Semnan University Press Mechanics of Advanced Composite Structures 2423-4826 14 1 2027 04 01 Mechanical Properties of Sandwich Composite with Polyurethane Core Reinforced by Biaxial Geogrid and Carbon-Glass Fiber/Polyester as Skin 180 189 10735 10.22075/macs.2026.36976.1809 EN Ganjar Pramudi Manufacturing Engineering Technology, Universitas Sebelas Maret, Surakarta, 57126, Indonesia 0000-0002-2362-3986 Nur Ikhsan Ismail Mechanical Engineering, Universitas Sebelas Maret, Surakarta, 57126, Indonesia Journal Article 2025 02 26 The development of sandwich panels as structural materials is increasingly driven by the diversification of constituent materials. In this study, carbon-glass/polyester fibers were selected for the outer skins due to their high strength-to-density ratio, while polyurethane foam was used as the core for its lightweight characteristics despite its relatively low mechanical strength. To enhance the core’s performance, two-way geogrid reinforcement was incorporated. The primary objective of this research is to investigate the effect of geogrid reinforcement and the influence of core thickness on the mechanical properties of the resulting sandwich composite, with particular emphasis on identifying the optimal geogrid configuration and core thickness that yield the highest structural performance. The novelty of this research is the addition of a geogrid used as a sandwich composite reinforcement. Variations in the number of geogrid layers and core thickness were examined. The composite sandwich panels undergo flexural and compressive tests. The results indicated that the composite with a core thickness of 50 mm and five layers of geogrid reinforcement exhibited the highest performance, achieving a flexural strength of 47.59 MPa and a shear stress of 1856.68 MPa. In contrast, one layer of geogrid achieved a flexural strength of 45.46 MPa and a shear stress of 1768.60 MPa. Similar results were observed in the composite compression tests, where the composite with five geogrid layers achieved a compressive strength of 0.18 MPa, significantly higher than the 0.12 MPa achieved with a single layer of geogrid. The decreasing distance between geogrid layers increases the core density, thus enhancing resistance to compressive loads. This material can be used as a structural material to withstand vibrations such as earthquakes. https://macs.semnan.ac.ir/article_10735_58b7483ba899e0ce4d97ac5eecf6fa99.pdf