Alper Polat

Purpose: This study aims to design a damage detection and characterization system (targeting cracks and delamination) for aeronautical composite structures. Design/methodology/approach: This methodology relies on a multidisciplinary approach combining polymer-reinforced/metallic carbon fiber hybrid structures with an integrated network of PZT sensors. It leverages experimental data and employs advanced signal processing and imaging techniques to monitor structural integrity and assess the severity of damage. Findings: Verified experimental results confirm the method's reliability in real-life situations. Research limitations/implications: Research Limits: “The primary challenges involve signal processing complexity due to the hybrid nature of AL7075-T6 and CFRP materials, as well as the potential influence of environmental factors (temperature, pressure) on PZT sensor reliability”. Research Implications: “This work enables a shift toward condition-based maintenance, significantly reducing operational costs while enhancing structural safety and extending the service life of critical aerospace and maritime assets.” Practical implications: This study enables a shift from scheduled to real-time structural monitoring. There is a drastic reduction in inspection time and aircraft downtime. Monitoring the fatigue of hybrid AL/CFRP structures helps to safely extend their service life. The study helps in providing precise diagnostics to optimize repair strategies and minimize human error. Social implications: There is a drastic reduction of structural failure risks through early-stage damage detection. Cost savings in maintenance can lead to more affordable air travel for the general public. The study helps in promoting a circular economy by safely extending the lifespan of complex structures and reducing material waste and also in shifting maintenance roles toward high-tech data analysis and specialized software expertise. Originality/value: The study investigates the complex damage mechanics at the interface of AL7075-T6 and CFRP laminates and helps in combining PZT sensor networks with advanced imaging software for real-time damage characterization. Beyond mere detection, the system assesses “structural criticality,” providing high-value diagnostic data for maintenance optimization and cost reduction.

One of the most common problems in engineering is contact problems. In recent years, researchers have turned to alternative methods that can offer effective solutions in a shorter time, instead of solutions containing complex and long mathematical expressions. This study focuses on the estimation of the contact lengths in a homogeneous elastic layer suppressed by two elastic punches with two solution methods. Firstly, a new model was designed for estimation using Deep Learning Neural Network (DNN), one of the deep learning structures. Estimation of contact lengths was provided with the output of the DNN model, which was fed with the homogeneous elastic layer, the ratio of shear modules of the punches and the input parameters of punch radii. The finite element method was used as the second solution method. The problem was modeled in the ANSYS programme and the solution was made with the same parameters used in DNN modeled. The results obtained from both solutions were compared with the solutions obtained by the theory of elasticity and classical NN in the literature. It had been seen that the results obtained with DNN and ANSYS were compatible with the results obtained with analytical and classical NN and the margin of error was smaller.

Bridges can be subjected to a variety of external loads that can lead to instability and cause vibrations. Fortunately, such vibrations can be a source of unlimited sustainable energy that may powers the devices used to monitor the bridges. A possible way to convert such vibrations is by utilizing the direct piezoelectric effect, a process known as piezoelectric based energy harvesting. The present study investigates piezoelectric energy harvesting from a bridge. A model of the bridge with mounted piezoelectric harvesters was developed under ANSYS APDL. Various scenarios with different moving loads were investigated in time and frequency domains. Moreover, the effect of the positions of the harvesters was also explored. Results confirmed that harvesting vibration energy from bridge systems is a promising source of energy. Also, it can be profitable if the harvesters are located near the maximum mode shape amplitude and they are designed in a way to make their natural frequency match the natural frequency of the moving loads.

This paper investigates the optimal placement of piezoelectric actuators for the active vibration attenuation of beams. The governing equation of the beam is achieved by coupled first order shear deformation theory with two node element. The velocity feedback controller is designed and used to calculate the feedback gain and then apply to the beam. In order to search for the optimal placement of the piezoelectric actuators, a new optimization criterion is considered based on the use of genetic algorithm to reduce the displacement output of the beam. The proposed optimization technique has been tested for two boundary conditions configurations; clamped -free and clamped-clamped beam. Numerical examples have been provided to analyze the effectiveness of the proposed technic.

In this study, the continuous contact problem of a homogeneous layer of constant thickness perfectly bonded to a rigid support on its bottom surface and loaded a rigid stamp is investigated using the finite element method (FEM). It is assumed that the all contact surfaces are frictionless. The homogenous layer is loaded by rigid circular stamp with external load P. Two-dimensional finite element analysis of the problem is performed using ANSYS software. Also, normal stresses and shear stresses are investigated along the depth of the layer for different shear modulus ratios. Besides, contact length and contact stress between rigid block and homogenous layer are determined. The obtained results are compared to analytical solution and they are shown in graphs and tables.

In this study, continuous contact problem in the functionally graded (FG) layer loaded with two rigid flat blocks resting on the elastic semi-infinite plane was analyzed by the finite element method. The two-dimensional numerical model of the FG layer was made with the software added to the ANSYS program. This software can be adapted to all contact problem types by making minor changes. The accuracy check of the program was performed by comparing with the analytical solution of the problem by homogeneous layer and its solution by the finite element method. So, fast and practical solutions can be obtained by the developed finite element method on many applications such as; automotive, aviation and space industry applications. The comparisons made showed that the proposed solution gave good results at acceptable levels. In the problem, it was thought that all surfaces were frictionless. The external loads P and Q were transmitted to the FG layer via two flat rigid blocks. Normal stresses between the FG layer and the elastic plane, initial separation loads, initial separation distances and contact stresses under the blocks were investigated for various dimensionless quantities.