Dynamic Behaviour Of Composite Structures Research Articles

Dynamic Effect of Ply Angle and Fiber Orientation on Composite Plates

Composite materials have revolutionized industries such as aerospace and automotive with their impressive strength-to-weight ratios and customizable properties. Ply angle and fiber orientation are critical factors that significantly impact the dynamic behavior of composite structures, influencing stiffness, strength, and vibrational characteristics. This research delves into the dynamic characteristics of composite plates, explicitly examining how ply angle and fiber orientation affect vibrational behavior. Through finite element analysis (FEA), composite plates with varying ply angles and fiber orientations were modeled to understand their influence on natural frequencies, mode shapes, and dynamic responses under various loading conditions. The study reveals that cross-ply [0/0/0/0] exhibits the highest stiffness and superior stress handling, while the cross-ply balanced laminate [90/0/0/90] demonstrates better vibrational characteristics. The findings highlight the intricate relationships between design parameters and structural vibrational behavior, offering opportunities for optimizing composite structures. Additionally, harmonic analysis showed that a cut-out increases the natural frequency. The results underscore the importance of optimizing composite plate configurations to enhance vibrational characteristics and align natural frequencies with operational requirements, thereby mitigating resonance-related issues.

Prediction of System Parameters of Carbon-Based Composite Structure for Different Carbon Fiber Orientations with Mode Information at Reference Angle Only.

The prediction of system parameters is important for understanding the dynamic behavior of composite structures or selecting the configuration of laminated carbon in carbon-based composite (CBC) structures. The dynamic nature of CBC structures allows the representation of system parameters as modal parameters in the frequency domain, where all modal parameters depend on the carbon fiber orientations. In this study, the variation in the system parameters of a carbon fiber was derived from equivalent modal parameters, and the system parameters at a certain carbon fiber orientation were predicted using the modal information at the reference carbon fiber orientation only and a representative curve-fitted function. The target CBC structure was selected as a simple rectangular structure with five different carbon fiber orientations, and the modal parameters were formulated based on a previous study for all modes. Second-order curve-fitted polynomial functions were derived for all possible cases, and representative curve-fitting functions were derived by averaging the polynomial coefficients. The two system parameters were successfully predicted using the representative curve-fitting function and the modal information at only the reference carbon fiber orientation, and the feasibility of parameter prediction was discussed based on an analysis of the error between the measured and predicted parameters.

Dynamic behavior of thin-walled elements of aircraft made of composite materials, excited by heat shock

To improve the performance characteristics of modern aerospace systems, research is conducted and expensive programs are being carried out to provide for reducing the weight of the aircraft structure through the use of new, more promising materials, which include the so-called composite materials. Special attention is paid to the dynamic behaviour of composite structures under the influence of high-intensity heat fluxes of various physical nature. The paper considers the dynamic behaviour of composite structures of modern aerospace systems under the influence of high-intensity heat fluxes. As an example, the axisymmetric transverse vibrations of a composite circular plate connected to an elastic base, excited by thermal shock, are investigated. The plate material is modelled with a three-layer composite. To describe the kinematics of an asymmetric plate pack, the hypotheses of a broken normal are accepted. In thin bearing layers, Kirchhoff's hypotheses are valid. In a relatively thick lightweight core, the normal does not change its length, remains rectilinear, but rotates through some additional angle. The base reaction is described by the Winkler model. The statement of the initial-boundary value problem is given. The analytical solution is obtained as a series expansion in terms of eigenfunctions. Its numerical parametric analysis is carried out.

Modal Identification of Output-Only Systems of Composite Discs Using Zernike Modes and MAC.

The analysis of the structural dynamic behaviour of composite rotor–discs by a valid description of the eigenfrequencies and mode shapes can provide significant information for action-taking before a failure occurs. Specifically, vibration-based diagnostic methods, which are able to take into consideration the interdependencies and sequential changes of the modal properties could benefit from such an analysis. Here, on the example of composite rotors, a correlation method for experimentally determined mode shapes is developed. For this purpose the Zernike polynomials are used to enhance the identification of mode shapes. Furthermore, the modal assurance criterion (MAC) in combination with the frequency response criterion and a data processing approach are applied in order to characterize changing modal properties of composite rotors. In addition, the developed algorithms can be further extended in order to simplify the experimental evaluation of the complex dynamic behaviour of composite structures.

Study of the Dynamic Response of Polymer-Matrix Composites Using an Innovative Hydraulic Crash Machine

This paper describes the design and implementation of a new innovative machine for hydraulic crash of composite materials. Polymer-matrix composite (PMC) plates with polyamide 11 (PA11) matrix/woven glass fibers were impacted with the new machine at 10 bars during 5 ms and their dynamic response, in terms of crash pressure and deflection at the pole, was evaluated respectively by two pressure transducers and a laser system. During the hydraulic crash test generating a shock wave within a metal enclosure, PMC plates undergo a tensile/compressive loading cycles which produce a damped vibration following the viscous aspect of the thermoplastic resin PA11. In view of the anisotropy and heterogeneity of composite materials, a numerical simulation with ABAQUS code has been proposed for predicting the dynamic behavior of PMC plates during the pressure rise phase of a proposed hydraulic crash cycle. Numerical deflection at the pole and the stresses field are investigated and compared with the experimental study. The obtained results show a very interesting potential of this machine for studying the dynamic behavior of composite structures under low-velocity impact test.

Maximization of Fundamental Frequency of Laminated Composite Cylindrical Shells by Ant Colony Algorithm

http://dx.doi.org/10.5028/jatm.v5i1.233The success in developing modern aerospace systems addresses competitive subjects as optimization, reduced costs, sustainability, environment, weight, and safety. There is an increased demand for lighter materials such as laminated composites. In order to match the demand of aeronautical companies, the shell structures are very important. The dynamic behavior of composite structures is also essential to improve the potential applications of these materials. The knowledge of the dynamic response of the cylindrical shell structures is an important issue in their design, in which the ply thicknesses are often preestablished and the ply orientations are usually restricted to a small set of angles due to manufacturing constraints. Obtaining the best stacking sequence of laminated shell may lead to a problem of combinatorial optimization. As this problem is hard to be solved, several techniques have been developed. Ant colony optimization is a class of heuristic optimization algorithms inspired by the behavior of real ants, related to their ability to find the shortest path between the nest and the food source. Thus, this paper deals with optimal stacking sequence of laminated cylindrical composite shells with the aim of maximizing their fundamental frequency using this approach. The ant colony algorithm was implemented in Matlab platform and was linked to Abaqus academic version to compute the structural response. Cylindrical shells with and without a cutout geometry were studied. Fundamental frequencies were maximized for both cases, and results were presented and discussed.

Damping Analysis of 3D Composite Structure Embedded with Visco-Elastic Layer

Recently, the fiber reinforced composite embedded with visco-elastic layer has received great attention because of its good damping capability. Damping is an important feature for dynamic behaviour of composite structures, which alleviates the resonant vibrations and thus prolongs the service life of structures under fatigue loading or impact. The present paper deals with the dynamic response of a 3D composite structure embedded with visco-elastic layer. The modal analysis, harmonic analysis and transient analysis are carried out respectively. The amplitude of z-displacement of a specific node on the bottom reduces quickly due to the high damping of the visco-elastic layer.

Maximization of Fundamental Frequencies of Axially Compressed Laminated Plates Against Fiber Orientation

Summary The applications of fiber-composite laminate materials to aerospace industrial such as spacecraft, high-speed aircraft, missile and satellite have increased rapidly in recent years. The most major components of the aerospace structures are frequently made of curved panels and subjected to various kinds of compressive forces. Therefore, knowledge of the dynamic characteristics of composite laminated curved panels in compression, such as their fundamental natural frequency, is essential. The fundamental natural frequency of composite laminated curved panels highly depends on the ply orientation, end conditions, geometries (i.e., aspect ratio and curvature) and compressive force. Therefore, proper selection of appropriate lamination to maximize the fundamental frequency of composite laminated curved panels in compression becomes a crucial problem. Research on the subject of structural optimization has been reported by many investigators and has been widely employed to study the dynamic behavior of composite structures. Among various optimization schemes, the golden section method is a simple technique and can be easily programmed for solution on the computer. In this investigation, maximization of the fundamental natural frequency of composite laminated curved panels in compression with respect to fiber orientations is performed by using the golden section method. The fundamental frequencies of the composite laminated curved panels are calculated by using the Abaqus finite element program. In the paper, the constitutive equations for fiber-composite lamina, vibration analysis and golden section method are briefly reviewed. The influence of the end conditions, the panel aspect ratio, the panel curvature and the compressive force on the maximum fundamental natural frequency, the associated optimal fiber orientations and the vibration mode of the laminated curved panels is presented and important conclusions obtained from the study are given.

Static and Dynamic Behaviour of Composite Structures with Shape Memory Alloy Components

In this work selected results have been presented for the static and dynamic behaviour of composite beams, plates, and rotors, all fitted with integral SMA wires or strips. Changes in the static deflections, natural frequencies and critical loads, natural modes, amplitudes of forced vibration, and stress distributions, have all been investigated. Applications of the Active Property Tuning (APT) method and the Active Strain Energy Tuning (ASET) method have been proposed, and the finite element method (FEM) has been used to calculate the static and dynamic responses of these structures. Along with the authors' bespoke programs, two FEM commercial packages PATRAN and ABAQUS have been applied to obtain the relevant data. The ultimate intention is to use embedded SMAs within a composite structure as an actuator for the control of rotor vibration.