Experimental and numerical analysis of drilled- and molded-hole glass fiber reinforced polymer matrix (GFRP) composites


Polymer Composites, vol.45, no.9, pp.7811-7819, 2024 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 45 Issue: 9
  • Publication Date: 2024
  • Doi Number: 10.1002/pc.28305
  • Journal Name: Polymer Composites
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.7811-7819
  • Keywords: bending, failure, flexural, hole drilling, mechanical behavior, molded-hole, polymer matrix composites
  • Bursa Uludag University Affiliated: Yes


Drilling glass fiber reinforced polymer matrix (GFRP) composites typically causes burrs, splintering, and microcracks within the GFRP structure, as well as delamination, fiber pull-out, and thermal degradation of the polymer matrix. Designing and manufacturing molded-hole GFRP components, as opposed to drilling, has recently been proposed as a promising method for overcoming the issues associated with drilling, for which there is limited research. Specifically, the mechanical response of molded-hole GFRP has not been fully addressed in the literature. In the present study, molded and drilled GFRP composites with epoxy matrix were fabricated by hand lay-up, and then the samples were analyzed utilizing experimental and numerical analysis techniques. Stress and strain analyses of GFRP samples were performed in Ansys Transient Structural Analysis. Although the fiber orientations of the layer geometries [0°/90°] and 3D models were the same, an additional layer was defined in the direction of the fiber orientation [45°/−45°] of molded-hole composites to simulate the fiber accumulation effect. Experimental findings revealed that the flexural strength of molded composites was 12% greater than that of drilled composites. According to the numerical analysis, 98.7% proximity was achieved between the experimental and numerical results. Thus, the present study has provided numerical modeling to understand the flexural strength of molded composites for the first time, which will contribute to the increased use of molded composites in numerous applications in the fields of aerospace, automotive, and marine. Highlights: Drilled- and molded-hole GFRP composites were produced by hand lay-up. Flexural properties of the composites were examined via 4P bending tests. Flexural strength of molded composites was higher than that of drilled ones. 98.7% proximity was achieved between the experimental and FEM results. A unified FEM method is proposed for the molded-hole composites.