Experimental Stress Analysis

This paper presents the failure analysis of the turbine blade of a gas turbine engine 9E GE type, installed in a certain type of simple systems consisting of the gas turbine driving an electrical power generator. A non-linear finite element method was utilized to determine the stress state of the blade segment under operating conditions. High stress zones were found at the region of the lower fir-tree slot, where the failure occurred. A computation was also performed with excessive rotational speed. Attention of this study is devoted to the mechanisms of damage of the turbine blade and also the critical high stress areas.

Numerical estimation of residual stress developed in glass products during its production process is necessary for its product quality improvement. Cooling stage of production process is the key stage for development of residual stress in glass products. Heat transfer mechanisms involved during this stage is complex. Hence, in FE simulation of the glass manufacturing process, thermal boundary conditions becomes one of the major unknown parameter that dictates the residual stress level developed in glass. In this paper, a hybrid approach, coupled experimental and numerical results, is used to estimate the unknown contact conductance boundary condition in FE simulation. Further selection of FE modeling approach (2D or 3D) is also demonstrated. Integrated residual birefringence distribution obtained from photoelastic experiments is compared with the same being computed by post-processing FE results until they match for estimation of the thermal boundary conditions.

A seat frame structure in automotive vehicles made of polymer matrix composite(PMC) with reinforced by X-shape steel frame was developed to obtain weight reduction at low cost. The frame structure was designed and analysed using finite element analysis(FEA) and was compared with experimental impact test to verify the structural safety after fabricated. The design model based on safety was analysed with appropriate boundary conditions and loading conditions. Each result was utilized to modify the actual shape to obtain a lighter, safer and stabler design. It was found that the substitution of PMC material reinforced by an X-shaped steel frame resulted in a weight reduction effect with equivalent strength, impact characteristics and fracture property.

This paper presents the failure analysis of the turbine blade of a gas turbine engine 9E GE type, installed in a certain type of simple systems consisting of the gas turbine driving an electrical power generator. A non-linear finite element method was utilized to determine the stress state of the blade segment under operating conditions. High stress zones were found at the region of the lower fir-tree slot, where the failure occurred. A computation was also performed with excessive rotational speed. Attention of this study is devoted to the mechanisms of damage of the turbine blade and also the critical high stress areas.

Stress is an unavoidable factor in everyone’s lives, people deal with it more than once in their lifetime. Stress may be defined as a feeling of physical, psychological or emotional tension which is developed by different circumstances or events that occur in our lives. In every organization, employees are the backbone that ensures the smooth running of the business, but as a matter of fact, these employees are ordinary people who are vulnerable to any and all threats, be it physical, emotional and psychological and this includes stress which can cause them to lose focus in their activities and accumulate low performance in most and/or all their functions as they may be distracted thinking about their own problems at the expense of  their work.

Despite that, stress can also be positive because it pushes people to do more and fulfil their obligations. Stress is not uncontrollable, It can be managed in order to protect any sort of negative impacts/ effects. This process is called stress management which means methods of handling and/or controlling stress. Stress management has a huge effect on employees and their performance as it brings about positivity and competence, therefore, it has an even greater impact on the organization because if their employees are stress-free, they are at least 95% focused in their duties, thus the businesses advantages increase. This study therefor is undertaken to investigate the Challenges Affecting Stress Management within an Organization and its Consequences on Employees’ Performance, to determine what causes stress, identify the different dimensions of stress, and how to handle or manage stress.

Mild steel and stainless steels are the two utmost steels used in the automotive industries as well as in various constructional and industrial applications. Welding of these steels with lesser defects and higher strengths is the most important need of the current industries. In this paper, TIG and MIG welding is preformed between two dissimilar steels. Transitional changes happen frequently in physical and microstructural properties; therefore, this study carries out an experimental and microstructural analysis to determine the properties like hardness, impact strength, tensile strength and microstructure of the weld zone.

To investigate the feasibility of a highly efficient flapping system capable of avian maneuvers, such as rapid takeoff, hover and gliding, a full scale bird-like (ornithopter) flapping-wing micro aerial vehicle (MAV) shaped and patterned after a typical pigeon (Columba livia) has been designed and constructed. Both numerical and experimental methods have been used in the development of this vehicle. This flapping-wing micro aerial vehicle utilizes both the flapping and feathering motions of an avian wing by employing a novel flapping-feathering mechanism, which has been synthesized and constructed so as to best describe the properly coordinated flapping and feathering wing motions at phase angle difference of 90-degree in a horizontal steady level flight condition. This design allows high flapping and feathering amplitudes and is configurable for asymmetric wing motions which are desirable in high-speed flapping flight and maneuvering. The preliminary results indicate its viability as a practical and an efficient flapping-wing micro aerial vehicle.

Measurement of residual stresses in glass with high transmittance in visible range and relatively low stress optic coefficient (‘C’ ≈ 0 TPa-1) using digital photoelasticity is vital in precision glass molding industries. Quantification of residual stresses in them necessitates the evaluation of photoelastic constant of glass. Photoelastic calibration methodologies of glass with low C using beam as the specimen needs a very high external load, sometimes beyond fracture point, for formation of significant and measurable retardations. In this paper a methodology of photoelastic calibration of glasses with low C using the solution of Flamant’s problem is demonstrated for a Schott glass, SF-57™ which has high transmittance and low C. Phase Shifting Technique (PST) is used to determine the retardations for a point load acting on a free surface. An automatic polariscope is used here to employ PST. The loading axis is precisely detected using Sobel edge detection algorithm available in MATLAB. Along the loading axis, retardation at multiple pointsis extracted for various loads from the whole field retardation data. The slope of retardation vs. load graph for various points along the load axis is used in solution of Flamant’s problem to evaluate C.

Thick walled components such as high pressure (HP) steam turbine casings operating under high parameter conditions are subjected to a complex stress state. As a result of that stress state, some parts of HP turbine casing undergo to the creep fatigue caused by the combination of thermal fatigue resulted from repeated start/stop operation and the creep which occurs during long-term operation at high temperature and high-pressure. It is well known that domestic thermal power plants have been in use over 100000 h which means that significant cost is required not only for maintenance, but often for renewal of equipment. Based on comprehensive investigation, the results of residual life assessment of one high pressure steam turbine casing, which belongs to the older turbine generation, taking into account simultaneous action of thermal fatigue and creep, are presented in this paper. Also, the critical flaw crack size of HP turbine casing is determined because this parameter has a strong influence on casing integrity and residual life. The results of residual life assessment provide not only a basis for further maintenance, but also estimated time for reparation or renewal.

Prior research conducted on welded wire reinforcement and fatigue resistance has resulted in proposed changes to American Association of State Highway Officials (AASHTO) design standards for bridge superstructures that may be overly conservative for reinforced concrete box culverts. This paper describes an experimental program conducted to evaluate the fatigue effects on reinforced concrete (RC) box culverts, and whether the changes recommended for fatigue resistance were valid for box culverts. Two full-scale RC box culvert sections designed and manufactured according to ASTM C1577 were tested. The first specimen was 12 ft x 4 ft x 12 in. (3657.6 x 1219.2 x 304.8 mm), and the second was 7 ft x 4 ft x 8 in. (2133.6 x 1219.2 x 203.2 mm). Test results show a good distribution of the load resistance between the two reinforcement directions in box culvert sections. Fatigue effect on the flexural capacity of the RC box culvert sections was minimal. These findings indicate that the fatigue check for RC box culverts designed according to ASTM C1577 can be eliminated. This waiver of the fatigue requirements in box culvert design will appear in the next version of the AASHTO Load and Resistance Factor Design standards.

Methodology for design of a thin-walled cylindrical thank with a flat bottom is presented in this paper. Except design, methodology for analytical, numerical and experimental analysis of stresses on the thank is also presented. After analytical calculations, geometrical modeling is carried out using CAD/CAM/CAE system CATIA. Distribution and values of principal strains and stresses are presented. Mathematical and numerical model is developed for linear elastic and isotropic material. In addition, introduction is given for theory of stresses for thin-walled thanks. For numerical structural analysis finite element method is used. Experimental stress analysis is carried out by tensometric measuring. Comparison of results from analytical, numerical and experimental analysis a predominantly good agreement with certain deviations can be found. Based on the comparison of the results obtained using analytical calculation, numerical method and experiment, a good match of the results can be observed. By comparing the results, the FEM model was verified.

Thick walled components such as high pressure (HP) steam turbine casings operating under high parameter conditions are subjected to a complex stress state. As a result of that stress state, some parts of HP turbine casing undergo to the creep fatigue caused by the combination of thermal fatigue resulted from repeated start/stop operation and the creep which occurs during long-term operation at high temperature and high-pressure. It is well known that domestic thermal power plants have been in use over 100000 h which means that significant cost is required not only for maintenance, but often for renewal of equipment. Based on comprehensive investigation, the results of residual life assessment of one high pressure steam turbine casing, which belongs to the older turbine generation, taking into account simultaneous action of thermal fatigue and creep, are presented in this paper. Also, the critical flaw crack size of HP turbine casing is determined because this parameter has a strong ...

"Electron backscatter diffraction (EBSD) is a widely available and relatively easy-to-use scanning-electron-microscopy-based diffraction technique. Recently, Wilkinson, Meaden, and Dingley presented two papers on a new cross-correlation-based analysis of EBSD patterns which allow variations in the elastic strain and lattice rotation tensors to be measured at a sensitivity of about 10^−4 at high spatial resolution. This paper briefly describes the basis of the technique and how the resulting lattice curvatures can be used to estimate the geometrically necessary dislocation (GND) content in a sample. To illustrate the utility of the method for microscale deformation studies the following examples are described: first, nanoindentation near a grain boundary in α-Ti; second, transformation-induced GNDs in a dual-phase steel; third, thermally-induced and mechanically-induced deformation near carbides in a superalloy; fourth, GND accumulation during fatigue of a polycrystalline Ti–6Al–4V alloy.

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Examination is the process by which the ability and the quality of the examinees can be measured. It is necessary to ensure the quality of the examinees. Online examination system is the process by which the participants can appear at the examination irrespective of their locations by connecting to examination site via Internet using desktop computers, laptops or smart phones. Automated score generation is the process by which the answer scripts of the examinations are evaluated automatically to generate scores. Although, there are many existing online examination systems, the main drawback of these systems is that they cannot compute automated score accurately, especially from the text-based answers. Moreover, most of them are unilingual in nature. As a result, examinees can appear at the examination in a particular language. Considering this fact, in this paper, we present a framework that can take Multiple Choice Questions (MCQ) examinations and written examinations in two differ...

Examination is the process by which the ability and the quality of the examinees can be measured. It is necessary to ensure the quality of the examinees. Online examination system is the process by which the participants can appear at the examination irrespective of their locations by connecting to examination site via Internet using desktop computers, laptops or smart phones. Automated score generation is the process by which the answer scripts of the examinations are evaluated automatically to generate scores. Although, there are many existing online examination systems, the main drawback of these systems is that they cannot compute automated score accurately, especially from the text-based answers. Moreover, most of them are unilingual in nature. As a result, examinees can appear at the examination in a particular language. Considering this fact, in this paper, we present a framework that can take Multiple Choice Questions (MCQ) examinations and written examinations in two different languages English and Bangla. We develop a database where the questions and answers are stored. The questions from the database are displayed in the web page with answering options for the MCQ questions and text boxes for the written questions. For generating the scores of the written questions, we performed several types of analysis of the answers of the written questions. However, for generating the scores of the MCQ questions, we simply compared between the database answers and the user's answers. We conducted several experiments to check the accuracy of score generation by our system and found that our system can generate 100% accurate scores for MCQ questions and more than 90% accurate scores from text based questions.

The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minim...

Development process of Knowledge Based Engineering (KBE) system for structural size optimization of external fixation device is presented in this paper. System is based on algorithms for generative modeling, finite element model (FEM) analysis and size optimization. All these algorithms are integrated in CAD/CAM/CAE system CATIA. Initial CAD/FE model of external fixation device is verified using experimental verification on real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement trans-ducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on Simulated Annealing (SA) method and local algorithm based on Conjugate Gradient (CG) method. Cost function of size optimization is minimization of design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for material of external fixation device. Optimization variables are chosen as design parameters of external fixation device. Optimized model of external fixation device has smaller mass, better stress distribution and smaller interfragmentary displacement in correlation to initial model.

Effetti esistenziali ed economici del coronavirus. Invito alla comunità accademica per una tempestiva ricerca globale e multidisciplinare. premessa Mentre siamo immersi, a livello planetario, nel momento culminante della pandemia, occorre dare un contributo scientifico, positivo e propositivo, utile per evitare il ripetersi di valutazioni e decisioni (rivelatesi inadeguate se non errate alla prova di fatti) tardive o inefficaci a fronteggiare tempestivamente il virus sin dal momento della sua comparsa. La situazione in atto, che ha raggiunto o sta raggiungendo il culmine del suo sviluppo, ha fatto emergere scenari impensabili fino a qualche mese fa. Scenari che , per la loro ampiezza e forza, rappresentano una sfida completamente inedita per l'intera Umanità. La disponibilità delle risultanze di studi tempestivi, rigorosi e basati su dati noti, per essere efficace, deve essere tempestiva e commisurata all'entità dei problemi. La comunità accademica, che possiede strumenti e qualificazioni idonee allo scopo, potrebbe attivare studi settoriali specifici, multisettoriali, specialistici e interdisciplinari. Da ciascuno secondo le sue competenze e possibilità. E' un Auspicio ed insieme una speranza: pensiamo in positivo, parliamo in positivo, agiamo in positivo.
Sul tema:
https://www.academia.edu/42587140/LE_PREVISIONI_PER_LITALIA._QUALI_CONDIZIONI_PER_LA_TENUTA_ED_IL_RILANCIO_DELLECONOMIA
https://www.academia.edu/42549790/IN_SCIENZA_E_COSCIENZA
https://www.academia.edu/42288952/Terza_guerra_mondiale_-Third_World_War
https://www.academia.edu/42330272/INFORMAZIONE_DISINFORMAZIONE_CONTRO-DISINFORMAZIONE
https://www.academia.edu/42364273/Guerra_al_coronavirus_vs_guerra_batteriologica_-Guerre_contre_les_coronavirus_vs_guerre_bactériologique_-War_on_coronavirus_vs_bacteriological_war
https://www.academia.edu/42470685/Effetti_esistenziali_ed_economici_del_coronavirushttps://www.academia.edu/42711747/Riflessioni_di_Intelligence_Economica_in_tempi_di_Emergenza_Corona_Virus._Massimo_Giannini_e_Francesco_Farina

1. Abstract: In this work, a hybrid fiber reinforced composite rod fixed from one end, while the other end is left free and subjected to a static torsional load, and left to vibrate freely after load releasing. Fiber volume fraction of 40% is considered to rod of interest, the matrix is composed of 20% short fibers and 40% pure matrix (this type of matrix is called composite matrix, which is well known and widely used in fiber reinforced hybrid composites). Such a ratio is adopted since it gives enough strength and reinforcement and meet the economic requirements as well, as mentioned in Mechanics of Composite Materials by Jones 1999. Four various long and short fibers of the same type and four matrices are taken to construct the rod in order to introduce the different properties to investigate their effects on natural frequency under torsional excitation. The problem is manipulated using software of AnsysV.14. The elastic properties of materials are determined using software of Matlab v.7. The results show that natural frequency is mainly highly affected by matrix longitudinal elastic modulus than that of fibers, and displays a regular pattern of behavior. The fibers show an irregular behavior towards the natural frequency variation. This can be attributed to the interaction effects between three types of constituents, matrix, long and short fibers composing the whole structure of the rod. In addition, there is the effect of anisotropy of material effective elastic properties, which plays an important role in results irregularities.

Electron backscatter diffraction (EBSD) is a microscopy technique that reveals in situ crystallographic information. Currently, it is widely used for the characterization of geological materials and in studies of biomineralization. Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. Overall, the usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is discussed as well as its application to similar studies.▶ Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. ▶ Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. ▶ The usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is highlighted as well as its application to similar studies.

Collective rituals are ubiquitous and resilient features of all known human cultures. They are also functionally opaque, costly, and sometimes dangerous. Social scientists have speculated that collective rituals generate benefits in excess of their costs by reinforcing social bonding and group solidarity, yet quantitative evidence for these conjectures is scarce. Our recent study measured the physiological effects of a highly arousing Spanish fire-walking ritual, revealing shared patterns in heart-rate dynamics between participants and related spectators. We briefly describe our results, and consider their implications.

Cross-correlation-based analysis of electron back-scatter diffraction (EBSD) patterns has been used to obtain high angular resolution maps of lattice rotations and elastic strains near carbides in a directionally solidified superalloy MAR-M-002. Lattice curvatures were determined from the EBSD measurements and used to estimate the distribution of geometrically necessary dislocations (GNDs) induced by the deformation. Significant strains were induced by thermal treatment due to the lower thermal expansion coefficient of the carbide inclusions compared to that of the matrix. In addition to elastic strains the mismatch was sufficient to have induced localized plastic deformation in the matrix leading to a GND density of 3 × 10^13 m–2 in regions around the carbide. Three-point bending was then used to impose strain levels within the range ±12% across the height of the bend bar. EBSD lattice curvature measurements were then made at both carbide-containing and carbide-free regions at different heights across the bar. The average GND density increases with the magnitude of the imposed strain (both in tension and compression), and is markedly higher near the carbides particles. The higher GND densities near the carbides (order of 10^14 m–2) are generated by the large strain gradients produced around the plastically rigid inclusion during mechanical deformation with some minor contribution from the pre-existing residual deformation caused by the thermal mismatch between carbide and nickel matrix.

Stress is a universal experience that can fundamentally alter neural responses to incoming information. Recent research has begun to clarify the substrates of stress-induced modulations of neural processing. Based on this work, it has been hypothesized that stress and anxiety shift the balance of attention away from a task-directed mode, governed by prefrontal cortex (PFC), to a sensory-vigilance mode, governed by the amygdala and other threat-sensitive regions. A key untested prediction of this framework is that stress exerts dissociable effects on different stages of information processing. Here, we exploited the temporal resolution afforded by event-related potentials (ERPs) to disentangle the impact of stress on sensory-vigilance, indexed by early perceptual activity, from its impact on task-directed cognition, indexed by later postperceptual activity. Results indicated that threat-of-shock produced sustained increases in both the experience and expression of stress, measured using retrospective ratings and concurrent facial electromyography (EMG). During this same period, stress double dissociated the early sensory-specific and later task-directed (postperceptual) processing of emotionally-neutral stimuli. In particular, stress amplified N1 (184-236 ms) and attenuated P3 (316-488 ms) visually-evoked activity. These observations provide compelling new evidence that stress can exert fundamentally different consequences across successive stages of information processing. Consistent with recent suggestions, stress amplified earlier extrastriate activity in a manner consistent with vigilance for threat, but disrupted later activity associated with the evaluation of task-relevant information. These results provide a novel basis for understanding how stress can modulate information processing in everyday life and disorders characterized by hypersensitivity to threat.

Advent of high power diode laser has substantially contributed to the popularity of laser welding in industry where its virtues such as low heat input and good weld strength are highly appreciated. However, one of the drawbacks of the laser welding is distortion of the welded bodies that is closely linked with the generation and/or redistribution of residual stresses in the vicinity of the weld. In this contribution, mapping of surface macroscopic residual stresses in two directions, i.e. parallel and perpendicular to the welds, were performed for two bodies. The first contained a weld created with the high power diode laser beam speed of 2 m/min and the second with the speed of 15 m/min. Our aim was to compare not only resulting fields of residual stresses, but also to perform qualitative assessment of the possible presence of crystallographic texture and gain a qualitative apprehension about the grain sizes in the vicinity of a laser weld joining two steel sheets. Larger distortio...

The purpose of tins study was to investigate the stability of kinematics responses related to stretch shortening cycle (SSC) during 10 consecutive soccer instep kicks The kicking motions of dominant legs were captured from five experienced adult male soccer players (body height 184 60 +/- 4 49 cm, body mass 80 +/- 4 24 kg, age 25 60 +/- 1 14 years) using a three-dimensional infra-red high speed camera at 200 Hz Sonic important kinematic parameters include eccentric angular velocity (AVe), concentric angular velocity (AVc), duration of eccentric (Te), and duration of concentric (Tc) at forward and impact phases selected to analyses The AVe result of the sixth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p <= 0 001.) The AVc result of the fifth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p <= 0 001) The Te result of the fourth kick, relative to the first kick, was significantly lower when compared to the other kicks (with p <= 0 011) The Tc result of the Nth kick, relative to the first kick, was significantly lower when compared to the other kicks (p <= 0 029) We concluded that 5 consecutive kicks arc adequate to achieve high kinematic responses related to SSC

http://versita.metapress.com/content/hg7uk19056374488/