation 3. The distortion occurring in the inner bottom construction for X=720 mm is 4.2 mm and for X=-720 mm, the distortion is 4.92 mm. The distortion is obtained from the variation 3. Near the welding area, distortion value reaches its minimum point. This is because the stiffeners in the form of frames serves as anchoring.
The Stress and Stiffness Analysis of Diaphragm
Directory of Open Access Journals (Sweden)
Qu Dongyue
2017-01-01
Full Text Available Diaphragm coupling with its simple structure, small size, high reliability, which can compensate for its input and output displacement deviation by its elastic deformation, is widely used in aerospace, marine, and chemical etc. This paper uses the ANSYS software and its APDL language to analysis the stress distribution when the diaphragm under the load of torque, axial deviation, centrifugal force, angular deviation and multiple loads. We find that the value of maximum stress usually appears in the outer or inner transition region and the axial deviation has a greater influence to the distribution of the stress. Based on above, we got three kinds of stiffness for axial, angular and torque, which the stiffness of diaphragm is nearly invariable. The results can be regard as an important reference for design and optimization of diaphragm coupling.
Methods for predicting isochronous stress-strain curves
International Nuclear Information System (INIS)
Kiyoshige, Masanori; Shimizu, Shigeki; Satoh, Keisuke.
1976-01-01
Isochronous stress-strain curves show the relation between stress and total strain at a certain temperature with time as a parameter, and they are drawn up from the creep test results at various stress levels at a definite temperature. The concept regarding the isochronous stress-strain curves was proposed by McVetty in 1930s, and has been used for the design of aero-engines. Recently the high temperature characteristics of materials are shown as the isochronous stress-strain curves in the design guide for the nuclear energy equipments and structures used in high temperature creep region. It is prescribed that these curves are used as the criteria for determining design stress intensity or the data for analyzing the superposed effects of creep and fatigue. In case of the isochronous stress-strain curves used for the design of nuclear energy equipments with very long service life, it is impractical to determine the curves directly from the results of long time creep test, accordingly the method of predicting long time stress-strain curves from short time creep test results must be established. The method proposed by the authors, for which the creep constitution equations taking the first and second creep stages into account are used, and the method using Larson-Miller parameter were studied, and it was found that both methods were reliable for the prediction. (Kako, I.)
Inelastic analysis methods for piping systems
International Nuclear Information System (INIS)
Boyle, J.T.; Spence, J.
1980-01-01
The analysis of pipework systems which operate in an environment where local inelastic strains are evident is one of the most demanding problems facing the stress analyst in the nuclear field. The spatial complexity of even the most modest system makes a detailed analysis using finite element techniques beyond the scope of current computer technology. For this reason the emphasis has been on simplified methods. It is the aim of this paper to provide a reasonably complete, state-of-the-art review of inelastic pipework analysis methods and to attempt to highlight areas where reliable information is lacking and further work is needed. (orig.)
Non-linear elastic thermal stress analysis with phase changes
International Nuclear Information System (INIS)
Amada, S.; Yang, W.H.
1978-01-01
The non-linear elastic, thermal stress analysis with temperature induced phase changes in the materials is presented. An infinite plate (or body) with a circular hole (or tunnel) is subjected to a thermal loading on its inner surface. The peak temperature around the hole reaches beyond the melting point of the material. The non-linear diffusion equation is solved numerically using the finite difference method. The material properties change rapidly at temperatures where the change of crystal structures and solid-liquid transition occur. The elastic stresses induced by the transient non-homogeneous temperature distribution are calculated. The stresses change remarkably when the phase changes occur and there are residual stresses remaining in the plate after one cycle of thermal loading. (Auth.)
Bellman, Richard Ernest
1970-01-01
In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;methods for low-rank mat
Evaluation methods of vibration stress of small bore piping
Energy Technology Data Exchange (ETDEWEB)
Hiramatsu, Miki; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)
2001-09-01
Fatigue fracture by vibration stress is one of the main causes of troubles which occur at small bore piping in nuclear power plants. Therefore at the plants they manage small bore piping using a method in which their vibration accelerations are measured and the vibration stresses are calculated. In this work, vibration tests for two sets of mock-ups simulating actual piping in the plants by sinusoidal oscillation and by that obtained at an actual plant were carried out, and then an evaluation method was developed to obtain proper value of vibration stress from the measured data by the vibration tests. In comparison of the vibration stress obtained from the measured acceleration with that directly measured using strain gauges, it is confirmed that accurate vibration stress can be evaluated by a formula in which the real center of gravity of small bore piping and the acceleration of main (system) piping are considered. (author)
Stress analysis and evaluation of a rectangular pressure vessel
International Nuclear Information System (INIS)
Rezvani, M.A.; Ziada, H.H.; Shurrab, M.S.
1992-10-01
This study addresses structural analysis and evaluation of an abnormal rectangular pressure vessel, designed to house equipment for drilling and collecting samples from Hanford radioactive waste storage tanks. It had to be qualified according to ASME boiler and pressure vessel code, Section VIII; however, it had the cover plate bolted along the long face, a configuration not addressed by the code. Finite element method was used to calculate stresses resulting from internal pressure; these stresses were then used to evaluate and qualify the vessel. Fatigue is not a concern; thus, it can be built according to Section VIII, Division I instead of Division 2. Stress analysis was checked against the code. A stayed plate was added to stiffen the long side of the vessel
Method for accelerated aging under combined environmental stress conditions
International Nuclear Information System (INIS)
Gillen, K.T.
1979-01-01
An accelerated aging method which can be used to simulate aging in combined stress environment situations is described. It is shown how the assumptions of the method can be tested experimentally. Aging data for a chloroprene cable jacketing material in single and combined radiation and temperature environments are analyzed and it is shown that these data offer evidence for the validity of the method
Method for measuring biaxial stress in a body subjected to stress inducing loads
Clotfelter, W. N. (Inventor)
1977-01-01
A method is described for measuring stress in test articles including the steps of obtaining for a calibrating specimen a series of transit time differentials between the second wave echo for a longitudinal wave and the first wave echo for each of a pair of shear waves propagated through the specimen as it is subjected to known stress load of a series of stress loads for thus establishing a series of indications of the magnitudes for stress loads induced in the specimen, and thereafter obtaining a transit time differential between the second wave echo for a longitudinal wave and the first wave echo for each of a pair of shear waves propagated in the planes of the stress axes of a test article and comparing the transit time differential thus obtained to the series of transit time differentials obtained for the specimen to determine the magnitude of biaxial stress in the test article.
Stress analysis of heated concrete using finite elements
International Nuclear Information System (INIS)
Majumdar, P.; Gupta, A.; Marchertas, A.
1994-01-01
Described is a finite element analysis of concrete, which is subjected to rapid heating. Using thermal mass transport calculation, the moisture content, temperature and pore pressure distribution over space and time is obtained first. From these effects, stress at various points of the concrete are computed using the finite element method. Contribution to the stress formulation comes from three components, namely the thermal expansion, pore pressure, and the shrinkage of concrete due to moisture loss (from dehydration). The material properties of concrete are assumed to be homogeneous, elastic, and cracking is not taken into consideration. (orig.)
Methods of Coping with Stress: A Taxonomy
1992-03-01
techniques and meditational exercises: breath control, progressive relaxation, autogenic training, transcendental medita- tion and others. REFERENCE: Norfolk...Relaxation/ Meditation : A category including any one of several techniques whose major purpose is to offset or diffuse the normal but negative...of Chicago Press. 5 APPENDIX A SELECTED COPING METHODS: SOURCES AND BRIEF DEFINITIONS A-0 #:I NAME: MEDITATION DEFINITION: Anything that redirects
The Methods of Stress Management and Their Classification
Directory of Open Access Journals (Sweden)
Honchar Mykhailo F.
2017-12-01
Full Text Available The article considers the content and classification of methods of stress management, which provides systematization of their varieties by the number of existing (character, time interval of application, direction of impact, period of action, way of account the interests of employees, level of formation, method of substantiation, content and the allocated new attributes (scale of changes in terms of stress management systems, level of novelty at enterprise, consistency, which allows to choose the appropriate types of such methods in overcoming undesirable deviations that have a significant negative impact on the functioning of economic entities. It has been determined that such methods are formed in the implementing of technology of stress-management; are the result of management activities of the steering subsystem of organization at each level of management; have alternative nature; form an information-management base for the adoption of managerial decisions in terms of the systems of stress administration. It has been specified that, with the assistance of certain methods in terms of stress management systems, managers can track existing and potential problems in the complex and dynamic environment of the organization, identify their relationships, identify «weak signals», adjust goals and tasks of management of critical undesirable deviations, determine indicators and criteria of stress-management, etc.
Piping stress analysis with personal computers
International Nuclear Information System (INIS)
Revesz, Z.
1987-01-01
The growing market of the personal computers is providing an increasing number of professionals with unprecedented and surprisingly inexpensive computing capacity, which if using with powerful software, can enhance immensely the engineers capabilities. This paper focuses on the possibilities which opened in piping stress analysis by the widespread distribution of personal computers, on the necessary changes in the software and on the limitations of using personal computers for engineering design and analysis. Reliability and quality assurance aspects of using personal computers for nuclear applications are also mentioned. The paper resumes with personal views of the author and experiences gained during interactive graphic piping software development for personal computers. (orig./GL)
Image decomposition as a tool for validating stress analysis models
Directory of Open Access Journals (Sweden)
Mottershead J.
2010-06-01
Full Text Available It is good practice to validate analytical and numerical models used in stress analysis for engineering design by comparison with measurements obtained from real components either in-service or in the laboratory. In reality, this critical step is often neglected or reduced to placing a single strain gage at the predicted hot-spot of stress. Modern techniques of optical analysis allow full-field maps of displacement, strain and, or stress to be obtained from real components with relative ease and at modest cost. However, validations continued to be performed only at predicted and, or observed hot-spots and most of the wealth of data is ignored. It is proposed that image decomposition methods, commonly employed in techniques such as fingerprinting and iris recognition, can be employed to validate stress analysis models by comparing all of the key features in the data from the experiment and the model. Image decomposition techniques such as Zernike moments and Fourier transforms have been used to decompose full-field distributions for strain generated from optical techniques such as digital image correlation and thermoelastic stress analysis as well as from analytical and numerical models by treating the strain distributions as images. The result of the decomposition is 101 to 102 image descriptors instead of the 105 or 106 pixels in the original data. As a consequence, it is relatively easy to make a statistical comparison of the image descriptors from the experiment and from the analytical/numerical model and to provide a quantitative assessment of the stress analysis.
Stress analysis of cylinder to cylinder intersections
International Nuclear Information System (INIS)
Revesz, Z.
1983-01-01
Cylinder to cylinder intersections have numerous applications in the power industry from different piping junctions to pressure vessel nozzles. A specific purpose computer program has been installed at the author's establishment for finite element analysis of such geometries. Some of the experiences are presented giving a short overview of the analysis of unreinforced man-holes, demonstrating how a more economical design has been verified by analysis. The program installed has linear-elastic and elasto-plastic capabilities. Further, it is prepared for heat transfer analysis with subsequent thermal stress computation. An efficient pre- and post-processor has also been installed and enhanced by the author. The software used is at its present stage capable for problem definition with input data such as outside/ inside diameters, length and number of subdivisions. Similarly simple is the load definition and the graphic representation of the full output. (author)
Standard test method for determining residual stresses by the hole-drilling strain-gage method
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 Residual Stress Determination: 1.1.1 This test method specifies a hole-drilling procedure for determining residual stress profiles near the surface of an isotropic linearly elastic material. The test method is applicable to residual stress profile determinations where in-plane stress gradients are small. The stresses may remain approximately constant with depth (“uniform” stresses) or they may vary significantly with depth (“non-uniform” stresses). The measured workpiece may be “thin” with thickness much less than the diameter of the drilled hole or “thick” with thickness much greater than the diameter of the drilled hole. Only uniform stress measurements are specified for thin workpieces, while both uniform and non-uniform stress measurements are specified for thick workpieces. 1.2 Stress Measurement Range: 1.2.1 The hole-drilling method can identify in-plane residual stresses near the measured surface of the workpiece material. The method gives localized measurements that indicate the...
Multivariate analysis: models and method
International Nuclear Information System (INIS)
Sanz Perucha, J.
1990-01-01
Data treatment techniques are increasingly used since computer methods result of wider access. Multivariate analysis consists of a group of statistic methods that are applied to study objects or samples characterized by multiple values. A final goal is decision making. The paper describes the models and methods of multivariate analysis
Multivariate analysis methods in physics
International Nuclear Information System (INIS)
Wolter, M.
2007-01-01
A review of multivariate methods based on statistical training is given. Several multivariate methods useful in high-energy physics analysis are discussed. Selected examples from current research in particle physics are discussed, both from the on-line trigger selection and from the off-line analysis. Also statistical training methods are presented and some new application are suggested [ru
Methods in algorithmic analysis
Dobrushkin, Vladimir A
2009-01-01
…helpful to any mathematics student who wishes to acquire a background in classical probability and analysis … This is a remarkably beautiful book that would be a pleasure for a student to read, or for a teacher to make into a year's course.-Harvey Cohn, Computing Reviews, May 2010
Communication Network Analysis Methods.
Farace, Richard V.; Mabee, Timothy
This paper reviews a variety of analytic procedures that can be applied to network data, discussing the assumptions and usefulness of each procedure when applied to the complexity of human communication. Special attention is paid to the network properties measured or implied by each procedure. Factor analysis and multidimensional scaling are among…
Complementing Gender Analysis Methods.
Kumar, Anant
2016-01-01
The existing gender analysis frameworks start with a premise that men and women are equal and should be treated equally. These frameworks give emphasis on equal distribution of resources between men and women and believe that this will bring equality which is not always true. Despite equal distribution of resources, women tend to suffer and experience discrimination in many areas of their lives such as the power to control resources within social relationships, and the need for emotional security and reproductive rights within interpersonal relationships. These frameworks believe that patriarchy as an institution plays an important role in women's oppression, exploitation, and it is a barrier in their empowerment and rights. Thus, some think that by ensuring equal distribution of resources and empowering women economically, institutions like patriarchy can be challenged. These frameworks are based on proposed equality principle which puts men and women in competing roles. Thus, the real equality will never be achieved. Contrary to the existing gender analysis frameworks, the Complementing Gender Analysis framework proposed by the author provides a new approach toward gender analysis which not only recognizes the role of economic empowerment and equal distribution of resources but suggests to incorporate the concept and role of social capital, equity, and doing gender in gender analysis which is based on perceived equity principle, putting men and women in complementing roles that may lead to equality. In this article the author reviews the mainstream gender theories in development from the viewpoint of the complementary roles of gender. This alternative view is argued based on existing literature and an anecdote of observations made by the author. While criticizing the equality theory, the author offers equity theory in resolving the gender conflict by using the concept of social and psychological capital.
Psychotherapeutic Methods of Coping with Stress in Everyday Life
Directory of Open Access Journals (Sweden)
Senol TURAN
2015-12-01
Full Text Available Stress is an inevitable part of life. Knowing the ways of coping with stress are necessary to preserve our mental and physical health and to maintain good social and/or occupational functioning in daily life activities. Different ways of coping with stress have been developed throughout history. Various type of therapies offer quite effective remedies for coping with stress in everyday life. Among psychotherapeutic treatments cognitive behavioral therapy which involves teaching stressful individuals to develop coping strategies have yielded very promising results. It is helpful to determine first whether stress source can be changed, several therapeutic approaches may then be used. Lazarus and Folkman have identified two major approaches for coping with stress so-called "problem-focused" and "emotion-focused". In "problem-focused" approaches targets are acquiring time management, self-monitoring, problem-solving skills, while in "emotion-focused" approaches, through ways of accepting or rejecting of stress associated negative emotions, or reconciling with these emotions, the target is learning how to keep emotions under control. "Problem-focused" and "emotion-focused" approaches may independently be used effectively in appropriate cases, their simultaneous practice may increase chances of successful treatment. Apart from this methods, psychodynamic therapy may be indicated in some cases. [JCBPR 2015; 4(3.000: 133-140
Thermoelastic stress analysis system developed for industrial applications
DEFF Research Database (Denmark)
Haldorsen, Lars Magne
The thesis is divided into three parts. The first part describes an extensive evaluation of the existing thermoelastic theory. The second part describes the development and results af a reliable numerical simulation code of the thermoelastic effect and the associated heat transfer effects. Finall......, theories, methods and additional equipment are developed in order to adopt a commercial IR-imaging system to preform Termoelastic Stress Analysis (TSA)....
Composite Analysis of Concrete - Creep, Relaxation and Eigenstrain/stress
DEFF Research Database (Denmark)
Nielsen, Lauge Fuglsang
1996-01-01
approach.The model is successfully justified comparing predicted results with recent experimental data obtained in tests made at the Danish Technological Institute and at the Technical University of Denmark on creep, relaxation, and shrinkage of very young concretes (hours) - and also with experimental...... results on creep, shrinkage, and internal stresses caused by drying shrinkage reported in the literature on the mechanical behavior of mature concretes.Shrinkage (autogeneous or drying) of mortar and concrete and associated internal stress states are examples of analysis made in this report......A composite-rheological model of concrete is presented by which consistent predictions of creep, relaxation, and internal stresses can be made from known concrete composition, age at loading, and climatic conditions. No other existing "creep prediction method" offers these possibilities in one...
SIGMARZ, Stress Analysis of Axisymmetric or Plane Structures
International Nuclear Information System (INIS)
1978-01-01
1 - Nature of the physical problem solved: Classic stress analysis program for axisymmetric or plane geometric structures. 2 - Method of solution: The finite element method is used. Input are the finite element nodes, the imposed displacements, the applied forces at the nodes and the volumetric distributed forces. The linear equation system is solved by the Cholesky method. 3 - Restrictions on the complexity of the problem: Maximum number of nodes: 800; Maximum number of elements: 1300; Maximum number of displacements: 300; Maximum band width: 72
Stress analysis in oral obturator prostheses, part II: photoelastic imaging
Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; da Silva, Emily Vivianne Freitas; Haddad, Marcela Filié; Moreno, Amália; Zahoui, Abbas; dos Santos, Daniela Micheline
2014-06-01
In part I of the study, two attachment systems [O-ring; bar-clip (BC)] were used, and the system with three individualized O-rings provided the lowest stress on the implants and the support tissues. Therefore, the aim of this study was to assess the stress distribution, through the photoelastic method, on implant-retained palatal obturator prostheses associated with different attachment systems: BOC-splinted implants with a bar connected to two centrally placed O-rings, and BOD-splinted implants with a BC connected to two distally placed O-rings (cantilever). One photoelastic model of the maxilla with oral-sinus-nasal communication with three parallel implants was fabricated. Afterward, two implant-retained palatal obturator prostheses with the two attachment systems described above were constructed. Each assembly was positioned in a circular polariscope and a 100-N axial load was applied in three different regions with implants by using a universal testing machine. The results were obtained through photograph record analysis of stress. The BOD system exhibited the highest stress concentration, followed by the BOC system. The O-ring, centrally placed on the bar, allows higher mobility of the prostheses and homogeneously distributes the stress to the region of the alveolar ridge and implants. It can be concluded that the use of implants with O-rings, isolated or connected with a bar, to rehabilitate maxillectomized patients allows higher prosthesis mobility and homogeneously distributes the stress to the alveolar ridge region, which may result in greater chewing stress distribution to implants and bone tissue. The clinical implication of the augmented bone support loss after maxillectomy is the increase of stress in the attachment systems and, consequently, a higher tendency for displacement of the prosthesis.
STOCHASTIC METHODS IN RISK ANALYSIS
Directory of Open Access Journals (Sweden)
Vladimíra OSADSKÁ
2017-06-01
Full Text Available In this paper, we review basic stochastic methods which can be used to extend state-of-the-art deterministic analytical methods for risk analysis. We can conclude that the standard deterministic analytical methods highly depend on the practical experience and knowledge of the evaluator and therefore, the stochastic methods should be introduced. The new risk analysis methods should consider the uncertainties in input values. We present how large is the impact on the results of the analysis solving practical example of FMECA with uncertainties modelled using Monte Carlo sampling.
X-ray stress measurement of ferritic steel using fourier analysis of Debye-Scherrer ring
International Nuclear Information System (INIS)
Fujimoto, Yohei; Sasaki, Toshihiko; Miyazaki, Toshiyuki
2015-01-01
In this study, X-ray stress measurements of ferritic steel based on Fourier analysis are conducted. Taira et al. developed the cosα method for X-ray stress measurements using a two-dimensional X-ray detector. Miyazaki et al. reported that the cosα method can be described more concisely by developing the Fourier series (the Fourier analysis method). The Fourier analysis method is expected to yield the stress measurement with an imperfect Debye-Scherrer ring and there is a possibility that the materials evaluation is different compared with the conventional method, that is, the sin 2 ψ method. In the Fourier analysis method, the strain measured by X-rays is developed as a Fourier series, and all the plane-stress components can be calculated from the Fourier series. In this study, the normal stress calculation was confirmed. In addition, the Fourier-analysis and cosα methods were used for X-ray stress measurements during a four-point bending test on a S45C test piece, and the effectiveness of the Fourier analysis method was confirmed. It was found that the experimental results from the Fourier analysis and cosα methods were nearly identical. In addition, the measurement accuracies of both the methods were equivalent. (author)
Ichihara, Takashi; George, Richard T.; Silva, Caterina; Lima, Joao A. C.; Lardo, Albert C.
2011-02-01
The purpose of this study was to develop a quantitative method for myocardial blood flow (MBF) measurement that can be used to derive accurate myocardial perfusion measurements from dynamic multidetector computed tomography (MDCT) images by using a compartment model for calculating the first-order transfer constant (K1) with correction for the capillary transit extraction fraction (E). Six canine models of left anterior descending (LAD) artery stenosis were prepared and underwent first-pass contrast-enhanced MDCT perfusion imaging during adenosine infusion (0.14-0.21 mg/kg/min). K1 , which is the first-order transfer constant from left ventricular (LV) blood to myocardium, was measured using the Patlak plot method applied to time-attenuation curve data of the LV blood pool and myocardium. The results were compared against microsphere MBF measurements, and the extraction fraction of contrast agent was calculated. K1 is related to the regional MBF as K1=EF, E=(1-exp(-PS/F)), where PS is the permeability-surface area product and F is myocardial flow. Based on the above relationship, a look-up table from K1 to MBF can be generated and Patlak plot-derived K1 values can be converted to the calculated MBF. The calculated MBF and microsphere MBF showed a strong linear association. The extraction fraction in dogs as a function of flow (F) was E=(1-exp(-(0.2532F+0.7871)/F)) . Regional MBF can be measured accurately using the Patlak plot method based on a compartment model and look-up table with extraction fraction correction from K1 to MBF.
Stress estimation in reservoirs using an integrated inverse method
Mazuyer, Antoine; Cupillard, Paul; Giot, Richard; Conin, Marianne; Leroy, Yves; Thore, Pierre
2018-05-01
Estimating the stress in reservoirs and their surroundings prior to the production is a key issue for reservoir management planning. In this study, we propose an integrated inverse method to estimate such initial stress state. The 3D stress state is constructed with the displacement-based finite element method assuming linear isotropic elasticity and small perturbations in the current geometry of the geological structures. The Neumann boundary conditions are defined as piecewise linear functions of depth. The discontinuous functions are determined with the CMA-ES (Covariance Matrix Adaptation Evolution Strategy) optimization algorithm to fit wellbore stress data deduced from leak-off tests and breakouts. The disregard of the geological history and the simplified rheological assumptions mean that only the stress field, statically admissible and matching the wellbore data should be exploited. The spatial domain of validity of this statement is assessed by comparing the stress estimations for a synthetic folded structure of finite amplitude with a history constructed assuming a viscous response.
The stress analysis and stress evaluates of γ-spectrometer-probe station
International Nuclear Information System (INIS)
Li Hailong
2005-01-01
γ-Spectrometer -Probe Station is used for monitoring the reactor core fuel assemblies. The structural framework of this equipment possessed the massive lead bricks and linear supports. The article uses the finite element method and the conversion density method for processing lead bricks. Using shell element makes the analysis of liberating shape. The rigid supports are proposed and the stacking of the lead-bricks is improved. Meanwhile, the optimized design has been conducted for the equipment component. Using the computed results, the stress evaluate of the equipment is strictly made according to the ASME codes and standards. (author)
Basic methods of isotope analysis
International Nuclear Information System (INIS)
Ochkin, A.V.; Rozenkevich, M.B.
2000-01-01
The bases of the most applied methods of the isotope analysis are briefly presented. The possibilities and analytical characteristics of the mass-spectrometric, spectral, radiochemical and special methods of the isotope analysis, including application of the magnetic resonance, chromatography and refractometry, are considered [ru
Bauer, S. M.; Venatovskaya, L. A.
2018-05-01
The mathematical model of measuring of the intraocular pressure (IOP) by Maklakoff tonometer in the software package ANSYS, Inc. is presented. The dependence of the tonometric pressure on the weight of the tonometer before and after LASIK and Femto LASIK surgical corrections of hyperopia is analized. Cornea-scleral eye shell is modeled as two thin transversely isotropic joint spherical shells with different radii of curvature and biomechanical properties. To analyze the biomechanical state of the corneoscleral shell of the eye after the surgery the elastotonometry method is used. Firstly sequential measurements of intraocular pressure by Maklakoff tonometers weighting 5; 7.5; 10 and 15 g is carried out, then the dependence curve of tonometric IOP vs. tonometer weight is plotted and analyzed. The results of the calculations are compared with the clinical data.
Stress Analysis for Mobile Hot Cell Design
International Nuclear Information System (INIS)
Muhammad Hannan Bahrin; Anwar Abdul Rahman; Mohd Arif Hamzah
2015-01-01
Prototype and Plant Development Centre (PDC) is developing a Mobile Hot Cell (MHC) to handle and manage Spent High Activity Radioactive Sources (SHARS), such as teletherapy heads and dry irradiators. At present, there are two units of MHC in the world, one in South Africa and the other one in China. Malaysian Mobile MHC is developed by Malaysian Nuclear Agency with the assistance of IAEA expert, based on the design of South Africa and China, but with improved features. Stress analysis has been performed on the design to fulfill the safety requirement in MHC operation. This paper discusses the loading effect analysis from the radiation shielding materials to the MHC wall structure, roof supporting column and window structure. (author)
Stress analysis in a non axisymmetric loaded reactor pressure vessel
International Nuclear Information System (INIS)
Albuquerque, Levi Barcelos; Assis, Gracia Menezes V. de; Miranda, Carlos Alexandre J.; Cruz, Julio Ricardo B.; Mattar Neto, Miguel
1995-01-01
In this work we intend to present the stress analysis of a PWR vessel under postulated concentrated loads. The vessel was modeled with Axisymmetric solid 4 nodes harmonic finite elements with the use of the ANSYS program, version 5.0. The bolts connecting the vessel flanges were modeled with beam elements. Some considerations were made to model the contact between the flanges. The perforated part of the vessel tori spherical head was modeled (with reduced properties due to its holes) to introduce its stiffness and loads but was not within the scope of this work. The loading consists of some usual ones, as pressure, dead weight, bolts preload, seismic load and some postulated ones as concentrated loads, over the vessel, modeled by Fourier Series. The results in the axisymmetric model are taken in terms of linearized stresses, obtained in some circumferential positions and for each position, in some sections along the vessel. Using the ASME Code (Section III, Division 1, Sub-section NB) the stresses are within the allowable limits. In order to draw some conclusions about stress linearization, the membrane plus bending stresses (Pl + Pb) are obtained and compared in some sections, using three different methods. (author)
Spartan Release Engagement Mechanism (REM) stress and fracture analysis
Marlowe, D. S.; West, E. J.
1984-01-01
The revised stress and fracture analysis of the Spartan REM hardware for current load conditions and mass properties is presented. The stress analysis was performed using a NASTRAN math model of the Spartan REM adapter, base, and payload. Appendix A contains the material properties, loads, and stress analysis of the hardware. The computer output and model description are in Appendix B. Factors of safety used in the stress analysis were 1.4 on tested items and 2.0 on all other items. Fracture analysis of the items considered fracture critical was accomplished using the MSFC Crack Growth Analysis code. Loads and stresses were obtaind from the stress analysis. The fracture analysis notes are located in Appendix A and the computer output in Appendix B. All items analyzed met design and fracture criteria.
[Occupational stress situation analysis of different types of train drivers].
Zhou, Wenhui; Gu, Guizhen; Wu, Hui; Yu, Shanfa
2014-11-01
To analyze the status of occupational stress in different types of train drivers. By using cluster sampling method, a cross-sectional study was conducted in 1 339 train drivers (including 289 passenger train drivers, 637 freight trains drivers, 339 passenger shunting train drivers, and 74 high speed rail drivers) from a Railway Bureau depot. The survey included individual factors, occupational stress factors, stress response factors and stress mitigating factors. The occupational stress factors, stress response factors and mitigating factors were measured by the revised effort-reward imbalance (ERI) model questionnaires and occupational stress measurement scale. By using the method of covariance analysized the difference of occupational stress factors of all types train drivers, the method of Stepwise regression was used to analyze the effection (R(2)) of occupational stress factors and stress mitigating factors on stress response factors. Covariance analysis as covariates in age, education level, length of service and marital status showed that the scores of ERI (1.58 ± 0.05), extrinsic effort (19.88 ± 0.44), rewards (23.43 ± 0.43), intrinsic effort (17.86 ± 0.36), physical environment (5.70 ± 0.22), social support (30.51 ± 0.88) and daily tension (10.27 ± 0.38 ) of high speed rail drivers were higher than other drivers (F values were 6.06, 11.32, 7.05, 13.25, 5.20, 9.48 and 6.14 respectively, P occupational stress factors and mitigating factors to depressive symptoms of train drivers was high speed rail drivers (R(2) = 0.64), passenger train drivers (R(2) = 0.44), passenger shunting train drivers (R(2) = 0.39), freight trains drivers (R(2) = 0.38); job satisfaction of train drivers was high speed rail drivers (R(2) = 0.68), passenger train drivers (R(2) = 0.62), freight trains drivers (R(2) = 0.43), passenger shunting train drivers(R(2) = 0.38); to daily tension of train drivers was high speed rail drivers (R(2) = 0.54), passenger train drivers (R(2) = 0
International Nuclear Information System (INIS)
Sera, Takehiko; Hirano, Shinro; Chigusa, Naoki; Okano, Shigetaka; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi
2012-01-01
Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by accelerated test. However, the effectiveness of stress improvement by surface treatment is limited to thin layers and the effect of complicated residual stress distribution in the weld metal beneath the surface is not strictly taken into account for long-term stability. This paper, therefore, describes the accelerated tests, which confirmed that the long-term stability of the layer subjected to buffing treatment was equal to that subjected to WJP. The long-term reliability of very thin stress improved layer was also confirmed through a trial evaluation by thermal elastic-plastic creep analysis, even if the effect of complicated residual stress distribution in the weld metal was excessively taken into account. Considering the above findings, an approach is proposed for constructing the prediction method of the long-term reliability of stress improvement by surface finishing. (author)
Finite element analysis of thermal stress distribution in different ...
African Journals Online (AJOL)
Nigerian Journal of Clinical Practice. Journal Home ... Von Mises and thermal stress distributions were evaluated. Results: In all ... distribution. Key words: Amalgam, finite element method, glass ionomer cement, resin composite, thermal stress ...
Stochastic thermal stress analysis of clad cylindrical fuel elements
International Nuclear Information System (INIS)
Barrett, P.R.
1975-01-01
After a review of deterministic elastic thermal stress analysis by means of the displacement method for a cylindrical system in which the temperature distribution is not only radially variable but azimuthally and axially variable also, a method is shown for the determination of the statistical moments of the stress components when (a) the outer boundary of the cladding is a stochastic quantity, and (b) the uncertainties in the elastic and thermal constants of the materials and in the magnitude of the heat generation term are taken into account. A typical model is proposed for describing the statistics of the outer radius of the cladding which is a stochastic variable owing to uncertainties produced by the extrusion process. The theory is illustrated by means of a simple example by examining a meaningful reliability index and the relative importance of each of the uncertainties. (Auth.)
International Nuclear Information System (INIS)
Hirao, Keiichi; Yamane, Toshimi; Minamino, Yoritoshi
1991-01-01
This report is to show how the life due to stress corrosion cracking breakdown of fuel cladding tubes is evaluated by applying the statistical techniques to that examined by a few testing methods. The statistical distribution of the limiting values of constant load stress corrosion cracking life, the statistical analysis by making the probabilistic interpretation of constant load stress corrosion cracking life, and the statistical analysis of stress corrosion cracking life by the slow strain rate test (SSRT) method are described. (K.I.)
A review of residual stress analysis using thermoelastic techniques
Energy Technology Data Exchange (ETDEWEB)
Robinson, A F; Dulieu-Barton, J M; Quinn, S [University of Southampton, School of Engineering Sciences, Highfield, Southampton, SO17 1BJ (United Kingdom); Burguete, R L [Airbus UK Ltd., New Filton House, Filton, Bristol, BS99 7AR (United Kingdom)
2009-08-01
Thermoelastic Stress Analysis (TSA) is a full-field technique for experimental stress analysis that is based on infra-red thermography. The technique has proved to be extremely effective for studying elastic stress fields and is now well established. It is based on the measurement of the temperature change that occurs as a result of a stress change. As residual stress is essentially a mean stress it is accepted that the linear form of the TSA relationship cannot be used to evaluate residual stresses. However, there are situations where this linear relationship is not valid or departures in material properties due to manufacturing procedures have enabled evaluations of residual stresses. The purpose of this paper is to review the current status of using a TSA based approach for the evaluation of residual stresses and to provide some examples of where promising results have been obtained.
A review of residual stress analysis using thermoelastic techniques
International Nuclear Information System (INIS)
Robinson, A F; Dulieu-Barton, J M; Quinn, S; Burguete, R L
2009-01-01
Thermoelastic Stress Analysis (TSA) is a full-field technique for experimental stress analysis that is based on infra-red thermography. The technique has proved to be extremely effective for studying elastic stress fields and is now well established. It is based on the measurement of the temperature change that occurs as a result of a stress change. As residual stress is essentially a mean stress it is accepted that the linear form of the TSA relationship cannot be used to evaluate residual stresses. However, there are situations where this linear relationship is not valid or departures in material properties due to manufacturing procedures have enabled evaluations of residual stresses. The purpose of this paper is to review the current status of using a TSA based approach for the evaluation of residual stresses and to provide some examples of where promising results have been obtained.
X-ray stress analysis of residual stress gradients in surface layers of steel
International Nuclear Information System (INIS)
Ganev, N.; Kraus, I.; Gosmanova, G.; Pfeiffer, L.; Tietz, H.-D.
2001-01-01
The aim of the contribution is to present the theoretical possibilities of X-ray non-destructive identification of stress gradients within the penetration depth of used radiation and its utilization for experimental stress analysis. Practical usefullness of outlined speculations is illustrated with results of stress measurements on cut and shot-penned steel samples. (author)
Probabilistic methods for rotordynamics analysis
Wu, Y.-T.; Torng, T. Y.; Millwater, H. R.; Fossum, A. F.; Rheinfurth, M. H.
1991-01-01
This paper summarizes the development of the methods and a computer program to compute the probability of instability of dynamic systems that can be represented by a system of second-order ordinary linear differential equations. Two instability criteria based upon the eigenvalues or Routh-Hurwitz test functions are investigated. Computational methods based on a fast probability integration concept and an efficient adaptive importance sampling method are proposed to perform efficient probabilistic analysis. A numerical example is provided to demonstrate the methods.
Directory of Open Access Journals (Sweden)
Kang Ma
2017-01-01
Full Text Available Coherent gradient sensing (CGS method can be used to measure the slope of a reflective surface, and has the merits of full-field, non-contact, and real-time measurement. In this study, the thermal stress field of thermal barrier coating (TBC structures is measured by CGS method. Two kinds of powders were sprayed onto Ni-based alloy using a plasma spraying method to obtain two groups of film–substrate specimens. The specimens were then heated with an oxy-acetylene flame. The resulting thermal mismatch between the film and substrate led to out-of-plane deformation of the specimen. The deformation was measured by the reflective CGS method and the thermal stress field of the structure was obtained through calibration with the help of finite element analysis. Both the experiment and numerical results showed that the thermal stress field of TBC structures can be successfully measured by CGS method.
International Nuclear Information System (INIS)
Fujioka, Terutaka
2015-01-01
This paper proposes methods for assessing Bree-type ratcheting in a cylinder subjected to constant internal pressure and cyclic thermal loading. The proposed methods are elastic analysis-route and elastic–plastic analysis-route. The former is based on the polynomial approximation of the elastic stress distributions for thermal stresses and the reference stress concept for estimating primary stress. The latter elastic–plastic route method is based on the concept of relative elastic core size. The methods proposed were validated by performing elastic–plastic finite element analyses of a smooth cylinder that exhibited Bree-type ratcheting. - Highlights: • Rationalization of the ratcheting assessment has been made. • The proposed methods include both elastic and elastic-plastic routes. • The elastic route method is based on skeletal point stress by elastic FEA. • The elastic-plastic route is based on elastic core size in elastic-plastic FEA. • These have been validated by elastic-plastic FEA causing Bree-type ratcheting
FEA stress analysis for SAFKEG 2863B
International Nuclear Information System (INIS)
Puckett, A.
1997-01-01
This report covers the evaluation of the structural design of the two stainless steel containment vessels in CROFT SAFKEG Model Number 2863B, for conformance to the design criteria of the NRC Regulatory Guide 7.6, NRC Regulatory Guide 7.8, and the applicable requirements of the ASME Boiler and Pressure Vessel Code, Section 3, and Section 8. The two containment vessels are designated Cans 2870 and 2871. Each of these containment vessels was analyzed for the loadings specified in chapter 2, Section 2.1.2 of the SARP. Structural assessment of Cans 2870 and 2871 due to loading considerations beyond the evaluation of pressure and temperature are presented. This report is organized as follows: (1) overview of the design of each containment vessel and pressure boundary; (2) brief description of both containment vessels; (3) discussion of normal and accident conditions; (4) analysis assumptions; (5) detailed structural evaluation of each component of each containment vessel; (6) demonstration of compliance to Regulatory Guide 7.6 stress evaluations; (7) demonstration of compliance to Regulatory Guide 7.8 loading combinations; and (8) summary of the calculated stresses, comparison with design allowables, estimates of margins of safety and a summary of results and conclusions
Numerical analysis of residual stresses reconstruction for axisymmetric glass components
Tao, Bo; Xu, Shuang; Yao, Honghui
2018-01-01
A non-destructive measurement method for 3D stress state in a glass cylinder using photoelasticity has been analyzed by simulation in this research. Based on simulated stresses in a glass cylinder, intensity of the cylinder in a circular polariscope can be calculated by Jones calculus. Therefore, the isoclinic angle and optical retardation can be obtained by six steps phase shifting technique. Through the isoclinic angle and optical retardation, the magnitude and distribution of residual stresses inside the glass cylinder in cylindrical coordinate system can be reconstructed. Comparing the reconstructed stresses with numerical simulated stresses, the results verify this non-destructive method can be used to reconstruct the 3D stresses. However, there are some mismatches in axial stress, radial stress and circumferential stress.
Advanced stress analysis of PWR containments in the region of nozzles
International Nuclear Information System (INIS)
Schauer, G.
1977-01-01
As an example of the stress analysis of a nozzle in a PWR steel containment, an advanced stress analysis of a personnel lock is presented. Contrary to the calculations by means of numerical shell programs usual till now, this advanced stress analysis was executed with the finite-element-method. Because of their theory, the shell programs compute mathematically exact results, but at the intersection of two shells the notch stresses cannot be analyzed well. A further disadvantage must be seen in the fact that there is a great distance between the real critical region near the intersection line and the calculation point, which lies on the neutral axis of the shell
Analysis of Precision of Activation Analysis Method
DEFF Research Database (Denmark)
Heydorn, Kaj; Nørgaard, K.
1973-01-01
The precision of an activation-analysis method prescribes the estimation of the precision of a single analytical result. The adequacy of these estimates to account for the observed variation between duplicate results from the analysis of different samples and materials, is tested by the statistic T...
Probabilistic structural analysis methods for space transportation propulsion systems
Chamis, C. C.; Moore, N.; Anis, C.; Newell, J.; Nagpal, V.; Singhal, S.
1991-01-01
Information on probabilistic structural analysis methods for space propulsion systems is given in viewgraph form. Information is given on deterministic certification methods, probability of failure, component response analysis, stress responses for 2nd stage turbine blades, Space Shuttle Main Engine (SSME) structural durability, and program plans. .
Doan, Son; Ritchart, Amanda; Perry, Nicholas; Chaparro, Juan D; Conway, Mike
2017-06-13
Stress is a contributing factor to many major health problems in the United States, such as heart disease, depression, and autoimmune diseases. Relaxation is often recommended in mental health treatment as a frontline strategy to reduce stress, thereby improving health conditions. Twitter is a microblog platform that allows users to post their own personal messages (tweets), including their expressions about feelings and actions related to stress and stress management (eg, relaxing). While Twitter is increasingly used as a source of data for understanding mental health from a population perspective, the specific issue of stress-as manifested on Twitter-has not yet been the focus of any systematic study. The objective of our study was to understand how people express their feelings of stress and relaxation through Twitter messages. In addition, we aimed at investigating automated natural language processing methods to (1) classify stress versus nonstress and relaxation versus nonrelaxation tweets, and (2) identify first-hand experience-that is, who is the experiencer-in stress and relaxation tweets. We first performed a qualitative content analysis of 1326 and 781 tweets containing the keywords "stress" and "relax," respectively. We then investigated the use of machine learning algorithms-in particular naive Bayes and support vector machines-to automatically classify tweets as stress versus nonstress and relaxation versus nonrelaxation. Finally, we applied these classifiers to sample datasets drawn from 4 cities in the United States (Los Angeles, New York, San Diego, and San Francisco) obtained from Twitter's streaming application programming interface, with the goal of evaluating the extent of any correlation between our automatic classification of tweets and results from public stress surveys. Content analysis showed that the most frequent topic of stress tweets was education, followed by work and social relationships. The most frequent topic of relaxation tweets
Analysis apparatus and method of analysis
International Nuclear Information System (INIS)
1976-01-01
A continuous streaming method developed for the excution of immunoassays is described in this patent. In addition, a suitable apparatus for the method was developed whereby magnetic particles are automatically employed for the consecutive analysis of a series of liquid samples via the RIA technique
Energy Technology Data Exchange (ETDEWEB)
Scholtes, B.; Nau, Andreas
2015-06-01
Residual stresses can be result in both detrimental as well as beneficial consequences on the component's strength and lifetime. A most detailed knowledge of the residual stress state is a pre-requisite for the assessment of the component's performance. The mechanical methods for residual stress measurements are classified in non-destructive, destructive and semi-destructive methods. The two commonly used (semi-destructive) mechanical methods are the hole drilling and the ring core method. In the context of reactor safety research of the Federal Ministry of Economic Affairs and Energy (BMWi), two fundamental and interacting weak points of the hole drilling as well as ofthe ring core method are investigated. On the one hand, there are effects concerning geometricalboundary conditions of the components and on the other hand, there are influences of plasticity due to notch effects. Both aspects affect the released strain field, when the material is removed and finally, the calculated residual stresses. The first issue mentioned above is under the responsibility of Institute of Materials Engineering - Metallic Materials (KasselUniversity) and the last one will be investigated by University of Stuttgart-Otto-Graf-Institut - materials testing institute. As a consequence of a successful project, the present knowledgebase will be considerably improved and will be available for various engineering fields. Especially,the quantitative consideration of real residual stress states for optimized component designs will be feasible and finally the consequences of residual stresses on the component's safety, which are used in nuclear facilities, can be evaluated. The findings of the application-oriented research period (phase 2) at Kassel University are documented in this report.
Justification of indirect methods of bending stresses polyethylene pipes evaluation
Serebrennikov, A. A.; Serebrennikov, D. A.; Hakimov, Z. R.
2017-10-01
The world and Russian companies have a long experience of the polyethylene pipeline installation and operation. At the same time, the significant attention is paid to the improvement of the relevant machines and the production technology. The polyethylene pipeline installation experience proves that its operation properties (reliability and durability) depend on physical and mechanical characteristics of polyethylene, which should be saved during its installation. Defects can occur, including in cases when the pipe is subjected to the significant bending stresses during installation. To evaluate these stresses, including when exposed to cold weather conditions, an indirect method based on the relationship between strength characteristics and occurred deformations is proposed.
Stress strain modelling of casting processes in the framework of the control volume method
DEFF Research Database (Denmark)
Hattel, Jesper; Andersen, Søren; Thorborg, Jesper
1998-01-01
Realistic computer simulations of casting processes call for the solution of both thermal, fluid-flow and stress/strain related problems. The multitude of the influencing parameters, and their non-linear, transient and temperature dependent nature, make the calculations complex. Therefore the nee......, the present model is based on the mainly decoupled representation of the thermal, mechanical and microstructural processes. Examples of industrial applications, such as predicting residual deformations in castings and stress levels in die casting dies, are presented...... for fast, flexible, multidimensional numerical methods is obvious. The basis of the deformation and stress/strain calculation is a transient heat transfer analysis including solidification. This paper presents an approach where the stress/strain and the heat transfer analysis uses the same computational...... domain, which is highly convenient. The basis of the method is the control volume finite difference approach on structured meshes. The basic assumptions of the method are shortly reviewed and discussed. As for other methods which aim at application oriented analysis of casting deformations and stresses...
Nonlinear programming analysis and methods
Avriel, Mordecai
2012-01-01
This text provides an excellent bridge between principal theories and concepts and their practical implementation. Topics include convex programming, duality, generalized convexity, analysis of selected nonlinear programs, techniques for numerical solutions, and unconstrained optimization methods.
Chemical methods of rock analysis
National Research Council Canada - National Science Library
Jeffery, P. G; Hutchison, D
1981-01-01
A practical guide to the methods in general use for the complete analysis of silicate rock material and for the determination of all those elements present in major, minor or trace amounts in silicate...
Privacy and Psychosomatic Stress: An Empirical Analysis.
Webb, Stephen D.
1978-01-01
Examines the supposition that insufficient privacy is stressful to the individual. Data were obtained from urban centers in New Zealand. Findings support the hypothesis that a percieved lack of privacy is associated with psychosomatic stress. The relationship is specified by measures of stress and sex of respondents. (Author)
Yield stress fluids slowly yield to analysis
Bonn, D.; Denn, M.M.
2009-01-01
We are surrounded in everyday life by yield stress fluids: materials that behave as solids under small stresses but flow like liquids beyond a critical stress. For example, paint must flow under the brush, but remain fixed in a vertical film despite the force of gravity. Food products (such as
[Interpersonal games as a method for doctors' occupational stress].
Samborska-Sablik, Anna; Sablik, Zbigniew; Gaszyński, Tomasz; Drożdż, Jarosław
2015-03-01
Doctors are frequently expose to stress during their occupational work. It is mainly the result of burdens caused by taking care of patients, dysfunctional arrangements of the health care system and difficult relationships in their workplace. Chronic stress brings negative emotions and they need to cope with them . Doctors, willing to achieve it, may initiate interpersonal games with the hidden motive of restoring their internal balance. Based on transactional analysis, the authors describe some of the games which may be found in doctors' environment: "How to get out of there", "Mine is better than yours", "Scapegoat", "Fault" and "double bind". The outcome of the games may be receiving a support, proving a benefit derived from stress, getting the feeling of being not guilty, justification, or releasing emotions in apparently unintended way. Interpersonal games may help stressed doctors to get rid of internal tension but at the same time they may be a source of stress for other participants in the games. The way to limit their destructive impact is to create such administrative and organizational solutions which allow to make working conditions more friendly. © 2015 MEDPRESS.
Enhancement of wind stress evaluation method under storm conditions
Chen, Yingjian; Yu, Xiping
2016-12-01
Wind stress is an important driving force for many meteorological and oceanographical processes. However, most of the existing methods for evaluation of the wind stress, including various bulk formulas in terms of the wind speed at a given height and formulas relating the roughness height of the sea surface with wind conditions, predict an ever-increasing tendency of the wind stress coefficient as the wind speed increases, which is inconsistent with the field observations under storm conditions. The wave boundary layer model, which is based on the momentum and energy conservation, has the advantage to take into account the physical details of the air-sea interaction process, but is still invalid under storm conditions without a modification. By including the energy dissipation due to the presence of sea spray, which is speculated to be an important aspect of the air-sea interaction under storm conditions, the wave boundary layer model is improved in this study. The improved model is employed to estimate the wind stress caused by an idealized tropical cyclone motion. The computational results show that the wind stress coefficient reaches its maximal value at a wind speed of about 40 m/s and decreases as the wind speed further increases. This is in fairly good agreement with the field data.
Proteomic analysis of cold stress responses in tobacco seedlings ...
African Journals Online (AJOL)
Cold stress is one of the major abiotic stresses limiting the productivity and the geographical distribution of many important crops. To gain a better understanding of cold stress responses in tobacco (Nicotiana tabacum), we carried out a comparative proteomic analysis. Five-week-old tobacco seedlings were treated at 4°C ...
Structural and stress analysis of nuclear piping systems
International Nuclear Information System (INIS)
Hata, Hiromichi
1982-01-01
The design of the strength of piping system is important in plant design, and its outline on the example of PWRs is reported. The standards and guides concerning the design of the strength of piping system are shown. The design condition for the strength of piping system is determined by considering the requirements in the normal operation of plants and for the safety design of plants, and the loads in normal operation, testing, credible accident and natural environment are explained. The methods of analysis for piping system are related to the transient phenomena of fluid, piping structure and local heat conduction, and linear static analysis, linear time response analysis, nonlinear time response analysis, thermal stress analysis and fluid transient phenomenon analysis are carried out. In the aseismatic design of piping system, it is desirable to avoid the vibration together with a building supporting it, and as a rule, to make it into rigid structure. The piping system is classified into high temperature and low temperature pipings. The formulas for calculating stress and the allowable condition, the points to which attention must be paid in the design of piping strength and the matters to be investigated hereafter are described. (Kako, I.)
Boundary element analysis of stress singularity in dissimilar metals by friction welding
International Nuclear Information System (INIS)
Chung, N. Y.; Park, C. H.
2012-01-01
Friction welded dissimilar metals are widely applied in automobiles, rolling stocks, machine tools, and various engineering fields. Dissimilar metals have several advantages over homogeneous metals, including high strength, material property, fatigue endurance, impact absorption, high reliability, and vibration reduction. Due to the increased use of these metals, understanding their behavior under stress conditions is necessary, especially the analysis of stress singularity on the interface of friction-welded dissimilar metals. To establish a strength evaluation method and a fracture criterion, it is necessary to analyze stress singularity on the interface of dissimilar metals with welded flashes by friction welding under various loads and temperature conditions. In this paper, a method analyzing stress singularity for the specimens with and without flashes set in friction welded dissimilar metals is introduced using the boundary element method. The stress singularity index (λ) and the stress singularity factor (Γ) at the interface edge are computed from the stress analysis results. The shape and flash thickness, interface length, residual stress, and load are considered in the computation. Based on these results, the variations of interface length (c) and the ratio of flash thickness (t2 t1) greatly influence the stress singularity factors at the interface edge of friction welded dissimilar metals. The stress singularity factors will be a useful fracture parameter that considers stress singularity on the interface of dissimilar metals
Seismic design and analysis methods
International Nuclear Information System (INIS)
Varpasuo, P.
1993-01-01
Seismic load is in many areas of the world the most important loading situation from the point of view of structural strength. Taking this into account it is understandable, that there has been a strong allocation of resources in the seismic analysis during the past ten years. In this study there are three areas of the center of gravity: (1) Random vibrations; (2) Soil-structure interaction and (3) The methods for determining structural response. The solution of random vibration problems is clarified with the aid of applications in this study and from the point of view of mathematical treatment and mathematical formulations it is deemed sufficient to give the relevant sources. In the soil-structure interaction analysis the focus has been the significance of frequency dependent impedance functions. As a result it was obtained, that the description of the soil with the aid of frequency dependent impedance functions decreases the structural response and it is thus always the preferred method when compared to more conservative analysis types. From the methods to determine the C structural response the following four were tested: (1) The time history method; (2) The complex frequency-response method; (3) Response spectrum method and (4) The equivalent static force method. The time history appeared to be the most accurate method and the complex frequency-response method did have the widest area of application. (orig.). (14 refs., 35 figs.)
Energy Technology Data Exchange (ETDEWEB)
Nau, Andreas; Scholtes, B.
2014-07-24
Residual stresses can be result in both detrimental as well as beneficial consequences on the component's strength and lifetime. A most detailed knowledge of the residual stress state is a pre-requisite for the assessment of the component's performance. The mechanical methods for residual stress measurements are classified in non-destructive, destructive and semi-destructive methods. The two commonly used (semi-destructive) mechanical methods are the hole drilling and the ring core method. In the context of reactor safety research of the Federal Ministry of Economic Affairs and Energy (BMWi), two fundamental and interacting weak points of the hole drilling as well as of the ring core method are investigated. On the one hand, there are effects concerning geometrical boundary conditions of the components and on the other hand, there are influences of plasticity due to notch effects. Both aspects affect the released strain field, when the material is removed and finally, the calculated residual stresses. The first issue mentioned above is under the responsibility of Institute of Materials Engineering - Metallic Materials (Kassel University) and the last one will be investigated by University of Stuttgart-Otto-Graf-Institut - materials testing institute. Within the framework of this project it could be demonstrated that updated calibration coefficients lead to more reliable residual stress calculation in contrast to existing ones. These findings are valid for points of measurements on components without geometrical boundary effects like edges or shoulders. Reasons are high developed Finite-Element software packages and the opportunity of modelling the point of measurement (hole geometry, layout of the strain gauges) and its vicinity more in detail. Special challenges are multi-axial residual stress depth distributions and the geometry of components composing edges and claddings. Unlike existing analyses considering uni-axial and homogeneous stress states, bi
Proposal on the mitigation methods of thermal stress near the sodium
International Nuclear Information System (INIS)
Ando, Masanori; Kasahara, Naoto
2003-09-01
A Reactor vessel of fast rector plants contains high temperature liquid sodium in its inside and its upper end is supported by a low temperature structures. Therefore, a significant temperature gradient will arise at the vessel wall near the sodium surface. For this reason, a large thermal stress will be generated around this part. To lower this stress and to protect the vessel, a number of methods have been applied the plants. Generally, these mitigation methods by protection equipments for thermal stress also have some problems such as, increase a mount of materials or to be complicate for control, hard to maintenance and so on. In this research, authors suggested another simple methods for thermal stress, and evaluated their effects using computer analysis. The results obtained in this research are as follows. Authors suggested one method, circulate high temperature gas around outside of the vessel and evaluated the effects of this method by analysis. In case of using this method, Sn (one of index values of design) value might be getting lower about 45%. Authors also suggested another method by setting up a heat transfer plate outside of the vessel and evaluated the effects of this method by analysis. Effects of this method depend on material of the plate. In case of using Carbon as material of plate, Sn value might be 27% lower and in case of using 12Cr steel as material of plate, Sn value might be 15% lower. Authors also suggested another method by changing material of the guard vessel to be the one which has good ability of heat transfer and evaluated the effects of this method by analysis. In case of changing material of guard vessel to 12Cr steel, Sn value might be lower about 12%. (author)
Factor analysis for exercise stress radionuclide ventriculography
International Nuclear Information System (INIS)
Hirota, Kazuyoshi; Yasuda, Mitsutaka; Oku, Hisao; Ikuno, Yoshiyasu; Takeuchi, Kazuhide; Takeda, Tadanao; Ochi, Hironobu
1987-01-01
Using factor analysis, a new image processing in exercise stress radionuclide ventriculography, changes in factors associated with exercise were evaluated in 14 patients with angina pectoris or old myocardial infarction. The patients were imaged in the left anterior oblique projection, and three factor images were presented on a color coded scale. Abnormal factors (AF) were observed in 6 patients before exercise, 13 during exercise, and 4 after exercise. In 7 patients, the occurrence of AF was associated with exercise. Five of them became free from AF after exercise. Three patients showing AF before exercise had aggravation of AF during exercise. Overall, the occurrence or aggravation of AF was associated with exercise in ten (71 %) of the patients. The other three patients, however, had disappearance of AF during exercise. In the last patient, none of the AF was observed throughout the study. In view of a high incidence of AF associated with exercise, the factor analysis may have the potential in evaluating cardiac reverse from the viewpoint of left ventricular wall motion abnormality. (Namekawa, K.)
Stress analysis of steam generator row-1 tubes
International Nuclear Information System (INIS)
Kim, Woo Gon; Ryu, Woo Seog; Lee, Ho Jin; Kim, Sung Chung
2000-01-01
Residual stresses induced in U-bending and tube-to-tubesheet joining processes of PWR's steam generator row-1 tube were measured by X-ray method and Hole-Drilling Method(HDM). The stresses resulting from the internal pressure and the temperature gradient in the steam generator were also estimated theoretically. In U-bent regions, the residual stresses at extrados were induced with compressive stress(-), and its maximum value reached -319 Mpa in axial direction at ψ=0 .deg. in position. Maximum tensile residual stress of 170 MPa was found to be at the flank side at position of ψ=90 deg., i.e., at apex region. In tube-to-tubesheet joining methods, the residual stresses induced by the explosive joint method were found to be lower than that by the mechanical roll method. The gradient of residual stress along the expanded tube was highest at the transition region, and the residual stress in circumferential direction was found to be higher than the residual stress in axial direction. Hoop stress due to an internal pressure between primary and secondary side was analyzed to be 76 MPa and thermal stress was 45 MPa
Numerical analysis of stress fields generated by quenching process
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A. Bokota
2011-04-01
Full Text Available In work the presented numerical models of tool steel hardening processes take into account mechanical phenomena generated by thermalphenomena and phase transformations. In the model of mechanical phenomena, apart from thermal, plastic and structural strain, alsotransformations plasticity was taken into account. The stress and strain fields are obtained using the solution of the Finite Elements Method of the equilibrium equation in rate form. The thermophysical constants occurring in constitutive relation depend on temperature and phase composite. For determination of plastic strain the Huber-Misses condition with isotropic strengthening was applied whereas fordetermination of transformation plasticity a modified Leblond model was used. In order to evaluate the quality and usefulness of thepresented models a numerical analysis of stresses and strains associated hardening process of a fang lathe of cone shaped made of tool steel was carried out.
Wen, Jici; Wei, Yujie; Cheng, Yang-Tse
2018-07-01
Monitoring in real time the stress state in high capacity electrodes during charge-discharge processes is pivotal to the performance assessment and structural optimization of advanced batteries. The wafer curvature measurement technique broadly employed in thin-film industry, together with stress analysis using the Stoney equation, has been successfully adopted to measure in situ the stress in thin film electrodes. How large plastic deformation or interfacial delamination during electrochemical cycles in such electrodes affects the applicability of Stoney equation remains unclear. Here we develop a robust electrochemical-mechanical coupled numerical procedure to investigate the influence of large plastic deformation and interfacial failure on the measured stress in thin film electrodes. We identify how the constitutive behavior of electrode materials and film-substrate interfacial properties affect the measured stress-capacity curves of electrodes, and hence establish the relationship of electrode material parameters with the characteristics of stress-capacity curves. Using Li-ions batteries as examples, we show that plastic deformation and interfacial delamination account for the asymmetric stress-capacity loops seen in in situ stress measurements. The methods used here, along with the finite-element code in the supplementary material, may be used to model the electrode behavior as a function of the state of charge.
International Nuclear Information System (INIS)
Nakacho, Keiji; Kasahara, Norifumi; Tamura, Ryota
2012-01-01
The measuring methods of the residual stress are classified into destructive one and nondestructive one. The inherent strain method (ISM) is destructive one. The neutron diffraction method (NDM) is nondestructive one. But the measurable depth is limited within about 20 mm and the method cannot measure the weld zone, without destruction of the object. So, in this study, the hybrid measuring method has been developed, by combining the ISM and the NDM. The theory of the hybrid method is the same as the ISM. In the analysis, the strains measured by the NDM without destruction are used. This hybrid measuring method is a true nondestructive measuring method for a thick welded joint. The applicability of the hybrid method has been verified by simulation, using a butt welded joint of thick pipes. In the simulation, the reliable order of the strains measured by the present NDM is very important, and was considered as 10 micro. The measurable regions by the present NDM were assumed. Under the above conditions, the data (the residual elastic strains assumed to be measured by the NDM) were made, and used in the ISM. As a result of such simulation, it has been cleared that the estimated residual stress has very high accuracy, if enough data are used. The required number of data is less than the ISM. (author)
Stress measurement and bolt tensioning by ultrasonic methods
International Nuclear Information System (INIS)
Smith, J.F.; Greiner, J.D.
1980-01-01
In the past decade, a new technique has been developed for measuring tensile stresses in solids. This ultrasonic technique has been used thus far primarily for measuring fastener tension. The precision of measurement is routinely to 2-3% and, with special care, to approx. 1%. The method is insensitive to the frictional losses which plague tensioning by torque wrench. Though the approach is relatively new, it promises a wide range of applicability
Methods of Measuring Stress Relaxation in Composite Tape Springs
2015-03-26
10 3. Cure Cycle Recommended for Patz F7 Prepreg . . . . . . . . . . . . . . . . . . . . . 17 4. Typical Stress...unique and dimensionally complex parts. Hand lay-up is the method by which prepreg tape or fibers are laid down and then the matrix is then ‘painted’ on...structure. Hand lay-up using a prepreg tape stands out as the inexpensive choice for the unique low number production of tape springs and should
Stress Measurement and Bolt Tensioning by Ultrasonic Methods
Smith, J. F.; Greiner, John D.
1980-07-01
In the past decade, a new technique has been developed for measuring tensile stresses in solids. This ultrasonic technique has been used thus far primarily for measuring fastener tension. The precision of measurement is routinely to 2-3% and, with special care, to ˜1%. The method is insensitive to the frictional losses which plague tensioning by torque wrench. Though the approach is relatively new, it promises a wide range of applicability.
Three dimensional, thermal stress analysis of a welded plate
International Nuclear Information System (INIS)
Koening, H.A.; Lai, C.K.-F.; Morral, J.E.
1985-01-01
A general finite element thermal stress analysis has been developed. The analysis can be uncoupled to solve either the heat transfer problem or the stress problem independently and it can accommodate non-linear material behavior, initial states of stress and strain, and moving boundary conditions. A unique feature of the model it that it properly accounts for the latent heat effect during phase changes. Applying the moving heat flux boundary condition to simulate arc welding, the model has been used to predict the transient thermal mechanical response of a welded plate. It is the absorption and liberation of latent heat in the fusion zone of a weld which complicates numerical methods of treating welding. For pure materials and eutectic alloys the latent heat effect is less of a problem because phase changes take place at a specific temperature. But for most alloys, phase changes take place over a range of temperatures bounded by the solidus, T S , and liquidus, T L , and the latent heat effect occurs continuously over the temperature range. (author)
Advanced stress analysis of PWR containments in the region of nozzles
International Nuclear Information System (INIS)
Schauer, G.
1977-01-01
As an example of the stress analysis of a nozzle in a PWR steel containment, an advanced stress analysis of a personnel lock is presented. Contrary to the calculations by means of numerical shell programs usual till now, this advanced stress analysis was executed with the finite-element-method. Because of their theory, the shell programs compute mathematically exact results, but at the intersection of two shells the notch stresses cannot be analyzed well. A further disadvantage must be seen in the fact that there is a great distance between the real critical region near the intersection line and the calculation point, which lies on the neutral axis of the shell. The study shows that the results obtained to date which are based on the shell theory and calculate stresses at a fictitious intersection line can be improved and that there is a possibility to get stress values adjacent to the real intersection line. (Auth.)
Finite element analysis of residual stress in plasma-sprayed ceramic
International Nuclear Information System (INIS)
Mullen, R.L.; Hendricks, R.C.; McDonald, G.
1985-01-01
Residual stress in a ZrO 2 -Y 2 O 3 ceramic coating resulting from the plasma spraying operation is calculated. The calculations were done using the finite element method. Both thermal and mechanical analysis were performed. The resulting residual stress field was compared to the measurements obtained by Hendricks and McDonald. Reasonable agreement between the predicted and measured moment occurred. However, the resulting stress field is not in pure bending
International Nuclear Information System (INIS)
Nishikawa, Masaaki; Soyama, Hitoshi
2011-01-01
Highlights: → The sensitivity to residual stress was improved by selecting the depth parameter. → Residual stress could be obtained while determining the effect of unknown parameters. → The estimated residual stress agreed well with those of X-ray diffraction. -- Abstract: The present study proposed a method to evaluate the equibiaxial compressive residual stress of a metal surface by means of a depth-sensing indentation method using a spherical indenter. Inverse analysis using the elastic-plastic finite-element model for an indentation test was established to evaluate residual stress from the indentation load-depth curve. The proposed inverse analysis utilizes two indentation test results for a reference specimen whose residual stress is already known and for a target specimen whose residual stress is unknown, in order to exclude the effect of other unknown mechanical properties, such as Young's modulus and yield stress. Residual stress estimated by using the indentation method is almost identical to that measured by X-ray diffraction for indentation loads of 0.49-0.98 N. Therefore, it can be concluded that the proposed method can effectively evaluate residual stress on metal surface.
Stress analysis on a PWR pressure vessel support structure
International Nuclear Information System (INIS)
Cruz, J.R.B.; Mattar Neto, M.; Jesus Miranda, C.A. de.
1992-01-01
The paper presents the stress analysis of a research PWR vessel support structure. Different geometries and thermal boundary conditions are evaluated. The finite element analysis is performed using ANSYS program. The ASME Section III criteria are applied for the stress verification and the following points are discussed: stress classification and linearization; jurisdictional boundary between ASME Subsection NB (Class 1 Components) and Subsection NF (Component Supports). (author)
Development of thermal stress screening method. Application of green function method
International Nuclear Information System (INIS)
Furuhashi, Ichiro; Shibamoto, Hiroshi; Kasahara, Naoto
2004-01-01
This work was achieved for the development of the screening method of thermal transient stresses in FBR components. We proposed an approximation method for evaluations of thermal stress under variable heat transfer coefficients (non-linear problems) using the Green functions of thermal stresses with constant heat transfer coefficients (linear problems). Detailed thermal stress analyses provided Green functions for a skirt structure and a tube-sheet of Intermediate Heat Exchanger. The upper bound Green functions were obtained by the analyses using those upper bound heat transfer coefficients. The medium and the lower bound Green functions were got by the analyses of those under medium and the lower bound heat transfer coefficients. Conventional evaluations utilized the upper bound Green functions. On the other hand, we proposed a new evaluation method by using the upper bound, medium and the lower bound Green functions. The comparison of above results gave the results as follows. The conventional evaluations were conservative and appropriate for the cases under one fluid thermal transient structure such as the skirt. The conventional evaluations were generally conservative for the complicated structures under two or more fluids thermal transients such as the tube-sheet. But the danger locations could exists for the complicated structures under two or more fluids transients, namely the conventional evaluations were non-conservative. The proposed evaluations gave good estimations for these complicated structures. Though above results, we have made the basic documents of the screening method of thermal transient stresses using the conventional method and the new method. (author)
Stress analysis of HLW containers. Compas project
International Nuclear Information System (INIS)
1989-01-01
This document reports the work carried out for the Compas project which looked at the performance of various computer codes in a selected benchmark exercise. This exercise consisted of several analyses on simplified models which have features typical of HLW containers. These analyses comprise two groups; one related to thick walled, stressed shell overpacks, the other related to thin walled, supported shell overpacks with a lead filler. The first set of analyses looked at an elastic-plastic behaviour and large deformation of a cylinder representative of the main body of thick walled containers). The second set looked at creep behaviour of the lead filler, and the shape the base of thin walled containers will take up, after hundreds of years in the repository. On the thick walled analyses with the cylinder subject to an external pressure all the codes gave consistent results in the elastic region and there is good agreement in the yield pressures. Once in the plastic region there is more divergence in the results although a consistent trend is predicted. One of the analyses predicted a non-axisymmetric mode of deformation as would be expected in reality. Fewer results were received for the creep analysis, however the transient creep results showed consistency, and were bounded by the final-state results
comparison of elastic-plastic FE method and engineering method for RPV fracture mechanics analysis
International Nuclear Information System (INIS)
Sun Yingxue; Zheng Bin; Zhang Fenggang
2009-01-01
This paper described the FE analysis of elastic-plastic fracture mechanics for a crack in RPV belt line using ABAQUS code. It calculated and evaluated the stress intensity factor and J integral of crack under PTS transients. The result is also compared with that by engineering analysis method. It shows that the results using engineering analysis method is a little larger than the results using FE analysis of 3D elastic-plastic fracture mechanics, thus the engineering analysis method is conservative than the elastic-plastic fracture mechanics method. (authors)
Estructuras de elevadores de carga. // Dumbwaiter structure stress analysis.
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G. Escobar Travieso
2006-09-01
Full Text Available Este trabajo tiene como objetivo analizar las tensiones y deformaciones que ocurren en las estructuras del marco de carro,plataforma y cabina de elevadores de carga mediante la aplicación del Método de los Elementos Finitos, específicamentedel montaplatos de 300 Kg. de capacidad, con vista a realizar el análisis de resistencia, racionalización del peso y material ylas posibles vías de solución.Palabras claves: Elevador de carga, estructuras, análisis de tensiones, elementos finitos.________________________________________________________________________________AbstractThis paper deals with the tension and deformation analysis in structures of lifter mark, platform and cabin offreight lifters by means of the Finite Elements Method, specifically the 300 kgs capacity dumbwaiter, in orderto carry out the resistance analysis, weight and material rationalization.Key words: Dumbwaiter, structures, stress analysis, finite elements.
Estructuras de elevadores de carga. // Dumbwaiter structure stress analysis.
Directory of Open Access Journals (Sweden)
G. Escobar Travieso
2004-05-01
Full Text Available Este trabajo tiene como objetivo analizar las tensiones y deformaciones que ocurren en las estructuras del marco de carro,plataforma y cabina de elevadores de carga mediante la aplicación del Método de los Elementos Finitos, específicamentedel montaplatos de 300 Kg. de capacidad, con vista a realizar el análisis de resistencia, racionalización del peso y material ylas posibles vías de solución.Palabras claves: Elevador de carga, estructuras, análisis de tensiones, elementos finitos._______________________________________________________________________________AbstractThis paper deals with the tension and deformation analysis in structures of lifter mark, platform and cabin offreight lifters by means of the Finite Elements Method, specifically the 300 kgs capacity dumbwaiter, in orderto carry out the resistance analysis, weight and material rationalization.Key words: Dumbwaiter, structures, stress analysis, finite elements.
Local stress analysis in devices by FIB
Kregting, R.; Gielen, A.W.J.; Driel, W. van; Alkemade, P.; Miro, H.; Kamminga, J.-D.
2010-01-01
Intrinsic stresses in bondpads may lead to early failure of IC's. In order to determine the intrinsic stresses in semiconductor structures, a new procedure is set up. This procedure is a combined experimental/numerical approach which consists of the following steps: First, a conductive gold layer
A simplified method of evaluating the stress wave environment of internal equipment
Colton, J. D.; Desmond, T. P.
1979-01-01
A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.
International Nuclear Information System (INIS)
Silva Junior, Silverio Ferreira da; Mansur, Tanius Rodrigues; Cruz, Julio Ricardo Barreto
2007-01-01
The knowledge about the stress state acting in structural elements has significant importance in the structural integrity evaluation of a specific component. The magnetic Barkhausen noise analysis can be used for this purpose. As a nondestructive testing method, it presents the advantage of not promote any changes in the tested component. In this paper, a study about the use of this new nondestructive test method for stress measurements is presented. The test system configuration and the reference standards used for this purpose, as well as the optimum test parameters determination are discussed. The experiments were carried out in ASTM A-36 steel, used for structural components manufacturing. A structure of this material was loaded and the resulting stresses were determined from strain gage measurements and Barkhausen noise analysis. The results obtained have showed a good sensitivity of the magnetic Barkhausen noise to stress changes occurred in the material. The main advantages and limitations of this test method for stress measurements are presented. (author)
Analysis of stress-strain relationships in silicon ribbon
Dillon, O. W., Jr.
1984-01-01
An analysis of stress-strain relationships in silicon ribbon is presented. A model to present entire process, dynamical Transit Analysis is developed. It is found that knowledge of past-strain history is significant in modeling activities.
Stress analysis of longwall top coal caving
Energy Technology Data Exchange (ETDEWEB)
Alehossein, H.; Poulsen, B.A. [CSIRO Exploration & Mining, Brisbane, Qld. (Australia)
2010-01-15
Longwall top coal caving (LTCC) is a relatively new method of mining thick coal seams that is currently achieving high productivity and efficiency. The technique is similar to traditional longwall mining in that a cutting head slices coal from the lower section of the coal seam onto a conveyor belt installed in front of the hydraulic support near the cutting face. In modern LTCC an additional rear conveyor belt is located behind the support, to which the flow of the caved coal from the upper part of the seam can be controlled by a moveable flipper attached to the canopy of the support. The mining method relies on the fracturing of the top coal by the front abutment pressure to achieve satisfactory caving into the rear conveyor. This paper develops a yield and caveability criterion based on in situ conditions in the top coal in advance of the mining face (yield) and behind the supports (caveability). Yielding and caving effects are combined into one single number called caving number (CN), which is the multiplication result of caving factor (CF) and yield factor (YF). Analytical derivations are based on in situ stress conditions, Mohr-Coulomb and/or Hoek-Brown rock failure criteria and an on-associated elastoplastic strain softening material behaviour. The yield and caveability criteria are in agreement with results from both numerical studies and mine data. The caving number is normalised to mining conditions of a reference Chinese mine (LMX mine) and is used to assess LTCC performance at fourteen other Chinese working longwalls that have had varying success with the LTCC technology. As a predictive model, results of this analytical/numerical study are useful to assess the potential success of caving in new LTCC operations and in different mining conditions.
Effect of heating method on stress-rupture life
Bizon, P. T.; Calfo, F. D.
1977-01-01
The effect of radiant(furnace), resistance(electric current), burner(hot gas stream), and a combination of resistance and burner heating on intermediate time (100 to 300 hr) stress-rupture life and reduction of area was evaluated. All heating methods were studied using the nickel-based alloy Udimet 700 while all but burner heating were evaluated with the cobalt-based alloy Mar-M 509. Limited test results of eight other superalloys were also included in this study. Resistance heated specimens had about 20 to 30 percent of the stress-rupture life of radiant heated specimens. The limited burner heating data showed about a 50 percent life reduction as compared to the radiant heated tests. A metallurgical examination gave no explanation for these reductions.
A novel hybrid stress-function finite element method immune to severe mesh distortion
International Nuclear Information System (INIS)
Cen Song; Zhou Mingjue; Fu Xiangrong
2010-01-01
This paper introduces a hybrid stress-function finite element method proposed recently for developing 2D finite element models immune to element shapes. Deferent from the first version of the hybrid-stress element constructed by Pian, the stress function φ of 2D elastic or fracture problem is regarded as the functional variable of the complementary energy functional. Then, the basic analytical solutions of φ are taken as the trial functions for finite element models, and meanwhile, the corresponding unknown stress-function constants are introduced. By using the principle of minimum complementary energy, these unknown stress-function constants can be expressed in terms of the displacements along element edges. Finally, the complementary energy functional can be rewritten in terms of element nodal displacement vector, and thus, the element stiffness matrix of such hybrid-function element can be obtained. As examples, two (8- and 12-node) quadrilateral plane elements and an arbitrary polygonal crack element are constructed by employing different basic analytical solutions of different stress functions. Numerical results show that, the 8- and 12-node plane models can produce the exact solutions for pure bending and linear bending problems, respectively, even the element shape degenerates into triangle and concave quadrangle; and the crack element can also predict accurate results with very low computational cost in analysis of stress-singularity problems.
Analysis of pipe stress using CAESAR II code
International Nuclear Information System (INIS)
Sitandung, Y.B.; Bandriyana, B.
2002-01-01
Analysis of this piping stress with the purpose of knowing stress distribution piping system in order to determine pipe supports configuration. As an example of analysis, Gas Exchanger to Warm Separator Line was chosen with, input data was firstly prepared in a document, i.e. piping analysis specification that its content named as pipe characteristics, material properties, operation conditions, guide equipment's and so on. Analysis result such as stress, load, displacement and the use support type were verified based on requirements in the code, standard, and regularities were suitable with piping system condition analyzed. As the proof that piping system is in safety condition, it can be indicated from analysis results (actual loads) which still under allowable load. From the analysis steps that have been done CAESAR II code fulfill requirements to be used as a tool of piping stress analysis as well as nuclear and non nuclear installation piping system
SWOT ANALYSIS ON SAMPLING METHOD
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CHIS ANCA OANA
2014-07-01
Full Text Available Audit sampling involves the application of audit procedures to less than 100% of items within an account balance or class of transactions. Our article aims to study audit sampling in audit of financial statements. As an audit technique largely used, in both its statistical and nonstatistical form, the method is very important for auditors. It should be applied correctly for a fair view of financial statements, to satisfy the needs of all financial users. In order to be applied correctly the method must be understood by all its users and mainly by auditors. Otherwise the risk of not applying it correctly would cause loose of reputation and discredit, litigations and even prison. Since there is not a unitary practice and methodology for applying the technique, the risk of incorrectly applying it is pretty high. The SWOT analysis is a technique used that shows the advantages, disadvantages, threats and opportunities. We applied SWOT analysis in studying the sampling method, from the perspective of three players: the audit company, the audited entity and users of financial statements. The study shows that by applying the sampling method the audit company and the audited entity both save time, effort and money. The disadvantages of the method are difficulty in applying and understanding its insight. Being largely used as an audit method and being a factor of a correct audit opinion, the sampling method’s advantages, disadvantages, threats and opportunities must be understood by auditors.
Recent Advances in the Method of Forces: Integrated Force Method of Structural Analysis
Patnaik, Surya N.; Coroneos, Rula M.; Hopkins, Dale A.
1998-01-01
Stress that can be induced in an elastic continuum can be determined directly through the simultaneous application of the equilibrium equations and the compatibility conditions. In the literature, this direct stress formulation is referred to as the integrated force method. This method, which uses forces as the primary unknowns, complements the popular equilibrium-based stiffness method, which considers displacements as the unknowns. The integrated force method produces accurate stress, displacement, and frequency results even for modest finite element models. This version of the force method should be developed as an alternative to the stiffness method because the latter method, which has been researched for the past several decades, may have entered its developmental plateau. Stress plays a primary role in the development of aerospace and other products, and its analysis is difficult. Therefore, it is advisable to use both methods to calculate stress and eliminate errors through comparison. This paper examines the role of the integrated force method in analysis, animation and design.
Tranos, Markos D.
2018-02-01
Synthetic heterogeneous fault-slip data as driven by Andersonian compressional stress tensors were used to examine the efficiency of best-fit stress inversion methods in separating them. Heterogeneous fault-slip data are separated only if (a) they have been driven by stress tensors defining 'hybrid' compression (R constitute a necessary discriminatory tool for the establishment and comparison of two compressional stress tensors determined by a best-fit stress inversion method. The best-fit stress inversion methods are not able to determine more than one 'real' compressional stress tensor, as far as the thrust stacking in an orogeny is concerned. They can only possibly discern stress differences in the late-orogenic faulting processes, but not between the main- and late-orogenic stages.
Problems of stress analysis of fuelling machine head components
International Nuclear Information System (INIS)
Mathur, D.D.
1975-01-01
The problem of stress analysis of fuelling machine head components are discussed. To fulfil the functional requirements, the components are required to have certain shapes where stress problems cannot be matched to a catalogue of pre-determined solutions. The areas where complex systems of loading due to hydrostatic pressure, weight, moments and temperature gradients coupled with the intricate shapes of the components make it difficult to arrive at satisfactory solutions. Particularly, the analysis requirements of the magazine housing, end cover, gravloc clamps and centre support are highlighted. An experimental stress analysis programme together with a theoretical finite element analysis is perhaps the answer. (author)
Stress analysis for nuclear power plant components
International Nuclear Information System (INIS)
Mueller, R.A.
1981-09-01
The general procedure for a meaningful stress evaluation will be outlined. The extremely aggravated conditions prevailing at elevated temperatures, at which creep effects can no longer be neglected, will also be touched upon briefly. (E.G.) [pt
DEVELOPMENT OF COILED TUBING STRESS ANALYSIS
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Davorin Matanović
1998-12-01
Full Text Available The use of coiled tubing is increasing rapidly with drilling of horizontal wells. To satisfy all requirements (larger mechanical stresses, larger fluid capacities the production of larger sizes and better material qualities was developed. Stresses due to axial forces and pressures that coiled tubing is subjected are close to its performance limits. So it is really important to know and understand the behaviour of coiled tubing to avoid its break, burst or collapse in the well.
Residual stresses analysis of friction stir welding using one-way FSI simulation
International Nuclear Information System (INIS)
Kang, Sung Wook; Jang, Beom Seon; Song, Ha Cheol
2015-01-01
When certain mechanisms, such as plastic deformations and temperature gradients, occur and are released in a structure, stresses remain because of the shape of the structure and external constraints. These stresses are referred to as residual stresses. The base material locally expands during heating in the welding process. When the welding is completed and cooled to room temperature, the residual stresses are left at nearly the yield strength level. In the case of friction stir welding, the maximum temperature is 80% to 90% of the melting point of the materials. Thus, the residual stresses in the welding process are smaller than those in other fusion welding processes; these stresses have not been considered previously. However, friction stir welding residual stresses are sometimes measured at approximately 70% or above. These residual stresses significantly affect fatigue behavior and lifetime. The present study investigates the residual stress distributions in various welding conditions and shapes of friction stir welding. In addition, the asymmetric feature is considered in temperature and residual stress distribution. Heat transfer analysis is conducted using the commercial computational fluid dynamics program Fluent, and results are used in the finite element structural analysis with the ANSYS Multiphysics software. The calculated residual stresses are compared with experimental values using the X-ray diffraction method.
Initial stress and nonlinear material behavior in patient-specific AAA wall stress analysis
Speelman, L.; Bosboom, E.M.H.; Schurink, G.W.H.; Buth, J.; Breeuwer, M.; Jacobs, M.J.; Vosse, van de F.N.
2009-01-01
Rupture risk estimation of abdominal aortic aneurysms (AAA) is currently based on the maximum diameter of the AAA. A more critical approach is based on AAA wall stress analysis. For that, in most cases, the AAA geometry is obtained from CT-data and treated as a stress free geometry. However, during
A comparative study of different techniques in the stress analysis of a nuclear component
International Nuclear Information System (INIS)
Dickenson, P.W.; Floyd, C.G.
1985-01-01
The inner surface stresses around the corner between the cylindrical wall and end plate of a flat ended pressure vessel have been determined using finite element, boundary element and photoelastic techniques. The results demonstrate severe deficiencies under certain conditions in the performance of the quadrilateral axisymmetric finite element which is commonly used in this type of analysis. The boundary element method is shown to provide an alternative analysis route giving more accurate results. The hybrid formulation finite element is also found to give reasonable results for the analysis of stresses in regions of rapidly varying stress. (orig.)
Detection of Stress Hormone in the Milk for Animal Welfare Using QCM Method
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Takeshi Ito
2017-01-01
Full Text Available We developed a rapid and sequential analysis system to determine stress marker in the milk. One of the famous stress markers, cortisol, was detected using our method. Quartz crystal microbalance (QCM method with a twin sensor was used in this study. One channel detected stress marker corresponding to antigen-antibody interaction and the other channel was used as a reference to remove environmental influences. Although nonspecific adsorption was monitored on each channel, frequency difference between them was within a few Hz on the injection of sample solution. One determination cycle including regeneration step could be performed within 10 minutes. The system could detect the cortisol level from 0.1 pg/mL to 100 pg/mL. These results show that our system has a potential to check the daily feeding condition for cows in terms of animal welfare.
Stress analysis of plate-fin structures in recuperator
International Nuclear Information System (INIS)
Matsui, Shingo; Muto, Yasushi; Shiina, Yasuaki
2001-01-01
A high performance compact recuperator with 95% effectiveness is required to achieve a high thermal efficiency power generation of up to 50% in High Temperature Gas Cooled Reactor (HTGR) coupled with closed cycle helium gas turbine. Though a plate-fin type heat exchanger is proposed for this recuperator, much research and development works are needed to establish this high performance goal since there exists no state-of-the-art technology in such a high pressure and high temperature one. One of the important works is to establish the structural analysis and evaluation method in this plate-fin type heat exchanger. This paper describes the results of stress analysis of the plate-fin structure under the internal pressure as the first step of this work. First, the modeling of a unit plate-fin structure for the analysis was examined and a three layers model was confirmed to be most adequate. The stress distribution within the structure was clarified by using this model. Second, the three layers model was simplified to one layer model with sufficient accuracy. By using this model, both the effects of an inclined angle of fin and a thickness of separate on the strength were examined parametrically. Under the relevant design conditions, it was revealed that the optimum inclined angle of fin locates in the neighborhood of 76 degree rather than most difficult fabrication angle 90 degree and there is possibility to adopt thinner thickness than 0.5 mm in the current design. (author)
PIPE STRESS and VERPIP codes for stress analysis and verifications of PEC reactor piping
International Nuclear Information System (INIS)
Cesari, F.; Ferranti, P.; Gasparrini, M.; Labanti, L.
1975-01-01
To design LMFBR piping systems following ASME Sct. III requirements unusual flexibility computer codes are to be adopted to consider piping and its guard-tube. For this purpose PIPE STRESS code previously prepared by Southern-Service, has been modified. Some subroutine for detailed stress analysis and principal stress calculations on all the sections of piping have been written and fitted in the code. Plotter can also be used. VERPIP code for automatic verifications of piping as class 1 Sct. III prescriptions has been also prepared. The results of PIPE STRESS and VERPIP codes application to PEC piping are in section III of this report
Probabilistic analysis of structures involving random stress-strain behavior
Millwater, H. R.; Thacker, B. H.; Harren, S. V.
1991-01-01
The present methodology for analysis of structures with random stress strain behavior characterizes the uniaxial stress-strain curve in terms of (1) elastic modulus, (2) engineering stress at initial yield, (3) initial plastic-hardening slope, (4) engineering stress at point of ultimate load, and (5) engineering strain at point of ultimate load. The methodology is incorporated into the Numerical Evaluation of Stochastic Structures Under Stress code for probabilistic structural analysis. The illustrative problem of a thick cylinder under internal pressure, where both the internal pressure and the stress-strain curve are random, is addressed by means of the code. The response value is the cumulative distribution function of the equivalent plastic strain at the inner radius.
Energy Technology Data Exchange (ETDEWEB)
Mirbach, David von
2014-07-28
Residual stresses in mechanical components can result in both detrimental but also beneficial effects on the strength and lifetime of the components. The most detailed knowledge of the residual stress state is of advantage or a pre-requisite for the assessment of the component performance. The mechanical methods for residual stress measurement are divided into the groups of non-destructive and destructive methods. Two commonly used mechanical methods for determination of residual stresses are the hole drilling method and the ring core method which can be regarded as semi-destructive methods. In the context of reactor safety research of the German Federal Ministry of Economic and Technology (BMWi) two fundamental and interacting weak points of the hole drilling method as well as of the ring core method, respectively, in order to determine residual stresses are going to be investigated. As a consequence reliability of the methods will be improved in this joint research project. On the one hand there are effects of geometrical boundary conditions of the components and on the other hand there is the influence of plasticity due to notch effects both affecting the released strain field after removing material and after all the calculated residual stresses. The first issue mentioned above is under the responsibility of the Institute of Materials Engineering (Kassel University) and the last one is investigated by Universitaet of Stuttgart-Otto-Graf-Institut - materials testing institute. As a consequence of a successful project the knowledge base will be considerably improved resulting in benefits for various engineering fields. Especially the quantitative consideration of real residual stress states for optimized component designs will be possible and after all the consequences of residual stresses on safety of components which are used in nuclear facilities can be evaluated. The state of art was reground in the first research chapter and the analysed strain gauges where
Stress analysis of pressure vessels in nuclear power plants: pt.2
International Nuclear Information System (INIS)
Kim, C.W.; Chu, Y.W.
1976-01-01
Stress analysis of tapered cylinder of reactor vessels in investigated by means of the intersection method. The tapered cylinder is approximated into three models average cylinder, conical frustum, and ring. The results are compared with those of the finite element method program and an experiment. In this paper, the following results are obtained: (1) the best approximation has been obtained by the ring model analysis: (2) the intersection analysis of the tapered cylinder by the ring model shows a sufficient accuracy for the stress analysis of reactor vessels. (author)
Mechanical stress calculations for toroidal field coils by the finite element method
International Nuclear Information System (INIS)
Soell, M.; Jandl, O.; Gorenflo, H.
1976-09-01
After discussing fundamental relationships of the finite element method, this report describes the calculation steps worked out for mechanical stress calculations in the case of magnetic forces and forces produced by thermal expansion or compression of toroidal field coils using the SOLID SAP IV computer program. The displacement and stress analysis are based on the 20-node isoparametric solid element. The calculation of the nodal forces produced by magnetic body forces are discussed in detail. The computer programs, which can be used generally for mesh generation and determination of the nodal forces, are published elsewhere. (orig.) [de
Flows method in global analysis
International Nuclear Information System (INIS)
Duong Minh Duc.
1994-12-01
We study the gradient flows method for W r,p (M,N) where M and N are Riemannian manifold and r may be less than m/p. We localize some global analysis problem by constructing gradient flows which only change the value of any u in W r,p (M,N) in a local chart of M. (author). 24 refs
Fracture mechanics and residual fatigue life analysis for complex stress fields. Technical report
International Nuclear Information System (INIS)
Besuner, P.M.
1975-07-01
This report reviews the development and application of an influence function method for calculating stress intensity factors and residual fatigue life for two- and three-dimensional structures with complex stress fields and geometries. Through elastic superposition, the method properly accounts for redistribution of stress as the crack grows through the structure. The analytical methods used and the computer programs necessary for computation and application of load independent influence functions are presented. A new exact solution is obtained for the buried elliptical crack, under an arbitrary Mode I stress field, for stress intensity factors at four positions around the crack front. The IF method is then applied to two fracture mechanics problems with complex stress fields and geometries. These problems are of current interest to the electric power generating industry and include (1) the fatigue analysis of a crack in a pipe weld under nominal and residual stresses and (2) fatigue analysis of a reactor pressure vessel nozzle corner crack under a complex bivariate stress field
Thermal stress measurement in continuous welded rails using the hole-drilling method
Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood
2016-04-01
The absence of expansion joints in Continuous Welded Rail (CWR) has created the need for the railroad industry to determine the in-situ level of thermal stresses so as to prevent train accidents caused by rail buckling in hot weather and by rail breakage in cold weather. The development of non-destructive or semi-destructive methods for determining the level of thermal stresses in rails is today a high research priority. This study explores the known hole-drilling method as a possible solution to this problem. A new set of calibration coefficients to compute the relieved stress field with the finer hole depth increments was determined by a 3D Finite Element Analysis that modeled the entire hole geometry, including the mechanics of the hole bottom and walls. To compensate the residual stress components, a linear relationship was experimentally established between the longitudinal and the vertical residual stresses of two common sizes of rails, the 136RE and the 141RE, with statistical significance. This result was then utilized to isolate the longitudinal thermal stress component in hole-drilling tests conducted on the 136RE and 141RE thermally-loaded rails at the Large-scale CWR Test-bed of UCSD's Powell Research Laboratories. The results from the Test-bed showed that the hole-drilling procedure, with the appropriate residual stress compensation, can indeed estimate the in-situ thermal stresses to achieve a +/-5°F accuracy of Neutral Temperature determination with a 90% statistical confidence, which is the desired industry gold standard.
Ceramic ball grid array package stress analysis
Badri, S. H. B. S.; Aziz, M. H. A.; Ong, N. R.; Sauli, Z.; Alcain, J. B.; Retnasamy, V.
2017-09-01
The ball grid array (BGA), a form of chip scale package (CSP), was developed as one of the most advanced surface mount devices, which may be assembled by an ordinary surface ball bumps are used instead of plated nickel and gold (Ni/Au) bumps. Assembly and reliability of the BGA's printed circuit board (PCB), which is soldered by conventional surface mount technology is considered in this study. The Ceramic Ball Grid Array (CBGA) is a rectangular ceramic package or square-shaped that will use the solder ball for external electrical connections instead of leads or wire for connections. The solder balls will be arranged in an array or grid at the bottom of the ceramic package body. In this study, ANSYS software is used to investigate the stress on the package for 2 balls and 4 balls of the CBGA package with the various force range of 1-3 Newton applied to the top of the die, top of the substrate and side of the substrate. The highest maximum stress was analyzed and the maximum equivalent stress was observed on the solder ball and the die. From the simulation result, the CBGA package with less solder balls experience higher stress compared to the package with many solder balls. Therefore, less number of solder ball on the CBGA package results higher stress and critically affect the reliability of the solder balls itself, substrate and die which can lead to the solder crack and also die crack.
Stress and deflection analyses of floating roofs based on a load-modifying method
International Nuclear Information System (INIS)
Sun Xiushan; Liu Yinghua; Wang Jianbin; Cen Zhangzhi
2008-01-01
This paper proposes a load-modifying method for the stress and deflection analyses of floating roofs used in cylindrical oil storage tanks. The formulations of loads and deformations are derived according to the equilibrium analysis of floating roofs. Based on these formulations, the load-modifying method is developed to conduct a geometrically nonlinear analysis of floating roofs with the finite element (FE) simulation. In the procedure with the load-modifying method, the analysis is carried out through a series of iterative computations until a convergence is achieved within the error tolerance. Numerical examples are given to demonstrate the validity and reliability of the proposed method, which provides an effective and practical numerical solution to the design and analysis of floating roofs
Texture, residual stress and structural analysis of thin films using a combined X-ray analysis
International Nuclear Information System (INIS)
Lutterotti, L.; Chateigner, D.; Ferrari, S.; Ricote, J.
2004-01-01
Advanced thin films for today's industrial and research needs require highly specialized methodologies for a successful quantitative characterization. In particular, in the case of multilayer and/or unknown phases a global approach is necessary to obtain some or all the required information. A full approach has been developed integrating novel texture and residual stress methodologies with the Rietveld method (Acta Cryst. 22 (1967) 151) (for crystal structure analysis) and it has been coupled with the reflectivity analysis. The complete analysis can be done at once and offers several benefits: the thicknesses obtained from reflectivity can be used to correct the diffraction spectra, the phase analysis help to identify the layers and to determine the electron density profile for reflectivity; quantitative texture is needed for quantitative phase and residual stress analyses; crystal structure determination benefits of the previous. To achieve this result, it was necessary to develop some new methods, especially for texture and residual stresses. So it was possible to integrate them in the Rietveld, full profile fitting of the patterns. The measurement of these spectra required a special reflectometer/diffractometer that combines a thin parallel beam (for reflectivity) and a texture/stress goniometer with a curved large position sensitive detector. This new diffraction/reflectivity X-ray machine has been used to test the combined approach. Several spectra and the reflectivity patterns have been collected at different tilting angles and processed at once by the special software incorporating the aforementioned methodologies. Some analysis examples will be given to show the possibilities offered by the method
Oeij, P.R.A.
2002-01-01
In this paper of the World Congress of Sociology 2002 of ISA (International Sociological Association), the content and uses of the Job Stress Self Diagnostic Method (JSSDM) are described. The JSSDM aim is (a) to diagnose work processes to determine the presence of conditions for control problems and stress risks, and (b) to develop solutions to combat stress risks on organisational level. The method is based on three theories of job and organisation design and on the insight to combine viewpo...
Test with different stress measurement methods in two orthogonal bore holes in Aespoe HRL
Energy Technology Data Exchange (ETDEWEB)
Janson, Thomas; Stigsson, Martin [Golder Associates AB, Stockholm (Sweden)
2002-12-01
Within the scope of work, to provide the necessary rock mechanics support for the site investigations, SKB has studied some available pieces of equipment for in situ stress measurements in deep boreholes. A project with the objective to compare three different pieces of equipment for in situ stress measurements under similar conditions has been carried out. The main objective for the project is to compare the three different pieces of equipment for in situ stress measurements and find a strategy for SKB's Site Investigations to determine the state of stress in the rock mass. Two units of equipment use the overcoring method while the third uses the hydraulic fracturing method. The overcoring was performed by AECL, using Deep Door stopper Gauge System (DDGS), and SwedPower, using their triaxial strain measuring instrument (Borre Probe). MeSy Geo Systeme GmbH performed the hydraulic fracturing. The DDGS system is a new method to SKB while the experience of the SwedPower overcoring and the hydraulic fracturing methods are long. The tests were performed in the same orthogonal boreholes at Aespoe Hard Rock Laboratory (HRL), Oskarshamn, Sweden. The measured results have been verified against known conditions at the Aespoe HRL. The results from the three in situ stress measurement methods rose more questions than answers. Which illustrate the complexity to determine the in situ stresses in a rock mass. To understand the difference in results and answer the questions, it was necessary to do deeper investigations such as laboratory tests and theoretical calculations such as geological structure model, analysis of the influence of a nearby fracture, P-wave measurements, uniaxial tests on small cores from the HQ-3 core, theoretical and numerical analyses of the hole bottom (theoretical strains, stress concentrations and microcracking), auditing of DDGS measurements results and assumptions in the DDGS analyse and microscopy investigations on the cores. The following
A different approach to X-ray stress analysis
Energy Technology Data Exchange (ETDEWEB)
Ogilvie, Robert E. [Massachusetts Institute of Technology, Room 13-5065, 77 Massachusetts Ave., Cambridge, MA (United States)], E-mail: bobogil@mit.edu
2007-07-15
A different approach to X-ray stress analysis has been developed. At the outset, it must be noted that the material to be analyzed is assumed homogeneous and isotropic. If a sphere with radius r within a specimen is subjected to a state of stress, the sphere is deformed into an ellipsoid. The semi-axes of the ellipsoid have the values of (r + {epsilon}{sub x}), (r + {epsilon}{sub y}), and (r + {epsilon}{sub z}), which are replaced by d{sub x}, d{sub y}, and d{sub z}, or for the cubic case, a{sub x}, a{sub y}, and a{sub z}. In this technique, at a particular {phi} angle (see ), the two-theta position of a high angle (hkl) peak is determined at {psi} angles of 0, 15, 30, and 45{sup o}. These measurements are repeated for 3 to 6 {phi} angles in steps of 30{sup o}. The d{sub {phi}}{sub {psi}} or a{sub {phi}}{sub {psi}} values are then determined from the peak positions. The data is then fitted to the general quadratic equation for an ellipsoid by the method of least squares. From the coefficients of the quadratic equation, the angle between the laboratory and the specimen coordinates (direction of the principle stress) can be determined. Applying the general rotation of axes equations to the quadratic, the equation of the ellipse in the x-y plane is determined. The a{sub x}, a{sub y}, and a{sub z} values for the principal axes of the lattice parameter ellipsoid are then evaluated. It is then possible to determine the unstressed a{sub 0} value from Hooke's Law using a{sub x}, a{sub y}, and a{sub z}. The magnitude of the principal strains/stresses is then determined.
SLAC divertor channel entrance thermal stress analysis
International Nuclear Information System (INIS)
Johnson, G.L.; Stein, W.; Lu, S.C.; Riddle, R.A.
1985-01-01
X-ray beams emerging from the new SLAC electron-positron storage ring (PEP) impinge on the entrance to tangential divertor channels causing highly localized heating in the channel structure. Analyses were completed to determine the temperatures and thermally-induced stresses due to this heating. These parts are cooled with water flowing axially over them at 30 0 C. The current design and operating conditions should result in the entrance to the new divertor channel operating at a peak temperature of 123 0 C with a peak thermal stress at 91% of yield. Any micro-cracks that form due to thermally-induced stresses should not propagate to the coolant wall nor form a path for the coolant to leak into the storage ring vacuum. 34 figs., 4 tabs
Analysis of primary teacher stress' sources
Directory of Open Access Journals (Sweden)
Katja Depolli Steiner
2011-12-01
Full Text Available Teachers are subject to many different work stressors. This study focused on differences in intensity and frequency of potential stressors facing primary schoolteachers and set the goal to identify the most important sources of teacher stress in primary school. The study included 242 primary schoolteachers from different parts of Slovenia. We used Stress Inventory that is designed for identification of intensity and frequency of 49 situations that can play the role of teachers' work stressors. Findings showed that the major sources of stress facing teachers are factors related to work overload, factors stemming from pupils' behaviour and motivation and factors related to school system. Results also showed some small differences in perception of stressors in different groups of teachers (by gender and by teaching level.
Energy Technology Data Exchange (ETDEWEB)
Han, Bing; Jing, Hongyuan; Liu, Jianping; Wu, Zhangzhong [PetroChina Pipeline RandD Center, Langfang, Hebei (China); Hao, Jianbin [School of Petroleum Engineering, Southwest Petroleum University, Chengdu, Sichuan (China)
2010-07-01
Landslides have a serious impact on the integrity of oil and gas pipelines in the tough terrain of Western China. This paper introduces a solving method of axial stress, which uses numerical simulation and regression analysis for the pipelines subjected to landslides. Numerical simulation is performed to analyze the change regularity of pipe stresses for the five vulnerability assessment indexes, which are: the distance between pipeline and landslide tail; the thickness of landslide; the inclination angle of landslide; the pipeline length passing through landslide; and the buried depth of pipeline. A pipeline passing through a certain landslide in southwest China was selected as an example to verify the feasibility and effectiveness of this method. This method has practical applicability, but it would need large numbers of examples to better verify its reliability and should be modified accordingly. Also, it only considers the case where the direction of the pipeline is perpendicular to the primary slip direction of the landslide.
Preliminary thermal and stress analysis of the SINQ window
International Nuclear Information System (INIS)
Heidenreich, G.
1991-01-01
Preliminary results of a finite element analysis for the SINQ proton beam window are presented. Temperatures and stresses are calculated in an axisymmetric model. As a result of these calculations, the H 2 O-cooled window (safety window) could be redesigned in such a way that plastic deformation resulting from excessive stress in some areas is avoided. (author)
Wu, Xian-Qian; Wang, Xi; Wei, Yan-Peng; Song, Hong-Wei; Huang, Chen-Guang
2012-06-01
Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and resistance to corrosion fatigue, cracking, etc. Compressive residual stress and dent profile are important factors to evaluate the effectiveness of shot peening process. In this paper, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of processing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were deduced by dimensional analysis method. Secondly, the influence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Furthermore, related empirical formulas were given for each dimensionless parameter based on the simulation results. Finally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this paper for analyzing the influence of each individual parameter.
Study on elastic-plastic deformation analysis using a cyclic stress-strain curve
International Nuclear Information System (INIS)
Igari, Toshihide; Setoguchi, Katsuya; Yamauchi, Masafumi
1983-01-01
This paper presents the results of the elastic-plastic deformation analysis using a cyclic stress-strain curve with an intention to apply this method for predicting the low-cycle fatigue life. Uniaxial plastic cycling tests were performed on 2 1/4Cr-1Mo steel to investigate the correspondence between the cyclic stress-strain curve and the hysteresis loop, and also to determine what mathematical model should be used for analysis of deformation at stress reversal. Furthermore, a cyclic in-plane bending test was performed on a flat plate to clarify the validity of the cyclic stress-strain curve-based theoretical analysis. The results obtained are as follows: (1) The cyclic stress-strain curve corresponds nearly to the ascending curve of hysteresis loop scaled by a factor of 1/2 for both stress and strain. Therefore, the cyclic stress-strain curve can be determined from the shape of hysteresis loop, for simplicity. (2) To perform the elastic-plastic deformation analysis using the cyclic stress-strain curve is both practical and effective for predicting the cyclic elastic-plastic deformation of structures at the stage of advanced cycles. And Masing model can serve as a suitable mathematical model for such a deformation analysis. (author)
Rethinking Stress in Parents of Preterm Infants: A Meta-Analysis
Schappin, Renske; Wijnroks, Lex; Uniken Venema, Monica M. A. T.; Jongmans, Marian J.
2013-01-01
Background With improved medical outcome in preterm infants, the psychosocial situation of their families is receiving increasing attention. For parents, the birth of a preterm infant is generally regarded as a stressful experience, and therefore many interventions are based on reducing parental stress. Nevertheless, it remains unclear whether parents of children born preterm experience more stress than parents of term-born children, which would justify these interventions. This meta-analysis provides a comprehensive account of parental stress in parents of preterm infants, from birth of the infant through to their adolescence. Mean levels of stress in specific domains of family functioning were investigated, and stress levels in parents of preterm and term infants, and fathers and mothers of preterm infants, were compared. Furthermore, we investigated moderators of parental stress. Methods and Findings A random-effects meta-analysis was conducted including 38 studies describing 3025 parents of preterm (stress was measured with two parent-reported questionnaires, the Parenting Stress Index and the Parental Stressor Scale: Neonatal Intensive Care Unit. The results indicate that parents of preterm-born children experience only slightly more stress than parents of term-born children, with small effect sizes. Furthermore, mothers have slightly more stress than fathers, but these effect sizes are also small. Parents report more stress for infants with lower gestational ages and lower birth weights. There is a strong effect for infant birth year, with decreasing parental stress from the 1980s onward, probably due to increased quality of care for preterm infants. Conclusions Based on our findings we argue that prematurity can best be regarded as one of the possible complications of birth, and not as a source of stress in itself. PMID:23405105
A novel method for estimating soil precompression stress from uniaxial confined compression tests
DEFF Research Database (Denmark)
Lamandé, Mathieu; Schjønning, Per; Labouriau, Rodrigo
2017-01-01
. Stress-strain curves were obtained by performing uniaxial, confined compression tests on undisturbed soil cores for three soil types at three soil water potentials. The new method performed better than the Gompertz fitting method in estimating precompression stress. The values of precompression stress...... obtained from the new method were linearly related to the maximum stress experienced by the soil samples prior to the uniaxial, confined compression test at each soil condition with a slope close to 1. Precompression stress determined with the new method was not related to soil type or dry bulk density......The concept of precompression stress is used for estimating soil strength of relevance to fieldtraffic. It represents the maximum stress experienced by the soil. The most recently developed fitting method to estimate precompression stress (Gompertz) is based on the assumption of an S-shape stress...
Thermal stress analysis of gravity support system for ITER based on ANSYS
International Nuclear Information System (INIS)
Liang Shangming; Yan Xijiang; Huang Yufeng; Wang Xianzhou; Hou Binglin; Li Pengyuan; Jian Guangde; Liu Dequan; Zhou Caipin
2009-01-01
A method for building the finite element model of the gravity support system for International Thermonuclear Experimental Reactor (ITER) was proposed according to the characteristics of the gravity support system with the cyclic symmetry. A mesh dividing method, which has high precision and an acceptable calculating scale, was used, and a three dimensional finite element model for the toroidal 20 degree sector of the gravity support system was built by using ANSYS. Meantime, the steady-state thermal analysis and thermal-structural coupling analysis of the gravity support system were performed. The thermal stress distributions and the maximal thermal stress values of all parts of the gravity support system were obtained, and the stress intensity of parts of the gravity support system was analyzed. The results of thermal stress analysis lay the solid foundation for design and improvement for gravity supports system for ITER. (authors)
Directory of Open Access Journals (Sweden)
Donald D. Anderson
2012-01-01
Full Text Available Recent findings suggest that contact stress is a potent predictor of subsequent symptomatic osteoarthritis development in the knee. However, much larger numbers of knees (likely on the order of hundreds, if not thousands need to be reliably analyzed to achieve the statistical power necessary to clarify this relationship. This study assessed the reliability of new semiautomated computational methods for estimating contact stress in knees from large population-based cohorts. Ten knees of subjects from the Multicenter Osteoarthritis Study were included. Bone surfaces were manually segmented from sequential 1.0 Tesla magnetic resonance imaging slices by three individuals on two nonconsecutive days. Four individuals then registered the resulting bone surfaces to corresponding bone edges on weight-bearing radiographs, using a semi-automated algorithm. Discrete element analysis methods were used to estimate contact stress distributions for each knee. Segmentation and registration reliabilities (day-to-day and interrater for peak and mean medial and lateral tibiofemoral contact stress were assessed with Shrout-Fleiss intraclass correlation coefficients (ICCs. The segmentation and registration steps of the modeling approach were found to have excellent day-to-day (ICC 0.93–0.99 and good inter-rater reliability (0.84–0.97. This approach for estimating compartment-specific tibiofemoral contact stress appears to be sufficiently reliable for use in large population-based cohorts.
High performance thermal stress analysis on the earth simulator
International Nuclear Information System (INIS)
Noriyuki, Kushida; Hiroshi, Okuda; Genki, Yagawa
2003-01-01
In this study, the thermal stress finite element analysis code optimized for the earth simulator was developed. A processor node of which of the earth simulator is the 8-way vector processor, and each processor can communicate using the message passing interface. Thus, there are two ways to parallelize the finite element method on the earth simulator. The first method is to assign one processor for one sub-domain, and the second method is to assign one node (=8 processors) for one sub-domain considering the shared memory type parallelization. Considering that the preconditioned conjugate gradient (PCG) method, which is one of the suitable linear equation solvers for the large-scale parallel finite element methods, shows the better convergence behavior if the number of domains is the smaller, we have determined to employ PCG and the hybrid parallelization, which is based on the shared and distributed memory type parallelization. It has been said that it is hard to obtain the good parallel or vector performance, since the finite element method is based on unstructured grids. In such situation, the reordering is inevitable to improve the computational performance [2]. In this study, we used three reordering methods, i.e. Reverse Cuthil-McKee (RCM), cyclic multicolor (CM) and diagonal jagged descending storage (DJDS)[3]. RCM provides the good convergence of the incomplete lower-upper (ILU) PCG, but causes the load imbalance. On the other hand, CM provides the good load balance, but worsens the convergence of ILU PCG if the vector length is so long. Therefore, we used the combined-method of RCM and CM. DJDS is the method to store the sparse matrices such that longer vector length can be obtained. For attaining the efficient inter-node parallelization, such partitioning methods as the recursive coordinate bisection (RCM) or MeTIS have been used. Computational performance of the practical large-scale engineering problems will be shown at the meeting. (author)
Data Analysis Methods for Paleogenomics
DEFF Research Database (Denmark)
Avila Arcos, Maria del Carmen
(Danmarks Grundforskningfond) 'Centre of Excellence in GeoGenetics' grant, with additional funding provided by the Danish Council for Independent Research 'Sapere Aude' programme. The thesis comprises five chapters, all of which represent different projects that involved the analysis of massive amounts......, thanks to the introduction of NGS and the implementation of data analysis methods specific for each project. Chapters 1 to 3 have been published in peer-reviewed journals and Chapter 4 is currently in review. Chapter 5 consists of a manuscript describing initial results of an ongoing research project......The work presented in this thesis is the result of research carried out during a three-year PhD at the Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, under supervision of Professor Tom Gilbert. The PhD was funded by the Danish National Research Foundation...
Materials properties, loads, and stress analysis, Spartan REM: Appendix A
Marlowe, D. S.; West, E. J.
1984-01-01
The mechanical properties, load tests, and stress analysis of the Spartan Release Engagement Mechanism (REM) is presented. The fracture properties of the components of the unit are also discussed. Detailed engineering drawings are included.
Energy Technology Data Exchange (ETDEWEB)
Weitman, J; Daaverhoeg, N; Farvolden, S
1970-07-01
In connection with fast neutron (n, {alpha}) cross section measurements a novel boron analysis method has been developed. The boron concentration is inferred from the mass spectrometrically determined number of helium atoms produced in the thermal and epithermal B-10 (n, {alpha}) reaction. The relation between helium amount and boron concentration is given, including corrections for self shielding effects and background levels. Direct and diffusion losses of helium are calculated and losses due to gettering, adsorption and HF-ionization in the release stage are discussed. A series of boron determinations is described and the results are compared with those obtained by other methods, showing excellent agreement. The lower limit of boron concentration which can be measured varies with type of sample. In e.g. steel, concentrations below 10-5 % boron in samples of 0.1-1 gram may be determined.
Analysis of stress and strain in a rotating disk mounted on a rigid shaft
Directory of Open Access Journals (Sweden)
Alexandrova Nelli N.
2006-01-01
Full Text Available The plane state of stress in an elastic-perfectly plastic isotropic rotating annular disk mounted on a rigid shaft is studied. The analysis of stresses, strains and displacements within the disk of constant thickness and density is based on the Mises yield criterion and its associated flow rule. It is observed that the plastic deformation is localized in the vicinity of the inner radius of the disk, and the disk of a sufficiently large outer radius never becomes fully plastic. The semi-analytical method of stress-strain analysis developed is illustrated by some numerical examples. .
International Nuclear Information System (INIS)
Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok; Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul
2010-01-01
Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods
Heat transfer and thermal stress analysis in grooved tubes
Indian Academy of Sciences (India)
ANSYS (1997) computer code has been used to analyse the thermal ... The numerical method is used succesfully to solve the governing equations ... thermal stress is an important criterion for consideration in the design of new compact heat.
Responses to Fiscal Stress: A Comparative Analysis
2013-12-01
of “a significant decline in market share by the middle of the 20th century as travelers and shippers turned increasingly to airlines, trucks, and...1995). Intercity passenger rail: Financial and operating conditions threaten Amtrak’s long-term viability (GAO-95-71). Washington, DC: U.S...I. (1980). Retrenchment and flexibility in public organizations. Fiscal Stress and Public Policy, 159–178. Scheinberg, P. F. (1998). Intercity
Municipal solid waste effective stress analysis
International Nuclear Information System (INIS)
Shariatmadari, Nader; Machado, Sandro Lemos; Noorzad, Ali; Karimpour-Fard, Mehran
2009-01-01
The mechanical behavior of municipal solid waste (MSW) has attracted the attention of many researchers in the field of geo-environmental engineering in recent years and several aspects of waste mechanical response under loading have been elucidated. However, the mechanical response of MSW materials under undrained conditions has not been described in detail to date. The knowledge of this aspect of the MSW mechanical response is very important in cases involving MSW with high water contents, seismic ground motion and in regions where landfills are built with poor operation conditions. This paper presents the results obtained from 26 large triaxial tests performed both in drained and undrained conditions. The results were analyzed taking into account the waste particles compressibility and the deformation anisotropy of the waste samples. The waste particles compressibility was used to modify the Terzaghi effective stress equation, using the Skempton (1961) proposition. It is shown that the use of the modified effective stress equation led to much more compatible shear strength values when comparing Consolidated-Drained (CD) and Consolidated-Undrained (CU), results, explaining the high shear strength values obtained in CU triaxial tests, even when the pore pressure is almost equal to the confining stress.
Analysis of in situ stress at Yucca Mountain
International Nuclear Information System (INIS)
Bauer, S.J.; Holland, J.F.
1987-01-01
A method has been developed to initialize far-field finite element models such that the measured in situ stress state appears to be reproduced well. The method includes use of the mechanical stratigraphy, mechanical effect of pore pressure, gravity loading, a horizontal ''tectonic'' component of stress, and use of a jointed rock model to calculate the mechanical response. Topographic effects and effects related to the vertical variation in mechanical properties are predicted for repository depths (∼ 300 m). Gravity loading with a small horizontal compression is used to calculate a minimum horizontal stress similar in magnitude to that measured in situ. 8 refs., 5 figs
COMPETITIVE INTELLIGENCE ANALYSIS - SCENARIOS METHOD
Directory of Open Access Journals (Sweden)
Ivan Valeriu
2014-07-01
Full Text Available Keeping a company in the top performing players in the relevant market depends not only on its ability to develop continually, sustainably and balanced, to the standards set by the customer and competition, but also on the ability to protect its strategic information and to know in advance the strategic information of the competition. In addition, given that economic markets, regardless of their profile, enable interconnection not only among domestic companies, but also between domestic companies and foreign companies, the issue of economic competition moves from the national economies to the field of interest of regional and international economic organizations. The stakes for each economic player is to keep ahead of the competition and to be always prepared to face market challenges. Therefore, it needs to know as early as possible, how to react to others’ strategy in terms of research, production and sales. If a competitor is planning to produce more and cheaper, then it must be prepared to counteract quickly this movement. Competitive intelligence helps to evaluate the capabilities of competitors in the market, legally and ethically, and to develop response strategies. One of the main goals of the competitive intelligence is to acknowledge the role of early warning and prevention of surprises that could have a major impact on the market share, reputation, turnover and profitability in the medium and long term of a company. This paper presents some aspects of competitive intelligence, mainly in terms of information analysis and intelligence generation. Presentation is theoretical and addresses a structured method of information analysis - scenarios method – in a version that combines several types of analysis in order to reveal some interconnecting aspects of the factors governing the activity of a company.
Minakov, A.; Medvedev, S.
2017-12-01
Analysis of lithospheric stresses is necessary to gain understanding of the forces that drive plate tectonics and intraplate deformations and the structure and strength of the lithosphere. A major source of lithospheric stresses is believed to be in variations of surface topography and lithospheric density. The traditional approach to stress estimation is based on direct calculations of the Gravitational Potential Energy (GPE), the depth integrated density moment of the lithosphere column. GPE is highly sensitive to density structure which, however, is often poorly constrained. Density structure of the lithosphere may be refined using methods of gravity modeling. However, the resulted density models suffer from non-uniqueness of the inverse problem. An alternative approach is to directly estimate lithospheric stresses (depth integrated) from satellite gravimetry data. Satellite gravity gradient measurements by the ESA GOCE mission ensures a wealth of data for mapping lithospheric stresses if a link between data and stresses or GPE can be established theoretically. The non-uniqueness of interpretation of sources of the gravity signal holds in this case as well. Therefore, the data analysis was tested for the North Atlantic region where reliable additional constraints are supplied by both controlled-source and earthquake seismology. The study involves comparison of three methods of stress modeling: (1) the traditional modeling approach using a thin sheet approximation; (2) the filtered geoid approach; and (3) the direct utilization of the gravity gradient tensor. Whereas the first two approaches (1)-(2) calculate GPE and utilize a computationally expensive finite element mechanical modeling to calculate stresses, the approach (3) uses a much simpler numerical treatment but requires simplifying assumptions that yet to be tested. The modeled orientation of principal stresses and stress magnitudes by each of the three methods are compared with the World Stress Map.
International Nuclear Information System (INIS)
Karow, K.
1984-01-01
The fatigue behaviour of reactor components is predominantly determined from the in-service thermal stresses. The calculation of such stresses for a number of temperature transients in the adjacent fluid may be expensive, particularly with complicated structures. Under certain conditions this expense can be reduced considerably with the aid of a rule, which permits interpolation of thermal stresses from known reference values instead of calculation. This paper presents the derivation and method of application of this interpolation rule. The derivation procedure is based on well-known proportionalities between thermal stress range Δsigma in the structure and temperature change ΔT and rate of change T of the fluid in the extreme cases of an ideal thermal shock and quasi-steady-state conditions, respectively. For the real transients in between the relationship Δsigma proportional (ΔT)sup(x) Tsup(1-x)αsup(y) is proposed, where x is the shock-degree and lies between 0 and 1, and, additionally, y designates the influence of the heat transfer coefficient α. This formula yields the interpolation rule. The rule permits interpolation of stress ranges for additional thermal transients from at least 3 reference stresses via x and y. The procedure is applicable to any metallic structure, reduces fatigue analysis effort considerably and yields excellent results. The paper is split up into 2 parts. In the following the derivation of the rule is presented. The second part describes its application and will be published shortly. (orig.)
International Nuclear Information System (INIS)
Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya; Fujii, Yoshiaki
2009-01-01
Understanding initial stress condition in deep underground is important for such construction as rock cavern for geological disposal of HLW and underground power plant. Neogene sedimentary rock is widely distributed in Japan. There are only a few studies of initial stress measurement in Neogene sedimentary rock mass in Japan due to difficulty of measurement. Evaluation of initial stress condition around Horonobe Underground Research Laboratory Project was carried out in order to understand initial stress condition and applicability of AE, DSCA and hydraulic fracturing (HF) methods to Neogene sedimentary rock. Initial stress values obtained from AE method is smaller than overburden pressure due to time dependency of Kaizer effect. It would be difficult to use AE method as initial stress measurement method for Horonobe Siliceous rocks. Principal stress values by DSCA are similar to those by HF tests. Directions of maximum horizontal principal stresses are approximately in E-W and corresponded to HF results. In HF, rod type and wire-line type systems were compared. Workability of rod type was much better than wire-line type. However, re-opening pressure were not able to be precisely measured in case of rod type system due to the large compliance of the packers and rods. Horizontal maximum and minimum principal stresses increase linearly in HF results. Deviatoric stress is acting at shallow depth. Initial stress condition approaches hydrostatic condition with depth. Direction of maximum horizontal principal stress was in E-W direction which was similar to tectonic movement around Horonobe URL by triangular surveying. (author)
Numerical analysis oriented biaxial stress-strain relation and failure criterion of plain concrete
International Nuclear Information System (INIS)
Link, J.
1975-01-01
A biaxial stress-strain relation and failure criterion is proposed, which is applicable to structural analysis methods. The formulation of material behavior of plain concrete in biaxial stress-state was developed. A nonlinear elastic, anisotropic stress-strain relation was derived with two moduli of elasticity, E 1 , E 2 and Poisson's ratios, ν 1 , ν 2 , which depend on the prevailing biaxial stress state. The stress-strain relation is valid in the whole biaxial stress field, that means with a smooth transition between the domains of tension/tension, tension/compression and compression/compression. The stress-dependent moduli E 1 , E 2 and the Poisson's ratios ν 1 , ν 2 are approximated by polynomials, trigonometrical and exponential functions. A failure criterion was defined by approximating the test results of the biaxial ultimate concrete strength with a 7th degree polynomial, which is also valid in the whole biaxial stress domain. The definition of the state of failure is given as a function of stresses as well as strains. Initial parameters of the formulation of the biaxial material behavior are the uniaxial cylindrical strength of concrete and the initial values of Young's modulus and Poisson's ratio. A simple expansion of this formulation makes it applicable not only to normal but also to light-weight concrete. Comparison of numerically calculated stress-strain curves up to the ultimate biaxial stresses which indicate the failure criteria with those obtained from tests show a very good agreement. It is shown, that the biaxial stress-strain relation can be extended for use in cases of triaxial tension/tension/compression stress state. Numerical examples of analysis of concrete slabs show the importance of incorporation of a realistic material behavior for better safety estimations
X-ray stress analysis in textured polycrystalline materials
International Nuclear Information System (INIS)
Yokoyama, Ryouichi; Harada, Jimpei
2010-01-01
The relationship between stress and strain in polycrystalline materials with fibre texture is examined on the basis of the strain analysis in the constituent crystallites within the Reuss approximation. By introducing the symmetry of reciprocal lattices for the constituent crystallites, the physical meaning of taking an average of the strains observed by X-ray diffraction (XRD) is made clear. By using formulae obtained by the present treatment for the stress-strain relation in cubic specimens with fibre texture in the Laue classes m3-bar m hkl Bragg reflections with h≠k≠l split into doublets owing to the existence of crystallites with two different orientations under the stress field. This technique was confirmed by the profile analysis in XRD data observed for reflections of 222 and 420 in a cubic TiN thin film sputtered on a polyimide film. The technique of the stress analysis and its confirmation are introduced. (author)
Restoring method for missing data of spatial structural stress monitoring based on correlation
Zhang, Zeyu; Luo, Yaozhi
2017-07-01
Long-term monitoring of spatial structures is of great importance for the full understanding of their performance and safety. The missing part of the monitoring data link will affect the data analysis and safety assessment of the structure. Based on the long-term monitoring data of the steel structure of the Hangzhou Olympic Center Stadium, the correlation between the stress change of the measuring points is studied, and an interpolation method of the missing stress data is proposed. Stress data of correlated measuring points are selected in the 3 months of the season when missing data is required for fitting correlation. Data of daytime and nighttime are fitted separately for interpolation. For a simple linear regression when single point's correlation coefficient is 0.9 or more, the average error of interpolation is about 5%. For multiple linear regression, the interpolation accuracy is not significantly increased after the number of correlated points is more than 6. Stress baseline value of construction step should be calculated before interpolating missing data in the construction stage, and the average error is within 10%. The interpolation error of continuous missing data is slightly larger than that of the discrete missing data. The data missing rate of this method should better not exceed 30%. Finally, a measuring point's missing monitoring data is restored to verify the validity of the method.
Residual stress analysis in reactor pressure vessel attachments
International Nuclear Information System (INIS)
Dexter, R.J.; Pont, D.
1991-08-01
Residual stresses in cladding and welded attachments could contribute to the problem of stress-corrosion cracking in boiling-water reactors (BWR). As part of a larger program aimed at quantifying residual stress in BWR components, models that would be applicable for predicting residual stress in BWR components are reviewed and documented. The review includes simple methods of estimating residual stresses as well as advanced finite-element software. In general, simple methods are capable of predicting peak magnitudes of residual stresses but are incapable of adequately characterizing the distribution of residual stresses. Ten groups of researchers using finite-element software are reviewed in detail. For each group, the assumptions of the model, possible simplifications, material property data, and specific applications are discussed. The most accurate results are obtained when a metallurgical simulation is performed, transformation plasticity effects are included, and the heating and cooling parts of the welding thermal cycle are simulated. Two models are identified which can provide these features. The present state of these models and the material property data available in the literature are adequate to quantify residual stress in BWR components
Residual stress analysis by neutron time-of-flight at a reactor source
International Nuclear Information System (INIS)
Priesmeyer, H.G.; Schroder, J.
1990-01-01
Non-destructive neutron diffractometry for stress analysis will be a powerful experimental tool in material science research performed at the GKSS 5 MW reactor FRG-1. Arguments which show the advantages of the time-of-flight method are given and a suitable high-resolution neutron-efficient type of spectrometer is introduced. First results derived from this method are presented
Gravimetric and titrimetric methods of analysis
International Nuclear Information System (INIS)
Rives, R.D.; Bruks, R.R.
1983-01-01
Gravimetric and titrimetric methods of analysis are considered. Methods of complexometric titration are mentioned, as well as methods of increasing sensitivity in titrimetry. Gravimetry and titrimetry are applied during analysis for traces of geological materials
Finite element modelling for fatigue stress analysis of large suspension bridges
Chan, Tommy H. T.; Guo, L.; Li, Z. X.
2003-03-01
Fatigue is an important failure mode for large suspension bridges under traffic loadings. However, large suspension bridges have so many attributes that it is difficult to analyze their fatigue damage using experimental measurement methods. Numerical simulation is a feasible method of studying such fatigue damage. In British standards, the finite element method is recommended as a rigorous method for steel bridge fatigue analysis. This paper aims at developing a finite element (FE) model of a large suspension steel bridge for fatigue stress analysis. As a case study, a FE model of the Tsing Ma Bridge is presented. The verification of the model is carried out with the help of the measured bridge modal characteristics and the online data measured by the structural health monitoring system installed on the bridge. The results show that the constructed FE model is efficient for bridge dynamic analysis. Global structural analyses using the developed FE model are presented to determine the components of the nominal stress generated by railway loadings and some typical highway loadings. The critical locations in the bridge main span are also identified with the numerical results of the global FE stress analysis. Local stress analysis of a typical weld connection is carried out to obtain the hot-spot stresses in the region. These results provide a basis for evaluating fatigue damage and predicting the remaining life of the bridge.
Stress analysis in oral obturator prostheses: imaging photoelastic
Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; dos Santos, Daniela Micheline; Haddad, Marcela Filié; Andreotti, Agda Marobo; Moreno, Amália
2013-06-01
Maxillary defects resulting from cancer, trauma, and congenital malformation affect the chewing efficiency and retention of dentures in these patients. The use of implant-retained palatal obturator dentures has improved the self-esteem and quality of life of several subjects. We evaluate the stress distribution of implant-retained palatal obturator dentures with different attachment systems by using the photoelastic analysis images. Two photoelastic models of the maxilla with oral-sinus-nasal communication were fabricated. One model received three implants on the left side of the alveolar ridge (incisive, canine, and first molar regions) and the other did not receive implants. Afterwards, a conventional palatal obturator denture (control) and two implant-retained palatal obturator dentures with different attachment systems (O-ring; bar-clip) were constructed. Models were placed in a circular polariscope and a 100-N axial load was applied in three different regions (incisive, canine, and first molar regions) by using a universal testing machine. The results were photographed and analyzed qualitatively using a software (Adobe Photoshop). The bar-clip system exhibited the highest stress concentration followed by the O-ring system and conventional denture (control). Images generated by the photoelastic method help in the oral rehabilitator planning.
Reliability analysis of offshore structures using OMA based fatigue stresses
DEFF Research Database (Denmark)
Silva Nabuco, Bruna; Aissani, Amina; Glindtvad Tarpø, Marius
2017-01-01
focus is on the uncertainty observed on the different stresses used to predict the damage. This uncertainty can be reduced by Modal Based Fatigue Monitoring which is a technique based on continuously measuring of the accelerations in few points of the structure with the use of accelerometers known...... points of the structure, the stress history can be calculated in any arbitrary point of the structure. The accuracy of the estimated actual stress is analyzed by experimental tests on a scale model where the obtained stresses are compared to strain gauges measurements. After evaluating the fatigue...... stresses directly from the operational response of the structure, a reliability analysis is performed in order to estimate the reliability of using Modal Based Fatigue Monitoring for long term fatigue studies....
Interlaminar stress analysis for carbon/epoxy composite space rotors
Directory of Open Access Journals (Sweden)
C Lian
2016-09-01
Full Text Available This paper extends the previous works that appears in the International Journal of Multiphysics, Varatharajoo, Salit and Goh (2010. An approach incorporating cohesive zone modelling technique is incorporated into an optimized flywheel to properly simulate the stresses at the layer interfaces. Investigation on several fiber stacking sequences are also conducted to demonstrate the effect of fiber orientations on the overall rotor stress as well as the interface stress behaviour. The results demonstrated that the rotor interlaminar stresses are within the rotor materials' ultimate strength and that the fiber direction with a combination of 45°/-45°/0° offers the best triple layer rotor among the few combinations selected for this analysis. It was shown that the present approach can facilitate also further investigation on the interface stress behaviour of rotating rotors.
Wafer scale lead zirconate titanate film preparation by sol-gel method using stress balance layer
International Nuclear Information System (INIS)
Lu Jian; Kobayashi, Takeshi; Yi Zhang; Maeda, Ryutaro; Mihara, Takashi
2006-01-01
In this paper, platinum/titanium (Pt/Ti) film was introduced as a residual stress balance layer into wafer scale thick lead zirconate titanate (PZT) film fabrication by sol-gel method. The stress developing in PZT film's bottom electrode as well as in PZT film itself during deposition were analyzed; the wafer curvatures, PZT crystallizations and PZT electric properties before and after using Pt/Ti stress balance layer were studied and compared. It was found that this layer is effective to balance the residual stress in PZT film's bottom electrode induced by thermal expansion coefficient mismatch and Ti diffusion, thus can notably reduce the curvature of 4-in. wafer from - 40.5 μm to - 12.9 μm after PZT film deposition. This stress balance layer was also found effective to avoid the PZT film cracking even when annealed by rapid thermal annealing with heating-rate up to 10.5 deg. C/s. According to X-ray diffraction analysis and electric properties characterization, crack-free uniform 1-μm-thick PZT film with preferred pervoskite (001) orientation, excellent dielectric constant, as high as 1310, and excellent remanent polarization, as high as 39.8 μC/cm 2 , can be obtained on 4-in. wafer
Stress Analysis in Managing the Region’s Budget Risks
Directory of Open Access Journals (Sweden)
Natalya Pavlovna Pazdnikova
2014-09-01
Full Text Available The article addresses the implementation of budget risk management methods into the practices of governmental authorities. Drawing on the example of a particular region the article aims to demonstrate the possible methods of budget risk management. The authors refine the existing approaches to the notion of risk in its relation to budget system by introducing the notion of “budget risk.” Here the focus is the risk of default of budget spending in full which causes underfunding of territories and decrease in quality of life in the region. The authors have particularized the classification of budget risks and grouped together the criteria and factors which significantly influence the assessment and choice of method to manage budget risks. They hypothesize that budget risk is a financial risk. Therefore, the methods of financial risks management can be applied to budget risks management. The authors suggest a methodological approach to risk assessment based on correlation and regression analysis of program financing. The application of Kendall rank correlation coefficient allowed to assess the efficiency of budget spending on the implementation of state programs in Perm Krai. Two clusters — “Nature management and infrastructure” and “Public security” — turned out to be in the zone of high budget risk. The method of stress analysis, which consists in calculating Value at Risk (VaR, was applied to budget risks that in terms of probability are classified as critical. In order to assess risk as probability rate, the amount of Perm Krai deficit budget was calculated as induced variable from budget revenues and spending. The results demonstrate that contemporary management of public resources in the regions calls for the implementation of new management tools of higher quality and budget risk management is one of them.
Statistical Analysis of Stress Signals from Bridge Monitoring by FBG System
Directory of Open Access Journals (Sweden)
Xiao-Wei Ye
2018-02-01
Full Text Available In this paper, a fiber Bragg grating (FBG-based stress monitoring system instrumented on an orthotropic steel deck arch bridge is demonstrated. The FBG sensors are installed at two types of critical fatigue-prone welded joints to measure the strain and temperature signals. A total of 64 FBG sensors are deployed around the rib-to-deck and rib-to-diagram areas at the mid-span and quarter-span of the investigated orthotropic steel bridge. The local stress behaviors caused by the highway loading and temperature effect during the construction and operation periods are presented with the aid of a wavelet multi-resolution analysis approach. In addition, the multi-modal characteristic of the rainflow counted stress spectrum is modeled by the method of finite mixture distribution together with a genetic algorithm (GA-based parameter estimation approach. The optimal probability distribution of the stress spectrum is determined by use of Bayesian information criterion (BIC. Furthermore, the hot spot stress of the welded joint is calculated by an extrapolation method recommended in the specification of International Institute of Welding (IIW. The stochastic characteristic of stress concentration factor (SCF of the concerned welded joint is addressed. The proposed FBG-based stress monitoring system and probabilistic stress evaluation methods can provide an effective tool for structural monitoring and condition assessment of orthotropic steel bridges.
Numerical weld modeling - a method for calculating weld-induced residual stresses
International Nuclear Information System (INIS)
Fricke, S.; Keim, E.; Schmidt, J.
2001-01-01
In the past, weld-induced residual stresses caused damage to numerous (power) plant parts, components and systems (Erve, M., Wesseling, U., Kilian, R., Hardt, R., Bruemmer, G., Maier, V., Ilg, U., 1994. Cracking in Stabilized Austenitic Stainless Steel Piping of German Boiling Water Reactors - Characteristic Features and Root Causes. 20. MPA-Seminar 1994, vol. 2, paper 29, pp.29.1-29.21). In the case of BWR nuclear power plants, this damage can be caused by the mechanism of intergranular stress corrosion cracking in austenitic piping or the core shroud in the reactor pressure vessel and is triggered chiefly by weld-induced residual stresses. One solution of this problem that has been used in the past involves experimental measurements of residual stresses in conjunction with weld optimization testing. However, the experimental analysis of all relevant parameters is an extremely tedious process. Numerical simulation using the finite element method (FEM) not only supplements this method but, in view of modern computer capacities, is also an equally valid alternative in its own right. This paper will demonstrate that the technique developed for numerical simulation of the welding process has not only been properly verified and validated on austenitic pipe welds, but that it also permits making selective statements on improvements to the welding process. For instance, numerical simulation can provide information on the starting point of welding for every weld bead, the effect of interpass cooling as far as a possible sensitization of the heat affected zone (HAZ) is concerned, the effect of gap width on the resultant weld residual stresses, or the effect of the 'last pass heat sink welding' (welding of the final passes while simultaneously cooling the inner surface with water) producing compressive stresses in the root area of a circumferential weld in an austenitic pipe. The computer program FERESA (finite element residual stress analysis) was based on a commercially
Impact of Low Anorectal Malformation on Parenting Stress: A Mixed-Method Study.
Wigander, Helena; Öjmyr-Joelsson, Maria; Frenckner, Björn; Wester, Tomas; Nisell, Margret
2018-05-17
The purpose of this study was to investigate parenting stress among parents of children with low ARM. 1) Compare parenting stress among parents of children with low ARM, with parents of healthy children using questionnaires. 2) Identify subscales within the questionnaire which needed to be further explored. 3) Use semi-structured interviews with parents of children with low ARM, to explore parenting stress and to explain, expand and or support the quantitative findings. An explanatory sequential mixed methods design was used in this follow up study. The parents completed the Swedish Parenthood Stress Questionnaire (SPSQ), semi-structured interviews were conducted. Fifteen mothers and 13 fathers of children with low ARM age 8-18, returned completed questionnaires. A control group of 17 mothers and 6 fathers of healthy children age 8-18 that had visited the hospital for a minor procedure was recruited for comparison purposes. There were no significant differences found between index group and controls except in the subscale Incompetence, where parents of children with low ARM reported lower levels of stress compared to controls. Nine semi-structured interviews were conducted with parents of children with low ARM. Qualitative content analysis was used and revealed three themes - Communication between parents, Expectations of parenthood, and Challenges concerning parenthood. Parents of children with low ARM did not report high levels of stress. When interviewed, they told about earlier experiences of emotional stress, feelings of guilt, and chaos at the time the child was born and during infancy. Copyright © 2018. Published by Elsevier Inc.
Stress analysis in curved composites due to thermal loading
Polk, Jared Cornelius
Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, longer fatigue life, lower density, possibilities in reduction of life cycle and/or acquisition cost, and greater adaptability to intended function of structure via material composition and geometry. To be able to design and manufacture a safe composite laminate or structure, it is imperative that the stress distributions, their causes, and effects are thoroughly understood in order to successfully accomplish mission objectives and manufacture a safe and reliable composite. The objective of the thesis work is to expand upon the knowledge of simply curved composite structures by exploring and ascertaining all pertinent parameters, phenomenon, and trends in stress variations in curved laminates due to thermal loading. The simply curved composites consist of composites with one radius of curvature throughout the span of the specimen about only one axis. Analytical beam theory, classical lamination theory, and finite element analysis were used to ascertain stress variations in a flat, isotropic beam. An analytical method was developed to ascertain the stress variations in an isotropic, simply curved beam under thermal loading that is under both free-free and fixed-fixed constraint conditions. This is the first such solution to Author's best knowledge
Research Progress on Measurement Methods and Influence Factors of Thin-film Stress
Directory of Open Access Journals (Sweden)
MA Yibo
2018-02-01
Full Text Available With the size of thin-film electronic devices decreasing, the film stress became an important reason for the failure of thin film devices. Film stress not only affected the membrane structure, but also associated with film optics, electricity, mechanics and other properties, therefore film stress turned into one hot spot in the research field of thin-film materials. This paper reviewed the latest research progress of film stress, substrate curvature method, X-ray diffraction technique and Raman spectroscopy, several frequently used stress measuring techniques were compared and analyzed, and composition ratios of thin film, substrate types, magnetron sputtering process parameters (sputtering power, work pressure, substrate temperature and annealing etc. factors influencing thin film stress were summarized. It was found that substrate curvature method was suitable for measuring almost all kinds of thin film materials. X-ray diffraction and Raman spectroscopy were just fit for measuring materials with characteristic peaks. Nanoindentation method required extra stress-free samples as comparison experiments. During film fabrication and annealing process, film stress usually transited from compressive to tensile status, and several factors combined together could affect stress, so film stress could be reached the minimum value or even stress-free status through setting appropriate parameters. Finally, combined with film stress research status, accurate stress measurement methods for different materials as a thin-film stress research direction were introduced, and challenges in thin film detection range were pointed out.
Analysis of rock stress and rock stress measurements with application to Aespoe HRL
International Nuclear Information System (INIS)
Lundholm, Beatrice
2000-11-01
the opening where no influence from the openings can be expected. Since the magnitudes of the rock stresses differ between overcoring and hydraulic fracturing, some efforts have been made to find possible causes for this. The rock stresses when conducting overcoring gave higher values overall, which could be explained by high Poisson's ratios and a minor influence from the opening as the stress measurements might have been done in the disturbed zone. The high Poisson's ratio may depend on the stress-induced microcracks, which might be initiated during the overcoring of the cell, during the drilling of the pilot borehole, in which the cell is installed, and during biaxial testing. Statistical analysis showed that there is significant differences between the mean values of Poisson's ratio obtained from biaxial tests of cores containing the CSIRO HI-cell and the SSPB-cell. Poisson's ratio is about 0.34 for CSIRO HI-cell while the SSPB-cell gave a Poisson's ratio of 0.23. The analysis also showed that Young's modulus does not differ between the techniques. The modelling in FLAC was made to simulate the overcoring and biaxial testing. The result show that it is possible to obtain extensional strain in the core during overcoring if the major principal stress is perpendicular to the borehole axis. This may lead to microcracking occurring in the core causing high Poisson's ratio, which results in higher stresses. It can also be seen from the simulation of the biaxial testing that extensional strain is achieved even if the hollow core is not damaged during overcoring. The analyses using UDEC was made to study the effect of different properties of a discontinuity, such as the dip angle, Young's modulus, Poisson's ratio, density and the normal and shear stiffness. The analyses showed that an inclined discontinuity affects the stresses especially if sliding occurs. So, the dip angle does not solely, determine the amount of disturbance of the state of stress around a discontinuity
Determination of the stresses and displacements in the cut off curtain body executed by the > method
International Nuclear Information System (INIS)
Snisarenko, V.I.; Mel'nikov, A.I.
1994-01-01
Construction of the cut-off-curtain (COC) is analyzed as a possible variant to reduce the rate of radioactive horizontal migration. Such constructions can be executed by the > method. The theoretical analysis of the stress-strained state of the carried out using the methods of the theory of elasticity and of the limit equilibrium of the strewing medium. Theoretical dependences are obtained and formulas for practical calculations of the COC-body stress-strained state in the depth intervals which are of practical interest are suggested. The dependences obtained may be used to calculate the consolidation parameters and filtration coefficients, to choose materials for the COC body, geometrical size and film elements included
Alternative methods for the seismic analysis of piping systems
International Nuclear Information System (INIS)
Anon.
1993-01-01
This document is a review of 12 methods and criteria for the seismic analysis of piping systems. Each of the twelve chapters in this document cover the important technical aspects of a given method. The technical aspects presented are those the Subcommittee on Dynamic Stress Criteria believe important to the application of the method, and should not be considered as a positive or negative endorsement for any of the methods. There are many variables in an analysis of a piping system that can influence the selection of the analysis method and criteria to be applied. These variable include system configuration, technical issues, precedent, licensing considerations, and regulatory acceptance. They must all be considered in selecting the appropriate seismic analysis method and criteria. This is relevant for nuclear power plants
International Nuclear Information System (INIS)
Rocha, A. da S.; Hirsch, T.
2005-01-01
This paper presents results obtained with a method for time and temperature resolved analysis of changes in phase composition and stresses/residual stresses during complete heat treatment cycles of steel, including quenching. Sample temperatures of up to 930 deg. C could be reached with a specially designed furnace, where fast cooling of the samples was realized by gas quenching. Measurements for phase and stress analysis could be performed with an acquisition rate of at least one value every 3 s. Results concerning residual stress relaxation during heating, and stress/residual stress development during quenching are presented and discussed for AISI E52100 ball bearing steel. The observed stress development during quenching followed the expected transformation behavior with some deviations that could be explained through the effects of surface decarburization. The system developed proved to be a suitable tool for characterizing phase and stress changes that occur during heat treatment of steels, as a function of time and temperature
Stress analysis and life prediction of gas turbine blade
Hsiung, H. C.; Dunn, A. J.; Woodling, D. R.; Loh, D. L.
1988-01-01
A stress analysis procedure is presented for a redesign of the Space Shuttle Main Engine high pressure fuel turbopump turbine blades. The analysis consists of the one-dimensional scoping analysis to support the design layout and the follow-on three-dimensional finite element analysis to confirm the blade design at operating loading conditions. Blade life is evaluated based on high-cycle fatigue and low-cycle fatigue.
CANDIDATE GENE ANALYSIS IN ISRAELI SOLDIERS WITH STRESS FRACTURES
Directory of Open Access Journals (Sweden)
Ran Yanovich
2012-03-01
Full Text Available To investigate the association of polymorphisms within candidate genes which we hypothesized may contribute to stress fracture predisposition, a case-control, cross- sectional study design was employed. Genotyping 268 Single Nucleotide Polymorphisms- SNPs within 17 genes in 385 Israeli young male and female recruits (182 with and 203 without stress fractures. Twenty-five polymorphisms within 9 genes (NR3C1, ANKH, VDR, ROR2, CALCR, IL6, COL1A2, CBG, and LRP4 showed statistically significant differences (p < 0.05 in the distribution between stress fracture cases and non stress fracture controls. Seventeen genetic variants were associated with an increased stress fracture risk, and eight variants with a decreased stress fracture risk. None of the SNP associations remained significant after correcting for multiple comparisons (false discovery rate- FDR. Our findings suggest that genes may be involved in stress fracture pathogenesis. Specifically, the CALCR and the VDR genes are intriguing candidates. The putative involvement of these genes in stress fracture predisposition requires analysis of more cases and controls and sequencing the relevant genomic regions, in order to define the specific gene mutations
Oil prices and financial stress: A volatility spillover analysis
International Nuclear Information System (INIS)
Nazlioglu, Saban; Soytas, Ugur; Gupta, Rangan
2015-01-01
This paper examines whether there is a volatility transmission between oil prices and financial stress by means of the volatility spillover test. We employ WTI crude oil prices and Cleveland financial stress index for the period 1991–2014 and divide the sample into pre-crisis, in-crisis, and post-crisis periods due to the downward trend in oil price in 2008. The volatility model estimations indicate that oil prices and financial stress index are dominated by long-run volatility. The volatility spillover causality test supports evidence on risk transfer from oil prices to financial stress before the crisis and from financial stress to oil prices after the crisis. The impulse response analysis shows that the volatility transmission pattern has similar dynamics before and after the crisis and is characterized by higher and long-lived effects during the crisis. Our results have implications for both policy makers and investors, and for future work. -- Highlights: •Volatility spillover between oil prices and financial stress index is examined. •Analysis is conducted for sub-periods: pre-crisis, in-crisis, and post-crisis •Oil prices spill on financial stress before the crisis, but spillover reversed after the crisis. •Volatility transmission pattern has similar dynamics before and after the crisis. •Implications for investors and policy makers are discussed
An Integrated Analysis of Changes in Water Stress in Europe
DEFF Research Database (Denmark)
Henrichs, T.; Lehner, B.; Alcamo, J.
2002-01-01
Future changes in water availability with climate change and changes in water use due to socio-economic development are to occur in parallel. In an integrated analysis we bring together these aspects of global change in a consistent manner, and analyse the water stress situation in Europe. We find...... that today high water stress exists in one-fifth of European river basin area. Under a scenario projection, increases in water use throughout Eastern Europe are accompanied by decreases in water availability in most of Southern Europe--combining these trends leads to a marked increase in water stress...
Preliminary analysis of knee stress in Full Extension Landing
Directory of Open Access Journals (Sweden)
Majid Davoodi Makinejad
2013-09-01
Full Text Available OBJECTIVE: This study provides an experimental and finite element analysis of knee-joint structure during extended-knee landing based on the extracted impact force, and it numerically identifies the contact pressure, stress distribution and possibility of bone-to-bone contact when a subject lands from a safe height. METHODS: The impact time and loads were measured via inverse dynamic analysis of free landing without knee flexion from three different heights (25, 50 and 75 cm, using five subjects with an average body mass index of 18.8. Three-dimensional data were developed from computed tomography scans and were reprocessed with modeling software before being imported and analyzed by finite element analysis software. The whole leg was considered to be a fixed middle-hinged structure, while impact loads were applied to the femur in an upward direction. RESULTS: Straight landing exerted an enormous amount of pressure on the knee joint as a result of the body's inability to utilize the lower extremity muscles, thereby maximizing the threat of injury when the load exceeds the height-safety threshold. CONCLUSIONS: The researchers conclude that extended-knee landing results in serious deformation of the meniscus and cartilage and increases the risk of bone-to-bone contact and serious knee injury when the load exceeds the threshold safety height. This risk is considerably greater than the risk of injury associated with walking downhill or flexion landing activities.
International Nuclear Information System (INIS)
Lacko, A.; Komarek, K.
2007-01-01
The study deals with to stress related problem and its psychological response in human body, such as influence of stress in the autonomous regulation of heart activity. The study has used the Stroop's test in order to determine the stress level. After that the spectral analysis of the heart rate variability was carried out in order to specify the impact of the stress on the regulation of the influence of the autonomous nervous system in the relation to the heart activity. Obtained results were compared with selected indicators of used psychodiagnostic methods (Stroop's test). Cardio vascular diseases represent a serious problem which is trying to be resolved by health care professionals nevertheless it should also be a concern of each individual as well as the whole society. This disease continually affects younger age categories. From the medical point of view the ambition of early diagnosis with consequent therapy should influence this adverse trend. Diagnosis of cardiovascular diseases by the nuclear medicine method has a substantial place. These particular examinations represent about 40 % of performed examinations in units of nuclear medicine. This very fact has glanced off in conception of nuclear medicine by establishment of a new subdivision of 'nuclear cardiology'. (authors)
Stress analysis of the tokamak engineering test breeder blanket
International Nuclear Information System (INIS)
Huang Zhongqi
1992-01-01
The design features of the hybrid reactor blanket and main parameters are presented. The stress analysis is performed by using computer codes SAP5p and SAP6 with the three kinds of blanket module loadings, i.e, the pressure of coolant, the blanket weight and the thermal loading. Numerical calculation results indicate that the stresses of the blanket are smaller than the allowable ones of the material, the blanket design is therefore reasonable
Temperature and thermal stress analysis of a switching tube anode
International Nuclear Information System (INIS)
Sutton, S.B.
1979-01-01
In the design of high power density switching tubes which are subjected to cyclic thermal loads, the temperature induced stresses must be minimized in order to maximize the life expectancy of the tube. Following are details of an analysis performed for the Magnetic Fusion Program at the Lawrence Livermore Laboratory on a proposed tube. The tube configuration is given. The problem was simplified to one-dimensional approximations for both the thermal and stress analyses. The underlying assumptions and their implications are discussed
Development of computational methods of design by analysis for pressure vessel components
International Nuclear Information System (INIS)
Bao Shiyi; Zhou Yu; He Shuyan; Wu Honglin
2005-01-01
Stress classification is not only one of key steps when pressure vessel component is designed by analysis, but also a difficulty which puzzles engineers and designers at all times. At present, for calculating and categorizing the stress field of pressure vessel components, there are several computation methods of design by analysis such as Stress Equivalent Linearization, Two-Step Approach, Primary Structure method, Elastic Compensation method, GLOSS R-Node method and so on, that are developed and applied. Moreover, ASME code also gives an inelastic method of design by analysis for limiting gross plastic deformation only. When pressure vessel components design by analysis, sometimes there are huge differences between the calculating results for using different calculating and analysis methods mentioned above. As consequence, this is the main reason that affects wide application of design by analysis approach. Recently, a new approach, presented in the new proposal of a European Standard, CEN's unfired pressure vessel standard EN 13445-3, tries to avoid problems of stress classification by analyzing pressure vessel structure's various failure mechanisms directly based on elastic-plastic theory. In this paper, some stress classification methods mentioned above, are described briefly. And the computational methods cited in the European pressure vessel standard, such as Deviatoric Map, and nonlinear analysis methods (plastic analysis and limit analysis), are depicted compendiously. Furthermore, the characteristics of computational methods of design by analysis are summarized for selecting the proper computational method when design pressure vessel component by analysis. (authors)
Residual stress analysis in carbon fiber-reinforced SiC ceramics
International Nuclear Information System (INIS)
Broda, M.
1998-01-01
Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated C fiber /SiC matrix specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface (μm) have been measured using characteristic X-radiation and applying the sin 2 ψ method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250μm) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB) [de
International Nuclear Information System (INIS)
Miyamoto, H.; Kubo, M.; Katori, T.
1981-01-01
Experimental investigation by 3-D photoelasticity has been carried out to measure the stress distribution of partial penetration welded nozzles attached to the bottom head of a pressure vessel. A 3-D photoelastic stress freezing method was chosen as the most effective means of observation of the stress distribution in the vicinity of the nozzle/wall weld. The experimental model was a 1:20 scale spherical bottom head. Both an axisymmetric nozzle and an asymmetric nozzle were investigated. Epoxy resin, which is a thermosetting plastic, was used as the model material. The oblique effect was examined by comparing the stress distribution of the asymmetric nozzle with that of the axisymmetric nozzle. Furthermore, the experimental results were compared with the analytical results using 3-D finite element method (FEM). The stress distributions obtained from the frozen fringe pattern of the 3-D photoelastic model were in good agreement with those by 3-D FEM. (orig.)
Diagnostic Methods for Predicting Performance Impairment Associated With Combat Stress
National Research Council Canada - National Science Library
Matthews, Gerald; Warm, Joel S; Washburn, David
2004-01-01
.... The research focuses especially on the measurement of cerebral bloodflow using transcranial doppler sonography, together with additional indices including salivary cortisol and subjective stress state...
Multiaxial stress analysis taking account of penetration depth of x-rays, 3
International Nuclear Information System (INIS)
Yoshioka, Yasuo; Sasaki, Toshihiko; Kuramoto, Makoto.
1985-01-01
In the past X-ray stress analysis in which the effect of stress gradients was taken into account within the penetration depth of X-rays, three assumptions have been made; 1) the stress gradient is linear in respect to the depth from the specimen surface, 2) the penetration depth of X-ray is a function of Sin 2 PSI and 3) the strain measured by X-rays corresponds to the weighted average strain on the intensity of the diffracted X-rays. A problem, however, still remains on the assumption of the X-ray penetration depth. We sometimes observed noticiable errors in the stage of the numerical simulation and these errors depend on the combination of stress components in a stress tensor. In the present paper, we proposed a new X-ray multiaxial stress analysis without using the assumption of the X-ray penetration depth. This analysis is also applicable to both the iso-inclination method ( OHM -goniometer) and the side inclination method (PSI-goniometer). The weighted average strain by X-rays, 1 >(phi), is expressed as a 4th degree function of cosPSI for iso-inclination method and 3rd degree for side inclination method. By rearranging this function as a sum of average strain, ( 1 >(0 0 )+ 1 >(90 0 )), and difference of average strain, ( 1 >(0 0 )- 1 >(90 0 )), we can solve the stress components with sufficient accuracy by a least squares method. The validity of this method was proved through numerical simulations and experiments. (author)
Neutron stress measurement using image plate and the cos α method
International Nuclear Information System (INIS)
Sasaki, Toshihiko; Hirose, Yukio; Minakawa, Nobuaki; Morii, Yukio
2004-01-01
A new type of the neutron stress measurement method, in which the stress is determined by the cos α method, was studied. A neutron image plate was used in this study for detecting the diffraction image. Steel specimens of 5 mm thickness were used for the tensile stress test. The stresses obtain from the experiment showed one-to-one ratio with respect to the applied stresses, though the misfit stress of about 400 MPa was also observed in the result. A simple correction technique for calibrating raw data was proposed to obtain the true stress. A simulation study was carried out to check the experimental result on the peak positions in the diffraction ring and the stress calculation by the cos α method. (author)
Analysis of residual stress in subsurface layers after precision hard machining of forging tools
Directory of Open Access Journals (Sweden)
Czan Andrej
2018-01-01
Full Text Available This paper is focused on analysis of residual stress of functional surfaces and subsurface layers created by precision technologies of hard machining for progressive constructional materials of forging tools. Methods of experiments are oriented on monitoring of residual stress in surface which is created by hard turning (roughing and finishing operations. Subsequently these surfaces were etched in thin layers by electro-chemical polishing. The residual stress was monitored in each etched layer. The measuring was executed by portable X-ray diffractometer for detection of residual stress and structural phases. The results significantly indicate rise and distribution of residual stress in surface and subsurface layers and their impact on functional properties of surface integrity.
Analysis methods (from 301 to 351)
International Nuclear Information System (INIS)
Analysis methods of materials used in the nuclear field (uranium, plutonium and their compounds, zirconium, magnesium, water...) and determination of impurities. Only reliable methods are selected [fr
International Nuclear Information System (INIS)
Nemoto, Y.; Ueda, K.
1998-01-01
Vanadium alloys are considered as candidate structural materials for fusion reactor system. When vanadium alloys are used in fusion reactor system, joining with ceramics for insulating is one of material issues to be solved to make component of fusion reactor. In the application of ceramics/metal jointing and coating, residual stress caused by difference of thermal expansion rate between ceramics and metals is an important factor in obtaining good bonding strength and soundness of coating. In this work, residual stress distribution in direct diffusion bonded vanadium/alumina joint (jointing temperature: 1400 C) was measured by small area X-ray diffraction method. And the comparison of finite element method (FEM) analysis and actual stress distribution was carried out. Tensile stress concentration at the edge of the boundary of the joint in alumina was observed. The residual stress concentration may cause cracks in alumina, or failure of bonding. Actually, cracks in alumina caused by thermal stress after bonding at 1500 C was observed. The stress concentration of the joint must be reduced to obtain good bonded joint. Lower bonding temperature or to devise the shape of the outer surface of the joint will reduce the stress concentration. (orig.)
Efficient multiscale magnetic-domain analysis of iron-core material under mechanical stress
Nishikubo, Atsushi; Ito, Shumpei; Mifune, Takeshi; Matsuo, Tetsuji; Kaido, Chikara; Takahashi, Yasuhito; Fujiwara, Koji
2018-05-01
For an efficient analysis of magnetization, a partial-implicit solution method is improved using an assembled domain structure model with six-domain mesoscopic particles exhibiting pinning-type hysteresis. The quantitative analysis of non-oriented silicon steel succeeds in predicting the stress dependence of hysteresis loss with computation times greatly reduced by using the improved partial-implicit method. The effect of cell division along the thickness direction is also evaluated.
Directory of Open Access Journals (Sweden)
Vemanna S Ramu
Full Text Available In nature plants are often simultaneously challenged by different biotic and abiotic stresses. Although the mechanisms underlying plant responses against single stress have been studied considerably, plant tolerance mechanisms under combined stress is not understood. Also, the mechanism used to combat independently and sequentially occurring many number of biotic and abiotic stresses has also not systematically studied. From this context, in this study, we attempted to explore the shared response of sunflower plants to many independent stresses by using meta-analysis of publically available transcriptome data and transcript profiling by quantitative PCR. Further, we have also analyzed the possible role of the genes so identified in contributing to combined stress tolerance. Meta-analysis of transcriptomic data from many abiotic and biotic stresses indicated the common representation of oxidative stress responsive genes. Further, menadione-mediated oxidative stress in sunflower seedlings showed similar pattern of changes in the oxidative stress related genes. Based on this a large scale screening of 55 sunflower genotypes was performed under menadione stress and those contrasting in oxidative stress tolerance were identified. Further to confirm the role of genes identified in individual and combined stress tolerance the contrasting genotypes were individually and simultaneously challenged with few abiotic and biotic stresses. The tolerant hybrid showed reduced levels of stress damage both under combined stress and few independent stresses. Transcript profiling of the genes identified from meta-analysis in the tolerant hybrid also indicated that the selected genes were up-regulated under individual and combined stresses. Our results indicate that menadione-based screening can identify genotypes not only tolerant to multiple number of individual biotic and abiotic stresses, but also the combined stresses.
Flux Balance Analysis of Escherichia coli under Temperature and pH Stress Conditions
Xu, Xiaopeng
2015-05-12
An interesting discovery in biology is that most genes in an organism are dispensable. That means these genes have minor effects on survival of the organism in standard laboratory conditions. One explanation of this discovery is that some genes play important roles in specific conditions and are essential genes under those conditions. E. coli is a model organism, which is widely used. It can adapt to many stress conditions, including temperature, pH, osmotic, antibiotic, etc. Underlying mechanisms and associated genes of each stress condition responses are usually different. In our analysis, we combined protein abundance data and mutant conditional fitness data into E. coli constraint-based metabolic models to study conditionally essential metabolic genes under temperature and pH stress conditions. Flux Balance Analysis was employed as the modeling method to analysis these data. We discovered lists of metabolic genes, which are E. coli dispensable genes, but conditionally essential under some stress conditions. Among these conditionally essential genes, atpA in low pH stress and nhaA in high pH stress found experimental evidences from previous studies. Our study provides new conditionally essential gene candidates for biologists to explore stress condition mechanisms.
Stress analysis program system for nuclear vessel: STANSAS
International Nuclear Information System (INIS)
Okamoto, Asao; Michikami, Shinsuke
1979-01-01
IHI has developed a computer system of stress analysis and evaluation for nuclear vessels: STANSAS (STress ANalysis System for Axi-symmetric Structure). The system consists of more than twenty independent programs divided into the following six parts. 1. Programs for opening design by code rule. 2. Calculation model generating programs. 3. Load defining programs. 4. Structural analysis programs. 5. Load data/calculation results plotting programs. 6. Stress evaluation programs. Each program is connected with its pre- or post-processor through three data-bases which enable automatic data transfer. The user can make his choice of structural analysis programs in accordance with the problem to be solved. The interface to STANSAS can be easily installed in generalized structural analysis programs such as NASTRAN and MARC. For almost all tables and figures in the stress report, STANSAS has the function to print or plot out. The complicated procedures of ''Design by Analysis'' for pressure vessels have been well standardized by STANSAS. The system will give a high degree of efficiency and confidence to the design work. (author)
Stress Analysis for the Critical Metal Structure of Bridge Crane
Ling, Zhangwei; Wang, Min; Xia, Junfang; Wang, Songhua; Guo, Xiaolian
2018-01-01
Based on the type of connection between the main girder and end beam of electrical single beam crane, the finite element analysis model of a full portal crane was established. The stress distribution of the critical structure under different loading conditions was analyzed. The results shown that the maximum Mises stress and deflection of the main girder were within the allowable range. And the connecting location between end beam web and main girder had higher stress than other region, especially at the lower edge and upper edge of the end beam web and the area near the bolt hole of upper wing panel. Therefore it is important to inspect the connection status, the stress condition and the crack situation nearing connection location during the regular inspection process to ensure the safety of the connection between the main girder and end beam.
Thermal stratification and fatigue stress analysis for pressurizer surge line
International Nuclear Information System (INIS)
Yu Xiaofei; Zhang Yixiong
2011-01-01
Thermal stratification of pressurizer surge line induced by the inside fluid results in the global bending moments, local thermal stresses, unexpected displacements and support loadings of the pipe system. In order to avoid a costly three-dimensional computation, a combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line of QINSHAN Phase II Extension Nuclear Power Project in this paper, using the computer codes SYSTUS and ROCOCO. According to the mechanical analysis results of stratification, the maximum stress and cumulative usage factor are obtained. The results indicate that the stress and fatigue intensity considering thermal stratification satisfies RCC-M criterion. (authors)
Stress analysis of aspherical coated particle with inner pressure
Energy Technology Data Exchange (ETDEWEB)
Liu Bing, E-mail: bingliu@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 (China); Yang Lin; Liang Tongxiang; Tang Chunhe [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 (China)
2012-10-15
Coated particles used in HTR fuel element sustain the inner pressure during irradiation as a pressure vessel. In actually the coated particle is not real spherical but with some asphericity, the stress distribution in the vessel is not uniform, coated layer in aspherical particle sustain more additional stress due to the asphericity. In this paper, the geometric shape distribution is summarized based on actual coated particle statistic. A mechanical analysis model is proposed for SiC layer by geometric combinations, and stress distribution of coated particle with a flat is calculated. The results show that the local maximum stress of aspherical particle increased two times than that of ideal spherical coated particle, which increase the failure probability under irradiation and high temperature.
Stress analysis of piping systems and piping supports. Documentation
International Nuclear Information System (INIS)
Rusitschka, Erwin
1999-01-01
The presentation is focused on the Computer Aided Tools and Methods used by Siemens/KWU in the engineering activities for Nuclear Power Plant Design and Service. In the multi-disciplinary environment, KWU has developed specific tools to support As-Built Documentation as well as Service Activities. A special application based on Close Range Photogrammetry (PHOCAS) has been developed to support revamp planning even in a high level radiation environment. It comprises three completely inter-compatible expansion modules - Photo Catalog, Photo Database and 3D-Model - to generate objects which offer progressively more utilization and analysis options. To support the outage planning of NPP/CAD-based tools have been developed. The presentation gives also an overview of the broad range of skills and references in: Plant Layout and Design using 3D-CAD-Tools; evaluation of Earthquake Safety (Seismic Screening); Revamps in Existing Plants; Inter-disciplinary coordination of project engineering and execution fields; Consulting and Assistance; Conceptual Studies; Stress Analysis of Piping Systems and Piping Supports; Documentation; Training and Supports in CAD-Design, etc. All activities are performed to the greatest extent possible using proven data-processing tools. (author)
DTI analysis methods : Voxel-based analysis
Van Hecke, Wim; Leemans, Alexander; Emsell, Louise
2016-01-01
Voxel-based analysis (VBA) of diffusion tensor imaging (DTI) data permits the investigation of voxel-wise differences or changes in DTI metrics in every voxel of a brain dataset. It is applied primarily in the exploratory analysis of hypothesized group-level alterations in DTI parameters, as it does
Bayesian methods for data analysis
Carlin, Bradley P.
2009-01-01
Approaches for statistical inference Introduction Motivating Vignettes Defining the Approaches The Bayes-Frequentist Controversy Some Basic Bayesian Models The Bayes approach Introduction Prior Distributions Bayesian Inference Hierarchical Modeling Model Assessment Nonparametric Methods Bayesian computation Introduction Asymptotic Methods Noniterative Monte Carlo Methods Markov Chain Monte Carlo Methods Model criticism and selection Bayesian Modeling Bayesian Robustness Model Assessment Bayes Factors via Marginal Density Estimation Bayes Factors
Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi
International Nuclear Information System (INIS)
Katanchi, B.; Choupani, N.; Khalil-Allafi, J.; Baghani, M.
2017-01-01
Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.
Photostress analysis of stress-induced martensite phase transformation in superelastic NiTi
Energy Technology Data Exchange (ETDEWEB)
Katanchi, B. [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Choupani, N., E-mail: choupani@sut.ac.ir [Mechanical Engineering Faculty, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Khalil-Allafi, J. [Research Center for Advance Materials, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Baghani, M. [School of Mechanical Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of)
2017-03-14
Phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase transformation in a superelastic NiTi (50.8% Ni) shape memory alloy was investigated by using the photo-stress method. First, the material's fabrication procedure has been described and then the material was studied using the metallurgical tests such as differential scanning calorimetry and X-ray diffraction to characterize the material features and the mechanical tensile test to investigate the superelastic behavior. As a new method in observation of the phase transformation, photo-stress pictures showed the formation of stress induced martensite in a superelastic dog-bone specimen during loading and subsequently it's disappearing during unloading. Finally, finite element analysis was implemented using the constitutive equations derived based on the Boyd-Lagoudas phenomenological model.
Substoichiometric method in the simple radiometric analysis
International Nuclear Information System (INIS)
Ikeda, N.; Noguchi, K.
1979-01-01
The substoichiometric method is applied to simple radiometric analysis. Two methods - the standard reagent method and the standard sample method - are proposed. The validity of the principle of the methods is verified experimentally in the determination of silver by the precipitation method, or of zinc by the ion-exchange or solvent-extraction method. The proposed methods are simple and rapid compared with the conventional superstoichiometric method. (author)
Global/local methods research using a common structural analysis framework
Knight, Norman F., Jr.; Ransom, Jonathan B.; Griffin, O. H., Jr.; Thompson, Danniella M.
1991-01-01
Methodologies for global/local stress analysis are described including both two- and three-dimensional analysis methods. These methods are being developed within a common structural analysis framework. Representative structural analysis problems are presented to demonstrate the global/local methodologies being developed.
NDE of stresses in thick-walled components by ultrasonic methods
International Nuclear Information System (INIS)
Goebbels, K.; Pitsch, H.; Schneider, E.; Nowack, H.
1985-01-01
The possibilty of measuring stresses - especially residual stresses - by ultrasonic methods has been presented at the 4th and 5th International Conference on NDE in Nuclear Industry. This contribution now presents results of several applications to thick walled components such as turbines and generators for power plants. The measurement technique using linearly polarized shear waves allows one to characterize the homogeneitry of the residual stress situation along and around cylindrically shaped components. Some important results show that the stress distribution integrated over the cross section of the component has not followed in any case the simple relations derived by stress analysts. Conclusions referring to the stress situation inside the components are discussed
Understanding Student Stress and Coping in Elementary School: A Mixed-Method, Longitudinal Study
Sotardi, Valerie A.
2016-01-01
This mixed-method, longitudinal study examined daily school stress and coping strategies of elementary schoolchildren in the United States. Students (n = 65) between the ages of 7 and 11 years reported daily school stress measures for 8 weeks and completed individual stress and coping interviews. Results highlight critical relations between…
Application of x-ray method for measuring internal stress in the gear teeth surface layer
International Nuclear Information System (INIS)
Zaborowski, T.
1996-01-01
This paper presents the methodics of the internal stress measurements concerning cylindrical gear teeth of involute profile. There are the method selected, relation between stress and strain presented and conditions of investigation discussed in the study, including preparation of samples for investigation and conditions of the strain measurement. Exemplifying results of stress measurements for teeth of gears made of 4OH steel are shown. Suitability of the developed investigation method is indicated
Halpin, Yvonne; Terry, Louise M; Curzio, Joan
2017-11-01
To investigate transition in newly qualified nurses through an exploration of their stressors and stress experiences during their first 12 months postqualifying. Globally, thousands of new nurses qualify annually. They are crucial for the profession and healthcare service delivery. Work-related stress has multiple serious consequences, yet there is a lack of robust, empirical evidence that directly analyses newly qualified nurses and the stress they feel and experience in the workplace. Understanding what causes newly qualified nurses' stress is vital to retaining and nurturing this vital component of the workforce. Longitudinal, explanatory sequential mixed methods, cohort study. At the point of qualification (n = 288), 6 months postqualifying (n = 107) and 12 months postqualifying (n = 86), newly qualified nurses completed the Nursing Stress Scale, with 14 completing a one-to-one interview at 12 months postqualifying. Data were collected from 2010 - 2012. Inferential statistics, "thematic analysis" and "side-by-side comparisons in a discussion" were used for analysis. Workload was consistently the highest reported stressor with inadequate staffing and managing multiple role demands given as explanations. Incivility within the workplace was a noted stressor. Conversely, being part of "a good team" provided a civil, supportive, facilitative work environment. Entering nurse education with previous healthcare experience had a mediating effect on the reported frequency of stressors. Newly qualified nurses encounter multiple work-related stressors over their first 12 months postqualifying, which are intrinsically entwined with their transition. Employing organizations need to be more proactive in managing their workload and addressing workplace incivility. © 2017 John Wiley & Sons Ltd.
Peening as a stress relieving method for welded joints
International Nuclear Information System (INIS)
Ferreira, M.L.R.
1984-01-01
The efficacy of the process of stress relieving by hammer-peening, in heavy plates of low carbon steel is analysed. The effects of peening in the mechanical properties of welded metal deposited by shield metal arc welding, using the electrodes E-6010, E-7018 and E-8018C-2, and the weld metal deposited by submerged arc welding, using the filler metals ENil and EA3, are also analysed. X-ray diffraction was used in order to verify the efficacy of peening as a stress-relieving process. The obtained results and the literature reviewed show that, peening is effective in stress relieving. (author) [pt
Meditation for posttraumatic stress: Systematic review and meta-analysis.
Hilton, Lara; Maher, Alicia Ruelaz; Colaiaco, Benjamin; Apaydin, Eric; Sorbero, Melony E; Booth, Marika; Shanman, Roberta M; Hempel, Susanne
2017-07-01
We conducted a systematic review and meta-analysis that synthesized evidence from randomized controlled trials of meditation interventions to provide estimates of their efficacy and safety in treating adults diagnosed with posttraumatic stress disorder (PTSD). This review was based on an established protocol (PROSPERO: CRD42015025782) and is reported according to PRISMA guidelines. Outcomes of interest included PTSD symptoms, depression, anxiety, health-related quality of life, functional status, and adverse events. Meta-analyses were conducted using the Hartung-Knapp-Sidik-Jonkman method for random-effects models. Quality of evidence was assessed using the Grade of Recommendations Assessment, Development, and Evaluation (GRADE) approach. In total, 10 trials on meditation interventions for PTSD with 643 participants met inclusion criteria. Across interventions, adjunctive meditation interventions of mindfulness-based stress reduction, yoga, and the mantram repetition program improve PTSD and depression symptoms compared with control groups, but the findings are based on low and moderate quality of evidence. Effects were positive but not statistically significant for quality of life and anxiety, and no studies addressed functional status. The variety of meditation intervention types, the short follow-up times, and the quality of studies limited analyses. No adverse events were reported in the included studies; only half of the studies reported on safety. Meditation appears to be effective for PTSD and depression symptoms, but in order to increase confidence in findings, more high-quality studies are needed on meditation as adjunctive treatment with PTSD-diagnosed participant samples large enough to detect statistical differences in outcomes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Analysis of Two Methods to Evaluate Antioxidants
Tomasina, Florencia; Carabio, Claudio; Celano, Laura; Thomson, Leonor
2012-01-01
This exercise is intended to introduce undergraduate biochemistry students to the analysis of antioxidants as a biotechnological tool. In addition, some statistical resources will also be used and discussed. Antioxidants play an important metabolic role, preventing oxidative stress-mediated cell and tissue injury. Knowing the antioxidant content…
Diffraction stress analysis of thin films; investigating elastic grain interaction
International Nuclear Information System (INIS)
Kumar, A.
2005-12-01
This work is dedicated to the investigation of specimens exhibiting anisotropic microstructures (and thus macroscopic elastic anisotropy) and/or inhomogeneous microstructures, as met near surfaces and in textured materials. The following aspects are covered: (i) Analysis of specimens with direction-dependent (anisotropic) elastic grain-interaction. Elastic grain-interaction determines the distribution of stresses and strains over the (crystallographically) differently oriented grains of a mechanically stressed polycrystal and the mechanical and diffraction (X-ray) elastic constants (relating (diffraction) lattice strains to mechanical stresses). Grain interaction models that allow for anisotropic, direction-dependent grain interaction have been developed very recently. The notion 'direction-dependent' grain-interaction signifies that different grain-interaction constraints prevail along different directions in a specimen. Practical examples of direction-dependent grain interaction are the occurrence of surface anisotropy in thin films and the surface regions of bulk polycrystals and the occurrence of grain-shape (morphological) texture. In this work, for the first time, stress analyses of thin films have been performed on the basis of these newly developed grain-interaction models. It has also been demonstrated that the identification of the (dominant) source of direction-dependent grain interaction is possible. The results for the grain interaction have been discussed in the light of microstructural investigations of the specimens by microscopic techniques. (ii) Analysis of specimens with depth gradients: Diffraction stress analysis can be hindered if gradients of the stress state, the composition or the microstructure occur in the specimen under investigation, as the so-called information depth varies in the course of a traditional stress measurement: Ambiguous results are thus generally obtained. In this work, a strategy for stress measurements at fixed
Stress analysis of HTR-10 steam generator heat exchanging tubes
International Nuclear Information System (INIS)
Dong Jianling; Zhang Xiaohang; Yin Dejian; Fu Jiyang
2001-01-01
Steam Generator (SG) heat exchanging tubes of 10 MW High Temperature Gas Cooled Reactor (HTR-10) are protective screens between the primary loop of helium with radioactivity and the secondary loop of feeding water and steam without radioactivity. Water and steam will enter into the primary loop when rupture of the heat exchanging tubes occurs, which lead to increase of the primary loop pressure and discharge of radioactive materials. Therefore it is important to guarantee the integrity of the tubes. The tube structure is spiral tube with small bending radius, which make it impossible to test with volumetric in-service detection. For such kind of spiral tube, using LBB concept to guarantee the integrity of the tubes is an important option. The author conducts stress analysis and calculation of HTR-10 SG heat exchanging tubes using the FEM code of piping stress analysis, PIPESTRESS. The maximum stress and the dangerous positions are obtained
Chemical methods of rock analysis
National Research Council Canada - National Science Library
Jeffery, P. G; Hutchison, D
1981-01-01
.... Such methods include those based upon spectrophotometry, flame emission spectrometry and atomic absorption spectroscopy, as well as gravimetry, titrimetry and the use of ion-selective electrodes...
International Nuclear Information System (INIS)
Kaneta, Kiyoshi; Nishizawa, Hidekazu; Arashiyama, Masaki.
1982-01-01
In order to evaluate the applicability of two kinds of techniques of the X-ray stress analysis, namely, the standard sin 2 psi method and the newly developed phi-sin 2 psi method, bending tests have been performed. The test results have proved that the values of the stresses measured by means of the mechanical devices and of those measured by the two kinds of the X-ray techniques coincide each other. Then, these two methods have been applied to measure the surface residual stresses of the box-typed, welded steel columns and the following conclusions have been drawn. 1. The principal stress of the surface residural stresses is, in most cases, oriented to the rolled directions at the center of the steel plates, and it tends to rotate in the neighborhood of the heat affected zones. 2. Tensile residual stresses of a large magnitude have been observed in the direction parallel to the beads of the weld, and the moderate compressive residual stresses can be detected in the direction normal to the beads. (author)
... can be life-saving. But chronic stress can cause both physical and mental harm. There are at least three different types of stress: Routine stress related to the pressures of work, family, and other daily responsibilities Stress brought about ...
School programs targeting stress management in children and adolescence: a meta-analysis
Kraag, G.C; Zeegers, M.P.; Kok, G.J.; Hosman, C.M.H.; Huijer Abu-Saad, H.
2006-01-01
Introduction This meta-analysis evaluates the effect of school programs targeting stress management or coping skills in school children. Methods Articles were selected through a systematic literature search. Only randomized controlled trials or quasi-experimental studies were included. The
Analysis of stresses and strains in the materials with limiting structure using x-ray
International Nuclear Information System (INIS)
Imafuku, Muneyuki
2010-01-01
This review outlines the principle of analysis and the measuring instruments using X-ray for the stresses and strains in the materials with limiting structure. Further the several experimental examples are shown. This method is expected to be useful widely for the characterization evaluation, the reliability insurance, and the development of materials. (M.H.)
Meta-Analysis of Dropout in Treatments for Posttraumatic Stress Disorder
Imel, Zac E.; Laska, Kevin; Jakupcak, Matthew; Simpson, Tracy L.
2013-01-01
Objective: Many patients drop out of treatments for posttraumatic stress disorder (PTSD); some clinicians believe that trauma-focused treatments increase dropout. Method: We conducted a meta-analysis of dropout among active treatments in clinical trials for PTSD (42 studies; 17 direct comparisons). Results: The average dropout rate was 18%, but it…
Residual stress analysis of drive shafts after induction hardening
Energy Technology Data Exchange (ETDEWEB)
Lemos, Guilherme Vieira Braga; Rocha, Alexandre da Silva; Nunes, Rafael Menezes, E-mail: lemos_gl@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Algre, RS (Brazil); Hirsch, Thomas Karl [Stiftung Institut für Werkstofftechnik (IWT), Bremen (Germany)
2014-08-15
Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable diffractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected. (author)
Modeling and Analysis of a Combined Stress-Vibration Fiber Bragg Grating Sensor.
Yao, Kun; Lin, Qijing; Jiang, Zhuangde; Zhao, Na; Tian, Bian; Shi, Peng; Peng, Gang-Ding
2018-03-01
A combined stress-vibration sensor was developed to measure stress and vibration simultaneously based on fiber Bragg grating (FBG) technology. The sensor is composed of two FBGs and a stainless steel plate with a special design. The two FBGs sense vibration and stress and the sensor can realize temperature compensation by itself. The stainless steel plate can significantly increase sensitivity of vibration measurement. Theoretical analysis and Finite Element Method (FEM) were used to analyze the sensor's working mechanism. As demonstrated with analysis, the obtained sensor has working range of 0-6000 Hz for vibration sensing and 0-100 MPa for stress sensing, respectively. The corresponding sensitivity for vibration is 0.46 pm/g and the resulted stress sensitivity is 5.94 pm/MPa, while the nonlinearity error for vibration and stress measurement is 0.77% and 1.02%, respectively. Compared to general FBGs, the vibration sensitivity of this sensor is 26.2 times higher. Therefore, the developed sensor can be used to concurrently detect vibration and stress. As this sensor has height of 1 mm and weight of 1.15 g, it is beneficial for minimization and integration.
Heat transfer and thermal stress analysis in grooved tubes
Indian Academy of Sciences (India)
Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was ...
ITER vacuum vessel dynamic stress analysis of a disruption
International Nuclear Information System (INIS)
Riemer, B.W.; Conner, D.L.; Strickler, D.J.; Williamson, D.E.
1994-01-01
Dynamic stress analysis of the International Thermonuclear Experimental Reactor vacuum vessel loaded by disruption forces was performed. The deformation and stress results showed strong inertial effects when compared to static analyses. Maximum stress predicted dynamically was 300 MPa, but stress shown by static analysis from loads at the same point in time reached only 80 MPa. The analysis also provided a reaction load history in the vessel's supports which is essential in evaluating support design. The disruption forces were estimated by assuming a 25-MA plasma current decaying at 1 MA/ms while moving vertically. In addition to forces developed within the vessel, vertical loadings from the first wall/strong back assemblies and the divertor were applied to the vessel at their attachment points. The first 50 natural modes were also determined. The first mode's frequency was 6.0 Hz, and its shape is characterized by vertical displacement of the vessel inner leg. The predicted deformation of the vessel appeared similar to its first mode shape combined with radial contraction. Kinetic energy history from the analysis also correlated with the first mode frequency
Contact stress analysis of involute spur gear by Finite Element ...
African Journals Online (AJOL)
In this paper the contact stress in rolling-sliding contact of involute spur gear and the effect of coefficient of friction was analyzed. To achieve this, first, three dimensional involute spur gear pairs were developed in Solid works 2012 Premium and the 3D model was exported to ANSYS workbench 14.5. Next, the analysis was ...
The Psychophysiology of Posttraumatic Stress Disorder: A Meta-Analysis
Pole, Nnamdi
2007-01-01
This meta-analysis of 58 resting baseline studies, 25 startle studies, 17 standardized trauma cue studies, and 22 idiographic trauma cue studies compared adults with and without posttraumatic stress disorder (PTSD) on psychophysiological variables: facial electromyography (EMG), heart rate (HR), skin conductance (SC), and blood pressure.…
Thermal stress analysis for fatigue damage evaluation at a mixing tee
International Nuclear Information System (INIS)
Kamaya, Masayuki; Nakamura, Akira
2011-01-01
Highlights: → Thermal stress and fatigue damage have been analyzed for a mixing tee. → Fatigue damage was accumulated near boundaries of the cold spot. → It was found that fatigue damage was brought about by fluctuation of cold spot. → Simple one-dimensional analysis could derive stress for fatigue evaluation. - Abstract: Fatigue cracks have been found at mixing tees where fluids of different temperature flow in. In this study, the thermal stress at a mixing tee was calculated by the finite element method using temperature transients obtained by a fluid dynamics simulation. The simulation target was an experiment for a mixing tee, in which cold water flowed into the main pipe from a branch pipe. The cold water flowed along the main pipe wall and caused a cold spot, at which the membrane stress was relatively large. Based on the evaluated thermal stress, the magnitude of the fatigue damage was assessed according to the linear damage accumulation rule and the rain-flow procedure. Precise distributions of the thermal stress and fatigue damage could be identified. Relatively large axial stress occurred downstream from the branch pipe due to the cold spot. The variation ranges of thermal stress and fatigue damage became large near the position 20 o from the symmetry line in the circumferential direction. The position of the cold spot changed slowly in the circumferential direction, and this was the main cause of the fatigue damage. The fatigue damage was investigated for various differences in the temperature between the main and branch pipes. Since the magnitude of accumulated damage increased abruptly when the temperature difference exceeded the value corresponding to the fatigue limit, it was suggested that the stress amplitude should be suppressed less than the fatigue limit. In the thermal stress analysis for fatigue damage assessment, it was found that the detailed three-dimensional structural analysis was not required. Namely, for the current case, a one
Transcriptomic analysis of salt stress responsive genes in Rhazya stricta.
Directory of Open Access Journals (Sweden)
Nahid H Hajrah
Full Text Available Rhazya stricta is an evergreen shrub that is widely distributed across Western and South Asia, and like many other members of the Apocynaceae produces monoterpene indole alkaloids that have anti-cancer properties. This species is adapted to very harsh desert conditions making it an excellent system for studying tolerance to high temperatures and salinity. RNA-Seq analysis was performed on R. stricta exposed to severe salt stress (500 mM NaCl across four time intervals (0, 2, 12 and 24 h to examine mechanisms of salt tolerance. A large number of transcripts including genes encoding tetrapyrroles and pentatricopeptide repeat (PPR proteins were regulated only after 12 h of stress of seedlings grown in controlled greenhouse conditions. Mechanisms of salt tolerance in R. stricta may involve the upregulation of genes encoding chaperone protein Dnaj6, UDP-glucosyl transferase 85a2, protein transparent testa 12 and respiratory burst oxidase homolog protein b. Many of the highly-expressed genes act on protecting protein folding during salt stress and the production of flavonoids, key secondary metabolites in stress tolerance. Other regulated genes encode enzymes in the porphyrin and chlorophyll metabolic pathway with important roles during plant growth, photosynthesis, hormone signaling and abiotic responses. Heme biosynthesis in R. stricta leaves might add to the level of salt stress tolerance by maintaining appropriate levels of photosynthesis and normal plant growth as well as by the participation in reactive oxygen species (ROS production under stress. We speculate that the high expression levels of PPR genes may be dependent on expression levels of their targeted editing genes. Although the results of PPR gene family indicated regulation of a large number of transcripts under salt stress, PPR actions were independent of the salt stress because their RNA editing patterns were unchanged.
Thermal stress analysis of a planar SOFC stack
Lin, Chih-Kuang; Chen, Tsung-Ting; Chyou, Yau-Pin; Chiang, Lieh-Kwang
The aim of this study is, by using finite element analysis (FEA), to characterize the thermal stress distribution in a planar solid oxide fuel cell (SOFC) stack during various stages. The temperature profiles generated by an integrated thermo-electrochemical model were applied to calculate the thermal stress distributions in a multiple-cell SOFC stack by using a three-dimensional (3D) FEA model. The constructed 3D FEA model consists of the complete components used in a practical SOFC stack, including positive electrode-electrolyte-negative electrode (PEN) assembly, interconnect, nickel mesh, and gas-tight glass-ceramic seals. Incorporation of the glass-ceramic sealant, which was never considered in previous studies, into the 3D FEA model would produce more realistic results in thermal stress analysis and enhance the reliability of predicting potential failure locations in an SOFC stack. The effects of stack support condition, viscous behavior of the glass-ceramic sealant, temperature gradient, and thermal expansion mismatch between components were characterized. Modeling results indicated that a change in the support condition at the bottom frame of the SOFC stack would not cause significant changes in thermal stress distribution. Thermal stress distribution did not differ significantly in each unit cell of the multiple-cell stack due to a comparable in-plane temperature profile. By considering the viscous characteristics of the glass-ceramic sealant at temperatures above the glass-transition temperature, relaxation of thermal stresses in the PEN was predicted. The thermal expansion behavior of the metallic interconnect/frame had a greater influence on the thermal stress distribution in the PEN than did that of the glass-ceramic sealant due to the domination of interconnect/frame in the volume of a planar SOFC assembly.
Stress analysis of closure bolts for shipping casks
International Nuclear Information System (INIS)
Mok, G.C.; Fischer, L.E.; Hsu, S.T.
1993-01-01
This report specifies the requirements and criteria for stress analysis of closure bolts for shipping casks containing nuclear spent fuels or high level radioactive materials. The specification is based on existing information conceming the structural behavior, analysis, and design of bolted joints. The approach taken was to extend the ASME Boiler and Pressure Vessel Code requirements and criteria for bolting analysis of nuclear piping and pressure vessels to include the appropriate design and load characteristics of the shipping cask. The characteristics considered are large, flat, closure lids with metal-to-metal contact within the bolted joint; significant temperature and impact loads; and possible prying and bending effects. Specific formulas and procedures developed apply to the bolt stress analysis of a circular, flat, bolted closure. The report also includes critical load cases and desirable design practices for the bolted closure, an in-depth review of the structural behavior of bolted joints, and a comprehensive bibliography of current information on bolted joints
FLEXURAL STRESS ANALYSIS OF RIGID PAVEMENTS USING AXI-SYMMETRIC AND PLANE STRAIN FEM
Directory of Open Access Journals (Sweden)
V.A. Sawant
2017-11-01
Full Text Available The design of pavement involves a study of soils and paving materials, their response under load for different climatic conditions. In the present study, an attempt has been made to compare stresses predicted using two finite element analyses. First analysis is based on the twodimensional plane strain assumption where as in second approach axi-symmetric condition is assumed to consider three-dimensional behavior of rigid pavement. The results are compared with flexural stresses obtained from conventional Portland Cement Association method. The computed flexural stresses obtained from axi-symmetric condition are found to be in close agreement with PCA method. Results of plane strain analysis show a fair agreement after application of an appropriate multiplication factor
Comparative proteomic analysis in Miscanthus sinensis exposed to antimony stress
International Nuclear Information System (INIS)
Xue, Liang; Ren, Huadong; Li, Sheng; Gao, Ming; Shi, Shengqing; Chang, Ermei; Wei, Yuan; Yao, Xiaohua; Jiang, Zeping; Liu, Jianfeng
2015-01-01
To explore the molecular basis of Sb tolerance mechanism in plant, a comparative proteomic analysis of both roots and leaves in Miscanthus sinensis has been conducted in combination with physiological and biochemical analyses. M. sinensis seedlings were exposed to different doses of Sb, and both roots and leaves were collected after 3 days of treatment. Two-dimensional gel electrophoresis (2-DE) and image analyses found that 29 protein spots showed 1.5-fold change in abundance in leaves and 19 spots in roots, of which 31 were identified by MALDI-TOF-MS and MALDI-TOF-TOF-MS. Proteins involved in antioxidant defense and stress response generally increased their expression all over the Sb treatments. In addition, proteins relative to transcription, signal transduction, energy metabolism and cell division and cell structure showed a variable expression pattern over Sb concentrations. Overall these findings provide new insights into the probable survival mechanisms by which M. sinensis could be adapting to Sb phytotoxicity. - Highlights: • Proteomics in Miscanthus sinensis leaves and roots exposed to Sb stress were studied. • There were 31 spots that were identified by mass spectrometry. • Most of these proteins were involved in antioxidant defense and stress response. • Our findings provide new insights into the tolerant mechanisms to Sb stress. - Miscanthus sinensis proteomic analysis under Sb stress reveals probable molecular mechanisms on Sb detoxification
Probabilistic methods in combinatorial analysis
Sachkov, Vladimir N
2014-01-01
This 1997 work explores the role of probabilistic methods for solving combinatorial problems. These methods not only provide the means of efficiently using such notions as characteristic and generating functions, the moment method and so on but also let us use the powerful technique of limit theorems. The basic objects under investigation are nonnegative matrices, partitions and mappings of finite sets, with special emphasis on permutations and graphs, and equivalence classes specified on sequences of finite length consisting of elements of partially ordered sets; these specify the probabilist
Methods in quantitative image analysis.
Oberholzer, M; Ostreicher, M; Christen, H; Brühlmann, M
1996-05-01
The main steps of image analysis are image capturing, image storage (compression), correcting imaging defects (e.g. non-uniform illumination, electronic-noise, glare effect), image enhancement, segmentation of objects in the image and image measurements. Digitisation is made by a camera. The most modern types include a frame-grabber, converting the analog-to-digital signal into digital (numerical) information. The numerical information consists of the grey values describing the brightness of every point within the image, named a pixel. The information is stored in bits. Eight bits are summarised in one byte. Therefore, grey values can have a value between 0 and 256 (2(8)). The human eye seems to be quite content with a display of 5-bit images (corresponding to 64 different grey values). In a digitised image, the pixel grey values can vary within regions that are uniform in the original scene: the image is noisy. The noise is mainly manifested in the background of the image. For an optimal discrimination between different objects or features in an image, uniformity of illumination in the whole image is required. These defects can be minimised by shading correction [subtraction of a background (white) image from the original image, pixel per pixel, or division of the original image by the background image]. The brightness of an image represented by its grey values can be analysed for every single pixel or for a group of pixels. The most frequently used pixel-based image descriptors are optical density, integrated optical density, the histogram of the grey values, mean grey value and entropy. The distribution of the grey values existing within an image is one of the most important characteristics of the image. However, the histogram gives no information about the texture of the image. The simplest way to improve the contrast of an image is to expand the brightness scale by spreading the histogram out to the full available range. Rules for transforming the grey value
Assessment on the methods of measuring the tyre-road contact patch stresses
Anghelache, G.; Moisescu, A.-R.; Buretea, D.
2017-08-01
The paper reviews established and modern methods for investigating tri-axial stress distributions in the tyre-road contact patch. The authors used three methods of measuring stress distributions: strain gauge method; force sensing technique; acceleration measurements. Four prototypes of instrumented pins transducers involving mentioned measuring methods were developed. Data acquisitions of the contact patch stresses distributions were performed using each transducer with instrumented pin. The results are analysed and compared, underlining the advantages and drawbacks of each method. The experimental results indicate that the three methods are valuable.
Dynamical System Analysis of Reynolds Stress Closure Equations
Girimaji, Sharath S.
1997-01-01
In this paper, we establish the causality between the model coefficients in the standard pressure-strain correlation model and the predicted equilibrium states for homogeneous turbulence. We accomplish this by performing a comprehensive fixed point analysis of the modeled Reynolds stress and dissipation rate equations. The results from this analysis will be very useful for developing improved pressure-strain correlation models to yield observed equilibrium behavior.
Two-dimensional imaging of Debye-Scherrer ring for tri-axial stress analysis of industrial materials
International Nuclear Information System (INIS)
Sasaki, T; Maruyama, Y; Ohba, H; Ejiri, S
2014-01-01
In this study, an application of the two-dimensional imaging technology to the X ray tri-axial stress analysis was studied. An image plate (IP) was used to obtain a Debye-Scherre ring and the image data was analized for determining stress. A new principle for stress analysis which is suitable to two-dimensional imaging data was used. For the verification of this two-dimensional imaging type X-ray stress measurement method, an experiment was conducted using a ferritic steel sample which was processed with a surface grinder. Tri-axial stress analysis was conducted to evaluate the sample. The conventional method for X-ray tri-axial stress analysis proposed by Dölle and Hauk was used to evaluate residual stress in order to compare with the present method. As a result, it was confirmed that a sufficiently highly precise and high-speed stress measurement was enabled with the two-dimensional imaging technology compared with the conventional method
Approximate methods and working rules for peak stress effects
International Nuclear Information System (INIS)
Jobson, D.A.
1983-01-01
In order to assess stress concentration effects and associated strain intensification at notches, Neuber's work on this subject is used frequently. Neuber refers to a particular nonlinear stress-strain relation which, he observed, led to the same deferential equation for the lateral displacements as that found by Chaplygin for the velocity potential of compressible flow. for a linearized adiabatic law. This finding has been examined by studying torsion problems, which Involve warping displacements. Although a deformation law of the type τ(γ) has been assumed, the shear strain components remain 'proportional' to the corresponding stress components for problems of the type considered. It has been found that the governing equations and boundary conditions for φ may be made completely analogous to those for the velocity potential of a corresponding compressible flow in a prismatic cylinder of the same shape as that of the solid bar, provided that the constitutive equation. for the solid and the gas correspond in a defined sense. This embodied Neuber's observation, which was restricted to a particular stress strain law, namely that which corresponded to a linear adiabatic gas relationship. The above finding also assimilates a well-known hydrodynamic analogy, to which it reduces for linearly elastic materials. Corresponding governing equations have further been established for the stress function and these have similarly been related to those for an analogous stream function, defined by reference to the flow density of the corresponding compressible fluid
Moyer's method of mixed dentition analysis: a meta-analysis ...
African Journals Online (AJOL)
The applicability of tables derived from the data Moyer used to other ethnic groups has ... This implies that Moyer's method of prediction may have population variations. ... Key Words: meta-analysis, mixed dentition analysis, Moyer's method
Residual stress measurement by X-ray diffraction with the Gaussian curve method and its automation
International Nuclear Information System (INIS)
Kurita, M.
1987-01-01
X-ray technique with the Gaussian curve method and its automation are described for rapid and nondestructive measurement of residual stress. A simplified equation for measuring the stress by the Gaussian curve method is derived because in its previous form this method required laborious calculation. The residual stress can be measured in a few minutes, depending on materials, using an automated X-ray stress analyzer with a microcomputer which was developed in the laboratory. The residual stress distribution of a partially induction hardened and tempered (at 280 0 C) steel bar was measured with the Gaussian curve method. A sharp residual tensile stress peak of 182 MPa appeared right outside the hardened region at which fatigue failure is liable to occur
Tchitchekova, Deyana S.; Morthomas, Julien; Ribeiro, Fabienne; Ducher, Roland; Perez, Michel
2014-07-01
A novel method for accurate and efficient evaluation of the change in energy barriers for carbon diffusion in ferrite under heterogeneous stress is introduced. This method, called Linear Combination of Stress States, is based on the knowledge of the effects of simple stresses (uniaxial or shear) on these diffusion barriers. Then, it is assumed that the change in energy barriers under a complex stress can be expressed as a linear combination of these already known simple stress effects. The modifications of energy barriers by either uniaxial traction/compression and shear stress are determined by means of atomistic simulations with the Climbing Image-Nudge Elastic Band method and are stored as a set of functions. The results of this method are compared to the predictions of anisotropic elasticity theory. It is shown that, linear anisotropic elasticity fails to predict the correct energy barrier variation with stress (especially with shear stress) whereas the proposed method provides correct energy barrier variation for stresses up to ˜3 GPa. This study provides a basis for the development of multiscale models of diffusion under non-uniform stress.
International Nuclear Information System (INIS)
Tchitchekova, Deyana S.; Morthomas, Julien; Perez, Michel; Ribeiro, Fabienne; Ducher, Roland
2014-01-01
A novel method for accurate and efficient evaluation of the change in energy barriers for carbon diffusion in ferrite under heterogeneous stress is introduced. This method, called Linear Combination of Stress States, is based on the knowledge of the effects of simple stresses (uniaxial or shear) on these diffusion barriers. Then, it is assumed that the change in energy barriers under a complex stress can be expressed as a linear combination of these already known simple stress effects. The modifications of energy barriers by either uniaxial traction/compression and shear stress are determined by means of atomistic simulations with the Climbing Image-Nudge Elastic Band method and are stored as a set of functions. The results of this method are compared to the predictions of anisotropic elasticity theory. It is shown that, linear anisotropic elasticity fails to predict the correct energy barrier variation with stress (especially with shear stress) whereas the proposed method provides correct energy barrier variation for stresses up to ∼3 GPa. This study provides a basis for the development of multiscale models of diffusion under non-uniform stress
Energy Technology Data Exchange (ETDEWEB)
Tchitchekova, Deyana S. [IRSN, PSN, SEMIA, LPTM, Saint-Paul-Lez-Durance (France); Univ. Lyon, INSA Lyon, MATEIS, UMR CNRS 5510, Villeurbanne (France); Morthomas, Julien; Perez, Michel [Univ. Lyon, INSA Lyon, MATEIS, UMR CNRS 5510, Villeurbanne (France); Ribeiro, Fabienne [IRSN, PSN, SEMIA, LPTM, Saint-Paul-Lez-Durance (France); Ducher, Roland [IRSN, PSN, SAG, LETR, Saint-Paul-Lez-Durance (France)
2014-07-21
A novel method for accurate and efficient evaluation of the change in energy barriers for carbon diffusion in ferrite under heterogeneous stress is introduced. This method, called Linear Combination of Stress States, is based on the knowledge of the effects of simple stresses (uniaxial or shear) on these diffusion barriers. Then, it is assumed that the change in energy barriers under a complex stress can be expressed as a linear combination of these already known simple stress effects. The modifications of energy barriers by either uniaxial traction/compression and shear stress are determined by means of atomistic simulations with the Climbing Image-Nudge Elastic Band method and are stored as a set of functions. The results of this method are compared to the predictions of anisotropic elasticity theory. It is shown that, linear anisotropic elasticity fails to predict the correct energy barrier variation with stress (especially with shear stress) whereas the proposed method provides correct energy barrier variation for stresses up to ∼3 GPa. This study provides a basis for the development of multiscale models of diffusion under non-uniform stress.
Applying critical analysis - main methods
Directory of Open Access Journals (Sweden)
Miguel Araujo Alonso
2012-02-01
Full Text Available What is the usefulness of critical appraisal of literature? Critical analysis is a fundamental condition for the correct interpretation of any study that is subject to review. In epidemiology, in order to learn how to read a publication, we must be able to analyze it critically. Critical analysis allows us to check whether a study fulfills certain previously established methodological inclusion and exclusion criteria. This is frequently used in conducting systematic reviews although eligibility criteria are generally limited to the study design. Critical analysis of literature and be done implicitly while reading an article, as in reading for personal interest, or can be conducted in a structured manner, using explicit and previously established criteria. The latter is done when formally reviewing a topic.
A multimodal stress monitoring system with canonical correlation analysis.
Unsoo Ha; Changhyeon Kim; Yongsu Lee; Hyunki Kim; Taehwan Roh; Hoi-Jun Yoo
2015-08-01
The multimodal stress monitoring headband is proposed for mobile stress management system. It is composed of headband and earplugs. Electroencephalography (EEG), hemoencephalography (HEG) and heart-rate variability (HRV) can be achieved simultaneously in the proposed system for user status estimation. With canonical correlation analysis (CCA) and temporal-kernel CCA (tkCCA) algorithm, those different signals can be combined for maximum correlation. Thanks to the proposed combination algorithm, the accuracy of the proposed system increased up to 19 percentage points than unimodal monitoring system in n-back task.
Comparison of residual stress measurement in thin films using surface micromachining method
International Nuclear Information System (INIS)
He, Q.; Luo, Z.X.; Chen, X.Y.
2008-01-01
Conductive, dielectric, semiconducting, piezoelectric and ferroelectric thin films are extensively used for MEMS/NEMS applications. One of the important parameters of thin films is residual stress. The residual stress can seriously affect the properties, performance and long-term stability of the films. Excessive compressive or tensile stress results in buckling, cracking, splintering and sticking problems. Stress measurement techniques are therefore essential for both process development and process monitoring. Many suggestions for stress measurement in thin films have been made over the past several decades. This paper is concentrated on the in situ stress measurement using surface micromachining techniques to determine the residual stress. The authors review and compare several types of stress measurement methods including buckling technique, rotating technique, micro strain gauge and long-short beam strain sensor
Kim, Jeongho; Dhital, Sukirti; Zhivago, Paul; Kaizer, Marina R; Zhang, Yu
2018-06-01
The main problem of porcelain-veneered zirconia (PVZ) dental restorations is chipping and delamination of veneering porcelain owing to the development of deleterious residual stresses during the cooling phase of veneer firing. The aim of this study is to elucidate the effects of cooling rate, thermal contraction coefficient and elastic modulus on residual stresses developed in PVZ dental crowns using viscoelastic finite element methods (VFEM). A three-dimensional VFEM model has been developed to predict residual stresses in PVZ structures using ABAQUS finite element software and user subroutines. First, the newly established model was validated with experimentally measured residual stress profiles using Vickers indentation on flat PVZ specimens. An excellent agreement between the model prediction and experimental data was found. Then, the model was used to predict residual stresses in more complex anatomically-correct crown systems. Two PVZ crown systems with different thermal contraction coefficients and porcelain moduli were studied: VM9/Y-TZP and LAVA/Y-TZP. A sequential dual-step finite element analysis was performed: heat transfer analysis and viscoelastic stress analysis. Controlled and bench convection cooling rates were simulated by applying different convective heat transfer coefficients 1.7E-5 W/mm 2 °C (controlled cooling) and 0.6E-4 W/mm 2 °C (bench cooling) on the crown surfaces exposed to the air. Rigorous viscoelastic finite element analysis revealed that controlled cooling results in lower maximum stresses in both veneer and core layers for the two PVZ systems relative to bench cooling. Better compatibility of thermal contraction coefficients between porcelain and zirconia and a lower porcelain modulus reduce residual stresses in both layers. Copyright © 2018 Elsevier Ltd. All rights reserved.
Trial Sequential Methods for Meta-Analysis
Kulinskaya, Elena; Wood, John
2014-01-01
Statistical methods for sequential meta-analysis have applications also for the design of new trials. Existing methods are based on group sequential methods developed for single trials and start with the calculation of a required information size. This works satisfactorily within the framework of fixed effects meta-analysis, but conceptual…
Modelling and analysis of the stress distribution in a multi-thin film system Pt/USG/Si
Yao, W. Z.; Roqueta, F.; Craveur, J. C.; Belhenini, S.; Gardes, P.; Tougui, A.
2018-04-01
Residual stress analysis is commonly achieved through curvature measurement with the help of Stoney’s formula. However, this conventional approach is inadequate for multi-layer thin film systems, which are widely used in today’s microelectronics. Also, for the thin film case, the residual stress is composed of thermal stress and intrinsic stress. Measuring the wafer curvature at room temperature provides a value for the average stresses in the layer, the two components cannot be distinguished by the existing methodologies of curvature measurement. To alleviate these problems, a modified curvature method combining finite element (FE) modelling is proposed to study the stress distribution in a Pt/USG/Si structure. A 2D FE model is firstly built in order to calculate the thermal stress in the multilayer structure, the obtained thermal stresses in respective films are verified by an analytical model. Then, we calculate the warpage of the multilayer structure by considering the intrinsic stress in the respective films. The residual stresses in the films are determined by minimizing the difference between the simulated warpage and that of experimental measurement. The proposed approach can be used to calculate not only the average residual stress but also thermal and intrinsic stress components in the USG and Platinum films. The obtained residual and intrinsic stresses from a numerical model are compared with the values of other studies. There is no limitation for the application of our methodologies regarding the number of the layers in the stack.
Non-Destructive Evaluation Method Based On Dynamic Invariant Stress Resultants
Directory of Open Access Journals (Sweden)
Zhang Junchi
2015-01-01
Full Text Available Most of the vibration based damage detection methods are based on changes in frequencies, mode shapes, mode shape curvature, and flexibilities. These methods are limited and typically can only detect the presence and location of damage. Current methods seldom can identify the exact severity of damage to structures. This paper will present research in the development of a new non-destructive evaluation method to identify the existence, location, and severity of damage for structural systems. The method utilizes the concept of invariant stress resultants (ISR. The basic concept of ISR is that at any given cross section the resultant internal force distribution in a structural member is not affected by the inflicted damage. The method utilizes dynamic analysis of the structure to simulate direct measurements of acceleration, velocity and displacement simultaneously. The proposed dynamic ISR method is developed and utilized to detect the damage of corresponding changes in mass, damping and stiffness. The objectives of this research are to develop the basic theory of the dynamic ISR method, apply it to the specific types of structures, and verify the accuracy of the developed theory. Numerical results that demonstrate the application of the method will reflect the advanced sensitivity and accuracy in characterizing multiple damage locations.
Regular and platform switching: bone stress analysis varying implant type.
Gurgel-Juarez, Nália Cecília; de Almeida, Erika Oliveira; Rocha, Eduardo Passos; Freitas, Amílcar Chagas; Anchieta, Rodolfo Bruniera; de Vargas, Luis Carlos Merçon; Kina, Sidney; França, Fabiana Mantovani Gomes
2012-04-01
This study aimed to evaluate stress distribution on peri-implant bone simulating the influence of platform switching in external and internal hexagon implants using three-dimensional finite element analysis. Four mathematical models of a central incisor supported by an implant were created: External Regular model (ER) with 5.0 mm × 11.5 mm external hexagon implant and 5.0 mm abutment (0% abutment shifting), Internal Regular model (IR) with 4.5 mm × 11.5 mm internal hexagon implant and 4.5 mm abutment (0% abutment shifting), External Switching model (ES) with 5.0 mm × 11.5 mm external hexagon implant and 4.1 mm abutment (18% abutment shifting), and Internal Switching model (IS) with 4.5 mm × 11.5 mm internal hexagon implant and 3.8 mm abutment (15% abutment shifting). The models were created by SolidWorks software. The numerical analysis was performed using ANSYS Workbench. Oblique forces (100 N) were applied to the palatal surface of the central incisor. The maximum (σ(max)) and minimum (σ(min)) principal stress, equivalent von Mises stress (σ(vM)), and maximum principal elastic strain (ε(max)) values were evaluated for the cortical and trabecular bone. For cortical bone, the highest stress values (σ(max) and σ(vm) ) (MPa) were observed in IR (87.4 and 82.3), followed by IS (83.3 and 72.4), ER (82 and 65.1), and ES (56.7 and 51.6). For ε(max), IR showed the highest stress (5.46e-003), followed by IS (5.23e-003), ER (5.22e-003), and ES (3.67e-003). For the trabecular bone, the highest stress values (σ(max)) (MPa) were observed in ER (12.5), followed by IS (12), ES (11.9), and IR (4.95). For σ(vM), the highest stress values (MPa) were observed in IS (9.65), followed by ER (9.3), ES (8.61), and IR (5.62). For ε(max) , ER showed the highest stress (5.5e-003), followed by ES (5.43e-003), IS (3.75e-003), and IR (3.15e-003). The influence of platform switching was more evident for cortical bone than for trabecular bone, mainly for the external hexagon
Hybrid methods for cybersecurity analysis :
Energy Technology Data Exchange (ETDEWEB)
Davis, Warren Leon,; Dunlavy, Daniel M.
2014-01-01
Early 2010 saw a signi cant change in adversarial techniques aimed at network intrusion: a shift from malware delivered via email attachments toward the use of hidden, embedded hyperlinks to initiate sequences of downloads and interactions with web sites and network servers containing malicious software. Enterprise security groups were well poised and experienced in defending the former attacks, but the new types of attacks were larger in number, more challenging to detect, dynamic in nature, and required the development of new technologies and analytic capabilities. The Hybrid LDRD project was aimed at delivering new capabilities in large-scale data modeling and analysis to enterprise security operators and analysts and understanding the challenges of detection and prevention of emerging cybersecurity threats. Leveraging previous LDRD research e orts and capabilities in large-scale relational data analysis, large-scale discrete data analysis and visualization, and streaming data analysis, new modeling and analysis capabilities were quickly brought to bear on the problems in email phishing and spear phishing attacks in the Sandia enterprise security operational groups at the onset of the Hybrid project. As part of this project, a software development and deployment framework was created within the security analyst work ow tool sets to facilitate the delivery and testing of new capabilities as they became available, and machine learning algorithms were developed to address the challenge of dynamic threats. Furthermore, researchers from the Hybrid project were embedded in the security analyst groups for almost a full year, engaged in daily operational activities and routines, creating an atmosphere of trust and collaboration between the researchers and security personnel. The Hybrid project has altered the way that research ideas can be incorporated into the production environments of Sandias enterprise security groups, reducing time to deployment from months and
Directory of Open Access Journals (Sweden)
Hsu Chih-Neng
2013-01-01
Full Text Available This paper focuses on the heat transfer and structural stress analysis of the micro- scale packaging structure of a high-power light emitting diode. The thermal-effect and thermal-stress of light emitting diode are determined numerically. Light emitting diode is attached to the silicon substrate through the wire bonding process by using epoxy as die bond material. The silicon substrate is etched with holes at the bottom and filled with high conductivity copper material. The chip temperature and structure stress increase with input power consumption. The micro light emitting diode is mounted on the heat sink to increase the heat dissipation performance, to decrease chip temperature, to enhance the material structure reliability and safety, and to avoid structure failure as well. This paper has successfully used the finite element method to the micro-scale light emitting diode heat transfer and stress concentration at the edges through etched holes.
Stress analysis of disconnected structures in contact through finite element gaps
International Nuclear Information System (INIS)
Stadter, J.T.; Weiss, R.O.
1976-07-01
A numerical procedure is presented for analyzing thermal stress problems of disconnected structures in contact across separations or gaps. The new procedure is called SAASGAPS, an adaptation of the basic SAAS III computer program. The SAAS program uses the finite element method and allows analyses of plane and axisymmetric bodies with temperature dependent material properties, subject to thermal and mechanical loads. A secant modulus approach with a bilinear stress-strain curve is used for elastic-plastic problems. The SAASGAPS version contains all of the features of the original SAAS program. A special gap element is used together with a stress invariance principle to model the contact process. The iterative procedure implemented in SAASGAPS is described. Results are discussed for five problems involving frictionless contact. Two of these problems are associated with the thermal stress analysis of the heat shield for the Multi-Hundred Watt Radioisotope Thermoelectric Generator. Input instructions for the program are described in an appendix
Directory of Open Access Journals (Sweden)
Vasile Cojocaru
2017-12-01
Full Text Available In the analysis of plain bearings by finite element method it is important to model as closely to real state the aspects that influence the stress and contact pressure: the loading mode, the properties of the materials, the lubrication system, the clearance between the shaft and the bearing body, the evolution in time of clearance correlated with the wear, etc. In order to study the effect of the clearance on the stress state, a plain bearing with nominal diameter d=40 mm was modeled. The contact pressure and the equivalent stress were computed for six discrete values of clearance, range from c=0 to c=0.3 mm. It has been shown that the increase of clearance generates an increase of the equivalent stress and contact pressure. The growth rate is higher for contact pressure, due to the decrease of the contact surface between the shaft and the bearing body
Thermal Stress FE Analysis of Large-scale Gas Holder Under Sunshine Temperature Field
Li, Jingyu; Yang, Ranxia; Wang, Hehui
2018-03-01
The temperature field and thermal stress of Man type gas holder is simulated by using the theory of sunshine temperature field based on ASHRAE clear-sky model and the finite element method. The distribution of surface temperature and thermal stress of gas holder under the given sunshine condition is obtained. The results show that the thermal stress caused by sunshine can be identified as one of the important factors for the failure of local cracked oil leakage which happens on the sunny side before on the shady side. Therefore, it is of great importance to consider the sunshine thermal load in the stress analysis, design and operation of large-scale steel structures such as the gas holder.
Micromechanical combined stress analysis: MICSTRAN, a user manual
Naik, R. A.
1992-01-01
Composite materials are currently being used in aerospace and other applications. The ability to tailor the composite properties by the appropriate selection of its constituents, the fiber and matrix, is a major advantage of composite materials. The Micromechanical Combined Stress Analysis (MICSTRAN) code provides the materials engineer with a user-friendly personal computer (PC) based tool to calculate overall composite properties given the constituent fiber and matrix properties. To assess the ability of the composite to carry structural loads, the materials engineer also needs to calculate the internal stresses in the composite material. MICSTRAN is a simple tool to calculate such internal stresses with a composite ply under combined thermomechanical loading. It assumes that the fibers have a circular cross-section and are arranged either in a repeating square or diamond array pattern within a ply. It uses a classical elasticity solution technique that has been demonstrated to calculate accurate stress results. Input to the program consists of transversely isotropic fiber properties and isotropic matrix properties such as moduli, Poisson's ratios, coefficients of thermal expansion, and volume fraction. Output consists of overall thermoelastic constants and stresses. Stresses can be computed under the combined action of thermal, transverse, longitudinal, transverse shear, and longitudinal shear loadings. Stress output can be requested along the fiber-matrix interface, the model boundaries, circular arcs, or at user-specified points located anywhere in the model. The MICSTRAN program is Windows compatible and takes advantage of the Microsoft Windows graphical user interface which facilitates multitasking and extends memory access far beyond the limits imposed by the DOS operating system.
Study on application of green's function method in thermal stress rapid calculation
International Nuclear Information System (INIS)
Zhang Guihe; Duan Yuangang; Xu Xiao; Chen Rong
2013-01-01
This paper presents a quick and accuracy thermal stress calculation method, the Green's Function Method, which is a combination of finite element method and numerical algorithm method. Thermal stress calculation of Safe Injection Nozzle of Reactor Coolant Line of PWR plant is performed with Green's function method for heatup and cooldown thermal transients as a demonstration example, and the result is compared with finite element method to verify the rationality and accuracy of this method. The advantage and disadvantage of the Green's function method and the finite element method are also compared. (authors)
Reduction method for residual stress of welded joint using random vibration
International Nuclear Information System (INIS)
Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro
2005-01-01
Welded joints are used for construction of many structures. Residual stress is induced near the bead caused by locally given heat. Tensile residual stress on the surface may reduce fatigue strength. In this paper, a new method for reduction of residual stress using vibration during welding is proposed. As vibrational load, random vibration, white noise and filtered white noise are used. Two thin plates are butt-welded. Residual stress is measured with a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. It is concluded that tensile residual stress near the bead is reduced by using random vibration during welding
CSIR Research Space (South Africa)
Napier, JAL
2002-09-01
Full Text Available The numerical solution of problems relating to crack fracture and failure can be accomplished using the displacement discontinuity boundary element method. This paper presents an extension to the normal formulation of this method to enable stress...
Microparticle analysis system and method
Morrison, Dennis R. (Inventor)
2007-01-01
A device for analyzing microparticles is provided which includes a chamber with an inlet and an outlet for respectively introducing and dispensing a flowing fluid comprising microparticles, a light source for providing light through the chamber and a photometer for measuring the intensity of light transmitted through individual microparticles. The device further includes an imaging system for acquiring images of the fluid. In some cases, the device may be configured to identify and determine a quantity of the microparticles within the fluid. Consequently, a method for identifying and tracking microparticles in motion is contemplated herein. The method involves flowing a fluid comprising microparticles in laminar motion through a chamber, transmitting light through the fluid, measuring the intensities of the light transmitted through the microparticles, imaging the fluid a plurality of times and comparing at least some of the intensities of light between different images of the fluid.
Contributions to robust methods of creep analysis
International Nuclear Information System (INIS)
Penny, B.K.
1991-01-01
Robust methods for the predictions of deformations and lifetimes of components operating in the creep range are presented. The ingredients used for this are well-tried numerical techniques combined with the concepts of continuum damage and so-called reference stresses. The methods described are derived in order to obtain the maximum benefit during the early stages of design where broad assessments of the influences of material choice, loadings and geometry need to be made quickly and with economical use of computers. It is also intended that the same methods will be of value during operation if estimates of damage or if exercises in life extension or inspection timing are required. (orig.)
Inserting Stress Analysis of Combined Hexagonal Aluminum Honeycombs
Directory of Open Access Journals (Sweden)
Xiangcheng Li
2016-01-01
Full Text Available Two kinds of hexagonal aluminum honeycombs are tested to study their out-of-plane crushing behavior. In the tests, honeycomb samples, including single hexagonal aluminum honeycomb (SHAH samples and two stack-up combined hexagonal aluminum honeycombs (CHAH samples, are compressed at a fixed quasistatic loading rate. The results show that the inserting process of CHAH can erase the initial peak stress that occurred in SHAH. Meanwhile, energy-absorbing property of combined honeycomb samples is more beneficial than the one of single honeycomb sample with the same thickness if the two types of honeycomb samples are completely crushed. Then, the applicability of the existing theoretical model for single hexagonal honeycomb is discussed, and an area equivalent method is proposed to calculate the crushing stress for nearly regular hexagonal honeycombs. Furthermore, a semiempirical formula is proposed to calculate the inserting plateau stress of two stack-up CHAH, in which structural parameters and mechanics properties of base material are concerned. The results show that the predicted stresses of three kinds of two stack-up combined honeycombs are in good agreement with the experimental data. Based on this study, stress-displacement curve of aluminum honeycombs can be designed in detail, which is very beneficial to optimize the energy-absorbing structures in engineering fields.
Stress analysis of glass-ceramic insulator and molybdenum cylinders in vacuum tube subassembly
International Nuclear Information System (INIS)
Spears, R.K.
1980-01-01
This study determined the state of stress between molybdenum cylinders and a glass-ceramic insulator of a vacuum tube during cooling when the glass-ceramic coefficient of expansion differed from molybdenum by +-2 x 10 -7 / 0 C. A thermoelastic stress analysis was performed on the vacuum tube subassembly using the finite element method. Two cases, which examined the effect of cooling over a 700 0 C range, were considered. In Case One, the expansion coefficient of the glass-ceramic was 2 x 10 -7 / 0 C less than that of molybdenum while for Case Two, it was 2 x 10 -7 / 0 C greater. For Case One, it was found that the tangential stresses in the insulator were entirely compressive but the maximum principal stresses in the r-z plane were mainly tensile. For Case Two, the tangential stresses were tensile in the insulator as were most of the maximum principal stresses in the r-z plane except for stress in the upper regions of the insulator. The magnitude of the stress at the maximum principal stress location appears to be substantially lower than what has been observed in practice (i.e., cracking of this design had never been a major problem, but it has been observed that if the coefficient of expansion of the glass-ceramic was 2 x 10 -7 / 0 C lower than molybdenum, cracking usually resulted). This analysis showed that the expansion coefficient of the glass-ceramic could be varied quite liberally from molybdenum before the ultimate strength (13,000 lb/in. 2 ) of the glass-ceramic was exceeded
Methods and Models of Market Risk Stress-Testing of the Portfolio of Financial Instruments
Directory of Open Access Journals (Sweden)
Alexander M. Karminsky
2015-01-01
Full Text Available Amid instability of financial markets and macroeconomic situation the necessity of improving bank risk-management instrument arises. New economic reality defines the need for searching for more advanced approaches of estimating banks vulnerability to exceptional, but plausible events. Stress-testing belongs to such instruments. The paper reviews and compares the models of market risk stress-testing of the portfolio of different financial instruments. These days the topic of the paper is highly acute due to the fact that now stress-testing is becoming an integral part of anticrisis risk-management amid macroeconomic instability and appearance of new risks together with close interest to the problem of risk-aggregation. The paper outlines the notion of stress-testing and gives coverage of goals, functions of stress-tests and main criteria for market risk stress-testing classification. The paper also stresses special aspects of scenario analysis. Novelty of the research is explained by elaborating the programme of aggregated complex multifactor stress-testing of the portfolio risk based on scenario analysis. The paper highlights modern Russian and foreign models of stress-testing both on solo-basis and complex. The paper lays emphasis on the results of stress-testing and revaluations of positions for all three complex models: methodology of the Central Bank of stress-testing portfolio risk, model relying on correlations analysis and copula model. The models of stress-testing on solo-basis are different for each financial instrument. Parametric StressVaR model is applicable to shares and options stress-testing;model based on "Grek" indicators is used for options; for euroobligation regional factor model is used. Finally some theoretical recommendations about managing market risk of the portfolio are given.
International Nuclear Information System (INIS)
Tamaoki, Masanori; Matsuyama, Takashi; Nakajima, Nobuyoshi; Aono, Mitsuko; Kubo, Akihiro; Saji, Hikaru
2004-01-01
Plants in the field are subjected to numerous environmental stresses. Lengthy continuation of such environmental stresses or a rapid increase in their intensity is harmful to vegetation. Assessments of the phytotoxicity of various stresses have been performed in many countries, although they have largely been based on estimates of leaf injury. We developed a novel method of detecting plant stresses that is more sensitive and specific than those previously available. This method is based on the detection of mRNA expression changes in 205 ozone-responsive Arabidopsis expressed sequence tags (ESTs) by cDNA macroarray analysis. By using this method, we illustrated shifts in gene expression in response to stressors such as drought, salinity, UV-B, low temperature, high temperature, and acid rain, as distinct from those in response to ozone. We also made a mini-scale macroarray with 12 ESTs for diagnosis of the above environmental stresses in plants. These results illustrate the potential of our cDNA macroarray for diagnosis of various stresses in plants
Infinitesimal methods of mathematical analysis
Pinto, J S
2004-01-01
This modern introduction to infinitesimal methods is a translation of the book Métodos Infinitesimais de Análise Matemática by José Sousa Pinto of the University of Aveiro, Portugal and is aimed at final year or graduate level students with a background in calculus. Surveying modern reformulations of the infinitesimal concept with a thoroughly comprehensive exposition of important and influential hyperreal numbers, the book includes previously unpublished material on the development of hyperfinite theory of Schwartz distributions and its application to generalised Fourier transforms and harmon
Development of advanced MCR task analysis methods
International Nuclear Information System (INIS)
Na, J. C.; Park, J. H.; Lee, S. K.; Kim, J. K.; Kim, E. S.; Cho, S. B.; Kang, J. S.
2008-07-01
This report describes task analysis methodology for advanced HSI designs. Task analyses was performed by using procedure-based hierarchical task analysis and task decomposition methods. The results from the task analysis were recorded in a database. Using the TA results, we developed static prototype of advanced HSI and human factors engineering verification and validation methods for an evaluation of the prototype. In addition to the procedure-based task analysis methods, workload estimation based on the analysis of task performance time and analyses for the design of information structure and interaction structures will be necessary
Development of stress relaxation measurement by a small size C-ring specimen method
International Nuclear Information System (INIS)
Shimanuki, Shizuka; Nakata, Kiyotomo; Kasahara, Shigeki; Kuniya, Jiro
2002-01-01
A stress relaxation measurement method has been developed by using C-ring specimens, and a specimen size effect has been evaluated taking radiation-induced stress relaxation into consideration. C-ring specimens were stressed by forcing a wedge in the gap. Giving an appropriate eccentric configuration in the half of the ring opposite the gap, the stress gradient along the circumference was eliminated in the section and the stress level could be varied by changing the gap spacing. The validity of the C-ring test method was confirmed by thermally stress relaxation experiments at annealing temperatures from 300 to 600degC for 1 min to 200 h in carbon steel: considerable stress relaxation could be measured for all levels of applied stress even at relatively low annealing temperatures. The relaxation results obtained from the C-ring test were in good agreement with those from a uniaxial tensile stress relaxation test. The smaller C-ring specimen with about 40 mm diameter, which is required for radiation-induced stress relaxation test, also showed adequate accuracy on stress relaxation at 600 to 830degC in stainless steel, compared with the large size C-ring specimen test. (author)
Current status of methods for shielding analysis
International Nuclear Information System (INIS)
Engle, W.W.
1980-01-01
Current methods used in shielding analysis and recent improvements in those methods are discussed. The status of methods development is discussed based on needs cited at the 1977 International Conference on Reactor Shielding. Additional areas where methods development is needed are discussed
Coupling image processing and stress analysis for damage identification in a human premolar tooth.
Andreaus, U; Colloca, M; Iacoviello, D
2011-08-01
Non-carious cervical lesions are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine. Damage identification was performed by image analysis techniques and allowed to quantitatively assess changes in teeth. A computerized two-step procedure was generated and applied to the first left maxillary human premolar. In the first step, dental images were digitally processed by a segmentation method in order to identify the damage. The considered morphological properties were the enamel thickness and total area, the number of fragments in which the enamel is chipped. The information retrieved by the data processing of the section images allowed to orient the stress investigation toward selected portions of the tooth. In the second step, a three-dimensional finite element model based on CT images of both the tooth and the periodontal ligament was employed to compare the changes occurring in the stress distributions in normal occlusion and malocclusion. The stress states were analyzed exclusively in the critical zones designated in the first step. The risk of failure at the CEJ and of crack initiation at the dentin-enamel junction through the quantification of first and third principal stresses, von Mises stress, and normal and tangential stresses, were also estimated. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
Simplified method of calculating residual stress in circumferential welding of piping
International Nuclear Information System (INIS)
Umemoto, Tadahiro
1984-01-01
Many circumferential joints of piping are used in as-welded state, but in these welded joints, the residual stress as high as the yield stress of materials arises, and causes to accelerate stress corrosion cracking and corrosion fatigue. The experiment or the finite element method to clarify welding residual stress requires much time and labor, and is expensive, therefore, the author proposed the simplified method of calculation. The heating and cooling process of welding is very complex, and cannot be modeled as it is, therefore, it was assumed that in multiple layer welding, the welding condition of the last layer determines the residual stress, that material constants are invariable regardless of temperature, that the temperature distribution and residual stress are axisymmetric, and that there is repeated stress-strain relation in the vicinity of welded parts. The temperature distribution at the time of welding, thermal stress and welding residual stress are analyzed, and the material constants used for the calculation of residual stress are given. As the example of calculation, the effect of welding heat input and materials is shown. The extension of the method to a thick-walled pipe is discussed. (Kako, I.)
International Nuclear Information System (INIS)
Parikin; Killen, P.; Anis, M.
2003-01-01
Tailoring of diffraction technique-Rietveld method on residual stress measurements of cold-canailed stainless steel 304 plates assuming the material is isotopic, the residual stress measurements using X-ray powder diffraction is just performed for a plane lying in a large angle. For anisotropic materials, the real measurements will not be represented by the methods. By Utilizing of all diffraction peaks in the observation region, tailoring diffraction technique-Rietveld analysis is able to cover the limitations. The residual stress measurement using X-ray powder diffraction tailored by Rietveld method, in a series of cold-canailed stainless steel 304 plates deforming; 0, 34, 84, 152, 158, 175, and 196 % reduction in thickness, have been reported. The diffraction data were analyzed by using Rietveld structure refinement method. Also, for all cold-canailed stainless steel 304 plates cuplikans, the diffraction peaks are broader than the uncanailed one, indicating that the strains in these cuplikans are inhomogeneous. From an analysis of the refined peak shape parameters, the average root-mean square strain, which describes the distribution of the inhomogeneous strain field, was calculated. Finally, the average residual stresses in cold-canailed stainless steel 304 plates were shown to be a combination effect of hydrostatic stresses of martensite particles and austenite matrix. The average residual stresses were evaluated from the experimentally determined average lattice strains in each phase. It was found the tensile residual stress in a cuplikan was maximum, reaching 442 MPa, for a cuplikan reducing 34% in thickness and minimum for a 196% cuplikan
Numerical methods for calculating thermal residual stresses and hydrogen diffusion
International Nuclear Information System (INIS)
Leblond, J.B.; Devaux, J.; Dubois, D.
1983-01-01
Thermal residual stresses and hydrogen concentrations are two major factors intervening in cracking phenomena. These parameters were numerically calculated by a computer programme (TITUS) using the FEM, during the deposition of a stainless clad on a low-alloy plate. The calculation was performed with a 2-dimensional option in four successive steps: thermal transient calculation, metallurgical transient calculation (determination of the metallurgical phase proportions), elastic-plastic transient (plain strain conditions), hydrogen diffusion transient. Temperature and phase dependence of hydrogen diffusion coefficient and solubility constant. The following results were obtained: thermal calculations are very consistent with experiments at higher temperatures (due to the introduction of fusion and solidification latent heats); the consistency is not as good (by 70 degrees) for lower temperatures (below 650 degrees C); this was attributed to the non-introduction of gamma-alpha transformation latent heat. The metallurgical phase calculation indicates that the heat affected zone is almost entirely transformed into bainite after cooling down (the martensite proportion does not exceed 5%). The elastic-plastic calculations indicate that the stresses in the heat affected zone are compressive or slightly tensile; on the other hand, higher tensile stresses develop on the boundary of the heat affected zone. The transformation plasticity has a definite influence on the final stress level. The return of hydrogen to the clad during the bainitic transformation is but an incomplete phenomenon and the hydrogen concentration in the heat affected zone after cooling down to room temperature is therefore sufficient to cause cold cracking (if no heat treatment is applied). Heat treatments are efficient in lowering the hydrogen concentration. These results enable us to draw preliminary conclusions on practical means to avoid cracking. (orig.)
An Improved Spectral Analysis Method for Fatigue Damage Assessment of Details in Liquid Cargo Tanks
Zhao, Peng-yuan; Huang, Xiao-ping
2018-03-01
Errors will be caused in calculating the fatigue damages of details in liquid cargo tanks by using the traditional spectral analysis method which is based on linear system, for the nonlinear relationship between the dynamic stress and the ship acceleration. An improved spectral analysis method for the assessment of the fatigue damage in detail of a liquid cargo tank is proposed in this paper. Based on assumptions that the wave process can be simulated by summing the sinusoidal waves in different frequencies and the stress process can be simulated by summing the stress processes induced by these sinusoidal waves, the stress power spectral density (PSD) is calculated by expanding the stress processes induced by the sinusoidal waves into Fourier series and adding the amplitudes of each harmonic component with the same frequency. This analysis method can take the nonlinear relationship into consideration and the fatigue damage is then calculated based on the PSD of stress. Take an independent tank in an LNG carrier for example, the accuracy of the improved spectral analysis method is proved much better than that of the traditional spectral analysis method by comparing the calculated damage results with the results calculated by the time domain method. The proposed spectral analysis method is more accurate in calculating the fatigue damages in detail of ship liquid cargo tanks.
On the influence of T-Stress on photoelastic analysis under pure mode II loading
Directory of Open Access Journals (Sweden)
Chiara Colombo
2008-01-01
Full Text Available According to the classical definition for in-plane modes of crack deformation, the constant stress term T exists only in the presence of mode I. However, recent studies show that this term can exist inmode II conditions as well, and significantly affect the elastic stress field around the crack tip. These effects can be visualized using the experimental method of photoelasticity. Based on the analytical studies, presence of the T-stress in mode II cracks transforms the isochromatic fringe patterns from symmetric closed loops to asymmetric and discontinuous shapes. In this paper, presence of the T-stress in mode II cracks and its effects on the fringe patterns is experimentally investigated. The test specimens are Brazilian disks containing very sharp central cracks: experimental results indicate that these specimens contain negative values of T-stress. Experimental values are then compared to numerical results. To better understand the differences between experimental and numerical values, a thee dimensional analysis is performed with the finite element method: results show the influence of the real geometry of the crack front on the stress intensity factors.
Ito, T.; Funato, A.; Tamagawa, T.; Tezuka, K.; Yabe, Y.; Abe, S.; Ishida, A.; Ogasawara, H.
2017-12-01
When rock is cored at depth by drilling, anisotropic expansion occurs with the relief of anisotropic rock stresses, resulting in a sinusoidal variation of core diameter with a period of 180 deg. in the core roll angle. The circumferential variation of core diameter is given theoretically as a function of rock stresses. These new findings can lead various ideas to estimate the rock stress from circumferential variation of core diameter measured after the core retrieving. In the simplest case when a single core sample is only available, the difference between the maximum and minimum components of rock stress in a plane perpendicular to the drilled hole can be estimated from the maximum and minimum core diameters (see the detail in, Funato and Ito, IJRMMS, 2017). The advantages of this method include, (i) much easier measurement operation than those in other in-situ or in-lab estimation methods, and (ii) applicability in high stress environment where stress measurements need pressure for packers or pumping system for the hydro-fracturing methods higher than their tolerance levels. We have successfully tested the method at deep seismogenic zones in South African gold mines, and we are going to apply it to boreholes collared at 3 km depth and intersecting a M5.5 rupture plane several hundred meters below the mine workings in the ICDP project of "Drilling into Seismogenic zones of M2.0 - M5.5 earthquakes in deep South African gold mines" (DSeis) (e.g., http://www.icdp-online.org/projects/world/africa/orkney-s-africa/details/). If several core samples with different orientation are available, all of three principal components of 3D rock stress can be estimated. To realize this, we should have several boreholes drilled in different directions in a rock mass where the stress field is considered to be uniform. It is commonly carried out to dill boreholes in different directions from a mine gallery. Even in a deep borehole drilled vertically from the ground surface, the
Reduction method for residual stress of welded joint using harmonic vibrational load
International Nuclear Information System (INIS)
Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji
2007-01-01
Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model
Calculation of mixed mode stress intensity factors using an alternating method
International Nuclear Information System (INIS)
Sakai, Takayuki
1999-01-01
In this study, mixed mode stress intensity factors (K I and K II ) of a square plate with a notch were calculated using a finite element alternating method. The obtained results were compared with the ones by a finite element method, and it was shown that the finite element alternating method can accurately estimate mixed mode stress intensity factors. Then, using this finite element alternating method, mixed mode stress intensity factors were calculated as changing the size and position of the notch, and its simplified equations were proposed. (author)
Damage approach: A new method for topology optimization with local stress constraints
DEFF Research Database (Denmark)
Verbart, Alexander; Langelaar, Matthijs; van Keulen, Fred
2016-01-01
In this paper, we propose a new method for topology optimization with local stress constraints. In this method, material in which a stress constraint is violated is considered as damaged. Since damaged material will contribute less to the overall performance of the structure, the optimizer...... will promote a design with a minimal amount of damaged material. We tested the method on several benchmark problems, and the results show that the method is a viable alternative for conventional stress-based approaches based on constraint relaxation followed by constraint aggregation....
International Nuclear Information System (INIS)
Haraguchi, Akira; Yamakawa, Hidetsugu; Abe, Hirotoshi
1981-01-01
The problems of the thermal stress in concrete structures are roughly divided into the initial stress due to setting heat and the stress due to external temperature after hardening. The initial stress exists in every concrete structure, and it is usually neglected in beams and columns, but it must be taken into account in case of the foundation mat structures in nuclear power stations, for example. In this paper, (1) the results of measurement of temperature, strain and stress in each lift at the time of and after placing concrete in the foundation mat of a nuclear power station and the comparison of them with the results of analysis, (2) the results of measurement of the temperature and stress in a foundation mat, which was carried out to rationalize the design method for the raft type foundation mats in thermal power stations, and (3) the results of examination on the analysis model, external force conditions and boundary conditions used for the design are reported. The analysis method for temperature and thermal stress by finite element method, developed by the Central Research Institute of Electric Power Industry, can take the changes in the heat of hydration in placed concrete, the creep phenomenon of concrete and the restraint at construction joints in consideration. It is necessary to collect the data on the measurement of mat concrete and to develop the accurate analysis method. (Kako, I.)
Residual stresses measurement by using ring-core method and 3D digital image correlation technique
International Nuclear Information System (INIS)
Hu, Zhenxing; Xie, Huimin; Zhu, Jianguo; Wang, Huaixi; Lu, Jian
2013-01-01
Ring-core method/three-dimensional digital image correlation (3D DIC) residual stresses measurement is proposed. Ring-core cutting is a mechanical stress relief method, and combining with 3D DIC system the deformation of the specimen surface can be measured. An optimization iteration method is proposed to obtain the residual stress and rigid-body motion. The method has the ability to cut an annular trench at a different location out of the field of view. A compression test is carried out to demonstrate how residual stress is determined by using 3D DIC system and outfield measurement. The results determined by the approach are in good agreement with the theoretical value. Ring-core/3D DIC has shown its robustness to determine residual stress and can be extended to application in the engineering field. (paper)
International Nuclear Information System (INIS)
Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun; Park, Chi Yong; Yang, Jun Seok; Kim, Tae Ryong; Park, Jai Hak
2009-01-01
Finite element (FE) analysis and experiment for weld residual stress (WRS) in the pressurizer safety nozzle mockup is described in various processes and results. Foremost of which is the dissimilar simulation metal welding (DMW) between carbon steel and austenitic stainless steel. Thermal and structural analyses were compared with actual residual stress, and actual measurements of. Magnitude and distribution of WRS in the nozzle mockup were assessed. Two measurement methods were used: hole-drilling method (HDM) with strain gauge for residual stress on the surface of the mockup, and block removal and splitting layer (BRSL) method for through-thickness. FE analysis and measurement data showed good agreement. In conclusion, the characteristics of weld residual stress of DMW could be well understood and the simplified FE analysis was verified as acceptable for estimating WRS
Energy Technology Data Exchange (ETDEWEB)
Lee, Kyoung Soo; Kim, W.; Lee, Jeong Geun; Park, Chi Yong; Yang, Jun Seok; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Park, Jai Hak [Chungbuk University, Cheongju (Korea, Republic of)
2009-11-15
Finite element (FE) analysis and experiment for weld residual stress (WRS) in the pressurizer safety nozzle mockup is described in various processes and results. Foremost of which is the dissimilar simulation metal welding (DMW) between carbon steel and austenitic stainless steel. Thermal and structural analyses were compared with actual residual stress, and actual measurements of. Magnitude and distribution of WRS in the nozzle mockup were assessed. Two measurement methods were used: hole-drilling method (HDM) with strain gauge for residual stress on the surface of the mockup, and block removal and splitting layer (BRSL) method for through-thickness. FE analysis and measurement data showed good agreement. In conclusion, the characteristics of weld residual stress of DMW could be well understood and the simplified FE analysis was verified as acceptable for estimating WRS
Stress analysis of fuelling machine magazine housing of PHWR
International Nuclear Information System (INIS)
Singh, R.K.; Mehra, V.K.; Charan, J.J.; Kakodkar, A.
1983-01-01
PWR has fuelling machines for on-line refuelling of the core. Magazine housing of this fuelling machine is a thick pressure vessel. It has a cylindrical vessel with flat head on one side and reservable flange closure on the other side. The vessel has many small and big openings. This paper describes the two sets of experiments conducted for its stress analysis. First set of experiment was conducted on a 1:5 photoelastic model which was stress frozen under load of internal pressure. The second set of experiment involved strain gauge measurements at some important locations of the magazine housing. The paper summarises results of the experiments. In conclusion comparison is made between the experimental results and the results of finite element analysis. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Enomoto, Kunio; Otaka, Masahiro; Kurosawa, Koichi; Saito, Hideyo; Tsujimura, Hiroshi; Tamai, Yasukata; Urashiro, Keiichi; Mochizuki, Masato
1996-09-03
The present invention is applied to a BWR type reactor, in which a high speed jetting flow incorporating cavities is collided against the surface of reactor structural components to form residual compression stresses on the surface layer of the reactor structural components thereby improving the stresses on the surface. Namely, a water jetting means is inserted into the reactor container filled with reactor water. Purified water is pressurized by a pump and introduced to the water jetting means. The purified water jetted from the water jetting means and entraining cavities is abutted against the surface of the reactor structural components. With such procedures, since the purified water is introduced to the water jetting means by the pump, the pump is free from contamination of radioactive materials. As a result, maintenance and inspection for the pump can be facilitated. Further, since the purified water injection flow entraining cavities is abutted against the surface of the reactor structural components being in contact with reactor water, residual compression stresses are exerted on the surface of the reactor structural components. As a result, occurrence of stress corrosion crackings of reactor structural components is suppressed. (I.S.)
International Nuclear Information System (INIS)
Enomoto, Kunio; Otaka, Masahiro; Kurosawa, Koichi; Saito, Hideyo; Tsujimura, Hiroshi; Tamai, Yasukata; Urashiro, Keiichi; Mochizuki, Masato.
1996-01-01
The present invention is applied to a BWR type reactor, in which a high speed jetting flow incorporating cavities is collided against the surface of reactor structural components to form residual compression stresses on the surface layer of the reactor structural components thereby improving the stresses on the surface. Namely, a water jetting means is inserted into the reactor container filled with reactor water. Purified water is pressurized by a pump and introduced to the water jetting means. The purified water jetted from the water jetting means and entraining cavities is abutted against the surface of the reactor structural components. With such procedures, since the purified water is introduced to the water jetting means by the pump, the pump is free from contamination of radioactive materials. As a result, maintenance and inspection for the pump can be facilitated. Further, since the purified water injection flow entraining cavities is abutted against the surface of the reactor structural components being in contact with reactor water, residual compression stresses are exerted on the surface of the reactor structural components. As a result, occurrence of stress corrosion crackings of reactor structural components is suppressed. (I.S.)
International Nuclear Information System (INIS)
Lee, Dew Hey; Lee, Young Shin; Ryu, Chung Hyun; Kim, Hyun Su; Choi, Kyung Joo; Choi, Young Jin; Lee, Jae Hyung; Na, Jae Yun; Kim, Seong Jong
2002-03-01
In this study, The regulatory condition and analysis condition is analyzed for thick plate free drop, heat and thermal stress analysis to develop the safety assessment technology. Analysis is performed with finite element method which is one of the many analysis methods of the shipping cask. ANSYS, LS-DYNA3D and ABAQUS is suitable for thick plate free drop, heat and thermal stress analysis of the shipping cask. For the analysis model, the KSC-4 that is the shipping cask to transport spent nuclear fuel is investigated. The results of both LS-DYNA3D and ABAQUS for thick plate free drop and the results of ANSYS, LS-DYNA3D and ABAQUS for heat and thermal stress analysis is completely corresponded. And the integrity of the shipping cask is verified. Using this study, the reliable safety assessment technology is supplied to the staff. The efficient and reliable regulatory tasks is performed using the standard safety assessment technology
Energy Technology Data Exchange (ETDEWEB)
Lee, Dew Hey [Korea Institute of Nuclear and Safety, Taejon (Korea, Republic of); Lee, Young Shin; Ryu, Chung Hyun; Kim, Hyun Su; Choi, Kyung Joo; Choi, Young Jin; Lee, Jae Hyung; Na, Jae Yun; Kim, Seong Jong [Chungnam National Univ., Taejon (Korea, Republic of)
2002-03-15
In this study, The regulatory condition and analysis condition is analyzed for thick plate free drop, heat and thermal stress analysis to develop the safety assessment technology. Analysis is performed with finite element method which is one of the many analysis methods of the shipping cask. ANSYS, LS-DYNA3D and ABAQUS is suitable for thick plate free drop, heat and thermal stress analysis of the shipping cask. For the analysis model, the KSC-4 that is the shipping cask to transport spent nuclear fuel is investigated. The results of both LS-DYNA3D and ABAQUS for thick plate free drop and the results of ANSYS, LS-DYNA3D and ABAQUS for heat and thermal stress analysis is completely corresponded. And the integrity of the shipping cask is verified. Using this study, the reliable safety assessment technology is supplied to the staff. The efficient and reliable regulatory tasks is performed using the standard safety assessment technology.
International Nuclear Information System (INIS)
Vila, M.; Prieto, C.; Miranzo, P.; Osendi, M.I.; Terry, A.E.; Vaughan, G.B.M.
2005-01-01
High resolution X-ray scanning diffractometry is used to study the residual stress in binary metal/ceramic (Ni/Si 3 N 4 ) diffusion bonds fabricated by simultaneous high temperature heating and uniaxial pressing. In order to diminish the experimental error on the stress determination, the method consists of three steps: (i) to measure the axial and radial strains following some selected lines at the inner volume of the ceramic; (ii) to fit the strain data using finite element method (FEM) analysis and (iii) to determinate stresses by using the results obtained from the FEM method in the strain calculation
Oeij, P.R.A.
2002-01-01
In this paper of the World Congress of Sociology 2002 of ISA (International Sociological Association), the content and uses of the Job Stress Self Diagnostic Method (JSSDM) are described. The JSSDM aim is (a) to diagnose work processes to determine the presence of conditions for control problems and
Analysis of stress intensity factors for a new mechanical corrosion specimen
International Nuclear Information System (INIS)
Rassineux, B.; Crouzet, D.; Le Hong, S.
1996-03-01
Electricite de France is conducting a research program to determine corrosion cracking rates in the steam generators Alloy 600 tubes of the primary system. The objective is to correlate the cracking rates with the specimen stress intensity factor K I . One of the samples selected for the purpose of this study is the longitudinal notched specimen TEL (TEL: ''Tubulaire a Entailles Longitudinales''). This paper presents the analysis of the stress intensity factor and its experimental validation. The stress intensity factor has been evaluated for different loads using 3D finite element calculations with the Hellen-Parks and G(θ) methods. Both crack initiation and propagation are considered. As an assessment of the method, the numerical simulations are in good agreement with the fatigue crack growth rates measured experimentally for TEL and compact tension (CT) specimens. (authors). 8 refs., 6 figs., 2 tabs
Coupling analysis of the target temperature and thermal stress due to pulsed ion beam
International Nuclear Information System (INIS)
Yan Jie; Liu Meng; Lin Jufang; An Li; Long Xinggui
2013-01-01
Background: Target temperature has an important effect on the target life for the sealed neutron generator without cooling system. Purpose: To carry out the thermal-mechanical coupling analysis of the film-substrate target bombarded by the pulsed ion beam. Methods: The indirect coupling Finite Element Method (FEM) with a 2-dimensional time-space Gaussian axisymmetric power density as heat source was used to simulate the target temperature and thermal stress fields. Results: The effects of the target temperature and thermal stress fields under difference pulse widths and beam sizes were analyzed in terms of the FEM results. Conclusions: Combining with the temperature requirement and the thermal stress inducing film thermal mechanical destruction effect of the sealed neutron generator film-substrate targets, an optimized pulsed ion beam work status was proposed. (authors)
Kwon, Kibum
A dynamic analysis of the interaction between a crack and an auxetic (negative Poisson ratio)/non-auxetic inclusion is presented. The two most important fracture parameters, namely the stress intensity factors and the T-stress are analyzed by using the symmetric Galerkin boundary element method in the Laplace domain for three different models of crack-inclusion interaction. To investigate the effects of auxetic inclusions on the fracture behavior of composites reinforced by this new type of material, comparisons of the dynamic stress intensity factors and the dynamic T-stress are made between the use of auxetic inclusions as opposed to the use of traditional inclusions. Furthermore, the technique presented in this research can be employed to analyze for the interaction between a crack and a cluster of auxetic/non-auxetic inclusions. Results from the latter models can be employed in crack growth analysis in auxetic-fiber-reinforced composites.
West, Phillip B [Idaho Falls, ID; Novascone, Stephen R [Idaho Falls, ID; Wright, Jerry P [Idaho Falls, ID
2011-09-27
Earth analysis methods, subsurface feature detection methods, earth analysis devices, and articles of manufacture are described. According to one embodiment, an earth analysis method includes engaging a device with the earth, analyzing the earth in a single substantially lineal direction using the device during the engaging, and providing information regarding a subsurface feature of the earth using the analysis.
Analysis of the Citrullus colocynthis transcriptome during water deficit stress.
Directory of Open Access Journals (Sweden)
Zhuoyu Wang
Full Text Available Citrullus colocynthis is a very drought tolerant species, closely related to watermelon (C. lanatus var. lanatus, an economically important cucurbit crop. Drought is a threat to plant growth and development, and the discovery of drought inducible genes with various functions is of great importance. We used high throughput mRNA Illumina sequencing technology and bioinformatic strategies to analyze the C. colocynthis leaf transcriptome under drought treatment. Leaf samples at four different time points (0, 24, 36, or 48 hours of withholding water were used for RNA extraction and Illumina sequencing. qRT-PCR of several drought responsive genes was performed to confirm the accuracy of RNA sequencing. Leaf transcriptome analysis provided the first glimpse of the drought responsive transcriptome of this unique cucurbit species. A total of 5038 full-length cDNAs were detected, with 2545 genes showing significant changes during drought stress. Principle component analysis indicated that drought was the major contributing factor regulating transcriptome changes. Up regulation of many transcription factors, stress signaling factors, detoxification genes, and genes involved in phytohormone signaling and citrulline metabolism occurred under the water deficit conditions. The C. colocynthis transcriptome data highlight the activation of a large set of drought related genes in this species, thus providing a valuable resource for future functional analysis of candidate genes in defense of drought stress.
Parametric Methods for Order Tracking Analysis
DEFF Research Database (Denmark)
Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm
2017-01-01
Order tracking analysis is often used to find the critical speeds at which structural resonances are excited by a rotating machine. Typically, order tracking analysis is performed via non-parametric methods. In this report, however, we demonstrate some of the advantages of using a parametric method...
Comparative analysis of stress in a new proposal of dental implants.
Valente, Mariana Lima da Costa; de Castro, Denise Tornavoi; Macedo, Ana Paula; Shimano, Antonio Carlos; Dos Reis, Andréa Cândido
2017-08-01
The purpose of this study was to compare, through photoelastic analysis, the stress distribution around conventional and modified external hexagon (EH) and morse taper (MT) dental implant connections. Four photoelastic models were prepared (n=1): Model 1 - conventional EH cylindrical implant (Ø 4.0mm×11mm - Neodent®), Model 2 - modified EH cylindrical implant, Model 3 - conventional MT Conical implant (Ø 4.3mm×10mm - Neodent®) and Model 4 - modified MT conical implant. 100 and 150N axial and oblique loads (30° tilt) were applied in the devices coupled to the implants. A plane transmission polariscope was used in the analysis of fringes and each position of interest was recorded by a digital camera. The Tardy method was used to quantify the fringe order (n), that calculates the maximum shear stress (τ) value in each selected point. The results showed lower stress concentration in the modified cylindrical implant (EH) compared to the conventional model, with application of 150N axial and 100N oblique loads. Lower stress was observed for the modified conical (MT) implant with the application of 100 and 150N oblique loads, which was not observed for the conventional implant model. The comparative analysis of the models showed that the new design proposal generates good stress distribution, especially in the cervical third, suggesting the preservation of bone tissue in the bone crest region. Copyright © 2017 Elsevier B.V. All rights reserved.
Internal Stress Monitoring of In-Service Structural Steel Members with Ultrasonic Method
Li, Zuohua; He, Jingbo; Teng, Jun; Wang, Ying
2016-01-01
Internal stress in structural steel members is an important parameter for steel structures in their design, construction, and service stages. However, it is hard to measure via traditional approaches. Among the existing non-destructive testing (NDT) methods, the ultrasonic method has received the most research attention. Longitudinal critically refracted (Lcr) waves, which propagate parallel to the surface of the material within an effective depth, have shown great potential as an effective stress measurement approach. This paper presents a systematic non-destructive evaluation method to determine the internal stress in in-service structural steel members using Lcr waves. Based on theory of acoustoelasticity, a stress evaluation formula is derived. Factor of stress to acoustic time difference is used to describe the relationship between stress and measurable acoustic results. A testing facility is developed and used to demonstrate the performance of the proposed method. Two steel members are measured by using the proposed method and the traditional strain gauge method for verification. Parametric studies are performed on three steel members and the aluminum plate to investigate the factors that influence the testing results. The results show that the proposed method is effective and accurate for determining stress in in-service structural steel members. PMID:28773347
Internal Stress Monitoring of In-Service Structural Steel Members with Ultrasonic Method.
Li, Zuohua; He, Jingbo; Teng, Jun; Wang, Ying
2016-03-23
Internal stress in structural steel members is an important parameter for steel structures in their design, construction, and service stages. However, it is hard to measure via traditional approaches. Among the existing non-destructive testing (NDT) methods, the ultrasonic method has received the most research attention. Longitudinal critically refracted (Lcr) waves, which propagate parallel to the surface of the material within an effective depth, have shown great potential as an effective stress measurement approach. This paper presents a systematic non-destructive evaluation method to determine the internal stress in in-service structural steel members using Lcr waves. Based on theory of acoustoelasticity, a stress evaluation formula is derived. Factor of stress to acoustic time difference is used to describe the relationship between stress and measurable acoustic results. A testing facility is developed and used to demonstrate the performance of the proposed method. Two steel members are measured by using the proposed method and the traditional strain gauge method for verification. Parametric studies are performed on three steel members and the aluminum plate to investigate the factors that influence the testing results. The results show that the proposed method is effective and accurate for determining stress in in-service structural steel members.
International Nuclear Information System (INIS)
Lavrentyev, Anton I.; Stucky, Paul A.; Veronesi, William A.
2000-01-01
Shot peening is a well-known method for extending the fatigue life of metal components by introducing compressive residual stresses near their surfaces. The capability to nondestructively evaluate the near surface residual stress would greatly aid the assurance of proper fatigue life in shot-peened components. This paper presents preliminary results from a feasibility study examining the use of ultrasonic and eddy current NDE methods for residual stress measurement in components where the stress has been introduced by shot peening. With an ultrasonic method, a variation of ultrasonic surface wave speed with shot peening intensity was measured. Near surface conductivity was measured by eddy current methods. Since the effective penetration depth of both methods employed is inversely related to the excitation frequency, by making measurements at different frequencies, each method has the potential to provide the stress-depth profile. Experiments were conducted on aluminum specimens (alloy 7075-T7351) peened within the Almen peening intensity range of 4C to 16C. The experimental results obtained demonstrate a correlation between peening intensity and Rayleigh wave velocity and between peening intensity and conductivity. The data suggests either of the methods may be suitable, with limitations, for detecting unsatisfactory levels of shot peening. Several factors were found to contribute to the measured responses: surface roughness, near surface plastic deformation (cold work) and residual stress. The contribution of each factor was studied experimentally. The feasibility of residual stress determination from the measured data is discussed
Evaluation of Quantitative Environmental Stress Screening (ESS) Methods. Volume 1
1991-11-01
required information on screening strength from the curvefitting parameters. The underlying theory and approach taken are discussed in Appendix A. To...in field 1020 arm St.,Vas AJ Ptr 0.4i Currpnt. c- ugt ~ing DU?/SYS 2.7264 Wll/IY.3 at Factory Stress- NaxiLMw outgoing W?is’ys 0.288 DrW/5?S at Field...182 125 K.W.Fertig and V.X. Murthy, Models for Reliability Growth During Burn-in: Theory and Applicat’ons,Proceedings 1978 Annual Reliability and
Stress corrosion crack preventive method for long housing
International Nuclear Information System (INIS)
Sugano, Maki.
1992-01-01
If a neutron flux monitoring housing or a control rod driving mechanism (CRD) housing, as a long housing, is welded to reactor container, a portion of the long housing put under the effect of heat upon welding is converted to a sensitized austenite stainless steel, to cause stress corrosion cracks (SCC). Then, the inner surface of the a region of the long housing put under the effect of heat by welding is melted by a relatively low amount of heat input so that δ-ferrite tissues are caused to deposit in this region. With such procedures, crack sensitivity can be lowered, thereby enabling to improve SCC resistance. (T.M.)
Yin, Shuai; Lv, Dawei; Jin, Lin; Ding, Wenlong
2018-04-01
Hydraulic fracturing is an effective measure of reservoir modification for the development of shale gas. The evaluation of rock brittleness can provide a basis for the optimization of fracturing. In this paper, the effect of stress on the brittleness of shale is systematically analyzed by designing triaxial mechanics tests. The strain analysis method was used to evaluate the shale brittleness. The research indicates that, with the increase of effective confining pressure, the value of the brittleness index (B 1) decreases. There is a linear and positive correlation between the average reduction ratio of B 1 and the buried depth. The stress has a significant effect on the shale brittleness. Therefore, the rock brittleness can be overestimated without considering the influence of the buried depth or the stress of formation when using the mineral composition method. Being affected by the stress, when the brittle mineral content of the shale reservoir is 70%, 65%, 60%, and 55%, the lower limit depth of the shale gas development is 5000 m, 4400 m, 3000 m, and 1800 m, respectively. However, when the brittle mineral content of the shale is less than 50%, the brittleness index is less than 50% in all of the buried depths. In this case, the shale will not have any commercial development potential. The logging interpretation results of the brittleness index conducted with stress correction are more consistent with the real situation, and thus, this method can be better used to help the optimization of the fracturing intervals of shale gas.
The delayed neutron method of uranium analysis
International Nuclear Information System (INIS)
Wall, T.
1989-01-01
The technique of delayed neutron analysis (DNA) is discussed. The DNA rig installed on the MOATA reactor, the assay standards and the types of samples which have been assayed are described. Of the total sample throughput of about 55,000 units since the uranium analysis service began, some 78% has been concerned with analysis of uranium ore samples derived from mining and exploration. Delayed neutron analysis provides a high sensitivity, low cost uranium analysis method for both uranium exploration and other applications. It is particularly suitable for analysis of large batch samples and for non-destructive analysis over a wide range of matrices. 8 refs., 4 figs., 3 tabs
Structural Stress Analysis of an Engine Cylinder Head
Directory of Open Access Journals (Sweden)
R. Tichánek
2005-01-01
Full Text Available This paper deals with a structural stress analysis of the cylinder head assembly of the C/28 series engine. A detailed FE model was created for this purpose. The FE model consists of the main parts of the cylinder head assembly, and it includes a description of the thermal and mechanical loads and the contact interaction between their parts. The model considers the temperature dependency of the heat transfer coefficient on wall temperature in cooling passages. The paper presents a comparison of computed and measured temperature. The analysis was carried out using the FE program ABAQUS.
Radiochemistry and nuclear methods of analysis
International Nuclear Information System (INIS)
Ehmann, W.D.; Vance, D.
1991-01-01
This book provides both the fundamentals of radiochemistry as well as specific applications of nuclear techniques to analytical chemistry. It includes such areas of application as radioimmunoassay and activation techniques using very short-lined indicator radionuclides. It emphasizes the current nuclear methods of analysis such as neutron activation PIXE, nuclear reaction analysis, Rutherford backscattering, isotope dilution analysis and others
Computational methods in power system analysis
Idema, Reijer
2014-01-01
This book treats state-of-the-art computational methods for power flow studies and contingency analysis. In the first part the authors present the relevant computational methods and mathematical concepts. In the second part, power flow and contingency analysis are treated. Furthermore, traditional methods to solve such problems are compared to modern solvers, developed using the knowledge of the first part of the book. Finally, these solvers are analyzed both theoretically and experimentally, clearly showing the benefits of the modern approach.
Constructing an Intelligent Patent Network Analysis Method
Directory of Open Access Journals (Sweden)
Chao-Chan Wu
2012-11-01
Full Text Available Patent network analysis, an advanced method of patent analysis, is a useful tool for technology management. This method visually displays all the relationships among the patents and enables the analysts to intuitively comprehend the overview of a set of patents in the field of the technology being studied. Although patent network analysis possesses relative advantages different from traditional methods of patent analysis, it is subject to several crucial limitations. To overcome the drawbacks of the current method, this study proposes a novel patent analysis method, called the intelligent patent network analysis method, to make a visual network with great precision. Based on artificial intelligence techniques, the proposed method provides an automated procedure for searching patent documents, extracting patent keywords, and determining the weight of each patent keyword in order to generate a sophisticated visualization of the patent network. This study proposes a detailed procedure for generating an intelligent patent network that is helpful for improving the efficiency and quality of patent analysis. Furthermore, patents in the field of Carbon Nanotube Backlight Unit (CNT-BLU were analyzed to verify the utility of the proposed method.
International Nuclear Information System (INIS)
Takemura, T.; Taniguchi, T.
2004-01-01
The purpose of this paper is to offer a new method for detecting stress in wood due to moisture along the lines of a theory reported previously. According to the theory, the stress in wood could be estimated from the moisture content of the wood and the power voltage of a microwave moisture meter (i.e., attenuation of the projected microwave). This seems to suggest a possibility of utilizing microwaves in the field of stress detection. To develop such an idea, the stress formulas were initially modified to the form of an uni-variable function of power voltage, and the application method of the formulas to detection was tried. Finally, these results were applied to the data of sugi (Cryptomeria japonica) lumber in the previous experiment. The estimated strains showed fairly good agreement with those observed. It could be concluded from this study that the proposed method might be available for detecting stress in wood due to moisture
Rating of the X-ray method of measurement of stresses in steels
International Nuclear Information System (INIS)
Skrzypinski, A.
1977-01-01
The possibilities of utilization of some dependencies occuring in the X-ray technique of measurement of natural stresses for determination of distances of a between - plane lattice without natural stresses (d 0 ) are discussed. The proposed methodics of determination of d 0 is illustrated with the investigations which were carried-out on bearing steel LH15. (author)
Energy Technology Data Exchange (ETDEWEB)
Kim, Wan Jae; Lee, Kyoung Soo; Kim, Tae Ryong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Song, Tae Kwang [Korea Univ., Seoul (Korea, Republic of)
2008-07-01
Distribution of welding residual stresses are mainly characterized by degrees and frequencies of thermal loads applied to materials. However, other effects as component size and clamping condition can also affect stress distributions to a certain extent thus careful manipulation of these parameters based on clear understanding of how they affect residual stresses distributions and why can be additional measure to mitigate residual stresses. This paper discusses aforementioned issues for the case of safety and relief nozzle in nuclear power plant through finite element analysis.
Text analysis methods, text analysis apparatuses, and articles of manufacture
Whitney, Paul D; Willse, Alan R; Lopresti, Charles A; White, Amanda M
2014-10-28
Text analysis methods, text analysis apparatuses, and articles of manufacture are described according to some aspects. In one aspect, a text analysis method includes accessing information indicative of data content of a collection of text comprising a plurality of different topics, using a computing device, analyzing the information indicative of the data content, and using results of the analysis, identifying a presence of a new topic in the collection of text.
International Nuclear Information System (INIS)
Kobayashi, Toshio; Adachi, Naohito; Masuda, Kiyoshi
1998-01-01
In a design of a thick RC slab such as a basemat of a nuclear reactor building, the design method as same as for RC column is usually used. In this method, bending moment and axial force which are obtained by linear Finite Element Method (FEM) for external force are considered. But the assumption for linear FEM in which concrete participates for tensile stress is different from that for reinforcement design in which concrete does not participate for tensile stress. This difference of the assumption results that in-plane tensile strain at the center of the slab depth in the reinforcement design is larger than that in linear FEM. Some effects will appear in stress distribution if this tensile strain is constrained by boundary condition. In this paper, a practical method to evaluate the boundary constrain effects for this in-plane tensile strain is proposed and a simulation analysis of a thick reinforced concrete slab with a large opening for out-of-plane force is also reported. (author)
A comparison of residual stresses in built-up steel beams using hole-drilling method
International Nuclear Information System (INIS)
Nawafleh, M. A.; Hunaiti, Y. M.; Younes, R. M.
2009-01-01
Residual stresses have a significant effect on the stability resistance of metal building systems. An experimental program was conducted to measure these stresses in built-up steel beams using incremental hole-drilling method. The experimental results reveal that the predicted residual stress type of pattern for built-up I-sections with fillet welds on one side of the web is not the same as the pattern of residual stresses in built-up I-sections with fillet welds on both sides of the web
Domack, Marcia S.
1987-01-01
The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.
Nuclear analysis methods. Rudiments of radiation protection
International Nuclear Information System (INIS)
Roth, E.
1998-01-01
The nuclear analysis methods are generally used to analyse radioactive elements but they can be used also for chemical analysis, with fields such analysis and characterization of traces. The principles of radiation protection are explained (ALARA), the biological effects of ionizing radiations are given, elements and units used in radiation protection are reminded in tables. A part of this article is devoted to how to use radiation protection in a nuclear analysis laboratory. (N.C.)
Osten, W.; Pedrini, G.; Weidmann, P.; Gadow, R.
2015-08-01
A minimum invasive but high resolution method for residual stress analysis of ceramic coatings made by thermal spraycoating using a pulsed laser for flexible hole drilling is described. The residual stresses are retrieved by applying the measured surface data for a model-based reconstruction procedure. While the 3D deformations and the profile of the machined area are measured with digital holography, the residual stresses are calculated by FE analysis. To improve the sensitivity of the method, a SLM is applied to control the distribution and the shape of the holes. The paper presents the complete measurement and reconstruction procedure and discusses the advantages and challenges of the new technology.
Stress analysis studies in optimised 'D' shaped TOKAMAK magnet designs
International Nuclear Information System (INIS)
Diserens, N.J.
1975-07-01
A suite of computer programs TOK was developed which enabled simple data input to be used for computation of magnetic fields and forces in a toroidal system of coils with either D-shaped or circular cross section. An additional requirement was that input data to the Swansea stress analysis program FINESSE could be output from the TOK fields and forces program, and that graphical output from either program should be available. A further program was required to optimise the coil shape. This used the field calculating routines from the TOK program. The starting point for these studies was the proposed 40 coil Princeton design. The stresses resulting from three different shapes of D-coil were compared. (author)
Energy Technology Data Exchange (ETDEWEB)
Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)
2016-12-15
Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.
Macro design effects on stress distribution around implants: A photoelastic stress analysis
Directory of Open Access Journals (Sweden)
Serhat Emre Ozkir
2012-01-01
Conclusion: As there were observable differences between the implant types, straight placed cylindrical implants showed better stress distribution characteristics, while inclined tapering implants had better stress distribution characteristics.
Assessment of the reference stress method for combined tensile bending and thermal loading
International Nuclear Information System (INIS)
Philipp, A.; Munz, D.
1984-01-01
The reference stress method has been investigated for combined tensile, bending and thermal loading by considering a uniformly bent beam subjected to superimposed tensile stress and lateral temperature gradients. The creep deformation of the beam can be calculated numerically applying a Norton-type creep law. It turns out that the ratio of curvature rate to strain at the outer fiber depends on the creep exponent. Therefore, the reference stresses for these two quantities must be expected to be different in general. In most load cases, however, it is possible to determine a reference stress which can be used to describe the complete deformation of the beam. The only exception is the case of high tensile loading if the side exposed to higher tensile stress is cooler. Approximate solutions for the reference stress which rely on elastic and limit analyses, can be used only for estimates because they lead to extremely non-conservative predictions. (author)
Development of an inelastic stress analysis code 'KINE-T' and its evaluations
International Nuclear Information System (INIS)
Kobatake, K.; Takahashi, S.; Suzuki, M.
1977-01-01
Referring to the ASME B and PVC Code Case 1592-7, the inelastic stress analysis is required for the designs of the class 1 components in elevated temperature if the results of the elastic stress analysis and/or simplified inelastic analysis do not satisfy the requirements. Authors programmed a two-dimensional axisymmetric inelastic analysis code 'KINE-T', and carried out its evaluations and an application. This FEM code is based on the incremental method and the following: elastic-plastic constitutive equation (yield condition of von Mises; flow rule of Prandtl-Reuss; Prager's hardening rule); creep constitutive equation (equation of state approach; flow rule of von Mises; strain hardening rule); the temperature dependency of the yield function is considered; solution procedure of the assembled stiffness matrix is the 'initial stress method'. After the completion of the programming, authors compared the output with not only theoretical results but also with those of the MARC code and the ANSYS code. In order to apply the code to the practical designing, authors settled a quasi-component two-dimensional axisymmetric model and a loading cycle (500 cycles). Then, an inelastic analysis and its integrity evaluation are carried out
In Silico Analysis of Mobilome Response to Salt Stress in Phaseolus vulgaris L.
Directory of Open Access Journals (Sweden)
Behcet İNAL
2018-02-01
Full Text Available Common bean is an important legume that grown and consumed as animal feed and for human nutrition. It is also an important source of protein in developing countries. Transposable elements (TEs constitute a large part of the genome in various eukaryotic species. TE was described as garbage DNA by researchers for a long time. Recently, it has been found that TEs can move near stress response genes and they have known effects on plant resistance to diverse stresses. With the acquisition of common bean genome sequence, one of the next step is to annotate the genome and define the functional DNA elements. TEs are the most abundant genetic elements of plant genomes and have an important impact on genome stress evolution and genetic variation. So, it is important to determine TEs in the common bean genome. In the current study, genome-wide transposon annotation and definition were achieved in root and leaf tissues of common bean under salt stress. Homology and sequence structure-based methods were used. Tont2-I-Copia and Copia-39 Copia retrotransposons were found to be more in salt-treated roots and leaves respectively. As a result of the analysis, we found TEs number ranging from 46 to 50 belonging to about twenty different plants. Gene ontology analysis of transposon sequences brought the light on diverse important pathways related to abiotic stress conditions.
Analysis of heat transfer and stress in the pipe with hot fluid flowing through
International Nuclear Information System (INIS)
Charoensri, Apisara; Pichestapong, Pipat; Rodthongkom, Chouvana
2003-10-01
At incomplete mixing area of high temperature and low temperature liquid near the surface of structures, temperature fluctuation of liquid gives thermal fatigue damage to wall structure. This phenomenon is called thermal striping. For designing of piping system, it is important to know thermal stresses of structure due to heat convection. In this study, authors proposed a simplified evaluation method to predict thermal stress from temperature fluctuation, for rational design against thermal striping. It is required to estimate structural responses to temperature fluctuation of fluid. The attenuation process is a thermal coupling problem between fluids and structures and has a sensitive characteristics to frequencies of temperature fluctuations were analyzed by FINAS, which is a computer program based on the finite element method by comparisons of theoretical method. When the inner surface of the pipe is due to heat convection of contained fluid with sinusoidal temperature fluctuation and the outer surface is kept insulated, temperature distribution of structure is analyzed by solving the equation of transient heat conduction. From these temperature distributions, induced thermal stresses in the structure are calculated by thermal elastic analysis. Frequency response characteristics of structures and its mechanism were investigated by both numerical and theoretical methods. Based on above investigation, a structural response diagram was derived, which can predict stress amplitude of structures from temperature amplitude and frequency of fluids
Directory of Open Access Journals (Sweden)
Marco Gonzalez
Full Text Available Abstract The analysis of cracked brittle mechanical components considering linear elastic fracture mechanics is usually reduced to the evaluation of stress intensity factors (SIFs. The SIF calculation can be carried out experimentally, theoretically or numerically. Each methodology has its own advantages but the use of numerical methods has become very popular. Several schemes for numerical SIF calculations have been developed, the J-integral method being one of the most widely used because of its energy-like formulation. Additionally, some variations of the J-integral method, such as displacement-based methods, are also becoming popular due to their simplicity. In this work, a simple displacement-based scheme is proposed to calculate SIFs, and its performance is compared with contour integrals. These schemes are all implemented with the Boundary Element Method (BEM in order to exploit its advantages in crack growth modelling. Some simple examples are solved with the BEM and the calculated SIF values are compared against available solutions, showing good agreement between the different schemes.
Analysis of crack opening stresses for center- and edge-crack tension specimens
Directory of Open Access Journals (Sweden)
Tong Di-Hua
2014-04-01
Full Text Available Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- and edge-crack tension specimens. It is found that the crack opening stress is affected by the crack tip element. By taking the crack tip element into account, a modified crack opening stress equation is given for the center-crack tension specimen. Crack surface displacement equations for an edge crack in a semi-infinite plate under remote uniform tension and partially distributed pressure are derived by using the weight function method. Based on these displacements, a crack opening stress equation for an edge crack in a semi-infinite plate under uniform tension has been developed. The study shows that the crack opening stress is geometry-dependent, and the weight function method provides an effective and reliable tool to deal with such geometry dependence.
A Non-parametric Method for Calculating Conditional Stressed Value at Risk
Directory of Open Access Journals (Sweden)
Kohei Marumo
2017-01-01
Full Text Available We consider the Value at Risk (VaR of a portfolio under stressed conditions. In practice, the stressed VaR (sVaR is commonly calculated using the data set that includes the stressed period. It tells us how much the risk amount increases if we use the stressed data set. In this paper, we consider the VaR under stress scenarios. Technically, this can be done by deriving the distribution of profit or loss conditioned on the value of risk factors. We use two methods; the one that uses the linear model and the one that uses the Hermite expansion discussed by Marumo and Wolff (2013, 2016. Numerical examples shows that the method using the Hermite expansion is capable of capturing the non-linear effects such as correlation collapse and volatility clustering, which are often observed in the markets.
Microlocal methods in the analysis of the boundary element method
DEFF Research Database (Denmark)
Pedersen, Michael
1993-01-01
The application of the boundary element method in numerical analysis is based upon the use of boundary integral operators stemming from multiple layer potentials. The regularity properties of these operators are vital in the development of boundary integral equations and error estimates. We show...
Li, Xiaofan; Nie, Qing
2009-01-01
Many applications in materials involve surface diffusion of elastically stressed solids. Study of singularity formation and long-time behavior of such solid surfaces requires accurate simulations in both space and time. Here we present a high-order boundary integral method for an elastically stressed solid with axi-symmetry due to surface diffusions. In this method, the boundary integrals for isotropic elasticity in axi-symmetric geometry are approximated through modified alternating quadratu...
Statistical methods for categorical data analysis
Powers, Daniel
2008-01-01
This book provides a comprehensive introduction to methods and models for categorical data analysis and their applications in social science research. Companion website also available, at https://webspace.utexas.edu/dpowers/www/