## 1 Introduction  
With the ongoing advancement of industrial society, the demand for high-rise, long-span, and large building structures is increasing, leading to increases in the performance, strength, and functionality of such structures. In accordance with this trend, high-quality, new composite materials and applications of cutting-edge structural engineering technology are being actively developed. In addition, recent research on the development of composite materials has focused on achieving multifunctionality and reducing the weight of such materials, and numerous studies have been conducted to improve the mechanical properties of the existing polymer materials. Basically, the reinforcement mechanisms of polymer composite materials can be classified into two types. The first method is particle reinforcement using powder. In this approach, by using graphene oxide [1; 2; 3; 4] and specially prepared coating powder [5; 6; 7; 8], the isotropic properties of the existing polymers can be improved. The second technique is fiber reinforcement, in which carbon nanotubes [9; 10; 11; 12], carbon fibers [13; 14; 15; 16], or various other materials are added to synthesize anisotropic composite materials. These materials have drawbacks in terms of difficulties in prediction and analysis based on classical theories due to the complex interplay among the bending-tensile, tensile-shear, and bending-torsion effects. Challenges informing the use of these materials have also been reported. To address these limitations, more in-depth research on isotropic composite materials is required. In the context of the research objectives for isotropic composite materials described above, ultra-high-molecular-weight polyethylene (UHMWPE) has emerged as an attractive option. This material has been one of the most relevant for total hip and knee replacements over the last 50 years [17] and has emerged as the material of choice for fabricating bearing components in various arthroplasties, such as acetabular cups, tibial inserts, and glenoid sections [18; 19]. Furthermore, due to the high tensile strength, wear resistance, and strength-to-weight ratios of UHMWPE fibers, UHMWPE is considered an excellent reinforcement material [20; 21; 22]. However, in general, UHMWPE is a fiber-type reinforcement. The fiber-reinforcing material may be classified as an anisotropic material, and, since the injection moldability is low, a disadvantage of processing occurs. To apply it to various industries, development of an isotropic UHMWPE-PP material suitable for injection molding is required. In this study, a composite material obtained by mixing UHMWPE and PP in powder form was proposed. Accordingly, the change in elastic properties according to the addition of UHMWPE was theoretically estimated. To develop isotropic composite materials by using UHMWPE with excellent properties in powder form and mixing the powder with the existing polymer material, polypropylene (PP), the elastic properties can be predicted through finite element analysis (FEA). Therefore, in this study, to predict the elastic properties of UHMWPE-particle-reinforced PP composite materials, FEA was performed with different volume fractions (2, 4, 6, 8, 10, and 15 VF%) of UHMWPE with a size of 10 \(\upmu\)m. The FEA results were compared to those of the conventional model for numerical analysis.