Characterization, quantification and prediction of the impact of structural defects in fiber composites and fiber-metal laminates on the processes of initiation and propagation of their degradation

OPUS 30

Funding Organization: National Science Centre

Project title: Characterization, quantification and prediction of the impact of structural defects in fiber composites and fiber-metal laminates on the processes of initiation and propagation of their degradation

Agreement number: UMO-2025/59/B/ST11/00490

Project implementation period: 09.07.2026 – 08.07.2030 

Principal Investigator: dr hab. inż. Patryk Jakubczak

Project value: 1 246 752,00 PLN

Funds granted for Lublin University of Technology: 1 246 752,00 PLN

Abstract:

Scientific Objective

The project addresses the problem of assessing the impact of micro- and meso-structural discontinuities in composite materials on their mechanical states, including the processes of damage initiation and propagation. Comprehensive knowledge of how the type, size, and location of defects affect changes in the strength of composites is of great cognitive significance. It will provide a scientific basis for understanding the relationships and causes behind these effects, leading to improvements in technology and more realistic computational engineering.

The explanatory and descriptive goal of the project is to evaluate the influence of the type, size and location of micro- and meso- structural discontinuities in polymer-fiber composites on their mechanical response, strength, and mechanisms of damage initiation and propagation, both qualitatively and quantitatively. The predictive goal is to adapt or develop machine learning algorithms to create a system for predicting the impact of defects on the strength changes in composites.

Significance of the Project

The research problem of identifying and quantitatively describing the impact of structural discontinuities in polymer-fiber composite materials on changes in their mechanical behaviour and strength under various loading conditions is a significant issue. The primary challenge is the current lack of knowledge regarding the nature and scale of this impact. To date, there are no published clear correlations indicating which type of defect, of what size and location, affects (decrease or increase?) the mechanical response of the composite. This response includes the distribution of stresses and strains, the acceleration (or delay) and location of damage initiation (micro-mechanisms of component cracking), areas of concentration and relaxation, and the values of modules and strength indicators.

This justifies the need to address this research problem due to its cognitive value and the necessity to implement this knowledge into increasingly advanced, precise, and realistic computational methods, enabling a shift away from idealized initial solids/surfaces towards more realistic structures (e.g., digital twins, X-FEM). The second area justifying the research problem lies within engineering sciences related to technology. Precise knowledge of how defects impact mechanical properties will allow for the appropriate prioritization of efforts to improve technology, particularly in developing solutions to eliminate the most critical discontinuities. Simultaneously, understanding the impact on mechanical states will enable better control of technological processes, for example, by supplementing them with additional elements (e.g. post-curing, robotic lamination).

In both cases, understanding not only which defect impacts which scale but also why, supported by scientific evidence (strain maps, strength, fracture analysis), will significantly increase the awareness of both theorists and practitioners in basic and applied research on composite materials, contributing to the improvement and prediction of the reliability of composite materials.

Research Concept and Methodology

The research concept involves designing, executing, testing, analyzing, and modelling a prediction system for the impact of structural discontinuities on the mechanical behaviour and strength properties of polymer-fiber composites. The planned work, including theoretical planning, technological development, research, analysis, and modelling, will prepare a catalog of significant structural defects in composite materials. Subsequently, technologies for reliably simulating defects in composite structures will be developed. Standard samples (without defects) and those with defects will be produced, subjected to varied strength tests (experimental and FEM simulations), and analyzed for damage and its initiation and propagation mechanisms. Ultimately, the collected data will be used to describe the impact of defects on the properties of composites, distinguishing the types and other characteristics of these defects. These data will also be transferred to machine learning datasets (training and testing sets) to develop a prediction system based on Machine Learning / AI tools.