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Thank you for interesting in our services. We are a non-profit group that run this website to share documents. We need your help to maintenance this website. Please help us to share our service with your friends. Share Embed Donate. No guarantee can be given with respect to the English translation. Beanspruchungen und Festigkeitsnachweis 5. Preliminary note of the guideline VDI Part 1 — new edition The guideline, which has been used in practice for over 25 years, is widely recognized and often referred to.
It is by now regarded as a standard work for calculating bolted joints not only within but also outside the German-speaking area. The aim of the guideline is to provide the designer and design engineer with a further improved systematic procedure for calculating bolted joints in the form of calculated steps, this procedure enabling him to design the bolted joints in a reliable manner in terms of function and operation while largely utilizing the bolt loading capacity.
Since the appearance of the edition in , a variety of experience has been gained with the use of the guideline and this has manifested itself, among other things, in a number of comments, queries and requests for changes on the part of the users. These and other changes in the standard work and in particular some new knowledge and research results have caused the VDI Committee to fundamentally revise Part 1 of the guideline and to postpone the planned Part 2 multi-bolted joints for the time being.
This revision is not just restricted to updating some sections, but rather a number of fundamental changes to the contents have been made. In addition, the structure of the guideline has been changed, with the aim of improving the clarity. Contents which are not directly required for calculation have either been completely removed e. Die Fertigstellung der nun After intensive discussion and revision of the draft submitted in the new version of the guideline VDI Part 1 appeared in October only in German language.
The available bilingual version does not contain fundamental changes to contents of the German-language version from October All honorary coworkers of this committee are thanked at this point for their engagement and for providing expert knowledge, tables and figures. Diese besteht in der Regel aus einer statischen oder dynamischen Axialkraft d.
Wirkungsrichtung parallel zur Schraubenachse. As a rule, the working load consists of a static or dynamic axial load i. In addition, bending moments and transverse loads may occur. The tabular values are given for the dimension range M 4 to M The guideline may be applied by analogy to bolts made of other materials, in the case of lower strength or strength differing from the strength grades according to DIN EN ISO The same applies to bolts of larger dimensions.
The guideline applies to a limited size of the contact areas at the inner interfaces dimension G, see Section 5. If this limiting value is exceeded, the specified relationships no longer apply, or a larger calculation error occurs.
Extreme Beanspruchungen z. Extreme stresses e. Dies ist insbesondere bei kritischen Verbindungen anzuraten. This is to be recommended, in particular in the case of critical joints. Den Berechnungen liegt die Annahme zu Grunde, dass die Querschnitte eben bleiben.
The calculations are based on the assumption that the cross sections remain flat. Von ausschlaggebender Bedeutung ist der Verspannungs- bzw.
The clamp or deformation solid in the joint region of the components is of decisive importance. This solid is described as a frustum of a hollow cone, which may be followed by a hollow cylinder. The position of the deformation solid determines the eccentricities of the clamping ssym and of the loading a in the plane of bolt axis — line of action of the axial working load and, together with its size and the bolt resilience, the loading of the bolt. The calculation of the alternating stress no longer refers to the cross section Ad3 at the minor diameter of the bolt thread, but to the stress cross section AS.
For opening joints special case , a simplified and proven approximation method has been included. The determination of the external loading still does not form part of the contents of this guideline. It is intended to transmit forces and moments between the joined parts in a clearly defined position relative to one another. The bolts are to be designed in such a way that they withstand the working loads which occur and the function of the joint produced can be fulfilled. Die Kenntnis der Kraftleitung bildet die Voraussetzung.
To calculate bolted joints, the configuration of the joint must be abstracted until it corresponds to a calculable mechanical model. The knowledge of the power transmission is the precondition. With this procedure, it has to be taken into account that, on account of this idealized situation, only an approximation to the actual conditions at the joint is possible. Given appropriate outlay, experimental and numerical methods, compared with the calculation, permit a better representation of the actual conditions .
Der Konstrukteur muss dazu gegebenenfalls eine komplexe, statisch unbestimmte Verbindung in mehrere Einschraubenverbindungen zerlegen. In Figure 3. All joint cases may in principle be calculated by means of the model for the single-bolted joint. To this end, the designer will possibly have to split a complex, statically undefined joint into several single-bolted joints. The quality of the result depends on the accuracy with which the sectional loads are determined with regard to magnitude and distribution.
In more complex calculation methods, this problem does not occur, since the bolt is considered in a larger surrounding area. The calculation of the single-bolted joint is based on the elastic behavior of the joint in the immediate surroundings of the bolt axis. During assembly and in the service case, this region has a considerable effect on the deformation and thus on the loading of the bolt.
In diesem Modell werden die Schraube und die ver- The forces and axial deformations in the singlebolted joint can be described by means of a simple mechanical spring model.
Druckfeder mit den elastischen Nachgiebigkeiten dS und dP betrachtet, Bild 3. Bild 3. During the assembly of the joint, an assembly preload FM is produced, and this produces a clamp load FK at the interface. An axial working load FA introduced via the clamped parts and acting on the bolt is proportionally transmitted via the clamped region of the interface, but also via the bolt.
The proportion of the working load loading the bolt in addition to the preload is designated as additional bolt load FSA, whereas the remaining proportion FPA relieves the clamped parts.
The proportion of this distribution depends on the elastic behavior of the joint partners and on the location of the action of force and thus determines to a considerable extent the loading of the bolt. Abschnitt 3. The forces and displacements which occur in the bolted joint can be illustrated in principle by means of a joint diagram.
Section 3. For the sake of clarity, assembly preload changes are not taken into account here see Section 5. For a more extensive analysis of possible effects on the additional bolt load, the simple spring model is no longer sufficient. In addition to the elastic axial resiliences dS and dP of the bolts and plates, the bending resiliences bS and bP of these parts also have to be taken into account.
Zum Vorzeichen von ssym siehe Abschnitt 3. In this case, in accordance with Figure 3. For the sign of ssym, see Section 3. Klemmkraft in der Trennfuge gefordert. The existing residual clamp load FKR at the interface can be determined according to Figure 3.
MB is taken into consideration only as a special case with regard to opening of the joint Section 5. Verspannungsschaubild einer druckbelasteten Verbindung mit zentrischer Krafteinleitung direkt unter Schraubenkopf und Mutter Setzen nicht beachtet Figure 3. Die Schraube wird beim Vorspannen also nicht gebogen. In this case, the bolt head is not disposed at an angle to the bolt axis during the preloading of the joint.
The bolt is thus not bent during the preloading. The parameter a indicates the distance of the substitional line of action A of the axial working load FA see Section 5. It is to be taken into account here that a is always to be introduced with a positive sign. The corresponding resiliences of the clamped parts for the concentrically z z clamped case are designated by bP and dP Figure 3. For small eccentricities ssym and a, the resulting errors are small.
For larger values, other models for determining the influencing factors have to be found. The equation takes into account the effect of the bending of the bolt. As a rule, this effect is ignored on account of the high bending resilence of the bolt, i.
With the above calculation approach, the bolt is first of all dimensioned while taking into account the clamp load which is required in order to avoid onesided opening of the interface, which is under pressure, as a result of the axial working load FA. Wenn auf die strenge Forderung nach Vermeidung einseitigen Aufklaffens der Trennfugen der verspannten Teile verzichtet werden kann, stellt sich das Kraft-Verformungs-Verhalten wie in Bild 5.
Es wird gleichzeitig eine bessere Ausnutzung der Schwingfestigkeit des Schraubengewindes erzielt. In this case, the working load FA exceeds the opening load FAab at which the one-sided opening of the interfaces as a result of an eccentrically applied axial working load starts. The partial opening of the interfaces can be tolerated within certain limits despite an increased additional bolt load FSA. At the same time, better utilization of the dynamic strength of the bolt thread is achieved.
Thus, for example, a smaller thread diameter or a lower strength grade for the bolt may be provided see Section 5. Bolted joints in general mechanical engineering are normally designed in such a way that transverse loads working loads acting perpendicularly to the bolt axis are transmitted to the interfaces of a preloaded joint by static friction friction-grip joint. The axial additional bolt load FSA can then often be ignored Section 5.
If a change of direction of the external loading leads to transverse shearing, self-loosening of the bolts by rotation can occur if the joints are unsecured. In highly preloaded bolted joints there is generally no risk of self-loosening by rotation.
In the case of bolts with low bending resistance, additional locking may be necessary in order to avoid an inadmissible loss of preload.
Captive locking means merely prevent complete neutralization of the thread pair, i. The amounts of embedding which occur in principle in transversely loaded bolted joints are greater than in joints which are only axially loaded Section 5.
VDI Richtlinie 2230 - 2003
VDI 2230 Blatt 1:2015-11