Investigation of Low-Cycle Fatigue on Structural Carbon Steel

2021 ◽  
Vol 887 ◽  
pp. 646-650
Author(s):  
O.A. Nasibullina ◽  
R.G. Rizvanov ◽  
E.Sh. Gaysin
Keyword(s):  
Regression Analysis ◽  
Thermodynamic Stability ◽  
Low Cycle Fatigue ◽  
Strong Relationship ◽  
Metal Structure ◽  
Crack Development ◽  
Metal Fatigue ◽  
Variable Loading ◽  
Loading Cycle ◽  
Cycle Loading

It is possible to explain the phenomenon of fatigue destruction and the patterns that are observed only in the deep study of the processes taking place in the material under conditions of repeated-variable loading, i.e. in the development of the physical theory of metal fatigue. Despite the large number of work on this issue, there is currently no single interpretation of the process of fatigue destruction of metals, which is primarily due to the exceptional complexity of the problem. The purpose of the study is to study low-cycle corrosion fatigue of steel using the example of A 414 Grade A steel. The work solved problems, such as research of kinetics of crack development in conditions of low-cycle loading of metal structure made of carbon structural steel A 414 Grade A. Regression analysis has also been applied to predict a change in the thermodynamic stability of the metal during cyclic loading. Analysis of fatigue crack development at alternating loading cycle was carried out. The results of calculations based on the proposed model of elastoplastic deformation near the top of the crack at the sign-alternating loading cycle can be described by non-linear dependence. The regression analysis revealed that the correlation coefficient of the selected model is-0.93, which indicates a relatively strong relationship between the variables. In experimental way it has been proved that reduction of thermodynamic stability of metal in corrosive medium is connected with increase of number of loading cycles, which leads to accumulation of fatigue damages.

Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them

2020 ◽  
Vol 86 (12) ◽  
pp. 46-53
Author(s):  
M. M. Gadenin
Keyword(s):  
Experimental Data ◽  
Elastoplastic Deformation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading Cycle ◽  
Additional Variable ◽  
Dynamic Creep ◽  
Variable Stresses ◽  
Kinetics Of ◽  
Deformation Diagrams

The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.

Low-Cycle Strength of Elements of Constructions

2018 ◽  
Author(s):  
Alexander Zvorykin ◽  
Roman Popov ◽  
Mykola Bobyr ◽  
Igor Pioro
Keyword(s):  
Stress State ◽  
Plane Stress ◽  
Low Cycle Fatigue ◽  
Plane Stress State ◽  
Structural Elements ◽  
Cycle Fatigue ◽  
Kinematic Equation ◽  
Effective Coefficients ◽  
Operational Life ◽  
Cycle Loading

Analysis of engineering approach to the operational life forecasting for constructional elements with respect to the low-cycle fatigue is carried out. Applicability limits for a hypothesis on existence of generalized cyclic-deforming diagram in case of complex low-cycle loading (deforming) are shown. It is determined, that under condition of plane-stress state and piecewise-broken trajectories of cycle loading with stresses and deformation checking the cyclic deforming diagram is united in limits of deformations, which are not exceeded 10 values of deformation corresponding material yield point. Generalized kinematic equation of material damageability is described. The method of damageability parameter utilization for increasing of accuracy calculation of structural elements low-cycle fatigue by using the effective coefficients of stresses and deformations taking into account the damageability parameter is given.

scholarly journals PengaruhUtangdan PerputaranModalKerjaTerhadapProfitabilitasPerusahaan(Studi Kasus Pada PT Bumi Sekar Tbk Periode 2013-2018)

2020 ◽  
Vol 15 (1) ◽  
pp. 32
Author(s):  
Saprudin ◽  
Bayu Hartono
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Quantitative Research ◽  
Linear Regression Analysis ◽  
Strong Relationship ◽  
Financial Statements ◽  
Working Capital ◽  
Weak Relationship ◽  
Spss Software ◽  
Relationship Of

This study aims to determine how much influence the debt, working capital turnover has on the profitability of PT Sekar Bumi Tbk. Debt is proxied by DER, working capital turnover is proxied by WCT, while profitability is proxied by ROA. Based on the nature of the data used in this study is a type of quantitative research. Samples were taken, namely PT Sekar Bumi Tbk with the objectof research of 2013-2018 financial statements. Linear regression analysis was used in this study, with the help of SPSS software for Windows 20.0. The results of this study explain that partially DER has a significant effect on ROA, and has a very strong relationship of 83.9%. WCT has no significant effect on ROA, and has a very weak relationship of 18.4%. However, simultaneously DER and WCT has a significant effect with a contribution of 70.8% to ROA. So companies need to pay attention and consider how much effective the use of debt as a source of funding for the company.

scholarly journals Suitability of Protein Content Measured by MilkoScan FT-Plus Milk Analyzer to Evaluate Bovine and Ovine Colostrum Quality

Animals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2587
Author(s):  
Anna Antonella Spina ◽  
Carlotta Ceniti ◽  
Francesca Trimboli ◽  
Domenico Britti ◽  
Vincenzo Lopreiato
Keyword(s):  
Regression Analysis ◽  
Protein Content ◽  
Indirect Method ◽  
Strong Relationship ◽  
Poor Quality ◽  
Bovine Colostrum ◽  
Gold Standard Method ◽  
Average Value ◽  
Correlation And Regression Analysis

The objective of this study was to evaluate MilkoScan FT-plus for the estimation of the immunoglobulin G (IgG) content in bovine and ovine colostrum. Between April and May 2016, a total of 94 colostrum samples (54 from Simmental dairy cows and 39 from Sarda ewes) were collected within 6 h (T0) and after 24 h (T24) from parturition. Colostrum samples were subjected to the radial immunodiffusion (RID) assay for the quantification of IgG and to MilkoScan FT-plus for the estimation of protein content (TP, %), which was then used as an indirect method for the evaluation of colostrum quality. To compare the two methods, correlation and regression analysis of IgG quantification by RID and protein (%) content estimation by MilkoScan FT-plus data was performed using Procedure CORR and Procedure REG of SAS, respectively (version 9.3, SAS Institute Inc., Cary, NC, USA). Thresholds for the classification of good colostrum quality (as determined by RID assay, the gold standard method) were set at 50 g of IgG/L in cows and 20 g of IgG/L in ewes. The concentration of IgG in bovine colostrum assayed by RID showed a variation ranging from 41.45 to 199.97 g/L with an average of 99.85 ± 40.84 g/L at T0, and from 2.83 to 75.93 g/L with an average of 19.76 ± 19.01 g/L at T24. Regarding ovine colostrum, the concentration of IgG assayed by RID ranged from 34.45 to 156.32 g/L with an average value of 77.82 ± 37.58 g/L at T0, and from 5.6 to 69.74 g/L with an average of 27.90 ± 19.81 g/L at T24. Colostrum TP ranged from 3.70 to 23.96% for bovine colostrum and 6.32 to 22.88% for ovine colostrum using MilkoScan FT-plus. MilkoScan FT-plus and RID data were highly and significantly correlated (r = 0.91 for bovine and r = 0.94 for ovine colostrum), and regression analysis showed a strong relationship between IgG concentration provided by RID assay and TP provided by MilkoScan FT-plus (R2 = 0.84 and 0.88 for bovine and ovine, respectively). Optimal cut-off points for the greatest accuracy of TP (%) determined by MilkoScan FT-plus were 12.8% in cows [with 88.9% sensitivity (Se) and 100% specificity (Sp)] and 9% in ewes (with 96.7% Se and 100% Sp). In conclusion, these outcomes indicate that MilkoScan FT-plus as an indirect method may be a reliable tool for the estimation of the total IgG concentration and quality in bovine and ovine colostrum. Moreover, the cut-off levels of 12.8% for bovine and 9% for ovine of TP, seem sufficient to ensure that all poor-quality colostrum can be classified as such, with only a low proportion of good-quality colostrum being misclassified as poor-colostrum, thereby increasing the probability of delivering good-quality colostrum to new-born calves and lambs.

Microwave Electromagnetic Field Influence on the Stability of Reinforced Carbon Plastics with Built-In Lightning Protective Coating during Dynamic Loads Action

2020 ◽  
Vol 992 ◽  
pp. 427-433
Author(s):  
I.V. Zlobina ◽  
N.V. Bekrenev
Keyword(s):  
Electromagnetic Field ◽  
Metal Structure ◽  
High Amplitude ◽  
Air Transport ◽  
Dynamic Loads ◽  
Damping Properties ◽  
Fiber Reinforced ◽  
Carbon Plastics ◽  
Cycle Loading ◽  
The Impact

Currently, significant part of advanced air transport structural elements is made of fiber-reinforced polymer composite materials (PCM), in particular, carbon plastics. In order to increase the resistance of these materials to static electricity and lightning discharges while air transport passes through lightning fronts, lightning protection coatings in the form of copper grids are incorporated into PCM structure . For load-bearing structures and aircraft shells, the influence of dynamic loads in the form of low-cycle high-amplitude loading and hitting by solid objects is typical. The presence of inbuilt metal structure introduces additional uncertainty into the anisotropic PCM perception of these loads. Studies of the strength of carbon-fiber-reinforced plastics with built-in LPC at low-cycle loading and their perception of shock load has been carried out. It is established that short-term processing in the microwave electromagnetic field leads to an increase in the strength of the samples under low-cycle loading by 210%. CFR with LPC absorbs a part of the shock impulse and does not transfer it completely to subsequent structures. The microwave electromagnetic field helps to improve the damping properties of materials by 19.5% in average with a low impact energy. With an increase in the impact force energy, the effect of the microwave electromagnetic field is manifested to a less extent; further improvement of the damping properties does not occur. It increases the elastic characteristics of the material and practically does not lead to cracking and exfoliation of the surface layer in the impact area. The results can be used in the development of technologies for final processing of the products made of PCM in order to increase their resistance to dynamic loads.

EMPIRICAL STUDY OF FEDERALISM AND POLITICAL STABILITY IN NIGERIA

2019 ◽  
Vol 6 (2) ◽  
pp. 177-196
Author(s):  
Ugo Chuks Okolie
Keyword(s):  
Regression Analysis ◽  
Linear Regression Analysis ◽  
Political Stability ◽  
Strong Relationship ◽  
Ethnic Violence ◽  
Survey Method ◽  
Questionnaire Data ◽  
Pearson Product Moment Correlation ◽  
The Relationship ◽  
Structured Questionnaire

Federalism and Political stability are two concepts that are of significance to all modern societies. Federalism promotes pluralism and dispersal of power which is good for a multi-ethnic society like Nigeria. But in Nigeria, the practice has generated unending tensions among the individuals, communities and ethnic groups within it. However, this study argues that healthy federalism is a political panacea for ethnic violence, governance crisis and political instability in Nigeria. This study empirically examined the relationship between federalism and political stability in Nigeria. The study adopted a descriptive and casual research design as well as the survey method. In the investigation, a total of 428 respondents were sampled using a structured questionnaire. Data were analyzed using Pearson product-moment correlation and linear regression analysis. Findings revealed that federalism has a positive and significant relationship with political stability in Nigeria at (R = .732, R2 = 614 at p = 0.000). The statistical result shows that there is a strong relationship between federalism and political stability in Nigeria and that federalism accounts for 61.4% of variations in political stability in Nigeria. Requisite conclusions and recommendations were provided in the light of empirical and theoretical findings.

Application of Coercimeters for Equipment Diagnostics

NDT World ◽  
2015 ◽  
Vol 18 (4) ◽  
pp. 22-24
Author(s):  
Сивирюк ◽  
Vladimir Siviryuk ◽  
Безруков ◽  
Aleksey Bezrukov
Keyword(s):  
Coercive Force ◽  
Measurement Method ◽  
Residual Life ◽  
Force Measurement ◽  
Early Recognition ◽  
Metal Structure ◽  
Pressure Vessels ◽  
Metal Fatigue ◽  
Emergency Situations ◽  
Manual Testing

Introduction. Changes of metal structure commonly result in equipment failures; early recognition of such changes is necessary in order to prevent emergency situations. Coercimetry is a simple and informative method for metal structure estimation. Method. The coercive force measurement method was used for estimation of the metal fatigue state. Results. The article presents the results of coercive force measurement application for the diagnosis of blast furnace jackets, overhead cranes, load-bearing elements of buildings and structures, pressure vessels, industrial pipelines, chimney stacks, ropes of hoisting devices. Manual testing of the equipment working under metallurgical production conditions is complicated; in hard-to-reach places and gas hazardous areas the stationary testing system has been used; the system has included permanently installed sensors connected to the switchboard. The equipment residual life has been determined by the coercive force maximum values with the use of nomograms. Conclusions. The coercive force measurement method for diagnostic survey of the equipment working under considerable thermal effect makes it possible to determine the metal stress state, predict zones of corrosion cracks formation and development, estimate the residual operation life, plan worn areas replacement/repair and as the final result – reduce unplanned and emergency shutdowns.

scholarly journals PENGARUH TUNJANGAN KINERJA (TUKIN) DAN MOTIVASI TERHADAP KINERJA PEGAWAI POLITEKNIK KELAUTAN DAN PERIKANAN SORONG

2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Saharuddin Saharuddin ◽  
B. Watunglawar ◽  
Muhammad Guzali Tafalas
Keyword(s):  
Regression Analysis ◽  
Data Analysis ◽  
Correlation Analysis ◽  
Employee Performance ◽  
Strong Relationship ◽  
Research Data ◽  
Descriptive Statistics ◽  
Primary Data

The Purpose of this research is to process, analyze, prove empirically and discuss: (a) the effect of perfrormance benefits on the performance of Sorong Maritime and Fisheries Polythecnic employess; (b) The influence of motivation on the performance of Sorong Polytechnic Maritime and Fisheries employess; and (c) The join effect of performance and motivation allowance on the performance of Sorong Polytechnic Maritime and Fisheries employees. This research was conducted in September to November 2018. The author collected data through questionnaires and observation for a month. The population in this study is the Polytechnic Maritime and Fisheries totaling 66 people. This study is a study of facts in the form of opinions/opinion, attitudes, experiences or characteristics of people (respondents) as subject data in the form of primary data obtained from interviews, questionnaire and observation, also seconday data. Analysis of research data using descriptive statistics, with a view to finding strong relationship between variables through correlation analysis with regression analysis, by making comparisons by comparing the average sampel data or population. The results showed that (1) Performance allowance (X1) with all the components of its formation had no effect on employee performance (Y), so the first hypothesis stating that performance allowance (X1) affected employee performance (Y) was not proven; (2) Motivation (X2) with all the components of its formation affect employee performance (Y), so the first hypothesis stating that Motivation (X2) influences employee performance (Y) is proven.  

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