Modified Goodman diagram

From Figure 13.11, it can be seen that the allowable stress line and the shaft stress line can both be drawn on the modified Goodman diagram. 

A fatigue analysis was made to determine if the tie rods will fail due to fatigue in the unlikely event that the rod vibrates in resonance with the von Karman vortex frequency. The modified Goodman diagram was used in this analysis. This method is described in Reference 6. 

The modified Goodman diagram is shown in Figure 12-4. The values for Su, S, and Sae are given by Reference 6 for AISI 304 stainless steel at 600°F. The maximum alternating stress and mean stress values given above determine the location of point (1) in Figure 12-4. 

One of the key limitations of the S-N curve is its inabUity to predict lifetimes at stress ratios different from those under which the curve was developed. To predict the lifetime of a certain component, a more useful presentation of fatigue life test data is the modified Goodman diagram. 

Fig. 8.22. Modified Goodman diagram showing fatigue stress amplitude required to cause failure in 10 cycles as a function of mean stress for two carbon-fibre reinforced epoxy resin materials (a) unidirectionally reinforced, stressed parallel to fibres, and (b) cross-plied laminate, with 45% of plies parallel to stress, and 55% transverse. Fibre volume fraction 60% (after R. Tetlow).

Figure 11.8 Modified Goodman diagram for fatigue strength of concrete subjected to compression with 2.10 cycles, after Neville (1997).

Therefore, the Goodman line turns into a two line diagram ECB called modified Goodman diagram. Looking at Fig. 5.43 and Eq. (3.53) the new maximum... 

Fig. 5.46 Smith or Modified Goodman diagram for axial and bending fully reversed loads,...

Fig. 5.56 Modified Goodman diagram for a 40NiCrMo7steel shaft, 85 mm diameter, subjected to fully reversed traction, rotating bending an rotating torsion, respectively...

Derive the modified Goodman diagram of a NiCrMo, type 40NiCrMo7, 850 MPa yield strength and 45 % reduction of area RA, under... 

The modified Goodman diagram is, therefore, the one BMFGHLECB shown in Fig. 5.56. Moving to rotating bending. Table 3.3 of Sect. 3.6 provides the load factor Cid = 1.1 since the shaft is not thick, therefore... 

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