scholarly journals Bending Fatigue Behaviors Analysis and Fatigue Life Prediction of 20Cr2Ni4 Gear Steel with Different Stress Concentrations near Non-metallic Inclusions

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3443 ◽  
Author(s):  
Zhiguo Xing ◽  
Zhiyuan Wang ◽  
Haidou Wang ◽  
Debin Shan
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Steel Production ◽  
The State ◽  
Heavy Duty ◽  
Stress Concentrations ◽  
Bending Fatigue ◽  
Gear Steel ◽  
Gear Steels ◽  
The Relationship

To investigate the relationship between inclusions and bending fatigue behaviors in 20Cr2Ni4 steel under different stress concentrations. This paper designs a new experimental method to prefabricate different size stress concentrations near the inclusions, and then conducts a new type of bending fatigue test to study the inclusions and their surrounding stress distributions in 20Cr2Ni4 steel. A microhardness tester was combined with laser etching equipment to realize the prefabrication of different stress concentrations at arbitrary positions around any inclusion on the gear steel surface. This method provides an experimental basis for the quantitative analysis of the relationship between stress distribution and fatigue life around the inclusions of heavy-duty gear steels. We also predict the bending fatigue lives of heavy-duty gear steels with different types of inclusions, stress states, and spatial distributions. Then, based on the prefabricated notch parameters and the state of inclusions in the steel, a mathematical model of quantitative analysis is proposed, which can accurately predict the fatigue limit of heavy-duty gear steel. The research results can be applied to the actual use of heavy-duty gears and to the accurate life estimation based on the state of gear stress, thereby providing a quantitative reference model for subsequent gear steel production and gear part processing.

scholarly journals Pitting and Bending Fatigue Evaluations of a New Case-Carburized Gear Steel

2007 ◽  
Author(s):  
Timothy Krantz ◽  
Brian Tufts
Keyword(s):  
Power Density ◽  
Fatigue Testing ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Surface Fatigue ◽  
Gear Steel ◽  
Single Tooth ◽  
Carburized Gear ◽  
Gear Steels

The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One approach to improving power density of gearing is to improve the steel properties by design of the alloy. The alloy tested in this work was designed to be case-carburized with surface hardness of Rockwell C66 after hardening. Test gear performance was evaluated using surface fatigue tests and single-tooth bending fatigue tests. The performance of gears made from the new alloy was compared to the performance of gears made from two alloys currently used for aviation gearing. The new alloy exhibited significantly better performance in surface fatigue testing, demonstrating the value of the improved properties in the case layer. However, the alloy exhibited lesser performance in single-tooth bending fatigue testing. The fracture toughness of the tested gears was insufficient for use in aircraft applications as judged by the behavior exhibited during the single tooth bending tests. This study quantified the performance of the new alloy and has provided guidance for the design and development of next generation gear steels.

An Experimental Study on Fatigue Life Variance, Residual Stress Variance, and Their Correlation of Face-Turned and Ground Ti 6Al-4V Samples

2002 ◽  
Vol 124 (4) ◽  
pp. 809-819 ◽  
Author(s):  
Xiaoping Yang ◽  
C. Richard Liu ◽  
A. F. Grandt
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Manufacturing Processes ◽  
Machining Processes ◽  
Stress Variation ◽  
Bending Fatigue ◽  
New Process ◽  
The Impact ◽  
The Relationship ◽  
Stress Variance

It is well known that there is a large variance associated with fatigue life. However, in literature little is found on the relationship between manufacturing processes and fatigue variance of the manufactured components. In this research, the influence of machining processes on the fatigue variance of the machined Ti 6Al-4V samples is studied experimentally. The impact is evaluated by comparing the safety ratios of face-turned samples with those of ground samples. The safety ratio is defined as the average fatigue life over the fatigue life with a reliability of 95%. In the computation, it is assumed that fatigue life follows Weibull distribution. Two sets of faced samples and two sets of ground samples are tested for bending fatigue. The test is under constant amplitude in high cycle fatigue regime under room temperature. The results show that the safety ratios of face-turned samples are significantly smaller than are those of ground samples. Consequently, it is suggested that fatigue life variance be considered as a new process capability. This capability serves as a basis in choosing manufacturing processes for making fatigue critical products such as aircraft. Another finding is the positive correlation between the residual stress variation and fatigue life variation. This correlation suggests that a better understanding and prediction of residual stress lead to a better prediction of fatigue life.

scholarly journals Design characteristics that improve the fatigue life of threaded pipe connections

2011 ◽  
Vol 2 (2) ◽  
pp. 334-341
Author(s):  
Jeroen Van Wittenberghe ◽  
Patrick De Baets ◽  
Wim De Waele ◽  
Timothy Galle ◽  
Tien Thanh Bui ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Local Stress ◽  
Experimental Tests ◽  
Element Model ◽  
Stress Concentrations ◽  
Bending Fatigue ◽  
Four Point Bending ◽  
Threaded Connections ◽  
Linear Material ◽  
Design Characteristics

Threaded pipe connections are commonly used to connect risers, tendons, drill pipes and wellcasing strings. In these applications fatigue resistance plays an important role. A large variety of patenteddesign features exist, all claiming to improve the connection’s fatigue life. However, patent documents onlycontain claims and numerical or experimental data about these connection’s performance is generally notpublished. This makes it hard to make a quantitative comparison between different designs. In this study anoverview is given of fatigue resistant threaded connections. Two major methods to improve the fatigue lifeof a connection were identified. First of all, local stress concentrations can be reduced by optimizing thegeometry of the threads. Second the global shape of the connection can be optimized to obtain a moreuniform load distribution.Using a parametric finite element model, different designs were compared. The connections were modelledby a 2D axisymmetric geometry with non-linear material properties and elaborate contact conditions.Selected designs have been subjected to experimental tests in a four-point bending fatigue setup. Theexperimental tests serve as a validation for the results of the numerical simulations. It was found that themultiaxial stress distribution at the thread roots is the defining factor for the fatigue life of the connection.Nevertheless, these stresses can be changed by the global geometry of the connection. It can beconcluded that the fatigue life of threaded connections is determined by a combination of global and localaspects which should both be analysed for fatigue life calculations.

Emotion Appraisals Predict Neuroticism and Extraversion

2015 ◽  
Vol 36 (1) ◽  
pp. 1-10
Author(s):  
Andrew Comensoli ◽  
Carolyn MacCann
Keyword(s):  
University Students ◽  
The State ◽  
The Relationship

The current study proposes and refines the Appraisals in Personality (AIP) model in a multilevel investigation of whether appraisal dimensions of emotion predict differences in state neuroticism and extraversion. University students (N = 151) completed a five-factor measure of trait personality, and retrospectively reported seven situations from the previous week, giving state personality and appraisal ratings for each situation. Results indicated that: (a) trait neuroticism and extraversion predicted average levels of state neuroticism and extraversion respectively, and (b) five of the examined appraisal dimensions predicted one, or both of the state neuroticism and extraversion personality domains. However, trait personality did not moderate the relationship between appraisals and state personality. It is concluded that appraisal dimensions of emotion may provide a useful taxonomy for quantifying and comparing situations, and predicting state personality.

Peranan Whistleblowing Dalam Meningkatkan Integriti Anggota Polis Diraja Malaysia (Pdrm): Kajian Ke Atas Kontinjen Perak

Sains Insani ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 17-27
Author(s):  
Megat Ayop Megat Arifin ◽  
Abd. Halim Ahmad
Keyword(s):  
Quantitative Analysis ◽  
Demographic Factors ◽  
Positive Perception ◽  
External Threats ◽  
Positive Practices ◽  
The Impact ◽  
The Relationship

Whitsleblowing is one of the positive practices in organizations that are able to raise the level of integrity among the members of an organization. However, the roles of whistleblowing also inevitably invites a response, especially among members of the organization itself. This is because such practices are viewed as one factor that may be detrimental to the organization in addition to revealing the reporter (whistleblower) to some external threats and intimidation of discrimination within the organization. This paper is an attempt to examine the relationship between perceptions of members of the Royal Malaysian Police (RMP) Contingent of Perak through the role of whistleblowing practices to increase the perception of the integrity of the members. Next, identify the purpose of the whistleblowing and its effect on the integrity of the members of the organization. This study used a descriptive quantitative analysis to identify patterns of relationship that exists between the perception of whistleblowing practices with perceptions of increased integrity based on three basic variables of demographic factors, response to whistleblowing and the impact of making the report. The results showed that members of the Perak’s police have a positive perception of whistleblowing practices which are seen to be done in improving the integrity of the members.Keywords: whistleblowing, perception, RMP members, culture, integrity, organization, influence. ABSTRAK: Whitsleblowing merupakan salah satu amalan positif dalam organisasi yang mampu untuk meningkatkan tahap integriti ahli-ahli dalam sesebuah organisasi. Namun begitu, amalan whistleblowing juga turut tidak dapat mengelak daripada mengundang pelbagai respon khususnya dalam kalangan ahli organisasi itu sendiri. Amalan sebegini turut dilihat sebagai salah satu faktor yang boleh memudaratkan organisasi di samping mendedahkan pelapor (whistleblower) kepada beberapa bentuk ancaman ugutan dari luar dan diskriminasi dalam organisasi. Kertas ini merupakan satu upaya untuk melihat perkaitan antara persepsi anggota Polis Diraja Malaysia (PDRM) Kontinjen Perak melalui peranan amalan whistleblowing terhadap persepsi peningkatan integriti anggota. Seterusnya, mengenalpasti maksud whistleblowing dan pengaruhnya terhadap tahap integriti anggota dalam organisasi. Kajian ini menggunakan analisis kuantitatif berbentuk deskriptif bagi mengenalpasti corak hubungan yang wujud antara persepsi terhadap amalan whistleblowing dengan persepsi terhadap peningkatan integriti berdasarkan tiga pembolehubah asas iaitu faktor demografi, tanggapan terhadap whistleblowing dan kesan daripada tindakan membuat laporan. Dapatan kajian menunjukkan bahawa anggota PDRM Perak mempunyai persepsi yang positif terhadap whistleblowing yang mana ianya dilihat perlu dilaksanakan dalam meningkatkan integriti anggota.Kata kunci: whistleblowing, persepsi, amalan, anggota PDRM, budaya, integriti, organisasi, pengaruh.  

GAGASAN PEMIKIRAN DAN GERAKAN DAKWAH M. NATSIR DI INDONESIA

1970 ◽  
Vol 4 (2) ◽  
pp. 284-295
Author(s):  
Muridan Muridan
Keyword(s):  
Boarding School ◽  
Religious Discourse ◽  
The State ◽  
Islamic State ◽  
The Relationship ◽  
Islamic Values

M. Natsir was one of the most prominent figures in religious discourse and movement in Indonesia. He was ada’wa reformer as well as a politician and a statesman.His most well known ideas were about the relationship between Islamand state, Islam and Pancasila, and his idea on da’wa. He stated that a country would be Islamic because of neither itsformal name as an Islamic state nor its Islamic state principles. The principles of the state could be generally formulated aslong as they referred to the Islamic values. Natsir also stated that the essence of Pancasila didn’t contradict with Islam; evensome parts of it went after the goals of Islam. However, it didn’t mean that Pancasila was identical with Islam. In relation toda’wa, he stated that it should be the responsibility of all Muslims, not only the responsibility of kiai or ulama. To make a da’wamovement successful, he suggested that it needed three integrated components; masjid, Islamic boarding school, andcampus.

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