PSI - Issue 83

Victor Rizov et al. / Procedia Structural Integrity 83 (2026) 85–94

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is shown in Fig. 4. The graphs in Fig. 4 reveal that the SERR can be reduced significantly by increasing h b / ratio.

b l

b l

b l

20 

40 

60 

Fig. 5. Change of SERR with time at

(graph 1),

(graph 2) and

(graph 3).

The influence of l b / ratio is also analyzed. Figure 5 contains the drawings for three l b / ratios. These drawings clearly indicate how strong the influence of the l b / ratio on the SERR is. Growth of this ratio increases the danger of fracture in the beam since the SERR rises rapidly. 4. Conclusion Longitudinal fracture in a functionally graded beam structure rotating uniformly around a vertical axis moving upwards is analyzed. Solution of the SERR in the moving beam is obtained. Besides for the effect of motion, the solution obtained accounts also for non-linear creep and the change of material properties, as the two basic material parameters in the creep equation and the mass per unit area, along the thickness of the beam. The change of SERR with time resulting from creep behaviour of the moving beam is investigated by applying the solution. It is analyzed also how the change of SERR with time is affected by the angular velocity and the acceleration of the beam at its motion upward. It is observed that increasing the parameters,  and  , of the rotation of the beam and its upward motion results in a growth of the SERR. The influence of  (when the values of  and  are equal) on the change SERR is significantly more pronounced. This finding indicates that longitudinal fracture behavior in the conditions of creep is more sensitive to the beam upward motion in comparison to the uniform rotation of the beam around the vertical axis (this observation can be explained by the fact that the inertia loading induced by the beam upward motion loads the beam in bending while the inertia loading induced by the normal acceleration loads the beam in eccentric tension). The analysis performed by using the SERR solution reveals that the SERR – time curve in the moving beam structure is significantly affected also by h b / and l b / ratios. In particular, it is observed that increasing the ratio h b / shifts the curve downwards, while increasing the ratio l b / results in an upward shift of the curve. The present analysis and the results obtained from it can be useful in the design of moving functionally graded beams based on fracture mechanics with consideration of non-linear creep. References

Bohidar, S.K., Sharma, R., Mishra, P.R., 2014. Functionally graded materials: A critical review. International Journal of Research 1, 289-301.