Numerical an‎d Experimental Study on the Effect of Drilling-Induced Delamination on the Reduction of Flexural Load carrying Capacity in Composite Laminates

10/20/2026 12:00:00 AM

Drilling-induced delamination is a critical issue concerning the mechanical response of composite laminates, which can significantly affect the strength an‎d service life of these materials. The study of this phenomenon is highly important because drilling is frequently necessary for the installation of equipment an‎d fasteners in composite structures, an‎d the resulting delamination can lead to a considerable decrease in structural integrity. Given the research gap regarding the specific influence of delamination on the reduction of flexural Load carrying capacity in composites, particularly woven composites, accurate research an‎d modeling are imperative for understan‎ding an‎d predicting this mechanism. Consequently, this thesis employs both numerical an‎d experimental methods to investigate the effect of drilling-induced delamination on the reduction of the flexural Load carrying capacity of woven Glass/Epoxy composite laminates. In the experimental phase, specimens were machined using two distinct drilling processes to isolate the effect of drilling-induced delamination from the effect of the hole itself on the reduction of the composite’s flexural capacity. One process resulted in samples that were virtually delamination-free, while the other yielded samples with significant delamination. In the numerical section, the meso-scale modeling approach was utilized to analyze the structural an‎d mechanical behavior of the material with greater precision. Numerical modeling at this scale has been infrequently employed in this specific field; however, the targeted application of this method can lead to cost reduction an‎d optimization of design. For this purpose, TexGen software was used to design the geometry of the yarns an‎d the resin matrix. The analysis was performed using the Abaqus explicit solver, an‎d material properties were defined through a VUMAT subroutine to ensure the modeling was conducted under realistic conditions. The results of the experimental method indicated that the presence of the hole led to a 21.4% reduction in the Load carrying capacity of the drilled, delamination-free specimens, an‎d a 26.6% reduction in the Load carrying capacity of the drilled specimens containing delamination. Comparing the experimental an‎d numerical findings demonstrated that the meso-scale modeling method accurately predicts the laboratory results with an average error of 2% for the critical load, 1.4% for the deviation at the onset of damage, 1.8% for the deviation at ultimate failure, an‎d 5.8% for the absorbed fracture energy.

كامپوزيت پايه پليمر , كامپوزيت‌هاي بافته‌شده , تورق ناشي از سوراخ‌كاري , مدل‌سازي عددي در مقياس مزو , آزمون خمش چهار نقطه‌اي , تأثير تورق بر ميزان افت بارپذيري

Polymer matrix composites , woven composites , delamination caused by drilling , mesoscale numerical simulation , four-point bending test , effect of delamination on load carrying capacity reduction

Saeed Bagherpour Kasseb

Dr. Fathollah Taheri Behrooz