Towards an understanding of the loosening characteristics of prevailing torque nuts

2010 ◽  
Vol 224 (2) ◽  
pp. 483-495 ◽  
Author(s):  
W Eccles ◽  
I Sherrington ◽  
R D Arnell
Keyword(s):  
Axial Load ◽  
Axial Loading ◽  
Transverse Displacement ◽  
Test Machine ◽  
Transverse Joint ◽  
Metal Type ◽  
Prevailing Torque ◽  
Transverse Movement ◽  
Complete Detachment ◽  
Constant Axial Load

Prevailing torque nuts are an extremely popular method of providing resistance to vibration-induced self-loosening of fasteners. Such nuts have a self-contained prevailing torque feature that provides a degree of resistance to rotation. Although such nuts are frequently used, it is not widely realized that they can occasionally come completely detached from bolts. The mechanism by which this can occur has hitherto been unidentified since it has not been possible to replicate detachment under laboratory testing. This article identifies a general condition that can result in the complete loosening and detachment of prevailing torque type nuts. This mechanism involves the application of an axial load when transverse joint slip is occurring. This article describes a modified Junker test machine that allows the application of axial loading to a joint while experiencing transverse displacement. Tests have been completed using an intermittent as well as a constant axial load. Loading in both modes has been demonstrated to result in the complete detachment of this nut type. Based on this investigation, if the magnitude of the axial loading exceeds the residual preload in the bolt retained from sustaining transverse movement alone, the all-metal type of prevailing torque nut can completely detach. Applications that involve shear and axial loading being simultaneously applied to a joint are numerous in engineering.

Vibration of Beams with a Single Delamination under Axial Loading

2011 ◽  
Vol 675-677 ◽  
pp. 477-480
Author(s):  
Dong Wei Shu
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Analytical Solutions ◽  
Axial Load ◽  
Natural Frequencies ◽  
Axial Loading ◽  
Composite Beams ◽  
Mode Shapes ◽  
Equilibrium Conditions ◽  
Monotonic Relation

In this work analytical solutions are developed to study the free vibration of composite beams under axial loading. The beam with a single delamination is modeled as four interconnected Euler-Bernoulli beams using the delamination as their boundary. The continuity and the equilibrium conditions are satisfied between the adjoining beams. The studies show that the sizes and the locations of the delaminations significantly influence the natural frequencies and mode shapes of the beam. A monotonic relation between the natural frequency and the axial load is predicted.

New Insight Into Energy Harvesting via Axially-Loaded Beams

2009 ◽  
Author(s):  
Mohammed F. Daqaq
Keyword(s):  
Steady State ◽  
Energy Harvesting ◽  
Axial Load ◽  
Excitation Frequency ◽  
Axial Loading ◽  
Response Amplitude ◽  
Resistive Load ◽  
Steady State Response ◽  
State Response ◽  
Axially Loaded

Driven by the study of Leland and Wright [1], this manuscript delves into the qualitative understanding of energy harvesting using axially-loaded beams. Using a simple nonlinear electromechanical model and the method of multiple scales, we study the general nonlinear physics of energy harvesting from a piezoelectric beam subjected to static axial loading and traversal dynamic excitation. We obtain analytical expressions for the steady-state response amplitude, the voltage drop across a resistive load, and the output power. We utilize these expression to study the effect of the axial loading on the overall nonlinear behavior of the harvester. It is demonstrated that, in addition to the ability of tuning the harvester to the excitation frequency via axial load variations, the axial load aids in i) increasing the electric damping in the system thereby enhancing the energy transfer from the beam to the electric load, ii) amplifying the effect of the external excitation on the structure, and hence, increases the steady-state response amplitude and output voltage, and iii) increasing the bandwidth of the harvester by enhancing the effective nonlinearity of the system.

scholarly journals Behavior of Columns Confined With FRP Fabrics under Repeated Lateral Loads

2019 ◽  
pp. 1-19
Author(s):  
Hesham A. Haggag ◽  
Nagy F. Hanna ◽  
Ghada G. Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Axial Load ◽  
Axial Loading ◽  
Concrete Columns ◽  
Fiber Reinforced Polymers ◽  
Lateral Loads ◽  
Reinforced Concrete Columns ◽  
Reinforced Polymers ◽  
Axial Capacity

The axial strength of reinforced concrete columns is enhanced by wrapping them with Fiber Reinforced Polymers, FRP, fabrics.  The efficiency of such enhancement is investigated for columns when they are subjected to repeated lateral loads accompanied with their axial loading.  The current research presents that investigation for Glass and Carbon Fiber Reinforced Polymers (GFRP and CFRP) strengthening as well.  The reduction of axial loading capacity due to repeated loads is evaluated. The number of applied FRP plies with different types (GFRP or CFRP) are considered as parameters in our study. The study is evaluated experimentally and numerically.  The numerical investigation is done using ANSYS software. The experimental testing are done on five half scale reinforced concrete columns.  The loads are applied into three stages. Axial load are applied on specimen in stage 1 with a value of 30% of the ultimate column capacity. In stage 2, the lateral loads are applied in repeated manner in the existence of the vertical loads.  In the last stage the axial load is continued till the failure of the columns. The final axial capacities after applying the lateral action, mode of failure, crack patterns and lateral displacements are recorded.   Analytical comparisons for the analyzed specimens with the experimental findings are done.  It is found that the repeated lateral loads decrease the axial capacity of the columns with a ratio of about (38%-50%).  The carbon fiber achieved less reduction in the column axial capacity than the glass fiber.  The column confinement increases the ductility of the columns under the lateral loads.

Study the Behavior of Castellated Steel Column Encasing by Different Reactive Powder Concrete Thickness with Laced Reinforcement

2021 ◽  
Vol 895 ◽  
pp. 97-109
Author(s):  
Mustafa Mazin Ghazi ◽  
Ahmad Jabbar Hussain Alshimmeri
Keyword(s):  
Axial Load ◽  
Local Buckling ◽  
Axial Loading ◽  
Longitudinal Axis ◽  
Load Test ◽  
Reactive Powder Concrete ◽  
Control Group ◽  
Load Carrying ◽  
Steel Column ◽  
Reactive Powder

Castellated columns are structural members that are created by breaking a rolled column along the center-line by flame after that rejoining the equivalent halves by welding such that for better structural strength against axial loading, the total column depth is increased by around 50 percent. The implementation of these institutional members will also contribute to significant economies of material value. The main objectives of this study are to study the enhancement of the load-carrying capacity of castellated columns with encasement of the columns by Reactive Powder Concrete (RPC) and lacing reinforcement, and serviceability of the confined castellated columns. The Castellated columns with RPC and Lacing Reinforcement improve compactness and local buckling (web and flange local buckling), as a result of steel section encasement. This study presents axial load test results for four specimens Castellated columns section encasement by Reactive powder concrete (RPC) with laced reinforcement. The encasement consists of, flanges unstiffened element height was filled with RPC for each side and laced reinforced which are used inclined continuous reinforcement of two layers on each side o0f the web of the castellated column. The inclination angle of lacing reinforcement concerning the longitudinal axis is 45o. Four specimens with four different configurations will be prepared and tested under axial load at columns. The first group was the control group (CSC1) Unconfined castellated steel column, the second group was consists of Castellated columns (web and flange) confined with 17mm of (RPC), welded web, and 6mm laced reinforcement (CSC3). While group three (CSC4) consists of a Castellated steel column same as the sample (CSC3), but without using welding between two parts of the castellated steel column. Groups four and five consist of a Castellated steel column same as sample (CSC4) encased partially with reactive powder concrete (25.5 mm) (CSC5) and full encased flange with reactive powder concrete (34mm) mm (CSC6), respectively. The tested specimens' results show that an increase in the strength of the column competitive with increasing the encased reactive powder concrete thickness. And the best sample was sample CSC6 with (34mm) mm in experimental and ABAQUS results.

The detachment of an inclined micro-pillar adhered to a dissimilar substrate

2021 ◽  
pp. 1-22
Author(s):  
Nitish Kumar ◽  
Syed Nizamuddin Khaderi
Keyword(s):  
Stress Intensity ◽  
Axial Load ◽  
Interfacial Crack ◽  
Axial Loading ◽  
Stress Fields ◽  
Singular Stress ◽  
Elastic Mismatch ◽  
Bending Loads ◽  
Singular Stress Fields ◽  
The Moment

Abstract We investigate the mechanics of the detachment of an inclined micro-pillar adhered to a dissimilar substrate when subjected to a combination of an axial load and end moment. When the micro-pillar has adhered to the substrate, singular stress fields exist at the bi-material corners. The order of singularity is estimated using asymptotic analysis. The first two terms in the asymptotic expansion lead to singular stress fields. The magnitude of the singularity is evaluated in terms of the elastic mismatch between the pillar and substrate and the micro-pillar inclination. The asymptotic stress due to the moment loading is more sensitive to the micro-pillar inclination when compared to that due to the axial loading. They are insensitive to the micro-pillar inclination when the micro-pillar is rigid when compared to the substrate. A short interfacial crack is further assumed to exist at the bi-material corner. This crack is embedded in the corner singularity region and is loaded by the singular fields due to axial and bending loads. A boundary layer analysis is performed on the singular zone to estimate the stress intensity factor when a short crack embedded in it is subjected to the singular fields. The stress intensity factors are also calculated for a long interfacial crack at the bi-material corner, which extends beyond the singular zone. Using the above results, we investigate the detachment of the inclined micro-pillar under the combination of an axial load and end moment.

The Small Scale Effect on Linear Vibration of Beam-Like Nanostructures

2012 ◽  
Vol 446-449 ◽  
pp. 3432-3435
Author(s):  
Cheng Li ◽  
Lin Quan Yao
Keyword(s):  
Axial Load ◽  
Vibration Mode ◽  
Multiple Scales ◽  
Separation Of Variables ◽  
Classical Mechanics ◽  
Small Scale ◽  
Transverse Displacement ◽  
Linear Vibration ◽  
Small Scale Effect ◽  
Multiple Scales Analysis

Transverse free dynamics of a beam-like nanostructure with axial load is investigated. The effects of a small size at nano-scale unavailable in classical mechanics are presented. Explicit solutions for natural frequency, vibration mode and transverse displacement are obtained by separation of variables and multiple scales analysis. Results by two methods are in close agreement.

Experimental Behavior of Nonconforming RC Columns with Plain Bars under Constant Axial Load and Biaxial Bending

2013 ◽  
Vol 139 (6) ◽  
pp. 897-914 ◽  
Author(s):  
M. Di Ludovico ◽  
G. M. Verderame ◽  
A. Prota ◽  
G. Manfredi ◽  
E. Cosenza
Keyword(s):  
Axial Load ◽  
Biaxial Bending ◽  
Rc Columns ◽  
Experimental Behavior ◽  
Plain Bars ◽  
Constant Axial Load

Seismic Evaluation of Existing Reinforced Concrete Building Columns

1996 ◽  
Vol 12 (4) ◽  
pp. 715-739 ◽  
Author(s):  
Abraham C. Lynn ◽  
Jack P. Moehle ◽  
Stephen A. Mahin ◽  
William T. Holmes
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Lateral Displacement ◽  
Concrete Columns ◽  
Vertical Load ◽  
Seismic Evaluation ◽  
Severe Damage ◽  
Reinforced Concrete Columns ◽  
Concrete Building ◽  
Constant Axial Load

Past earthquakes have emphasized the vulnerability of reinforced concrete columns having details typical of those built before the mid-1970's. These columns are susceptible to axial-flexural, shear, and bond failures, which subsequently may lead to severe damage or collapse of the building. Research was undertaken to investigate the lateral and vertical load-resisting behavior of reinforced concrete columns typical of pre-1970's construction. Eight full-scale specimens were constructed and were loaded with constant axial load and increasing cyclic lateral displacement increments until failure. Test data are presented and compared with behavior estimated by using various evaluation methods.

scholarly journals The Role of Lagrangian Strain in the Dynamic Response of a Flexible Connecting Rod

1999 ◽  
Vol 123 (4) ◽  
pp. 542-548 ◽  
Author(s):  
Jen-San Chen ◽  
Kwin-Lin Chen
Keyword(s):  
Dynamic Response ◽  
Axial Load ◽  
Slenderness Ratio ◽  
Equations Of Motion ◽  
Transverse Displacement ◽  
Linear Strain ◽  
Connecting Rod ◽  
Lagrangian Strain ◽  
Order Of Magnitude

Previous researches on the dynamic response of a flexible connecting rod can be categorized by the ways the axial load in the rod is being formulated. The axial load may be assumed to be (1) dependent only on time and can be obtained by treating the rod as rigid, (2) related to the transverse displacement by integrating the axial equilibrium equation, and (3) proportional to linear strain. This paper examines the validity of these formulations by first deriving the equations of motion assuming the axial load to be proportional to the Lagrangian strain. In order for the dimensionless displacements to be in the order of O(1), different nondimensionalization schemes have to be adopted for low and high crank speeds. The slenderness ratio of the connecting rod arises naturally as a small parameter with which the order of magnitude of each term in the equations of motion, and the implication of these simplified formulations can be examined. It is found that the formulations in previous researches give satisfactory results only when the crank speed is low. On the other hand when the crank speed is comparable to the first bending natural frequency of the connecting rod, these simplified formulations overestimate considerably the dynamic response because terms of significant order of magnitude are removed inadequately.

STRUCTURAL PERFORMANCE OF DAMAGED OPEN-WEB TYPE SRC BEAM-COLUMNS WITH BOLT-CONNECTED BATTEN STEEL PLATES AFTER RETROFITTING

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Takahiro Kume ◽  
Takashi Fujinaga ◽  
Yuping Sun
Keyword(s):  
Axial Load ◽  
Steel Plates ◽  
Analytical Models ◽  
Structural Performance ◽  
Test Results ◽  
Beam Columns ◽  
Cyclic Lateral Load ◽  
Load Carrying ◽  
Lower Load ◽  
Constant Axial Load

In this paper, structural performance of damaged SRC beam-columns with open-web type of batten steel plate after retrofitting was investigated. Three open-web type SRC beam-columns with bolt-connected batten steel plates were fabricated and tested under combined constant axial load and cyclic lateral load. At first, each beam-column was　cyclically loaded to the targeted displacement. After the first loading, the test columns were retrofitted and reloaded till large deformation or failure. The damaged portion of each column was retrofitted with the polymer cement mortar and epoxy resin was injected into the cracks. The measured stiffness of retrofitted columns varied between 71.4% and 85.5% of the initial one. And, test results also indicated that the column which experienced the larger displacement and higher axial load showed lower load carrying capacity, but the others showed approximately the same capacities as the initial columns. Numerical analysis was also conducted to explain the retrofitted columns. Analytical results predicted the experimental behavior fairly well, which verifies the validity of the analytical models in low axial load.

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