INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)
ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIV, Issue XII, December 2025
3. Data Preprocessing and Normalization: The collected experimental data undergoes preprocessing to
remove inconsistencies, noise, or outlier values that may distort model performance. Missing or anomalous
readings are corrected or removed after verifying with repeated trials. To enhance the accuracy of the fuzzy
system, all data is normalized within a standard range, enabling smoother mapping between inputs and outputs.
This preprocessing stage ensures that the dataset used for fuzzy modeling remains reliable, consistent, and
suitable for establishing strong rule-based relationships.
4. Development of Fuzzy Inference System (FIS): A fuzzy inference system is then constructed to model the
complex and uncertain relationship between machining parameters and delamination response. Linguistic
variables such as low, medium, and high are assigned to each input parameter, and corresponding membership
functions are designed. Using expert knowledge and trends observed from experiments, a fuzzy rule base is
formulated to represent the decision-making logic of the machining process. The FIS uses Mamdani or Sugeno
inference techniques to derive outputs, translating qualitative rule-based reasoning into quantitative predictions
of delamination and machining quality. This stage forms the intelligent core of the proposed methodology. To
enhance the transparency and interpretability of the fuzzy inference system, detailed modeling components are
defined within the proposed framework. Each input machining parameter, including spindle speed, feed rate,
tool geometry, and point angle, is represented using triangular or trapezoidal membership functions due to
their computational simplicity and effectiveness in capturing nonlinear trends observed in machining data.
Linguistic terms such as Low, Medium, and High are assigned to each input variable, while the output
variable, delamination factor, is expressed using graded linguistic levels ranging from Very Low to Very High.
A comprehensive rule base is formulated using expert knowledge and experimentally observed machining
behavior, resulting in a set of IF–THEN rules that describe the cause–effect relationship between machining
parameters and delamination. Mamdani-type fuzzy inference is employed to evaluate the rules due to its
intuitive reasoning and suitability for decision-making problems involving uncertainty. The aggregation of
fuzzy outputs is followed by defuzzification using the centroid method, which converts fuzzy conclusions into
a crisp numerical delamination value. This structured fuzzy modeling approach enables accurate prediction of
delamination while preserving interpretability and robustness.
5. Hybrid Optimization Using Fuzzy–Evolutionary Approach: To identify the optimal machining
parameter settings that minimize delamination, a hybrid optimization method combining fuzzy logic with an
evolutionary algorithm (such as Genetic Algorithm or Particle Swarm Optimization) is employed. The fuzzy
system evaluates the quality of each candidate solution based on its predicted delamination value, while the
evolutionary algorithm performs global search and refinement of parameters. This hybrid structure effectively
balances global exploration and local fine-tuning, allowing the optimization process to converge toward the
best feasible machining conditions. The result is a set of optimized parameters that yield minimal delamination
and improved hole quality. The selection of a hybrid Genetic Algorithm–Particle Swarm Optimization (GA–
PSO) approach is justified by the complementary strengths of the two evolutionary techniques in solving
complex, nonlinear, and multi-modal optimization problems encountered in GFRP machining. Genetic
Algorithm contributes strong global search capability through crossover and mutation operations, reducing the
likelihood of premature convergence and enhancing solution diversity. In contrast, Particle Swarm
Optimization offers fast convergence and efficient local search by exploiting collective learning and velocity-
based updates. By integrating GA with PSO, the proposed hybrid framework achieves an effective balance
between exploration and exploitation, allowing the optimization process to efficiently search the solution space
while refining promising regions identified by the fuzzy system. The fuzzy inference model serves as a fitness
evaluator for the GA–PSO algorithm, guiding the evolutionary search toward machining parameter
combinations that minimize delamination. This hybrid optimization strategy is particularly suitable for
machining optimization problems where analytical modeling is difficult and response surfaces are highly
nonlinear.
6. Validation and Performance Evaluation: The final step involves validating the optimized parameters by
conducting confirmation experiments under the predicted optimal conditions. The experimental delamination
values are compared with the fuzzy–optimized predictions to measure accuracy, consistency, and model
reliability. Performance metrics such as percentage reduction in delamination, prediction error, improvement
in surface finish, and comparative analysis with initial trials are used to assess the success of the proposed
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