تحليل الاهتزاز الحر للصفائح المركبة المتعامدة المقواة بمسحوق اوكسيد الالمنيوم(Al2O3)

Free vibration Analysis of Orthotropic Composite Plates Reinforced with Aluminum Oxide (Al2O3) Powder

Abstract

Vibration issues critically impact machine performance and lifespan. In order to reduce the effect of vibration in spacecraft and aircraft, the structures stiffness is enhanced to shift natural frequency away from critical excitation ranges.
This work presents a dynamic analysis of orthotropic composite plates reinforced with aluminum oxide (Al₂O₃) powder scattered across the polymer matrix. The objective is to enhance the mechanical characteristics and examine how adding alumina powder might affect the vibrational characteristics of the plates. Investigations are conducted into how the fiber stacking sequence, hybridization affect the mode shape and natural frequencies. A multidisciplinary methodology was adopted, combining experimental fabrication and testing with advanced numerical simulations and computational analysis.
In the experimental phase, composite plates were fabricated by integrating varying weight fractions of Al₂O₃ powder (2%, 5%, and 8%) into the resin matrix prior to lamination. The dispersion of the powder was carefully controlled to ensure uniform distribution and avoid agglomeration. To ascertain the mechanical and physical characteristics for analytical and numerical purposes, a tensile test was performed.
The results of dynamic analysis have been obtained; analytically by using (MATLAB R2021) was used based on classical laminated plate theory (CLPT), and numerically by using (finite element method) ANSYS (R1 2021) to simulate the vibrational behavior of the same plate geometries and material configurations. The FEM incorporated orthotropic material properties, realistic boundary conditions, and meshing suitable for accurate modal analysis. The vibration behavior of five models and several fiber angle arrangements was analyzed. The staking sequence of glass fiber includes five arrangements (0⁰ , 45⁰ , 90⁰ , 45⁰ , 0⁰), (90⁰ , 0⁰ , 60⁰ , 0⁰ , 90⁰), (0⁰ , 60⁰ , 90⁰ , 60⁰ , 0⁰), (0⁰ , 90⁰ , 45⁰ , 90⁰ , 0⁰), and (90⁰ , 30⁰ , 45⁰ , 30⁰ , 90⁰) .
The fifth model only with the highest natural Frequency was manufactured and tested in practice. The results of the study reveal a good enhancement in the dynamic performance of the composite plates with increasing Al₂O₃ content.
Where natural frequencies increased progressively with higher alumina concentrations, indicating improved stiffness and rigidity. The mode shapes remained consistent but showed sharper deformation patterns in plates with higher reinforcement levels. The fundamental frequency increased from 90.5 Hz to 104.5 Hz with FEM prediction differing from experimental by 1.6% .
The maximum value in natural frequency was observed at 8% Al₂O₃, although a balance must be maintained to avoid excessive weight increase.
It is noted that the incorporation of aluminum oxide powder into orthotropic composite plates significantly enhances their dynamic behavior, making them more suitable for applications where vibration control and dynamic stability are essential. The integrated use of testing in practice, finite element simulation, and analytical results provides a comprehensive and accurate framework for evaluating and optimizing advanced composite structures.