Thread Friction Torque in Bolted Joints

2005 ◽  
Vol 127 (4) ◽  
pp. 387-393 ◽  
Author(s):  
Sayed A. Nassar ◽  
Payam H. Matin ◽  
Gary C. Barber
Keyword(s):  
Friction Coefficient ◽  
Current Practice ◽  
Weighted Average ◽  
High Accuracy ◽  
Friction Torque ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Average Value ◽  
Highly Sensitive

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Due to the lack of exact formulas in the literature, current practice uses the average value of the minor and major thread radii, as an approximation, for determining the thread friction torque component. Results provided by these formulas are compared with those given by the current practice that uses the average value of the minor and major thread radii, instead of the exact value. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. High accuracy in the estimation of the friction torque components is critical, as it directly affects the reliability, safety, and the quality of bolted assemblies. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using five assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on a thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single nondimensional variable, namely, the ratio between the major and minor thread radii.

Thread Friction Torque in Bolted Joints

2004 ◽  
Author(s):  
Sayed A. Nassar ◽  
Payam H. Matin ◽  
Gary C. Barber
Keyword(s):  
Friction Coefficient ◽  
Current Practice ◽  
Weighted Average ◽  
Friction Torque ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Average Value ◽  
Highly Sensitive ◽  
Dimensional Variable

In this paper, formulas are developed for the calculation of the effective thread friction radius in fasteners, in order to determine the thread friction torque component. Results provided by these formulas are compared with those given by current practice that uses the average value of the minor and major thread radii. It is well known that the torque-tension relationship in threaded fastener applications is highly sensitive to the friction torque components: between threads, and under the turning fastener head or nut. Even moderate variations or inaccuracies in determining the friction torque components would significantly impact the fastener tension and the joint clamp load. This makes critical the accuracy in the estimation of the friction torque components, as it directly affects the reliability, safety, and the quality of bolted assemblies, especially in critical applications. This analysis focuses on the thread friction torque component. The new formulas for the thread friction radius are developed for a mathematical model of a bolted joint using three assumed scenarios of the contact pressure between male and female threads. Because of the fact that the variation in the sliding speed of various points on thread surface is insignificant, a uniform thread friction coefficient is used in the analysis. However, a contact area weighted average value is used for the thread friction coefficient. Numerical results and error analysis are presented in terms of a single non-dimensional variable; namely, the ratio between the major and minor thread radii.

Viscous Friction Effect During the Process of Tightening and Loosening of Bolted Joints

2021 ◽  
Author(s):  
Qingyuan Lin ◽  
Yong Zhao ◽  
Qingchao Sun ◽  
Kunyong Chen
Keyword(s):  
Friction Coefficient ◽  
Viscous Friction ◽  
Normal Pressure ◽  
Friction Model ◽  
Bolted Joints ◽  
Critical Parameters ◽  
Bolted Joint ◽  
Sliding Velocity ◽  
Friction Effect ◽  
Bearing Friction

Abstract Bolted connection is one of the most widely used mechanical connections because of its easiness of installation and disassembly. Research of bolted joints mainly focuses on two aspects: high precision tightening and improvement of anti-loosening performance. The under-head bearing friction coefficient and the thread friction coefficient are the two most important parameters that affect the tightening result of the bolted joint. They are also the most critical parameters that affect the anti-loosening performance of the bolted joint. Coulomb friction model is a commonly used model to describe under-head bearing friction and thread friction, which considers the friction coefficient as a constant independent of normal pressure and relative sliding velocity. In this paper, the viscous effect of the under-head bearing friction and thread friction is observed by measuring the friction coefficient of bolted joints. The value of the friction coefficient increases with the increase of the relative sliding velocity and the decrease of the normal pressure. It is found that the Coulomb viscous friction model can better describe the friction coefficient of bolted joints. Taking into account the dense friction effect, the loosening prediction model of bolted joints is modified. The experimental results show that the Coulomb viscous friction model can better describe the under-head bearing friction coefficient and thread friction coefficient. The model considering the dense effect can more accurately predict the loosening characteristics of bolted joints.

CHANGES IN THE TECHNICAL AND TECHNOLOGICAL LEVEL OF STEAM CULTIVATORS IN THE XXI CENTURY

2021 ◽  
Vol 2 (143) ◽  
pp. 174-183
Author(s):  
Andrey Yu. Nesmiyan ◽  
◽  
Anastasiya S. Kaymakova ◽  
Yuliya S. Tsench ◽  
Keyword(s):  
Weighted Average ◽  
Specific Weight ◽  
Research Purpose ◽  
Utilization Rate ◽  
Average Value ◽  
Technological Level ◽  
Short Test ◽  
Specific Material ◽  
The Cost

Most modern agricultural machines and tools consist of components, the main parameters, design features of which were justified in the first half of the twentieth century. Slowly and evolutionarily, these technical means are developing. (Research purpose) The research purpose is in identifying general trends in the technical and technological level of steam cultivators in the first quarter of the XXI century. (Materials and Methods) For the study there was analyzed the data of the short test reports of the selected machines. The production of steam cultivators in the Russian Federation is gradually increasing. (Results and discussion) For ten years of the beginning of the XXI century, only 27 machines were provided for testing, and from 2014 to 2017 – more than 40, while for "old" cultivators, the weighted average value of the tractor traction class was 2.8, for new ones it is about of four. For the study period (on average 10 years) the quality of soil cultivation in terms of such parameters as deviation from the specified depth of cultivation, crumbling and combing of the field surface has not changed much. The productivity of cultivator units increased by 7-21 percents, which is explained not only by an increase in the power of tractors, but also by an increase in the utilization rate of charge time on average from 0.72 to 0.77. The specific weight of the "new" cultivators was on average 22 kilogram-meters less than that of the "old" analogues, which can be explained by the evolution of their designs. (Conclusions) Increasing the class of tractors by one "level" the specific material consumption of the cultivators aggregated with them increases by about 58 kilogram-meters for both "old" and " new " cultivators. With an increase in the width of the tools from 4 to 16 meters, their weight will increase by 8 times, which affects the cost and operational and environmental characteristics of wide-reach cultivators.

The Impact of Qualified Bolting Specialists on the Safe, Reliable Assembly and Operation of Bolted Flanged Connections

2015 ◽  
Author(s):  
A. Fitzgerald (Jerry) Waterland ◽  
David Lay ◽  
Michael Dodge
Keyword(s):  
Work Force ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Critical Area ◽  
Bolted Joint ◽  
Learning Program ◽  
Guideline Document ◽  
The Impact ◽  
Joint Assembly

Why do we certify welders but require no evidence of training or competence from those performing the critical bolted flanged joint assembly of pressure vessels and piping throughout the same industries? To remedy this situation ASME has recently released the first comprehensive standard in ASME PCC-1-2013 Appendix A that establishes uniform criteria, not just for the quality of the bolted joints but for the workers who assemble them. To support this critical training and qualification standard, ASME Training & Development has created a unique blended learning program for pipe fitters and mechanics to become Qualified Bolting Specialists (QBS), per the requirements outlined in PCC-1-2013 Appendix A. The purpose of this technical presentation is to explain the opportunities presented by this new standard and how industry can benefit from a better-trained work force in this critical area of bolted joint assembly. The authors have been integrally involved in the development of both the PCC-1 guideline document, and the ASME qualification program, and can authoritatively answer industry’s questions.

scholarly journals Rekomendasi Penentuan Desa Terbaik dengan Kombinasi Metode OWA (Ordered Weighted Avarage) dan Metode SAW (Simple Additive Weighting) berbasis Web

2020 ◽  
pp. 99-104
Author(s):  
Agustina Simangunsong ◽  
Rita Hamdani
Keyword(s):  
National Level ◽  
Weighted Average ◽  
Weighting Method ◽  
Average Value ◽  
Analysis Process ◽  
City District ◽  
The Government ◽  
Simple Additive Weighting ◽  
The Village

The success of the government is determined by essential aspects of the village and has increased every day and has changed into a town that has independence in carrying out activities and survival by each of its residents, to support and improve the quality of government villages which motivate for villages to compete to become the best village through a series of costs to improve the quality of the town. The process of determining the best village starts from the sub-district. The winner will be smart at the city district level up to the national level, in the process of determining the best town according to government regulations in sending villages with five aspects and each aspect that has specified specifications and through validation from the government In the process of the government in the form of a committee conducting visits and conducting assessments based on the completeness of the data with the team for each aspect and giving to the committee based on individual orders, the value submitted will do the calculation by determining the final cost of the process of finding an average value -average overall and do the division of the total aspects. To assist the procedure in choosing the best village, the researcher wants to develop an online decision support system application with features that will be equipped in the developed application by uploading documents according to conditions in the field and documentation carried out by the team towards the village, so that the order process is open. It can be witnessed by all concerned, while in the Calculation and analysis Process using the OWA (ORDERED WEIGHTED AVERAGE) combination operator to determine the average value calculation and the SAW (Simple Additive Weighting) Method as part of the ranking of several existing villages

scholarly journals ANALISIS KUALITAS PELAYANAN PERUSAHAAN DAERAH AIR MINUM (PDAM) TIRTA ALAMI KABUPATEN KEPAHIANG

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Arminsyah ◽  
Merri Anitasari
Keyword(s):  
Drinking Water ◽  
Data Analysis ◽  
Quantitative Analysis ◽  
Services Quality ◽  
Weighted Average ◽  
Quality Of Services ◽  
Average Value ◽  
A Value ◽  
Water Company

Arminsyah, Merri Anitasari;An Analysis Of Services Quality at Drinking Water Company (PDAM) Tirta Alami Kepahiang. This research aims to investigate the quality of Services at drinking water Company (PDAM) Natural Tirta Kepahiang. This research then used questionnaire as the data collecting method. Quantitative analysis then also be used as a techniques for data analysis by using weighted average value formula formed by Men Pan decree Number KEP/25/m. PAN/2/2004 on the 14 items that are observed. From thequestionnaire it was obtained that the highest average of services is on the ease of servicing requirementswith a value of 3.03. While the lowest average value of service is on the services equity which gain a score 2.95. For IKM value,it get 63 which places between 62.51-81.25. This score means that the performance of PDAM Tirta Alami Kepahiang is good.Kata kunci:Kualitas Pelayanan

scholarly journals Bolted Joint Preload Distribution from Torque Tightening

2021 ◽  
Vol 71 (2) ◽  
pp. 329-342
Author(s):  
Welch Michael
Keyword(s):  
Friction Coefficient ◽  
Static Friction ◽  
Bolted Joints ◽  
Dynamic Friction ◽  
Bolted Joint ◽  
Classical Analysis ◽  
Joint Design ◽  
Static Friction Coefficient ◽  
Bolt Preload ◽  
Torque Wrench

Abstract The purpose of this paper is to develop an understanding of how bolt preloads are distributed within a joint as each bolt is tightened in turn by the use of a calibrated torque wrench. It discusses how the order that the joints nuts/bolts are tightened can affect the final bolt preload. It also investigates the effect on incrementally increasing the bolt preload through a series of applications of the controlled torque tightening sequence. Classical analysis methods are used to develop a method of analysis that can be applied to most preloaded bolted joints. It is assumed that the static friction coefficient is approximately 15% less than the dynamic friction. It is found that the bolt preload distribution across the joint can range from slightly above the target preload to significantly less than the target preload. The bolts with a preload greater than the target preload are found to be those tightened towards the end of the tightening sequence, usually located close to the outer edges of the joint’s bolt array. The bolts with a preload less than the target preload are those tightened early in the tightening sequence, located centrally within the joints bolt array. The methods presented can be used to optimise bolted joint design and assembly procedures. Optimising the design of preloaded bolted joints leads to more efficient use of the joints.

scholarly journals Calculation of the Amplitude and Initial Phase of the Signal from Its Most "Reliable" Fragments

2021 ◽  
Vol 2 (1) ◽  
pp. 17-24
Author(s):  
Oleksandr Brezgunov ◽  
Sergey Brezgunov
Keyword(s):  
Initial Phase ◽  
Radio Signal ◽  
High Accuracy ◽  
Maximum Point ◽  
Radio Communication ◽  
Noise Component ◽  
Average Value ◽  
Radio Signals ◽  
Zero Values

The idea of improving the methods of processing the received radio signals used in radio communication and radiolocation systems is considered. It is proposed to consider the radio signal as a noise-resistant code with repetition of its periods (symbols), each of which carries the same information about the value of its amplitude and initial phase. The possibility of realization of coherent reception of radio signals with amplitude or biphasic discrete modulation under the influence of powerful noise on them by their most "reliable" (suitable for calculations) fragments, determined by the values of samples, received at moments when the amplitude of a received signal shall be equal to zero (samples correspond to the value of the noise component – point A) or be maximum – point E (the phase of signals shifted with respect to the phase of noise, by π/2 or 3π/4). The considered approach on processing of a mix of a signal and noise allows to define some varieties of "reliable" fragments (at difference of phases of noise and a signal on π/2 or 3π/4, at a match of zero values of signals and noise, at difference of phases of noise and a signal on the value smaller, than ±π/24) on values of samples in points A and E, and also to exclude from consideration fragments, decision on which often is erroneous. The possibility of obtaining an additional estimation ∆ of the quality of the decision on a fragment of a discrete signal (BPSK), with already calculated its average value SСР on the set of its fragments, which allows to select the best or several best fragments for the decision on the received signal is shown. Fragments with a difference of noise and signal phases on the value smaller than ±π/24 occur most often from all considered variants and allow to distinguish with high accuracy the initial phases of opposite signals (BPSK). To solve the problem, we used all possible temporal representations of fragments of signal, noise and a mixture of signal and noise, mathematical models and formulas of the theory of circuits and signals.

scholarly journals ANALISIS PENERAPAN SISTEM INFORMASI MANAJEMEN KEUANGAN DAERAH (SIMDA KEUANGAN) DALAM PENGOLAHAN DATA KEUANGAN PADA ORGANISASI PEMERINTAH DAERAH (Studi Kasus Pada Dinas Lingkungan Hidup Kabupaten Tolitoli)

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Edi Yanto ◽  
Mr Afkir
Keyword(s):  
Internal Control ◽  
Ordinal Data ◽  
Weighted Average ◽  
Measurement Scale ◽  
Quality Of Information ◽  
Accounting Information System ◽  
Average Value ◽  
Qualitative Descriptive ◽  
Better Than

AbstractJenis penelitian ini merupakan penelitian deskriptif kualitatif dengan� tujuan untuk mengetahui penerapan SIMDA Keuangan sebagai sistem informasi akuntansi daerah dapat mempermudah tugas pelaporan dan pengelolaan keuangan daerah, pengendalian intern sistem yang diterapkan guna mencapai tujuan pelaporan, dan cakupan analisa kualitas informasi yang dihasilkan oleh sistem tersebut pada Dinas Lingkungan Hidup Kabupaten Tolitoli. Dengan skala pengukuran menggunakan data ordinal, nilai rata-rata tertimbang menunjukkan bahwa kualitas informasi saat sesudah/setelah menerapkan SIMDA Keuangan di Dinas Lingkungan Hidup lebih baik dari sebelumnya. Hal ini ditunjukkan oleh nilai rata-rata tertimbang sesudah menggunakan SIMDA Keuangan� sebesar 3,45 satuan, sedangkan sebelum menggunakan SIMDA Keuangan sebesar 2,00 satuan.�Keywords: SIMDA Keuangan & Pengolahan Data Keuangan.�AbstractThis type of research is a qualitative descriptive study with the aim to determine the application of SIMDA Finance as a regional accounting information system that can facilitate the task of reporting and management of regional finances, internal control systems that are applied to achieve reporting objectives, and the scope of analysis of the quality of information produced by the system at the Office Tolitoli Regency Environment With a measurement scale using ordinal data, the weighted average value indicates that the quality of information after / after applying SIMDA Finance in the Department of the Environment is better than before. This is indicated by the weighted average value after using SIMDA Financial by 3.45 units, whereas before using SIMDA Finance by 2.00 units.�Keywords: SIMDA Finance & Financial Data Processing.

scholarly journals ANALISIS INDEKS KEPUASAN MASYARAKAT (IKM) DI KANTOR KECAMATAN PALARAN KOTA SAMARINDA

2019 ◽  
Vol 6 (1) ◽  
pp. 19
Author(s):  
. Emi
Keyword(s):  
Public Service ◽  
Public Services ◽  
Weighted Average ◽  
Sample Population ◽  
Community Satisfaction ◽  
District Office ◽  
Average Percentage ◽  
Average Value ◽  
Satisfaction Index

This study aims to identify and analyze the Community Satisfaction Index (HPI) to public service organized by the District Office Palaran. Besides, this study also aimed to determine the factors supporting and hindering the implementation of public services at the District Office Palaran. This study uses a combined approach between quantitative and qualitative descriptive. A quantitative approach using the sample population as a source of data while the qualitative approach featuring informant as speakers or participants in answering the problem of research. The results showed that the average percentage method, Community Satisfaction Index (HPI) to public service organized by the District Office Palaran is 70.1%, this means that the quality of public services produced in the category quite well. While the results of the analysis by the method of the weighted average value, generating Community Satisfaction Index (HPI) to public service organized by the District Office Palaran with a score of 87.25, which means the value perception and quality of public services organized by the District Office in the category Palaran very Good (Grade A).Keyword : satisfaction, society, public service

Sign in / Sign up

Export Citation Format

Share Document