scholarly journals A Review of Bolt Tightening Force Measurement and Loosening Detection

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3165 ◽  
Author(s):  
Rusong Miao ◽  
Ruili Shen ◽  
Songhan Zhang ◽  
Songling Xue
Keyword(s):  
Force Measurement ◽  
Axial Stress ◽  
High Stress ◽  
Bolted Joints ◽  
Practical Applications ◽  
Tightening Force ◽  
Existing Structures ◽  
Strength Failure ◽  
Joint Connection ◽  
Art Research

Pre-stressed bolted joints are widely used in civil structures and industries. The tightening force of a bolt is crucial to the reliability of the joint connection. Loosening or over-tightening of a bolt may lead to connectors slipping or bolt strength failure, which are both harmful to the main structure. In most practical cases it is extremely difficult, even impossible, to install the bolts to ensure there is a precise tension force during the construction phase. Furthermore, it is inevitable that the bolts will loosen due to long-term usage under high stress. The identification of bolt tension is therefore of great significance for monitoring the health of existing structures. This paper reviews state-of-the-art research on bolt tightening force measurement and loosening detection, including fundamental theories, algorithms, experimental set-ups, and practical applications. In general, methods based on the acoustoelastic principle are capable of calculating the value of bolt axial stress if both the time of incident wave and reflected wave can be clearly recognized. The relevant commercial instrument has been developed and its algorithm will be briefly introduced. Methods based on contact dynamic phenomena such as wave energy attenuation, high-order harmonics, sidebands, and impedance, are able to correlate interface stiffness and the clamping force of bolted joints with respective dynamic indicators. Therefore, they are able to detect or quantify bolt tightness. The related technologies will be reviewed in detail. Potential challenges and research trends will also be discussed.

scholarly journals Tension Strength Prediction of Transverse Branch Plate-to-Rectangular Joint with Concrete Filling

2020 ◽  
Vol 14 (54) ◽  
pp. 136-152
Author(s):  
Zhihua Xiong ◽  
Yongjian Liu ◽  
Bin Liu ◽  
Lei Jiang
Keyword(s):  
Ultimate Strength ◽  
Stress Reduction ◽  
Axial Stress ◽  
Reduction Factor ◽  
Displacement Curve ◽  
Strength Failure ◽  
Tensile Performance ◽  
Joint Connection ◽  
Concrete Filling ◽  
Tension Strength

This paper predicts the tension strength of Concrete-filled Branch Plate-to-Rectangular Hollow (CBPRH) joint by conducting experimental and theoretical analysis. A total of 46 X-joints with different geometric parameters were investigated, in which 4 specimens were tested under ultimate tension and 42 specimens were numerically analyzed. The joint’s strength, failure mode and load-displacement curve were obtained. Perfobond Leister Rib (PBR) was welded in part of the specimens to investigate its effect on joint’s tensile performance. It is shown that the ultimate strength of transverse CBPRH joint benefit from grouting of chord and installation of PBR. The ultimate strength of CBPRH joint with PBR is larger than the counterpart without PBR. Tension strength equations were proposed for both CBPRH joints with and without PBR by nonlinear regression. The chord axial stress reduction factor was discussed and a modified equation originated from hollow joint was recommended for CBPRH joint. Connection efficiency was presented and compared among branch plate-to-rectangular hollow (BPRH) joint, CBPRH joint and CBPRH joint with PBR.

Experimental Analysis on Bond Behavior of GFRCM Applied on Clay Brick Masonry

2017 ◽  
Vol 747 ◽  
pp. 542-549
Author(s):  
Marianovella Leone ◽  
Valeria Rizzo ◽  
Francesco Micelli ◽  
Maria Antonietta Aiello
Keyword(s):  
Mechanical Performance ◽  
Tensile Tests ◽  
Brick Masonry ◽  
Test Results ◽  
Clay Brick ◽  
Hydraulic Lime ◽  
Bond Behavior ◽  
Existing Structures ◽  
Strength Failure ◽  
Hydraulic Lime Mortar

External bonded reinforcements (EBR), made by fibrous meshes embedded in a cementitious/hydraulic lime mortar, are getting a great deal of attention, mostly for strengthening, retrofitting and repair existing structures. In this context, the interest versus the FRCM (Fiber Reinforced Cementitious Matrix) is growing. The mechanical performance of these mortar-based reinforcements is not well known at the date and it needs to be investigated in terms of bond and tensile strength, strain and stiffness, in relation to the type of both substrate and fibers. The present work reports the results of an experimental study, still in progress, on different pre-cured GFRP grids embedded in inorganic matrices and applied on clay brick masonry. First, the mechanical properties of both pre-cured GFRP grid and GFRCM reinforcements were obtained through tensile tests. Then, the experimental investigation on bond behavior was carried out by direct shear bond test. The test results were collected and processed to evaluate bond strength, failure mode, load-slip relationship.

A machine learning approach for the automatic long-term structural health monitoring

2018 ◽  
Vol 18 (3) ◽  
pp. 819-837 ◽  
Author(s):  
Giacomo Vincenzo Demarie ◽  
Donato Sabia
Keyword(s):  
Machine Learning ◽  
Data Acquisition ◽  
Structural Behavior ◽  
Practical Applications ◽  
Existing Structures ◽  
Machine Learning Approach ◽  
Modes Of Vibration ◽  
Engineering Parameters ◽  
Over Time

Measuring the response of a structure to the ambient and service loads is a source of information that can be used to estimate some important engineering parameters or, to a certain extent, to characterize the structural behavior as a whole. By repeating the data acquisition over a period of time, it is possible to check for variations in the structure’s response, which may be correlated to the appearance or growth of a damage (e.g. following some exceptional event as the earthquake, or as a consequence of materials and components aging). The complexity of some existing structures and their environment very often requires the execution of a monitoring plan in order to support analyses and decisions through the evidence of measured data. If the monitoring is implemented through a sensor network continuously acquiring over time, then the evolution of the structural behavior may be tracked continuously as well. Such approach has become a viable option for practical applications since the last decade, as a consequence of the progress in the data acquisition and storage systems. However, proper methods and algorithms are needed for managing the large amount of data and the extraction of valuable knowledge from it. This article presents a methodology aimed at making automatic the process of structural monitoring in case it is carried continuously over time. It relies on some existing methods from the machine learning and data mining fields, which are casted into a process targeted to delimit the need of the human being intervention to the training phase and the engineering judgment of the results. The methodology has been successfully applied to the real-world case of an ancient masonry bell tower, the Ghirlandina Tower (Modena, Italy), where a network made of 12 accelerometers and 3 thermocouples has been acquiring continuously since August 2012. The structural characterization is performed by identifying the first modes of vibration, whose evolution over time has been tracked.

The Design Tradeoffs of Linear Functionally Graded Piezoceramic Actuators

Aerospace ◽  
2003 ◽  
Author(s):  
Paul W. Alexander ◽  
Diann Brei
Keyword(s):  
Material Properties ◽  
High Stress ◽  
Functionally Graded ◽  
Homogeneous Material ◽  
Stress Concentrations ◽  
Practical Applications ◽  
Complex Electric Field ◽  
Design Tradeoffs ◽  
A Minor ◽  
The Cost

It is common practice to reduce the voltage level within piezoelectric actuators by utilizing multiple layers, typically bonded together. Unfortunately, this has a tendency to result in device failure due to delamination. For example, with benders the typical lifetime is 105 to 106 cycles, limiting its use in practical applications. This poses an interesting design tradeoff: the stroke is increased due to sharper gradients between material layers; however, the higher gradients lead to high stress concentrations at those interfaces. One approach to reducing these stresses is to grade the material properties through a monolithic piece of piezoceramic so that no interfaces or bonding elements exist, but this comes at the cost of stroke. This paper explores the design tradeoff inherent to monolithic functionally graded piezoelectrics. An analytical free-displacement model for a monolithic piezoceramic beam with a generic gradient is derived. Key to this is the inclusion of the complex electric field distribution which rises from the non-homogeneous material properties. This model is used along with finite element models to examine the effect of continuous linear and stepwise material gradients on the displacement performance as well as the stress levels. The study shows that using monolithic functionally graded piezocermics can significantly reduce the stresses with only a minor impact on the device stroke.

Evaluation of Bolt Strength Characteristics in Bolted Joints Using an Optical Fiber Sensor System

2019 ◽  
Author(s):  
Atsushi Shirakawa ◽  
Toshiyuki Sawa
Keyword(s):  
Optical Fiber ◽  
Strain Distribution ◽  
Force Measurement ◽  
Optical Fiber Sensor ◽  
Effective Cross Section ◽  
Tensile Load ◽  
Bolted Joints ◽  
Strength Characteristics ◽  
Sensor System ◽  
Fiber Sensor

Abstract Bolted joints are used in many industrial products such as mechanical structures, automobiles, airplanes, chemical plants, and so on. In many cases, after the design of new products is finished, various tests on the bolt and bolted joints are carried out using actual parts to prevent accidents due to bolt loosening and fracture. At the same time, in the strength tests, external force measurement, axial bolt force measurement and so on are included. However, there are no advanced tests in which axial bolt strain distribution or bolt elongation in actual parts and so on are measured. Therefore, in this research, a new method for evaluating bolt strength characteristics using an optical fiber sensor system capable of measuring actual parts is demonstrated. First, a tensile strength test using an optical fiber sensor is carried out to measure strain distribution in a bolt, and a maximum strain value position in the measured clamp load-strain curve is shown. Then, the elongation at each part of the bolt is shown. Next, yield clamp bolt force is found using this sensor system in torque/clamp force testing. In addition, the measured yield clamp bolt force is compared with the values in the conventional measurement method and in the estimation formula. Also, discussed is the effective cross section area by which the stress at the engaged threads is calculated under tensile load. Finally, another case where an optical fiber sensor system is used for bolt fastening evaluation is discussed.

Wire Stress Calculations in Helical Strands Undergoing Bending

1992 ◽  
Vol 114 (3) ◽  
pp. 212-219 ◽  
Author(s):  
M. Raoof ◽  
Y. P. Huang
Keyword(s):  
Theoretical Model ◽  
Axial Stress ◽  
Operating Conditions ◽  
Radius Of Curvature ◽  
Axial Component ◽  
Practical Applications ◽  
Bending Stresses ◽  
Parametric Studies ◽  
Steel Cables ◽  
The Individual

Steel cables play an important role in many offshore applications. In many cases, an understanding of the magnitude and pattern of bending stresses in the individual component wires of a bent strand is essential for minimizing the risk of their failure under operating conditions. Following previously reported experimental observations, a theoretical model is proposed for obtaining the magnitude of wire bending stresses in a multi-layered and axially preloaded spiral strand fixed at one end and subsequently bent to a constant radius of curvature. The individual wire bending stresses are shown to be composed of two components. The first component is the axial stress generated in the wires due to interwire/interlayer shear interactions between the wires in a bent cable, and the second component is associated with the wires bending about their own axes. Using the theoretical model, which includes the effects of interwire friction, parametric studies on a number of realistic helical strands with widely different cable (and wire) diameters and lay angles subjected to a range of practical mean axial loads, and subsequently bent to a range of radii of curvature with one end of the cable fixed against rotation, have been carried out. It is shown that for most practical applications, the axial component of wire stresses due to friction is much greater than the second component of bending stresses associated with the individual wires bending about their own axes.

scholarly journals Investigation on Surrounding Rock Stability Control Technology of High Stress Roadway in Steeply Dipping Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Honglin Liu ◽  
Chen Xu ◽  
Hongzhi Wang ◽  
Guodong Li ◽  
Sanyang Fan
Keyword(s):  
Distinct Element ◽  
High Stress ◽  
Horizontal Stress ◽  
Stability Control ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Practical Applications ◽  
Rock Stability ◽  
Distinct Element Code ◽  
Dip Angle

There are a large amount of steeply dipping coal seams deposited in China, the safe and effective extraction of which are the challenge for coal operators due to the complicated geological characteristics, in particular, when the underground roadway is excavated in the steeply dipping coal seams with limited seam distance. The Universal Distinct Element Code (UDEC) was adopted in the present research to explore the stress distribution of surrounding rock of the roadway. Based on the numerical simulation, the damage coefficient was proposed and then used to classify the roof conditions into four groups. After that, the asymmetric support technique was proposed and put into practical applications. It is indicated that the stress concentration on the floor is the main feature of the extraction of steeply dipping coal seams. Moreover, the distributions of the maximum vertical stress and horizontal stress which are much different from each other mainly attributed to the effect of the large dip angle. This research also verified the feasibility of using the asymmetric and partition support technique to maintain the integrity of the surrounding rock, as from the case study conducted at the 12032 longwall coal face of Zhongwei coal mine.

scholarly journals Failure Analysis of Woven Glass- Epoxy Prepreg Bolted Joints under Different Clamping Moments

2008 ◽  
Vol 17 (5) ◽  
pp. 096369350801700 ◽  
Author(s):  
Ümran Esendemi̇r
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Failure Analysis ◽  
Failure Modes ◽  
Bolted Joints ◽  
Geometrical Parameters ◽  
Bearing Strength ◽  
Strength Failure ◽  
Specimen Width ◽  
Standard Tests

In this study, an experimental investigation was carried out, in order to study pin- bearing strength, failure modes under various clamping moments depending on the geometrical parameters. Two different geometrical parameters were investigated. For that reason, the ratio of the distance from the pin centre to the top edge top in diameter (E/D), and the ratio of the specimen width to the pin diameter (W/D) were suitably varied, in order to verify their influence on the failure modes consisting of net-tension, cleavage and bearing. Totally, 160 specimens were tested. The mechanical properties of prepreg composite were obtained from standard tests. Experimental results showed that failure modes and bearing strengths were strictly influenced from increasing value of applied clamping moments and geometrical parameters.

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