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Background <p>Rotating shell structures are widely used in aerospace, energy, and mechanical systems, where vibration control is crucial for performance and safety. However, the dynamic behavior of rotating complex shells made of functionally graded porous materials (FGPMs) with variable thickness remains insufficiently explored due to modeling challenges and the coupling of centrifugal and Coriolis effects.</p> Purpose <p>This study aims to analyze the backward-forward vibration characteristics of a rotating cylindrical–hemispherical shell composed of FGPMs with variable thickness, considering different boundary conditions. The objective is to clarify the influence of porosity, rotational speed, and geometric parameters on the system’s natural frequencies.</p> Methods <p>A three-dimensional elasticity formulation combined with the Ritz method is&#xa0;employed, using Legendre polynomials as admissible functions. The cylindrical and hemispherical sections are modeled as a single continuous structure to enhance geometric accuracy and eliminate discontinuities at the junction. The model’s validity&#xa0;is confirmed through convergence studies and comparison with existing analytical and numerical results.</p> Results <p>The findings show that increasing material porosity decreases the natural frequencies due to stiffness reduction, while higher axial mode numbers yield greater frequencies. Clamped–clamped boundary conditions provide the highest stiffness and frequency. The analysis reveals non-classical dynamic behavior in the rotating shell: the forward frequency decreases at low rotation speeds because of centrifugal softening, whereas the backward frequency increases monotonically with rotation speed due to Coriolis stiffening.</p> Conclusions <p>The integrated modeling approach significantly improves the prediction of dynamic characteristics in complex rotating FGPM shells. The results highlight that porosity, variable thickness, and rotation speed strongly influence vibration behavior,&#xa0;providing valuable insights for designing lightweight and high-performance rotating structures such as turbines, centrifuges, and aerospace rotors.</p>

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Backward-forward Vibration Analysis of Rotating FGP Complex Shells with Variable Thickness

  • 期刊论文

  • 发表日期：

    2025年11月17日

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  • Farzaneh Jafari Maryaki,
  • Alireza Shaterzadeh

摘要

Background

Rotating shell structures are widely used in aerospace, energy, and mechanical systems, where vibration control is crucial for performance and safety. However, the dynamic behavior of rotating complex shells made of functionally graded porous materials (FGPMs) with variable thickness remains insufficiently explored due to modeling challenges and the coupling of centrifugal and Coriolis effects.

Purpose

This study aims to analyze the backward-forward vibration characteristics of a rotating cylindrical–hemispherical shell composed of FGPMs with variable thickness, considering different boundary conditions. The objective is to clarify the influence of porosity, rotational speed, and geometric parameters on the system’s natural frequencies.

Methods

A three-dimensional elasticity formulation combined with the Ritz method is employed, using Legendre polynomials as admissible functions. The cylindrical and hemispherical sections are modeled as a single continuous structure to enhance geometric accuracy and eliminate discontinuities at the junction. The model’s validity is confirmed through convergence studies and comparison with existing analytical and numerical results.

Results

The findings show that increasing material porosity decreases the natural frequencies due to stiffness reduction, while higher axial mode numbers yield greater frequencies. Clamped–clamped boundary conditions provide the highest stiffness and frequency. The analysis reveals non-classical dynamic behavior in the rotating shell: the forward frequency decreases at low rotation speeds because of centrifugal softening, whereas the backward frequency increases monotonically with rotation speed due to Coriolis stiffening.

Conclusions

The integrated modeling approach significantly improves the prediction of dynamic characteristics in complex rotating FGPM shells. The results highlight that porosity, variable thickness, and rotation speed strongly influence vibration behavior, providing valuable insights for designing lightweight and high-performance rotating structures such as turbines, centrifuges, and aerospace rotors.