2 edition of method of measuring the tension in bolts. found in the catalog.
method of measuring the tension in bolts.
D. S. Moss
|Series||Reports / Road Research Laboratory -- LR100|
|Contributions||Road Research Laboratory.|
Tension is the application of force that causes stretching whereas torque causes twisting and tightening of the bolt and is an indirect indication of tension. In other words, tension is the stretch or elongation of a bolt that provides the clamping force of a joint where torque is a measure of the twisting force required to spin the nut up. The preload target can be achieved by a variety of methods: applying a measured torque to the bolt, measuring bolt extension, heating to expand the bolt then turning the nut down, torquing the bolt to the yield point, testing ultrasonically, or by applying a certain number of degrees of relative rotation of the threaded components. Each method has a range of uncertainties associated .
Page 2 of 5 ao Nah HS () Develop a Method to Estimate the Tension of Torque-Shear High Strength Bolts. Steel Struct Constr 3: doi: / J Steel Struct Constr, an open access journal Volume 3 Issue 2 ISSN: to measure tension and gather accumulated electric energy data. A method and apparatus for determining the residual force or tension in a bolt or stud is presented. The bolt or stud in a previously tightened joint is stressed by the imposition of a pulling force, the resulting strain on the bolt is measured to develop a force-strain relationship, and the measured force-strain relationship is compared to previously determined force-strain .
Provisions in the RCSC Specification Section include four methods for the pre-tensioning of high-strength bolts. The use of these procedures is governed by the provisions listed below: turn-of-nut pre-tensioning, calibrated wrench pre-tensioning, twist-off-type tension-control bolt pre-tensioning, and direct tension indicator pre-tensioning. When torque is the only method of measurement, a change in one element, such as thread lubricant, will modify the nut factor and therefore the clamp force developed on a bolted joint. This is because torque is not directly measuring bolt tension. It is a twisting force that results in rotation. The nut factor is the summary of all factors that.
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The bolt/nut by a small angle (typically 2 to 10 degrees) in the tightening direction. This is the most frequently used method of torque auditing. Off-torque method: Measuring the torque needed to rotate the bolt/nut in the untightening direction (which will normally be less than the tightening torque).
Size: 1MB. In this thesis, a novel methodology for estimating the tension in bolts using surface acoustic waves (SAWs) is investigated.
The tension is estimated using the reflection by of SAWs created by the bolt head interference. Increments in the bolt tension raise the points of interaction between the waves the bolt head (real area of contact),and andAuthor: Martinez Garcia, A Jairo. Bolts are normally tightened by applying torque to the head or nut, which causes bolt to stretch.
The stretching results in bolt tension, known as preload, which is the force that holds a joint together. Torque meter can be used to measure bolt tension. High preload tension helps to keep bolts tight,File Size: 1MB. almost always the Skidmore-Wilhelm Bolt Tension Indicator (pictured at left).
This device measures the tension in the bolt by measuring the hydraulic pressure in a cell that is squeezed when the nut is tightened. It can be used to verify the tension induced in a bolt by any tightening method, and is required for ALL high-strength bolt applications.
capable of determining stress after the bolt is in place and it requires no independent information about the present or unstressed length of bolt. Moreover, using this method, one can determine bolt stress with access to only one end of the bolt.
Our approach to determining stress requires two ultrasonicCited by: 3. By licensing NASA technology, Micro Control integrated the ultrasonic measurement aspect into its standard product, which enabled it to measure bolt tension directly using standard fasteners, and acquired the knowledge to measure torque/tension and angle rotation simultaneously.
For Bolts Too Short to Fit into the Bolt Tension Measurement Device (BTMD) Pretensioning. Inspection. Calibrated Wrench Method. Pre-Installation Verification - Installation Wrench Calibration Procedure.
78 Using Bolt Tension Measurement Device (BTMD) 78 For Bolts Too Short to Fit into the Bolt Tension Measurement Device File Size: KB. Actually, there are five methods of checking the tightness of connection bolts. There is “Direct Tension Indicator” or DTI. The direct tension indicator is usually written in the specification and one of the requirements to check the bolt for tightness.
There is that called “Turn-of-Nut” method which is also easy to use but hugely tedious. BOLT STRETCH – Bolt stretch is the most accurate method. Regardless of the other factors, and no matter how much actual torque it takes to stretch the fastener to the correct length, it’s not properly torqued until it’s properly stretched.
In this chapter, the different types of bolts and bolted connections used in steel structures are introduced. The scope of the present chapter is limited to bolted connections used in tension and compression members as well as in hangers.
Bolted connections, which resist moments and connections between structural members, will be covered in the File Size: KB. > Ultrasonic Bolt Measurement Ultrasonic Bolt Measurement In certain critical bolting applications, factors such as friction or bolt/joint geometry are such that the measurement of applied torque alone will not provide the degree of accuracy necessary to control the preload to be monitored over the service life of the fastener.
Marked as BOLT#2. The bolt pattern is continued as Bolt#1,Bolt#2 and 1,2. Around the flange. The number of tools is half the number of bolts. () === The studs are Numbered nuts for identification and control as per the steps listed below.
Tension pattern is noted as one tensioner (Set #1) is to be applied on every-other-stud (50%). () ===File Size: 38KB. A tension joint, as illustrated in the photo, is affected by loads that try to pull the joint apart. The forces on the joint and those on the bolts are roughly parallel to the axes of the bolts.
All tensile forces try to stretch and/or separate the joint. The tension load, no matter how small, will add to the stress in the bolt. Ultrasonic measurement devices ± 10% 4.
Bolt elongation measurement ± 5% 5. Instrumented bolts ± 5% Torque is relatively easy to measure with a torque wrench, so it is the most frequently used indicator of bolt tension.
Unfortunately, a torque wrench does not measure bolt tension accurately, mainly because it does not take friction into account. This video describes the method for measuring torque and tension of nuts and bolts for determination of friction.
There are three basic methods for the checking of torques applied to bolts after their installation; namely, taking the reading on a torque gauge when: 1. The socket begins to move away from the tightened position in the tightening direction. This method is frequently referred to as the "crack-on" method.
proper belt tensioning why it matters and how it affects belt life Tension loss occurs on all manufacturer’s belts. The highest quality belts still lose nearly 50% of installed tension, while lower quality belts lose over 70% of installed tension. You cannot “feel” the correct tension on a V-Belt.
On a test givenFile Size: KB. The charts below are listed for convenience and can be used to estimate the torque ranges for our structural bolts. Measuring the Torque-Tension Relationship.
The following is the basic equation to estimate the torque-tension relationship: T = K x P x D. Where: T = torque in foot-pounds K = coefficient of friction P = bolt tension in foot-pounds.
About the book "Measuring Torque Correctly" Rainer Schicker and Dr. Georg Wegener have written a page ebook which provides an overview of all the essential aspects of using torque describes the principle options for torque measurement and deals with the design and application of the torque transducers most commonly used today, those working on the.
TexA, Rotational Capacity Testing of Fasteners Using a Tension Measuring Device Section 1 — Overview Texas Department of Transportation 2 TxDOT 08/ Section 1 Overview This method covers the procedure for performing rotational capacity testing of fasteners with ASTM A and A The values shown in the tables of 'Part I, Rotational.
“Torque” is simply a measurement of the twisting force required to spin the nut up along the threads of a bolt, whereas “Tension” is the stretch or elongation of a bolt that provides the clamping force of a joint. Torque is a very indirect indication of tension, as many factors can affect this relationship, such as surface texture, rust.
The estimation of clamping force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect.
The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that Cited by: measurement method Tightening is controlled by the elongation of the bolt, generated by bolt tightening. Elongation is measured by a micrometer, ultrasonic, or an embedded gauge sensor in a bolt.
The dispersion of the bolt is very small. Tightening within the elastic zone is available. The efficiency of the bolted joint is large.