File Name: nuts and bolts magazine .zip
A topological mechanism is a zero-elastic-energy deformation of a mechanical structure that is robust against smooth changes in system parameters. Here, we map the nonlinear elasticity of a paradigmatic class of topological mechanisms onto a supersymmetric field theory introduced by Witten and Olive.
Bill Eccles of Bolt Science has written several articles that have been published in fastener magazines. On this page links to some of the articles are presented together with a brief summary of the article content. Click on the image next to the summary to load a PDF version of the article. A new approach to the tightness checking of bolts. Published in the Fastener and Fixing magazine in November , this article discusses a new approach to torque auditing of threaded fasteners.
The article discusses the current tightness checking approaches, the on-torque method, the off-torque method and the marked fastener method. Each of these three methods have their deficiencies. The key assumption in each method is that the torque value measured is a true assessment of the tightness of the connection.
The method described in this article is an attempt to improve upon the present tightness checking methods to allow the clamp force being provided by a previously bolted connection to be assessed and, potentially, corrected.
There are limitations to this new approach to fastener tightness checking, principally its accuracy in high friction conditions, but it is a useful indicator as to the retained fastener clamp force in many circumstances.
A case study in torque-angle tightening. Published in the Fastener and Fixing magazine in , this article discusses the torque-angle method of tightening. Because of space restraints, a manufacturer of construction equipment found that it was not possible to achieve the performance requirements for a high performance joint by using torque tightening. The joint shown in figure 1, consists of two steel outer members sandwiching an aluminium beam that are clamped together with a M12 flanged headed nut and bolt.
The article mentions the Bauschinger effect which is one of the reasons why a bolt tightened past its yield point will act elastically when loading is subsequently applied to the joint. For critical applications, the torque-angle method of tightening bolts provides a way of achieving the maximum clamp force in a joint and is often the way forward when torque control proves to be inadequate. Published in the Fastener and Fixing magazine in November , this article presents some fundamental ideas about bolted joints.
Over the last sixty years great improvements have been made by the fastener industry in improving the design and reliability of their products. However, no matter how well designed and made the fastener itself is, it cannot alone make the joint more reliable.
Fastener selection, based upon an understanding of the mechanics of how a threaded fastener sustains loading and the influence that tightening procedures can play, is also needed. This article provides an introduction to the basics of bolted joints and the major factors involved in the design of such joints. It is not widely understood how a bolted joint carries a direct load. A fully tightened bolt can survive in an application that an untightened, or loose bolt, would fail in a matter of seconds.
When a load is applied to a joint containing a tightened bolt it does not sustain the full effect of the load but usually only a small part of it.
This seems, at first sight, to be somewhat contrary to common sense but hopefully this article will explain why this is the case. Published in the Fastener and Fixing magazine in July , this article looks into the causes of self-loosening of threaded fasteners and what steps can be taken to prevent loosening.
A key advantage of threaded fasteners over the majority of other joining methods is that they can be dis-assembled and re-used. This feature is often the reason why threaded fasteners are used in preference to other joining methods and they often play a vital role in maintaining a product's structural integrity. However, they are also a significant source of problems in machinery and other assemblies. The reasons for such problems are due, in part, to them unintentionally self-loosening.
Such self-loosening has been a problem since the start of the industrial revolution and for the last years inventors have been devising ways in which it can be prevented. Many of the common types of locking methods for threaded fasteners were invented over years ago, however it is only relatively recently that the main mechanism that is considered to cause self loosening has become understood.
Published in the Fastener Technology International magazine in August , this article looks into the causes of the failure of M24 engine mounting bolts. An M24 property class 8. Following the introduction of the bus into service and some operational experience, reports started to be received that bolts were occasionally found loose and, on a number of occasions, the bolts were failing.
To prevent what was perceived to be a loosening problem, a split pin was introduced that passed through the bolt thread immediately below the nylon insert nut to prevent the possibility of the nut backing off. This fix proved to be only partially successful and instances were still being reported that the nuts continued to back off, leading to the split pin being completely sheared off in some instances.
Fatigue failures continued to be experienced. This failure illustrates two problems that inadequate preload can manifest itself as. Fatigue failure is a common by product of inadequate preload; joint movement, because the friction grip was inadequate, results in stresses being induced into the bolt that it was never designed to sustain. This same movement, when the fatigue strength of the bolt is able to sustain the induced stresses, will result in the tendency for the fastener to self loosen.
The importance of achieving and maintaining an adequate preload is often the crucial factor in ensuring that the structural integrity of the joint is assured. Published in the Fastener and Fixing magazine in July , this article provides some background to the fatigue failure of bolts. Somehow the metal got weaker, became tired i. For the last two hundred years it has been a known problem and has been the cause of numerous product failures including some involving the loss of life.
Nowadays, following a great deal of research, it is known that fatigue is due to one or more cracks progressing through a material. The crack can start at some existing defect, such as an inclusion in the metal, or at point of high stress, such as a notch, and slowly grow in length at each loading.
It may take millions of loadings and unloadings known as load or stress cycles before the crack is actually detectable. As the length of the crack increases, the material remaining is placed under increasing stress because there is less area to sustain the loading. When the crack actually reaches a critical length it progresses all the way through the material resulting in complete failure.
In the vast majority of applications, the most effective way to ensure that the bolt is fatigue resistant is to ensure that it is tightened sufficiently. The Loosening of Prevailing Torque Nuts. Published in the November issue of Fastener and Fixing magazine, this article looks into the causes of why prevailing torque type nuts can sometimes experience complete self-loosening.
The work is based upon some original work on the subject. Prevailing torque nuts, often referred to as stiff nuts, are one of the commonest methods of providing resistance to self-loosening. Patents for this type of nut began to appear in the 's and many of the principal types can be traced back over years. One advantage of this type of nut is that the locking feature can be checked at the time of assembly by measuring the prevailing torque. The present standard test code ISO specifies performance requirements to ensure that nuts meet a certain minimum standard.
Key requirements are that the first prevailing torque in the tightening direction must not exceed a maximum value and that the first and fifth prevailing torque in the untightening direction must achieve certain minimum values.
There have been a number of cases of prevailing torque nuts becoming detached from bolts leading to a catastrophic failure of the joint. The cause of such detachments has not been understood and one reason for this is that such complete loosening has not been able to be reproduced in a standard Junker test.
The article reports on how a Junker vibration machine was adapeted so that axial loading as well as transverse joint movement could be induced into a joint.
The experiments conducted using the modified Junkers machine have demonstrated that the combination of axial and transverse load have a profound effect on the loosening of prevailing torque nuts.
Published in the Fastener Fair magazine in March , this article provides some background as to the re-use of threaded fasteners.
On the face of it, this seems like a policy designed to increase spare part sales. However just what are the factors influencing whether or not a fastener should be re-used? In the majority of applications, there are three major considerations:.
Has the strength of the fastener been impaired by the first tightening in some way such that it is weaker if it is re-tightened again? Has the fastener been affected by corrosion to a degree that its performance will be impaired or from an aesthetic standpoint requires replacement? Has the torque-tension characteristics of the fastener changed so that its performance would be impaired if it was to be re-tightened?
This article reports upon a study investigating the third point — is the torque-tension relationship affected by repeated tightening. This, in many applications will be the determining factor on whether a fastener should be re-used or not. The stronger the better is not necessarily the case for fasteners. Published in the October-December issue of Fastener and Fixing magazine, this article looks at why having a fastener that is 'too strong' may actually increase overall risk.
In regard to fasteners, when a fastener fails the cost of the actual fastener is usually insignificant relative to the overall cost of the failure. But in regard to fasteners, given the adverse effect that hydrogen can have on high strength fasteners, stronger is often certainly not better.
Hydrogen embrittlement, is to some degree, unpredictable and it is sensible to, whenever possible, specify fasteners that are, to a large degree, inherently less prone to this type of failure. Experience indicates that if property class In some applications, the consequences of joint failure as a result of brittle fracture are such that a campaign change to replace all potentially defective fasteners from a product is deemed essential even when the failure rate is very low.
Usually the extent of the problem is unknown when a decision needs to be taken whether to replace the fasteners. It may be possible to identify a batch of fasteners affected and reduce the extent of the campaign but this can often be problematic. Typically, the cost of the fasteners is usually minimal compared to the other costs involved in such a campaign.
Considering that there are other valid options available, high strength fasteners The use of two nuts to prevent self-loosening. Published in the November issue of Fastener and Fixing magazine, this article looks at the use of two nuts to prevent self-loosening. Many types of old machinery have two nuts on the bolts. A thin nut is frequently used in these applications.
Although it may seem counter-intuitive, the thin nut should go next to the joint and not be put on last. In other applications, for example on column attachments, two standard thickness nuts are frequently used. A series of tests were conducted to investigate the effectiveness of the two-nut method in terms of resistance to self-loosening. A Junker transverse vibration test machine was used with M10 nuts and bolts.
The results are illustrated in figure 6. With the small nut on top, both nuts can be observed to rotate together and can subsequently come completely loose. The results are slightly better than is normally observed with a single plain nut. With the small nut next to the joint, some relaxation occurs but not a significant amount of self-loosening. The performance of the two-nut method, when properly applied, provides a superior locking capability when compared to many so-called lock nuts.
The proper application of the two-nut method is time intensive and requires a degree of skill and is hence unlikely to make a major comeback on new machinery any time soon. Published in , this article looks at the torque control and torque-angle tightening methods. Using torque to indirectly control a bolt's preload is by far the most popular controlled tightening method.
Fasteners Pdf. The term fasteners refers to hardware that can be easily installed and removed with hand or power tools. By natal tambunan. Where safety wiring is specified, do not safety wire any screws until they have passed the torque audit. The SF fastener is designed for joining metal to metal. Most are available in several lengths and grip strengths to accommodate a range of manufacturing processes. The fastener requirements were established twice; once for the original ALSEP fastener and once for the directed modified fastener.
In the normal operation of an offshore wind turbine, bolts can loosen due to long-term operation and exposure to vibration; however, a proposed device could help detect loosened bolts before extensive damage can occur. By Wang Fei and Qu Jun. For the problem of loosened bolts in the long-term operation of an offshore wind turbine, we proposed a device to detect loosened bolts. The device included a vibration sensor, a signal receiver and transmitter, a CCD sensor, a data analyzer, power supply, a communication line, and a power supply line. The combination of a data analyzer and CCD sensor was used to analyze whether the prefabricated symbols on the bolts change, so as to judge whether the bolts are loose.
This photo essays depicts life in Suame Magazine, a mile informal industrial area in Kumasi, Ghana. Over , skilled workers fill the open-air production lines, wooden stalls, and concrete factories. Around a million dollars passes through the hands of the 12, small businesses based at Suame Magazine daily.
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Извините, но для прогулок час слишком поздний. Тут рядом полицейский участок. Я занесу им, а вы, когда увидите мистера Густафсона, скажете ему, где его паспорт.
Сьюзан отгородилась от царившего вокруг хаоса, снова и снова перечитывая послание Танкадо. PRIME DIFFERENCE BETWEEN ELEMENTS RESPONSIBLE FOR HIROSHIMA AND NAGASAKI ГЛАВНАЯ РАЗНИЦА МЕЖДУ ЭЛЕМЕНТАМИ, ОТВЕТСТВЕННЫМИ ЗА ХИРОСИМУ И НАГАСАКИ - Это даже не вопрос! - крикнул Бринкерхофф. - Какой же может быть ответ. - Нам необходимо число, - напомнил Джабба. - Шифр-убийца имеет цифровую структуру.
You can download Nuts And Volts magazine (issues of ) free. Registration not required. Good quality. File format: pdf. Other magazines on electronics.
Беккер попридержал его еще минутку, потом отпустил. Затем, не сводя с него глаз, нагнулся, поднял бутылки и поставил их на стол. - Ну, доволен. Тот потерял дар речи. - Будь здоров, - сказал Беккер.
Все до единого - панки. И все внимательно смотрели на. У всех сегодня красно-бело-синие прически. Беккер потянулся и дернул шнурок вызова водителя. Пора было отсюда вылезать. Дернул. Никакой реакции.
- Чатрукьян уже, надеюсь, ушел. - Не знаю, я его не видела. - Господи Иисусе, - простонал Стратмор. - Ну прямо цирк. - Он провел рукой по подбородку, на котором темнела полуторасуточная щетина.
Беккер обернулся. Двери оказались прямо перед ним, словно приглашая его принять участие в празднестве, до которого ему не было никакого дела. Внезапно он понял, что входит в собор.
К ней как-то не шло сквернословие - как неуместны сточные воды в хрустальном графине. Но, приглядевшись, он убедился, что она вовсе не такая изысканная особа, как ему показалось вначале. Веки припухли, глаза красные, левая рука у локтя - вся в кровоподтеках с синеватым отливом.
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