An Experimental Investigation on Self-Loosening of Bolted Joints

2003 ◽  
Author(s):  
Yanyao Jiang ◽  
Ming Zhang ◽  
Tae-Won Park ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Endurance Limit ◽  
Early Stage ◽  
Surface Condition ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
Shear Loading ◽  
Bolted Joints ◽  
Transverse Load ◽  
Second Stage

The self-loosening process of a bolted joint consists of two distinct stages. The early stage of self-loosening is due to the cyclic plastic deformation of the materials. The second stage of self-loosening is characterized by the backing off of the nut. The current study is concentrated on the experimental investigation of the second stage of self-loosening with the aim to explore the mechanisms responsible for the phenomenon. Over a hundred bolted joints were experimentally tested using a specially designed testing apparatus. M12×1.75 bolts and nuts were used. The experiments mimicked two plates jointed by a bolt and a nut and were subjected to cyclic transverse shear loading. During an experiment, the relative displacement between the two clamped plates, denoted by δ, was a control parameter. The clamping force, the relative rotation between the nut and the bolt, and the applied transverse load were monitored and recorded for each loading cycle. For a given preload, the relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening followed a pattern similar to a fatigue curve. There existed an endurance limit below which self-loosening would not persist. A larger preload resulted in a larger endurance limit. However, a large preload increased the possibility for the bolt to fail in fatigue. It was found that the surface condition, which influenced the friction coefficient, had a significant influence on self-loosening resistance. The results also reveal that the use of a regular nut is superior to the use of a flange nut in terms of self-loosening resistance. An “endurance diagram” concept was developed that can be used directly for the design and evaluation of the bolted joints.

An Experimental Study of Self-Loosening of Bolted Joints

2004 ◽  
Vol 126 (5) ◽  
pp. 925-931 ◽  
Author(s):  
Yanyao Jiang ◽  
Ming Zhang ◽  
Tae-Won Park ◽  
Chu-Hwa Lee
Keyword(s):  
Endurance Limit ◽  
Early Stage ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
Shear Loading ◽  
Bolted Joints ◽  
Second Stage ◽  
Controlling Parameter ◽  
Cyclic Plastic Deformation ◽  
The Relationship

The self-loosening process of a bolted joint consists of two distinct stages. The early stage of self-loosening is due to the cyclic plastic deformation of the materials. The second stage of self-loosening is characterized by the backing off of the nut. The current work is concentrated on an experimental investigation of the second stage self-loosening. Over one hundred bolted joints with M12×1.75 bolts and nuts were experimentally tested using a specially designed testing apparatus. The experiments mimicked two plates jointed by a bolt and a nut and were subjected to cyclic transverse shear loading. During an experiment, the relative displacement between the two clamped plates, denoted by δ, was a controlling parameter. For a given preload, the relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening followed a pattern similar to a fatigue curve. There existed an endurance limit below which self-loosening would not persist. A larger preload resulted in a larger endurance limit. However, a large preload increased the possibility for the bolt to fail in fatigue. The results suggest that the use of a regular nut is superior to the use of a flange nut in terms of self-loosening resistance.

An Experimental Investigation of the Effects of Clamped Length and Loading Direction on Self-Loosening of Bolted Joints

2004 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
The Self ◽  
Bolted Joints ◽  
Transverse Load ◽  
External Loading ◽  
Loading Direction ◽  
Controlling Parameter ◽  
Load Carrying

An experimental investigation was conducted to study the effects of clamped length and loading direction on the self-loosening behavior of bolted joints. Specially designed fixtures were used for the study. The experiments mimicked two plates jointed by an M12×1.75 Class 10.9 bolt and a nut. The joints were subjected to cyclic external loading. A constant preload of 25 kN was used for all the experiments conducted. During an experiment, the relative displacement between the two clamped plates, δ, was a controlling parameter. The reduction in clamping force, the applied transverse load, and the nut rotation were measured cycle by cycle. The relationship between, Δδ/2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening is referred to as self-loosening curve and was obtained for different clamped lengths and applied load directions. Similar to a fatigue curve, an endurance limit can be identified from the self-loosening curve. It was found that increasing the clamped length can enhance the self-loosening endurance limits in terms of the controlled relative displacement of the two clamped plates. However, the load carrying capability was not influenced significantly due to the thickness of the clamped plates. For a given bolted jointed structure, an angle of the external load from the pure shearing direction resulted in an increase in self-loosening resistance.

An Experimental Investigation of the Effects of Clamped Length and Loading Direction on Self-Loosening of Bolted Joints

2005 ◽  
Vol 128 (3) ◽  
pp. 388-393 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Experimental Investigation ◽  
Fatigue Curve ◽  
Relative Displacement ◽  
The Self ◽  
Bolted Joints ◽  
Transverse Load ◽  
External Loading ◽  
Loading Direction ◽  
Controlling Parameter ◽  
Load Carrying

An experimental investigation was conducted to study the effects of clamped length and loading direction on the self-loosening behavior of bolted joints by using specially designed fixtures. The experiments mimicked two plates jointed by an M12×1.75 class 10.9 bolt and a nut. The joints were subjected to cyclic external loading. A constant preload of 25kN was used for all the experiments conducted. During an experiment, the relative displacement between the two clamped plates, δ, was a controlling parameter. The reduction in clamping force, the applied transverse load, and the nut rotation were measured cycle by cycle. The relationship between, Δδ∕2, the amplitude of the relative displacement between the two clamped plates, and, NL, the number of loading cycles to loosening is referred to as self-loosening curve and was obtained for different clamped lengths and applied load directions. Similar to a fatigue curve, an endurance limit can be identified from the self-loosening curve. It was found that increasing the clamped length can enhance the self-loosening endurance limits in terms of the controlled relative displacement of the two clamped plates. However, the load carrying capability was not influenced significantly due to the thickness of the clamped plates. For a given bolted jointed structure, an angle of the external load from the pure shearing direction resulted in an increase in self-loosening resistance.

Finite Element Modeling of Self-Loosening of Bolted Joints

2004 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Bending Moment ◽  
Shear Loading ◽  
Transverse Load ◽  
Fe Model ◽  
Bolted Joint ◽  
Cyclic Bending ◽  
Second Stage ◽  
Cyclic Bending Moment

A three-dimensional finite element (FE) model with the consideration of the helix angle of the threads was developed to simulate the second stage self-loosening of a bolted joint. The second stage self-loosening refers to the graduate reduction in clamping force due to the back-off of the nut. The simulations were conducted for two plates jointed by a bolt and a nut and the joint was subjected to transverse or shear loading. An M12×1.75 bolt was used. The application of the preload was simulated by using an orthogonal temperature expansion method. FE simulations were conducted for several loading conditions with different preloads and relative displacements between the two clamped plates. It was found that due to the application of the cyclic transverse load, micro-slip occurred between the contacting surfaces of the engaged threads of the bolt and the nut. In addition, a cyclic bending moment was introduced on the bolted joint. The cyclic bending moment resulted in an oscillation of the contact pressure on the contacting surfaces of the engaged threads. The micro-slip between the engaged threads and the variation of the contact pressure were identified to be the major mechanisms responsible for the self-loosening of a bolted joint. Simplified finite element models were developed that confirmed the mechanisms discovered. The major self-loosening behavior of a bolted joint can be properly reproduced with the FE model developed. The results obtained agree quantitatively with the experimental observations.

Finite Element Modeling of Self-Loosening of Bolted Joints

2006 ◽  
Vol 129 (2) ◽  
pp. 218-226 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Bending Moment ◽  
Shear Loading ◽  
Transverse Load ◽  
Fe Model ◽  
Bolted Joint ◽  
Cyclic Bending ◽  
Second Stage ◽  
Cyclic Bending Moment

A three-dimensional finite element (FE) model with the consideration of the helix angle of the threads was developed to simulate the second stage self-loosening of a bolted joint. The second stage self-loosening refers to the gradual reduction in clamping force due to the back-off of the nut. The simulations were conducted for two plates jointed by a bolt and a nut and the joint was subjected to transverse or shear loading. An M12×1.75 bolt was used. The application of the preload was simulated by using an orthogonal temperature expansion method. FE simulations were conducted for several loading conditions with different preloads and relative displacements between the two clamped plates. It was found that due to the application of the cyclic transverse load, microslip occurred between the contacting surfaces of the engaged threads of the bolt and the nut. In addition, a cyclic bending moment was introduced on the bolted joint. The cyclic bending moment resulted in an oscillation of the contact pressure on the contacting surfaces of the engaged threads. The microslip between the engaged threads and the variation of the contact pressure were identified to be the major mechanisms responsible for the self-loosening of a bolted joint. Simplified finite element models were developed that confirmed the mechanisms discovered. The major self-loosening behavior of a bolted joint can be properly reproduced with the FE model developed. The results obtained agree quantitatively with the experimental observations.

scholarly journals Relaxation of contact pressure and self-loosening in dynamic bolted joints

2016 ◽  
Vol 231 (18) ◽  
pp. 3462-3475 ◽  
Author(s):  
JT Stephen ◽  
MB Marshall ◽  
R Lewis
Keyword(s):  
Contact Pressure ◽  
Early Stage ◽  
Shear Loading ◽  
Bolted Joints ◽  
Joint Interface ◽  
Shear Load ◽  
Bolted Joint ◽  
Cyclic Shear ◽  
Constant Shear ◽  
Additional Constant

Bolted joints are widely used in a variety of engineering applications where they are dynamically loaded with frequencies of vibration spread over a wide spectrum with the same general effects. When under dynamic loading, bolted joints can become loose due to a loss in clamping pressure in the joints. This vibrational loosening sometimes can cause serious problems, and in some cases can lead to fatal consequences if it remains undetected. Non-intrusive ultrasonic and image processing techniques were simultaneously used to investigate the relaxation of contact pressure and loosening of bolted joints subjected to cyclic shear loading. Three critical areas, the contact interface of the bolted component, the bolt length and the rotation of the bolt head, were monitored during loosening of the joints. The results show that loosening of bolted joints can be grouped into three stages: very rapid, rapid, and gradual loosening. The earliest stage of the loosening of bolted joints is characterised by cyclic strain ratcheting–loosening of the bolted joint during vibration without rotation of the bolt head. The higher the rate of relaxation at this early stage, the lower is the resistance of the bolted joint to vibration-induced loosening. Both the dynamic shear load and an additional constant shear load in another direction were observed to affect the rate of loosening, and at this early stage, a rise in the magnitude of the additional constant shear load increases the rate of loosening. Furthermore, the contact pressure distribution affects the rate of loosening at the bolted joint interface, as loosening increases away from area of high contact pressure.

Experimental Investigation on the Friction Coefficients for Different Materials, Lubrication Conditions and Coatings in Bolted Joints

2021 ◽  
Author(s):  
Stefano Fini ◽  
Massimiliano De Agostinis ◽  
Dario Croccolo ◽  
Giorgio Olmi ◽  
Francesco Robusto ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Bolted Joints ◽  
Friction Coefficients ◽  
Lubrication Conditions

FACES OF V.M. SHUKSHIN: MARTIN IDEN, HAMLET, STEPAN RAZIN

2021 ◽  
pp. 59-65
Author(s):  
Т.А. Богумил
Keyword(s):  
Early Stage ◽  
Socialist Realism ◽  
Crowding Out ◽  
Behavioral Models ◽  
Cluster Approach ◽  
Second Stage ◽  
The Third ◽  
Third Stage ◽  
Early Departure ◽  
First Time

В статье предлагается концепция жизни и творческого роста В.М. Шукшина сквозь призму тезаурусного и кластерного подходов. Объяснительными «персональными моделями» для интерпретации биографического текста писателя являются кластеры Мартина Идена, Гамлета и Степана Разина. Ранее биографы и литературоведы указывали на важность этих персон для Шукшина, но разрозненно. Впервые предпринята попытка свести указанные персональные модели воедино, в целостный сюжет становления писателя в пространстве культуры. На разных этапах эволюции автора доминирует одна из указанных моделей, последовательно сменяя друг друга, но не вытесняя, а «внахлест». Ранний этап творчества, ориентированный на стратегию Мартина Идена, является попыткой «вписаться» в наличный культурный мейнстрим. Выражено это в следовании поэтике соцреализма. Второй этап подспудно начинается с реабилитации отца Шукшина в 1956 года, когда актуализируется «гамлетовский комплекс», проявляющийся в чувстве вины перед отцом, через стратегию утаивания подлинного «я», мотивы чудаковатости. Третий этап связан с личностью реального исторического лица, Степана Разина, и выражается в открытом протесте против власти. Все важные для В.М. Шукшина поведенческие модели объединены мотивом одинокого противостояния враждебному социуму и имеют трагический финал, что обусловило ранний уход писателя и порождение мифов о насильственном характере его смерти. В.М. Шукшин одновременно был фигурой неординарной и типичной, что позволило его биографии стать «персональной моделью» для последующих авторов, выходцев из сельской глубинки. The article proposes the concept of life and creative growth of V.M. Shukshin through the prism of the thesaurus and cluster approach. The explanatory "personal models" for interpreting the biographical text of the writer are clusters of Martin Eden, Hamlet and Stepan Razin. Earlier, biographers and literary critics pointed out the importance of these people for Shukshin, but it was scattered. For the first time, an attempt was made to bring these personal models together into an integral plot of the formation of the writer in the space of culture. At different stages of the writer’s evolution, one of these models dominates, successively replacing each other, but not crowding out, but “overlapping”. The early stage of creativity, focused on Martin Eden’s strategy, is an attempt to “fit in” the current cultural mainstream. This is expressed in following the poetics of socialist realism. The second stage implicitly begins with the rehabilitation of Shukshin’s father in 1956, when the “Hamletian complex” is actualized. It is manifested in a sense of guilt towards his father, the strategy of concealing the true “I”, eccentricities. The third stage is connected with the personality of a real historical person, Stepan Razin, and is expressed in an open protest against the authorities. All important for V.M. Shukshin's behavioral models are united by the motive of a lonely confrontation with a hostile society and have a tragic ending, which led to the early departure of the writer and the generation of myths about the violent nature of his death. V.M. Shukshin was an extraordinary and typical figure at the same time. That allowed his biography to become a “personal model” for subsequent authors who came from the rural outback.

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