The resilient slip friction joint tension-only brace beyond its ultimate level

2020 ◽  
Vol 172 ◽  
pp. 106225
Author(s):  
Hamed Bagheri ◽  
Ashkan Hashemi ◽  
Pouyan Zarnani ◽  
Pierre Quenneville
Keyword(s):  
Friction Joint

scholarly journals Microstructural Investigation of a Friction-Welded 316L Stainless Steel with Ultrafine-Grained Structure Obtained by Hydrostatic Extrusion

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1537
Author(s):  
Beata Skowrońska ◽  
Tomasz Chmielewski ◽  
Mariusz Kulczyk ◽  
Jacek Skiba ◽  
Sylwia Przybysz
Keyword(s):  
Stainless Steel ◽  
Electron Microscope ◽  
Friction Welding ◽  
High Speed ◽  
316L Stainless Steel ◽  
Welded Joint ◽  
Microstructural Investigation ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Friction Joint

The paper presents the microstructural investigation of a friction-welded joint made of 316L stainless steel with an ultrafine-grained structure obtained by hydrostatic extrusion (HE). Such a plastically deformed material is characterized by a metastable state of energy equilibrium, increasing, among others, its sensitivity to high temperatures. This feature makes it difficult to weld ultra-fine-grained metals without losing their high mechanical properties. The use of high-speed friction welding and a friction time of <1 s reduced the scale of the weakening of the friction joint in relation to result obtained in conventional rotary friction welding. The study of changes in the microstructure of individual zones of the friction joint was carried out on an optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron backscattered diffraction (EBSD) analysis system. The correlation between the microstructure and hardness of the friction joint is also presented. The heat released during the high-speed friction welding initiated the process of dynamic recrystallization (DRX) of single grains in the heat-affected zone (HAZ). The additional occurrence of strong plastic deformations (in HAZ) during flash formation and internal friction (in the friction weld and high-temperature HAZ) contributed to the formation of a highly deformed microstructure with numerous sub-grains. The zones with a microstructure other than the base material were characterized by lower hardness. Due to the complexity of the microstructure and its multifactorial impact on the properties of the friction-welded joint, strength should be the criterion for assessing the properties of the joint.

scholarly journals Modeling of Friction Contact and its Application to the Design of Shroud Contact

1996 ◽  
Author(s):  
Been-Der Yang ◽  
Chia-Hsiang Menq
Keyword(s):  
Friction Force ◽  
Normal Load ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Effective Stiffness ◽  
Force Model ◽  
Friction Forces ◽  
Friction Joint ◽  
Stiffness And Damping

Designers of aircraft engines frequently employ shrouds in turbine design. In this paper, a variable normal load friction force model is proposed to investigate the influence of shroud-like contact kinematics on the forced response of frictionally constrained turbine blades. Analytical criteria are formulated to predict the transitions between slick, slip, and separation of the interface so as to assess the induced friction forces. When considering cyclic loading, the induced friction forces are combined with the variable normal load so as to determine the effective stiffness and damping of the friction joint over a cycle of motion. The harmonic balance method is then used to impose the effective stiffness and damping of the friction joint on the linear structure. The solution procedure for the nonlinear response nf a two-degree-of-freedom oscillator is demonstrated. As an application, this procedure is used to study the coupling effect of two constrained forces, friction force and variable normal load, on the optimization of the shroud contact design.

Energy Absorption Capacity of Thermally Sprayed Aluminium Friction Damper

1996 ◽  
Author(s):  
S. Ono ◽  
Japan K. Nakahira ◽  
S. Tsujioka ◽  
K. Inoue
Keyword(s):  
High Strength ◽  
Absorption Capacity ◽  
Repeated Loading ◽  
Friction Damper ◽  
Faying Surface ◽  
New Type ◽  
Friction Joint ◽  
Force Contact ◽  
Thermally Sprayed ◽  
Hysteresis Characteristics

Abstract When buildings are subjected to earthquakes, dampers are effective in decreasing their failure by absorbing the input energy. An object of this study is to develop a new type of friction damper, on whose faying surface aluminium is sprayed, and the double friction joint is tightened with a high-strength bolt. When slip occurs on this friction damper, the slip coefficient is high and comparatively stable. Specimens of the friction damper were tested under the dynamic repeated loading condition to investigate the effect of the condition of the faying surface on the dynamic hysteresis characteristics. The parameters of the test are the type of sprayed metal, the sprayed side of the plate(s), thickness of sprayed metal, the finish of the sprayed surface, and initial clamping force (contact pressure). Results indicate that there exists the condition of suitable characteristics of a metal sprayed friction damper.

Improved Friction Joint With Self-Locking Grips

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Andrei Costache ◽  
Kristian Glejbøl ◽  
Ion Marius Sivebæk ◽  
Christian Berggreen
Keyword(s):  
Load Transfer ◽  
Production Equipment ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Ongoing Research ◽  
Optimal Load ◽  
Test Parameters ◽  
Friction Joint ◽  
Flexible Risers ◽  
And Performance

Flexible risers are used in the oil industry to transport liquids and gas from the seafloor to extraction and production equipment at the sea surface. Ongoing research aims at using composite materials instead of steel, in order to reduce weight and increase stiffness. Ensuring an optimal load transfer between the composite and metal components is very important. This paper presents an improved method for anchoring a flat fiber-reinforced tendon using a double grip system with self-locking grips. The novelty is the combination of new experimental results and finite element (FE) analysis to develop a superior dry friction grip. Experimental results are carried using a dedicated test setup, through which the test parameters can be accurately controlled. The efficiency of the grip system during pullout is superior to results obtained with flat grips. Numerical results offer an in-depth understanding of the influence between friction, geometrical parameters, and performance, making it possible to optimize the design. Results show that this grip system offers immediate technical applications, in a variety of conditions.

Numerical Assessment of Reduced Order Modeling Techniques for Dynamic Analysis of Jointed Structures With Contact Nonlinearities

2018 ◽  
Author(s):  
Jie Yuan ◽  
Fadi El-Haddad ◽  
Loic Salles ◽  
Chian Wong
Keyword(s):  
Dynamic Analysis ◽  
Contact Friction ◽  
Joint Interface ◽  
Test Case ◽  
Beam Model ◽  
Reduced Order ◽  
Trial Vector ◽  
Friction Joint ◽  
Fixed Interface ◽  
Vector Derivative

This work presents an assessment of classical and state of the art reduced order modelling (ROM) techniques to enhance the computational efficiency for dynamic analysis of jointed structures with local contact nonlinearities. These ROM methods include classical free interface method (Rubin method, MacNeal method), fixed interface method (Craig-Bampton), Dual Craig-Bampton (DCB) method and also recently developed joint interface mode (JIM) and trial vector derivative (TVD) approaches. A finite element jointed beam model is considered as the test case taking into account two different setups: one with a linearized spring joint and the other with a nonlinear macro-slip contact friction joint. Using these ROM techniques, the accuracy of dynamic behaviors and their computational expense are compared separately. We also studied the effect of excitation levels, joint region size and number of modes on the performance of these ROM methods.

THE INFLUENCE OF KINEMATIC CONDITION AND LUBRICANT PROPERTIES ON FRICTION IN COMPLEX SLIDE–ROLL MOTION

Tribologia ◽  
2020 ◽  
Vol 289 (1) ◽  
pp. 41-48
Author(s):  
Piotr KOWALEWSKI ◽  
Maciej PASZKOWSKI
Keyword(s):  
Variable Temperature ◽  
Slip Rate ◽  
Shear Velocity ◽  
Roll Motion ◽  
Lithium Grease ◽  
Lubricant Flow ◽  
Wide Range ◽  
Average Shear ◽  
Different Temperatures ◽  
Friction Joint

The paper presents the results of preliminary studies into the influence of selected lubricants (greases) and the variable temperature of the friction joint on the value of friction during complex slide-roll motion. The experiment was carried out for three different types of lubricants: bentonite grease (Benterm 2), lithium grease (GREASEN ŁT4S2), and calcium grease with the addition of graphite (GREASEN GRAFIT) at different temperatures. Tribological investigations were carried out in a roller-plate system at a wide range of plate dislocation velocities and at a constant slip rate; rheological investigations consisted in determining the changes in shear stress as a function of shear time at constant average shear velocity of 50 mm/s. The results showed a significant influence of kinematic conditions on the value of friction. Four different cases of lubricant flow during friction were identified. The least resistance to motion was found when the lubricant was applied in the same direction along the surface of the roller and plate. It has been shown that the greatest influence of the kinematics of working elements on friction occurs at low temperatures, i.e. at -10°C. This phenomenon is closely related to the rheological properties of the lubricant. It was also found that the lubricant thickened with bentonite is the most susceptible to kinematic changes of the friction joint.

Effect of interface gap on load–slip characteristics of timber joints fabricated with multiple nails

1985 ◽  
Vol 12 (1) ◽  
pp. 104-113 ◽  
Author(s):  
S. K. Malhotra ◽  
B. Thomas
Keyword(s):  
Structural Engineering ◽  
Load Capacity ◽  
Lateral Load ◽  
Experimental Program ◽  
Load Carrying Capacity ◽  
Timber Construction ◽  
Interface Characteristics ◽  
Load Carrying ◽  
Friction Joint ◽  
Timber Joints

An experimental program, exploratory in nature, has been carried out to investigate the effect of interface gap on the load–slip behaviour of joints fabricated with multiple nails. In total, 320 joint specimens have been tested. Modification factors are developed to account for the effects of number of nails and interface gap on the overall load-carrying capacity of joints with multiple nails. The current practice for the design of nailed joints is that a joint fastened together with multiple nails in a row, regardless of the interface characteristics of that joint, carries lateral load equal to the product of the lateral-load capacity of the corresponding joint with a single nail and the number of nails in a row of the joint. The findings of this investigation indicate this practice to be somewhat of an overestimation of the overall capacity of the joint. Key words: design, interface gap, interface friction, joint slip, loads (forces), modification factors, multiple fasteners, nailed joints, stiffness, structural engineering, tests, timber construction.

scholarly journals A rough surface damping contact model and its application in spatial variable stator vane mechanism with dry friction joint

2021 ◽  
Author(s):  
Shuai Cheng ◽  
Xianghui Meng ◽  
Rui Li ◽  
Ruichao Liu ◽  
Rui Zhang
Keyword(s):  
Contact Force ◽  
Dry Friction ◽  
Contact Model ◽  
Dynamics Simulation ◽  
Joint Clearance ◽  
Force Model ◽  
Calculation Process ◽  
Stator Vane ◽  
Friction Joint ◽  
Variable Stator

Abstract For the mechanical system without oil lubrication, the impact or collision often occurs in the joint clearance, such as the variable stator vane (VSV) mechanism. In the dry friction joint, the damping of the contact bodies has a significant effect on the simulation stability of the tribo-dynamics calculation process. In order to investigate the effect of contact damping and joint clearance on the VSV mechanism performance, this paper proposes a damping contact model on rough surfaces to calculate the clearance contact force between the trunnion and bushing, and the spatial tribo-dynamics of VSV is established by combining this model with spatial dynamics. In addition, the effect of clearance size on the tribo-dynamics is analyzed. The results show that the contact damping must be included in the contact force model of dry friction joints, otherwise the calculation process will oscillate or even not converge, but the contact damping effect can be ignored in the case of lubricating oil. The movement of the trunnion in the bushing is affected by the adjustment drive and the aerodynamic drag, which leads to the wear concentrated on the edge of the bushing. The clearance size affects the distribution of the damping forces and the rigid forces in the contact process, and the damping forces ensure the stability of the VSV tribo-dynamics simulation process. Moreover, with the increase of clearance, the adjustment accuracy of the VSV mechanism is reduced, and the wear of the bushing is intensified.

Sign in / Sign up

Export Citation Format

Share Document