KISSsoft Tutorial: Bolt selection and rating according to VDI guideline Starting KISSsoft

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1 KISSsoft Tutorial 004: Bolt selection and rating according to VDI guideline 2230 KISSsoft Tutorial: Bolt selection and rating according to VDI guideline 2230 For release 04/2006 Last modification :45 Starting KISSsoft Starting KISSsoft After having installed and released KISSsoft as test or commercial version (see installation instructions), start KISSsoft through Start/Programs/KISSsoft-Hirnware /KISSsoft- Hirnware. The following window will appear: Figure 0-1 Starting KISSsoft, start window of KISSsoft Select Calculation Using the menu Calculation, select the bolt analysis Figure 0-1 Selecting the bolt analysis. 1 / Mai 2006

2 Task description Calculation of a flanged connection Sizing and rating of the bolting for a flanged coupling with data as shown: Torque to be transmitted 13kNm Pitch diameter 258mm Number of bolts on pitch circle 12 Material flange (left/right) GG25/34CrNiMo6 Thickness flange(left/right) 22mm/18mm Surface flange (left/right) N7/N8 Coefficient of friction 0.15 Minimal axial force 0kN Maximum axial force 10kN Strength class of bolt 10.9 Hexagon head screw with shank (AB) ISO4014 Tightening: with dynamometric key This basic data is entered as follows: Figure 0-1 Input of known data. Choose VDI2230, 2003, as method / flange connection as configuration The strength class and type of the bolt is defined in Details of bolt : Figure 0-2 Choosing strength class and type of bolt In a first step, a suitable bolt diameter is to be choosen. Proposal for a sensible bolt diameter After having defined the loads acting and the type/strength of the bolt, the sizing button can be used in order to have the software proposing a suitable bolt diameter. This proposal is based on a simplified method as described in VDI guideline 2230, table 7. This methods tends to result in over-dimensioned bolts, experience shows that the minimal permissible bolt diameter is one to two sizes lower. Note the message issued once the sizing button is pressed. 2 / 8

3 Figure 0-1 Using the sizing button will result in a proposal for the bolt diameter (based on VDI2230), here, M20. Figure 0-2 Message indicating that the resulting bolt diameter may be to large. The nominal bolt diameter can be changed manually, here to 16mm. Figure 0-3 Nominal bolt diameter set to 16mm. Definition of clamped parts In the main window, Details of clamped parts is pressed to get a window where all clamped parts (all parts of the connection except for the bolt itself) can be defined. Since a circular flange is calculated, the software recommends by issuing a respective message to define the clamped parts as segments of a ring. 3 / 8

4 The clamped flanges are defined using Definition of parts..., see Figure 0-3 Application of force is according to figure SV3 (Use? button for figures). Both halves of the flange have through holes and the bolt is tightened using a nut Details of the through holes can be defined (see Figure 0-2, top left) Washers are used (acitvate respective flags), (see Figure 0-2, top right) Details on nut (see Figure 0-2, bottom right) Figure 0-1 Definitionen of the clamped parts. The flange is defined using ring segments. The geometry can further be defined using Detail (see Figure 0-2, bottom left) Detailing the through hole. A hole diameter may be defined using Own definition in Standard. Input diameter in field Bore diameter Defining the washer (once for the washer underneath the nut, once for underneath the bolt head). Choose from standard or define own geometry. Information on outer and inner diameter of flange, pitch diameter and bolt pitch (calculate useing sizing button) Choose nut from standard or define own geometry Figure 0-2 Detailled input on nut, washer and flange geometry Now, the two flanges have to be defined using Definition of parts (button in top right corner of window shown in Figure 0-1): 4 / 8

5 Definition of left flange, acitvate second second using the >> button Figure 0-3 Definition of the two flanges. Definition of the right flange, terminate input with Ok. A maximum of eight layers may be defined. Once the input is terminated/accepted, the following message that the clamping length is adjusted will show (see Figure 0-5): Figure 0-4 Message indicating that clamping length is adapted. Figure 0-5 Modified clamping length once the clamped parts have been defined. With this, the definition of the clamped parts is completed and the window Details of clamped parts can be closed using Ok to accept all data. Definition of the bolt Using the button Details of bolt in the main window, a window to further define the bolt itself opens up (ignore a possible error message that Thread length has to be > 0. ). The only input for the bolt missing is its length. The length can be calculated using the sizing button (then, the smallest possible length is calculated, using nominal bolt lengths) or can be defined manually. The definition of the connection is now completed and may be viewed using Display screw : 5 / 8

6 Figure 0-1 Calculation or definition of bolt length. Figure 0-2 Connection with flange, bolt, washers and nut Final input The assumed coefficients of friction between thread and thread hole and between the head of the bolt and the clamped part or washer have a great effect on the analysis. These valus have to be defined in the window Coef. of frcition. The VDI guideline 2230 recommends values to be used depending on the lubrication applied. These recommendations may be viewed using the? buttons. Figure 0-1 Coefficients of friction, review recommended values using? buttons. Furthermore, the tightening method is to be chosen. The tightening factor is then calculated accordingly: Figure 0-2 Selection of tightening method, resulting tightening factor. Calculation and results Execution of analysis, reports The analysis is executed using Calculate F5. The most important results are shown in the lower portion of the main window. The report including all details is generated using Write 6 / 8

7 Report F6. The force-deformation diagram can be viewed using the button Force- Deformation Diagram : Figure 0-1 Execution of analysis, generate report, main results and force-deformation diagram Figure 0-2 Force-deformation diagram Comments on the results generated Results shown in the main window: Vorspannkraft (N), alphaa=1, The required mounting pre-tension such that the connection will withstand the alphaa eff loads. A minimal value (tightening factor=1) and a maximum value (tightening Anzugsdrehmoment (Nm), alphaa=1, alphaa eff Sicherheit Schraube Sicherheit Pressung Sicherheit Wechsellast Results shown in the report Vorspannkraft nach Tabelle, (N), [FMtab] factor=1.6 in this example) are shown. Information on the achieved tightening torque. A minimal value (tightening factor=1) and a maximum value (tightening factor=1.6 in this example) are shown. Besides the required pre-tension (see table above), in the report, the nominal pre-tension according to VDI2230 is shown. This value is higher than the maximum value of the required mounting pre-tension. Further calculations Analysis with a smaller bolt To complete the example, a test is run to check whether M16 is the smallest possible bolt diameter. For this, the bolt diameter is reduced to M14 and the analysis is executed again. The error message indicates that the connection can not be used with an M14 bolt. 7 / 8

8 Figure 0-1 New bolt diameter M14, execution of analysis, error message indicating that permissible pretension force is exceeded. Constraints, settings In Constraints of calculation and Settings/Module-Specific, constraints may be defined. The application of these settings requires detailled knowledge of the VDI guide-line Figure 0-1 Constraints of calculation Figure 0-2 Module-specific settings 8 / 8