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Subject: search.filters.subject.mechanical properties

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    PublicationOpen Access
    Waste Polyethylene Reinforced with Coconut Fibers for Sustainable Construction: A Mechanical and Physical Property Evaluation Study
    (Dr D. Pylarinos, 2025-10-06) Dharmaratne, P. D; Galabada G.H; Malkanthi S.N; U.Halwatura R.
    This study evaluates the feasibility of using waste polyethylene as a construction material. To achieve this, a series of polymer composites were developed using waste Low-Density Polyethylene (LDPE) reinforced with coconut fiber (coir). The mechanical properties, including the tensile strength, flexural strength, impact strength, and elastic modulus, were assessed, along with the water absorption as a key physical property by following the ASTM standards. The composites were fabricated using the hand layup technique with varying coir-to-LDPE weight ratios and fiber lengths, followed by a hot-press machine manufacturing under controlled conditions. The results demonstrated that different fiber lengths and content levels influenced the mechanical properties, optimizing them at various configurations. A maximum tensile strength of 12.56 MPa was achieved using 40% coir content with 4 cm fiber length. The highest elastic modulus value of 0.46 GPa was achieved at 50% fiber content with 4 cm fibers. At 30% fiber content with 3 cm length, the maximum flexural strength value of 33.77 MPa was obtained. The impact strength reached its maximum value of 1.22 kJ/m² with 40% fiber content and 2 cm fiber length. The high water absorption exhibited by the composites, can be mitigated by applying waterproofing chemicals immediately after fabrication. It was found that the integration of fiber content and length affects the composite's properties. Depending on the required characteristics, appropriate fiber lengths and mix proportions can be selected, making these composites suitable for various applications in the construction industry. Additionally, proper waterproofing immediately after manufacturing the composite is proposed to enhance its performance as a construction material.
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    PublicationEmbargo
    Effects of free edges and vacancy defects on the mechanical properties of graphene
    (IEEE, 2014-08-18) Dewapriya, M. A. N; Rajapakse, R. K. N. D
    Defects are unavoidable during synthesizing and fabrication of graphene based nanoelecromechanical systems. This paper presents a comprehensive molecular dynamics simulation study on the mechanical properties of finite graphene with vacancy defects. We characterize the strength and stiffness of graphene using the concept of surface stress in three-dimensional crystals. Temperature and strain rate dependent atomistic model is also presented to evaluate the strength of defective graphene. Free edges have a significant impact on the stiffness; the strength, however, is less affected. The vacancies exceedingly degrade the strength and the stiffness of graphene. These findings provide a remarkable insight into the strength and the stiffness of defective graphene, which is critical in designing experimental and instrumental applications.
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    PublicationEmbargo
    Influence of temperature and free edges on the mechanical properties of graphene
    (IOP Publishing, 2013-08-12) Dewapriya, M. A. N; Phani, A Srikantha; Rajapakse, R. K. N. D
    A systematic molecular dynamics simulation study is performed to assess the effects of temperature and free edges on the ultimate tensile strength and Young's modulus of a single-layer graphene sheet. It is observed that graphene sheets at higher temperatures fail at lower strains, due to the high kinetic energy of atoms. A numerical model, based on kinetic analysis, is used to predict the ultimate strength of the graphene under various temperatures and strain rates. As the width of a graphene reduces, the excess edge energy associated with free edge atoms induces an initial strain on the relaxed configuration of the sheets. This initial strain has a greater influence on the Young's modulus of the zigzag sheet compared with that of the armchair sheets. The simulations reveal that the carbon–carbon bond length and amplitude of intrinsic ripples of the graphene increases with temperature. The initial out-of-plane displacement of carbon atoms is necessary to simulate the physical behaviour of a graphene when the Nosé–Hoover or Berendsen thermostat is used.