19 Rough Estimation of Bolted Joints According to VDI 2230 Sheet 1 (2003-02)

A bolted joint is a typical connection of two or more parts that are held together by a bolts. The main function of the bolts is to transmit the forces and moments between the connected parts. The minimum bolt diameter can be roughly determined according to the VDI 2230 guideline. The guideline VDI 2230 is one of the common methods of design used for bolted joints. VDI 2230 applies to steel bolts in high-duty and high-strength bolted joints (for strength grades 8.8 to 12.9) and a frictional transmission of the working load. The working load consists of a static or dynamic axial load. In addition, bending moments and transverse loads may occur.

Figure 19.1:

Estimation of bolted joints

With entering the maximum axial load and/or transverse load, the mimimum and maximum preload as well as minimum bolt diameter can be estimated. For the estimation of the transverse load, the friction value is taken into consideration at the interface.

19.1 Axial Load

Die Axialkraft $FA$ ist eine in Schraubenachse gerichtete und anteilig auf eine Schraube wirkende Betriebskraft.

Figure 19.2:

Axial load

19.2 Transverse Load

Figure 19.3:

Transverse load

Bolted joints are designed that the transverse loads are transmitted to the interface of a preload joint by static friction. It is also possible that the connecting elements (fit bolts, pins, sleeves) transmit transverse loads in a positive manner. Please click the ‘Question mark’ button next to the friction coefficient in order to open the following table. this table shows approximate values for the static friction coefficients at the interface:


Approximate Values for Static Friction Coefficients at the Interface According to VDI 2230¹

Material Combination	Static Friction Coefficient in the State

	Dry	Lubricated

Steel - Steel/Cast Steel	0,1 bis 0,23	0,07 bis 0,12

Steel - Gray Cast Iron	0,12 to 0,24	0,06 to 0,1

Gray Cast Iron - Gray Cast Iron	0,15 to 0,3	0,2

Bronze - Steel	0,12 to 0,28	0,18

Gray Cast Iron - Bronze	0,28	0,15 to 0,2

Steel - Copper Alloy	0,07	-

Steel - Aluminum Alloy	0,1 to 0,28	0,05 to 0,18

Aluminum - Aluminum	0,21	-

¹ Table from: VDI 2230, Sheet 1, February 2003: Systematic Calculation of High-Duty Bolted Joints, Joints with One Cylindrical Bolt, Table A6, Approximate Values for Static Friction Coefficients, p. 114

19.3 Strength Grade

The calculation module takes three strength grades into consideration: 8.8, 10.9 and 12.9. The strength grades describe the properties of a bolt (e.g., hardness, tensile strength $Rm$ and yield point $Re$ ). The most common grade for bolted joints is grade 8.8. The strength grades 10.9 and 12.9 are used in particular for preloaded bolted joints.

Figure 19.4:

Strength grade

19.4 Load Introduction

Figure 19.5:

Load introduction

Clicking the ‘Question mark’ button next to the listbox opens a new window showing an illustration of the load introduction.

Figure 19.6:

‘Question mark’ button

Static or Dynamic Transverse Load

Figure 19.7:

Static or dynamic transverse load

Static and Concentric Axial Load

Figure 19.8:

Static and concentric axial force

Dynamic and Concentric Axial Load

Figure 19.9:

Dynamic and concentric axial load

Static and Eccentric Axial Load

Figure 19.10:

Static and eccentric axial load

Dynamic and Eccentric Axial Load

Figure 19.11:

Dynamic and eccentric axial load

19.5 Tightening Technique

The tightening technique may influence the required dimensions of the bolt and must be carefully considered. Select the following tightening techniques from the listbox:

Figure 19.12:

Tightening technique

19.6 Preload

During the assembly of the joint, a preload $FM$ is produced and this produces a clamp load $FK$ . $FMmin$ is the required minimum assembly preload which can occur at $FMmax$ resulting from inaccuracies in the tightening technique and maximum friction. $FMmax$ is the maximum preload for which a bolt must be designed so that, in spite of inaccuracies in the tightening technique, the required clamp load in the joint is produced and maintained.

19.7 Further Possibilities

Clicking the link ‘More calculation modules’ leads you to our web site. Here you can register for a free test account in order to use all eAssistant calculation modules (e.g., shafts, cylindrical gears, bevel gears, springs). Find more information in section 2 ‘Registration’).

Figure 19.13:

Link to our web site

Please Note: If you registrate for the first time, you will receive a password in order to login. The project manager helps you to start the calculation modules. The list window ‘Calculation type’ shows all calculation modules including the free modules. If you use these modules, then no time will be deducted from your account (see section 3.6 ‘Time account’ for more information).

Our manual is improved continually. Of course we are always interested in your opinion, so we would like to know what you think. We appreciate your feedback and we are looking for ideas, suggestions or criticism. If you have anything to say or if you have any questions, please let us know via telephone +49 (0) 531 129 399-0 or email eAssistant@gwj.de.

Chapter 19Rough Estimation of Bolted Joints According to VDI 2230 Sheet 1 (2003-02)