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Abstract: Interpenetrating phase composites (IPC) are materials with two or more mutually continuous, interconnected phases. This structure allows each phase to retain its properties, while together they exhibit enhanced synergistic properties. In this work, polymer-metal IPCs with Triply Periodical Minimal Surface (TPMS) structures were fabricated and tested for their mechanical properties at different impact velocities (ranging from 0.1 mm/s to 250 m/s). Samples. The samples comprise a stainless steel reinforcement phase and two polymeric matrices (silicone and epoxy). Computed tomography was used to evaluate the internal structure and the fabrication quality. The results showed that the samples were thoroughly infiltrated with polymeric filler, achieving a high degree of homogeneity in the composite. The compression tests of silicone-filled IPCs showed an increase in stiffness. Still, the Specific Energy Absorption (SEA) was not improved due to the non-optimal stiffness ratio between the polymeric matrix and the metallic reinforcement phase. However, using epoxy as the matrix resulted in the SEA enhancement of 38 %. This is attributed to the interlocking mechanism between the two phases, which improved the macroscopic mechanical properties. The compression tests showed significant strain rate hardening due to the base material’s strain rate sensitivity and the inertia effects.
Keywords: TPMS, interpenetrating phase composite, polymer filler, hybrid structure, experimental testing, mechanical properties, strain rate effect
Published in DKUM: 26.05.2025; Views: 0; Downloads: 4
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Abstract: A conventional compound fabric was used to develop a modern, multifunctional material with an auxetic behaviour and a tailored open area for particle filtration. Such material was produced using traditional textile technology and laser cutting, to induce a rotating squares unit geometry. The behaviour was investigated of three different rotating unit cell sizes. The laser slit thickness and the length of the hinges were equal for all three-unit cells. The tensile properties, Poisson’s ratio and auxetic behaviour of the tested samples were investigated, especially the influence of longitudinal displacement on the fabric’s open area and the filtered particle sizes (average and maximum). Results show that the developed compound fabric possesses an average negative Poisson’s ratio of up to −1, depending on the applied auxetic geometry. The larger rotating cell size samples offer a higher average negative Poisson’s ratio and a higher breaking strength due to the induced slits. The findings highlight the usefulness of patterned cuts in conventional textile materials to develop advanced auxetic textile materials with tailored geometrical and mechanical properties.
Keywords: compound textile material, auxetic structure, open area, filtration, mechanical properties, Poisson’s ratio
Published in DKUM: 25.03.2025; Views: 0; Downloads: 4
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Keywords: computational simulations, solid mechanics, finite element method, design, numerical methods
Published in DKUM: 28.02.2025; Views: 0; Downloads: 1
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Abstract: Uniform lattices composed of one type of lattice structure repeated periodically have been extensively investigated in literature for their mechanical and physical properties. Their promising properties, which include a desirable combination of high strength, stiffness and toughness, suggest that hybrid structures made of two or more lattice types can exhibit even more advantageous and desired properties. In this work, the mechanical properties of hybrid cellular structures designed using implicit functions are investigated both experimentally and numerically. Two proposed samples are investigated comprised of a Gyroid and a Diamond unit cells hybridised linearly and radially. First, a finite element computational model was utilised in LS-DYNA to capture the mechanical properties of the additively manufactured constituent lattices (i.e., Gyroid and Diamond) made of stainless steel 316L and tested under dynamic and quasi-static loading conditions. The model was validated for three different relative densities. Then, the validated computational model was then tested to predict the mechanical behaviour of the proposed hybrid lattices. Finally, the proposed hybrid lattices were fabricated and mechanically tested to obtain their mechanical properties. A good agreement between experimental and computational results was achieved. The validated computational models will be used to evaluate other designs of TPMS lattices and their crashworthiness performance for protective equipment applications.
Keywords: cellular materials, triply periodical minimal surface, hybrid lattices, experimental testing, computational modelling, multi-morphology
Published in DKUM: 27.11.2024; Views: 3; Downloads: 11
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Abstract: Diplomsko delo raziskuje obnašanje enorednega krogličnega ležaja pod statičnimi obremenitvami. Cilj je razumeti pomike, deformacije in napetosti, ki nastanejo v ležaju pod obremenitvijo osne sile. Raziskava uporablja analitične metode, teorijo elastičnosti in metodo končnih elementov (MKE) za modeliranje in simulacijo ležaja. Rezultati teh metod so primerjani s standardi. Predpostavke vključujejo linearne elastične lastnosti, homogenost materialov, statične obremenitve in idealno geometrijo. Omejitve obsegajo analizo enega ležaja na osi, idealne pogoje delovanja, poenostavitve v analitičnih in numeričnih metodah ter primerjavo z eksperimentalnimi ali že znanimi rezultati. Za izvedbo numerične simulacije je uporabljen ustrezen programski paket PrePoMax.
Keywords: Ležaj, statične obremenitve, deformacije, napetosti, numerična analiza
Published in DKUM: 09.10.2024; Views: 0; Downloads: 27
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