Effects of different friction coefficients on input torque distribution in the bolt tightening process based on the energy method

2021 ◽  
pp. 1-21
Author(s):  
Kai Jiang ◽  
Zhifeng Liu ◽  
Yida Wang ◽  
Yang Tian ◽  
caixia Zhang ◽  
...  
Keyword(s):  
Conversion Rate ◽  
Tensile Force ◽  
Distribution Model ◽  
Experimental Investigations ◽  
Contact Radius ◽  
Friction Coefficients ◽  
Torque Distribution ◽  
Tightening Force ◽  
Finite Element Technology ◽  
Input Torque

Abstract Bolted joints are one of the most common fastening methods in engineering applications. To meet the requirements of structural parts, the torque method is often used for controlling the bolted joint performance. However, only a few investigations have been carried out on the conversion efficiency of bolt torque to the tensile force, leading to uncertainty and potential safety hazards during the bolt tightening. In order to study the input torque distribution and overcome problems caused by the Motosh method and experimental investigations, a new energy-based torque distribution model is established in the present study. In the proposed model, numerous affecting parameters, including the effective bearing radius, effective thread contact radius, spiral angle, and connector deformation are considered. Then a parameterized thread mesh model using finite element technology is proposed to analyze the influence of different bolt friction coefficients on the bolt tightening process. Based on 16 types of tightening analyses, it is concluded that as bolt friction coefficient increases, the corresponding torque conversion rate decreases from 14.45% to 7.89%. Compared with the Motosh method, the torque conversion rate obtained by the proposed method is relatively large, which makes the actual pre-tightening force larger than the design value. However, there is still a possibility of bolt failure.

The influence of lubrication on the frictional characteristics of threaded joints for planetary gearboxes

2016 ◽  
Vol 230 (15) ◽  
pp. 2553-2563 ◽  
Author(s):  
M De Agostinis ◽  
S Fini ◽  
G Olmi
Keyword(s):  
Ring Gear ◽  
Friction Coefficients ◽  
Tightening Torque ◽  
Experimental Stress Analysis ◽  
Threaded Joints ◽  
Breakaway Torque ◽  
The Difference ◽  
Numerical Finite Element ◽  
Input Torque

Planetary gearboxes generally consist of a ring gear, or gear body, connected with the input and output flanges by means of several screws, equally spaced along the diameter. The ring gear is manufactured with steel, whereas the flanges are usually made of cast iron. These screws must provide axial preload between the parts, allowing the assembly withstanding the breakaway torque given by the difference between the output and input torque applied to the gearbox. For a given screw geometry, the axial preload can be calculated, provided that the friction coefficients in the thread and in the underhead are known. Most often, the tightening torque is the only parameter being controlled during assembly and service operations. Hence, it is mandatory to know the friction coefficients of the joint. These depend, among others, on the hardness, roughness and texture of the mating surfaces, as well as on the lubrication state of the joint. In fact, the addition of a lubricant modifies the tribological behavior of the joint, thus the wearing evolution of the surfaces across repeated tightening operations. The present work tackles the following two aspects: (i) the characterization of the preloading force–tightening torque relationship on the actual component by means of a dedicated specimen, (ii) the evaluation of the influence of lubrication on the evolution of the frictional characteristics of the joint across several re-tightening operations. The present work has been carried out by means of both numerical finite element analyses and experimental stress analysis techniques.

Theoretical Method of Calculation to Determination the Change of Axial Force in a Reinforcing Bar during the Destruction of the Support Zone of the Central Column in the RC Structures

2016 ◽  
Vol 821 ◽  
pp. 555-562
Author(s):  
Barbara Wieczorek
Keyword(s):  
Structural Integrity ◽  
Concrete Slab ◽  
Tensile Force ◽  
Experimental Investigations ◽  
Reinforced Concrete Slab ◽  
Linear Change ◽  
Rc Structures ◽  
Method Of Calculation ◽  
Support Zone ◽  
The Impact

The behaviour of reinforced concrete slab-column structures under the impact of accidental loading is very significant due to safety reasons. The failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. However, the instructions on how to prevent such situations are not very detailed. According to the guidelines of standard EC2, the structural integrity reinforcement should be continuous throughout the length and consist of at least two bars above the column in every perpendicular direction. EC2 does not state the amount of necessary reinforcement. The article presents a theoretical model of calculation that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar rigidity and considerable deflections. The calculation model was verified on the basis of the results of experimental investigations. It enables to estimate the tensile force of the bar at which it is ruptured during the destruction of the support zone.

scholarly journals Numerical investigation of initial crack growth in composite laminates under tension

2019 ◽  
Vol 304 ◽  
pp. 01017
Author(s):  
Evgeny Dubovikov ◽  
Alexander Shanygin ◽  
Dmitry Vedernikov
Keyword(s):  
Composite Laminates ◽  
Composite Laminate ◽  
Tensile Force ◽  
Volume Ratio ◽  
Initial Crack ◽  
Experimental Investigations ◽  
Fe Model ◽  
Fe Method ◽  
Stiffness Characteristics ◽  
Composite Samples

The simplified automated strength model of a fragment of composite laminate at microlevel based on the finite elements (FE) method is offered. The model allows investigating the growth of microcracks which arise in the resin in monolayers, orthogonal to a direction of external tensile force. On the basis of automated strength FE model of a fragment of composite laminate and the method of reduction of stiffness characteristics of the resin, the scenario of growth of primary destructions at the microlevel is offered and proved. The scenario is confirmed with experimental investigations of composite samples under tension with registration of acoustic emission. In the work, the dependences of decrease of strength characteristics of composite laminates are obtained as functions of characteristics of resin, angles of orientation of monolayers, volume ratio of fibres in a composite laminate.

Experimental Investigations on Cylindrical Grinding Temperature of Silicon Carbide

2015 ◽  
Vol 1120-1121 ◽  
pp. 1251-1256 ◽  
Author(s):  
Chong Jun Wu ◽  
Bei Zhi Li ◽  
Steven Y. Liang ◽  
Jian Guo Yang
Keyword(s):  
Silicon Carbide ◽  
High Speed ◽  
Ground Surface ◽  
High Energy ◽  
Dynamics Simulation ◽  
Distribution Model ◽  
Experimental Investigations ◽  
Grinding Temperature ◽  
Temperature Characteristics ◽  
High Speed Grinding

The grinding process requires a high energy expenditure per unit volume of material removed. The high temperature generated in abrasive processes is the main factor responsible for thermal damage to a ground surface. An investigation was undertaken to explore the temperature characteristics in high speed grinding (HSG) of silicon carbide (SiC) with a vitrified diamond wheel. A grindable thermocouople technique including a NI-DAQ device will be used to measure the grinding temperature. This paper will discuss the temperature characteristics in high speed grinding of SiC in detail and give an experiment-based temperature distribution model for SiC. A molecular dynamics simulation will be used to illustrate the effect of a high loading rate on SiC material’s mechanical property, which will further elaborate its unique HSG temperature characteristics. The experimental investigation will provide more practical application support in utilizing HSG technology in a high quality ceramic grinding.

scholarly journals Uniaxial tension of drying sieves

2013 ◽  
Vol 67 (4) ◽  
pp. 655-662 ◽  
Author(s):  
Nada Bojic ◽  
Ruzica Nikolic ◽  
Branimir Jugovic ◽  
Zvonimir Jugovic ◽  
Milica Gvozdenovic
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Tension ◽  
Tensile Force ◽  
Nonlinear Behavior ◽  
Experimental Investigations ◽  
Elastoplastic Behavior ◽  
Insight Into

Although the literature contains numerous studies that have been developed to describe the nonlinear behavior of drying sieves' operation, there are no papers in this which report deeper investigation of the drying sieve behavior when exposed to tension and thermo stabilization. The aim of this paper is to provide insight into the elastoplastic behavior of the thermo stabilized and not stabilized sieves subjected to the tensile force. Within this work both theoretical and experimental investigations were performed. The sieves were joined by using a spiral. In separate experiments tests of wire base and weft of the weave mesh were performed, both for thermo stabilized and not thermo stabilized sieves, sieves joining and the sieve thermo stabilization itself. It was established that the thermo stabilization of sieves provides for stability of sieves' dimensions and that open thermo stabilized drying sieve exhibits better mechanical properties and exploitation characteristics then the sieves joining.

Distribution of Forces in Reinforcing Bars in Slab-Column Connections of RC Structures

2016 ◽  
Vol 837 ◽  
pp. 79-84 ◽  
Author(s):  
Barbara Wieczorek
Keyword(s):  
Structural Integrity ◽  
Progressive Collapse ◽  
Tensile Force ◽  
Calculation Model ◽  
Experimental Investigations ◽  
Reinforcing Bars ◽  
Linear Change ◽  
Rc Structures ◽  
Support Zone ◽  
Internal Forces

The article deals with the analysis of the problem of the load-bearing capacity of reinforcing bars placed above the columns in slab-column connections of reinforced concrete structures. Failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. The EC2 standard guidelines recommend the use of integrity reinforcement, however, they lack any instructions concerning the amount of necessary reinforcement. The article presents a theoretical calculation model that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar stiffness and considerable deflections. The calculation model is based on the results of experimental investigations. On the basis of a theoretical model it is possible to estimate the tensile force of the bar at which the bars located directly in the support zone are ruptured.

Test Method for Friction Characterization of Rivets

2020 ◽  
Vol 404 ◽  
pp. 132-137
Author(s):  
Simon Wituschek ◽  
Clara Maria Kuball ◽  
Marion Merklein ◽  
Michael Lechner
Keyword(s):  
Process Parameters ◽  
Composite Structures ◽  
Numerical Models ◽  
Test Method ◽  
Experimental Investigations ◽  
Friction Coefficients ◽  
Friction Parameters ◽  
The Individual ◽  
Simulation And Evaluation ◽  
Joining Process

Due to continuously increasing requirements on lightweight sheet metal constructions, new processes and technologies are necessary to face current and future challenges. A trend in lightweight construction is the multi-material mix with sheets of different geometric and mechanical properties. To manufacture these so-called composite structures, new joining technologies and methods are required. One possibility is the further development of the self-pierce riveting joining process. For the simulation and evaluation of new and adapted processes of self-pierce riveting, numerical models are used to investigate process parameters and constraints. Besides precise material models for the numerical simulation of this joining process, the identification of friction parameters between the individual sheets and rivet elements is necessary to achieve exact results. Thus, a method is necessary to identify the friction coefficients between rivet elements and sheets. Such a method is presented and evaluated in this work. Different process parameters like the relative speed are varied for the experimental investigations and an analysis of the respective influence on the resulting friction coefficients is conducted. For the use of the test set-up, coefficients of friction are determined for rivet elements “RIVSET® C 5.3x5.5” (Böllhoff GmbH) coated with Almac® in combination with two different sheet materials HCT590X+Z and EN‑AW 6014.

Study on the Distribution of Frictional Forces on Z-Yarn Continuous Implanted Preforms and Its Application

2021 ◽  
Author(s):  
Zitong Guo ◽  
Zhongde Shan ◽  
JiHua Huang ◽  
Debo Xue
Keyword(s):  
Friction Force ◽  
Fracture Strength ◽  
Frictional Force ◽  
Tensile Force ◽  
Distribution Model ◽  
Tensile Fracture ◽  
Fiber Fracture ◽  
Measuring Device ◽  
Frictional Forces ◽  
The One

Abstract In order to improve the quality and efficiency of the Z-directional 3D preform forming, the Z-yarn friction force distribution model of the preform and its wear mechanism were investigated. Designed the tensile force measuring device of the replacement guide sleeves,the measured tensile force is equivalent to the Z-yarn friction force. Found that the frictional force was proportional to the number of preform layers, the frictional force applied to the one preform decreased from the corner, edge, sub-edge and middle in order. Established BP neural network model to predict the friction at different positions of preform with different layers, the error is within1.9%. The wear of Z-yarn was studied at different frictional positions and after different times of successive implantation into the preform, showed that with the increase of the number of Z-yarn implantation and the friction force, the amount of carbon fiber bundle hairiness gradually increase, and the tensile fracture strength damage of the fiber is increasingly affected by the friction force,and in the corner position of the preform, when the number of implantation is 25 times, the fiber fracture strength will occur non-linearly and substantially decreased, in order to avoid fiber fracture in the implantation process, the Z-yarn needs to be replaced in time after 20~25 times of continuous

scholarly journals EXPERIMENTAL DEFINITION OF BASING ACCURACY AND TOOL FASTENING

2019 ◽  
Vol 2019 (9) ◽  
pp. 15-24
Author(s):  
Ольга Казакова ◽  
Ol'ga Kazakova ◽  
Лана Гаспарова ◽  
Lana Gasparova
Keyword(s):  
Angular Position ◽  
Experimental Investigations ◽  
Plant Design ◽  
Tightening Force ◽  
Spindle Unit ◽  
Machine Spindle ◽  
Series Of Experiments ◽  
The Moment ◽  
Definition Of ◽  
Operation Results

There are presented results of experimental investigations allowing the definition of factors (parameters) influencing the accuracy of basing and fastening a tool in a machine spindle. The plant design developed allows modeling the work of elements and mechanisms of a spindle unit of a jig-boring machine (JBM) at the moment of tool changing. The series of experiments carried out allowed drawing the following conclusions: - the accuracy of a tool installation in a machine spindle depends upon its angular position in a spindle taper; - angular errors of a tool cone element decrease a rigidity of a “spindle-tool” subsystem by 10…15%; - elastic movements in the area of a contact increase by 2-2.5 times at the presence of ovality in the cross-section of a holder (at ovality 18mkm); - the accuracy of tool location in a spindle increases with the increase of an axial tightening force (recommended tightening force – 3 ≤ Ptight. ≤ 5kN); - the holder operation results in the rigidity decrease of a tool system by 10…15% (operation term – 5 years).

Kinetic Versus Static Frictional Torque Components in Threaded Fastener Applications

2006 ◽  
Author(s):  
Sayed A. Nassar ◽  
Saravanan Ganeshmurthy ◽  
Xianjie Yang
Keyword(s):  
Static Friction ◽  
Joint Surface ◽  
Frictional Torque ◽  
Contact Radius ◽  
Friction Coefficients ◽  
Threaded Fasteners ◽  
Bolt Preload ◽  
Breakaway Torque ◽  
Set Up ◽  
The Stability

This paper investigates the kinetic and static frictional torque components in threaded fasteners during the initial fastener tightening, subsequent torque audit, as well as during the loosening of previously tightened bolts. In less critical applications, the peak kinetic torque value is often used for predicting the bolt preload. The peak value of the tightening torque and its frictional components are mainly determined by the kinetic friction coefficients between the engaged threads and between the rotating nut (or head) and the joint surface. During subsequent quality inspection of the joint after its initial assembly, an audit residual torque value (in the tightening direction) is often used for predicting the residual fastener tension and joint clamp load, as well as for predicting the stability of the clamp load. In contrast with the peak kinetic torque, the audit torque and its thread and under head/nut frictional components are mainly determined by the static friction coefficients. In some cases, the careful application of a breakaway torque in the loosening direction (loosening torque) may be used as a measure for the residual clamp load; similar to the quality audit torque, the loosening torque is determined by the static friction coefficients of the bolted system. An experimental procedure and test set up are proposed to investigate the effect underhead contact radius, thread pitch, surface coating, and fastener head versus nut side tightening on the static and kinetic frictional torque components.

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