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標題: | 使用離散元素法模擬基於黏彈性顆粒材料之新型阻尼可行性研究 The Feasibility Study On Viscoelastic Granular Materials Based New Generation Vibration Isolators Using Discrete Element Simulation |
作者: | Wei-Cheng Chiu 邱偉誠 |
指導教授: | 張國鎮(Kuo-Chun Cheng) |
關鍵字: | 黏彈性材料,應力鬆弛曲線,儲存模數,耗損模數,靜水壓,顆粒型阻尼元件,離散元素法, Viscoelastic Material,Stress Relaxation Curve,Storage Modulus,Loss Modulus,Hydrostatic Pressure,Granular Damping Element,Discrete Element Method, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 至今,水平隔減震系統已於工程實務上取得成熟的發展,但於垂直向之隔減震尚有相當大的發展空間,因此未來需要研究並開發具垂直隔減震潛能的相關應用,而Igor et al.提出一種新型阻尼裝置之概念,透過黏彈性材料之特徵,其發展勁度及阻尼具可變性,以達吸收能量及消能的效果。本文採用有限元素軟體LS-Dyna模擬基於黏彈性顆粒材料之新型阻尼,探討此裝置於未來工程應用之可行性,並取用Igor et al.理論及專利敘述推得之材料試驗參數,即所指定三種熱塑性聚氨酯(TPU)材料於室溫20度及0.1MPa邊界條件下之應力鬆弛主曲線。 本文建立所提出顆粒型阻尼元件(Granular Damping Element)之LS-Dyna數值模型,包覆方面採用常用於軍事用途且具低密度、高強度之Kelvar KM2纖維,防止顆粒阻尼裝置於高壓下破裂影響其使用性。顆粒方面,材料採用前人試驗所述之三種熱塑性聚氨酯,分別為TPU1190A、1175A及1195D,並於LS-Dyna無網格離散元素法生成所需顆粒,選擇級配於半徑0.5mm至3mm之間黏彈性材料顆粒,以符合多峰分佈之需求。首先,對試體內部進行顆粒填充,以觀察壓力及孔隙率之變化,再對填充後的試體進行單向壓縮試驗獲得其勁度及變形後之強度,亦測試顆粒阻尼裝置於不同預加載下,使用低頻、低速之位移控制循環,測試其能量吸收,並觀察其於逐增預壓下之勁度及阻尼發展情形。 So far, the horizontal vibration isolation system has achieved mature development in engineering practice, but there is still considerable room for development in vertical vibration isolation. Therefore, it is necessary to research and develop related applications which with vertical vibration isolation potential in the future, and Igor et al. proposed the concept of a new type of damping device, which is known as Granular Damping Element. Through the characteristics of viscoelastic materials, the stiffness and damping are changeable to achieve the effect of absorbing energy and dissipating energy. In this study, the finite element software LS-Dyna is used to simulate a new type of damping based on viscoelastic granular materials, and the feasibility of this device in future engineering applications is discussed. The material experiments were derived from the theory and the patent description of Igor et al., which the stress relaxation curves of the specified three thermoplastic polyurethane (TPU) materials were shifted toward the room temperature of 20 degrees and the pressure of 0.1MPa.In this study, the LS-Dyna numerical model of the proposed granular damping element (Granular Damping Element) is established. The coating uses Kelvar KM2 fiber, which is commonly used in military applications and has low density and high strength, to prevent the granular damping device from breaking under high pressure.In terms of particles, the material uses three types of thermoplastic polyurethanes described in previous experiments, namely TPU 1190A, 1175A, and 1195D, and also generates the required particles in the LS-Dyna meshless discrete element method, chooses to grade within the radius of 0.5mm to 3mm viscoelastic material particles to meet the needs of multimodal distribution. First, fill in the test body with particles to observe the changes in pressure and porosity, and then use the one-way compression test to obtain its stiffness and deformation strength after filling. Also, test the granular damping element under different preloads with low-frequency, low-speed displacement control cycle, to obtain the energy absorption, and observe the stiffness and damping development under increasing preload. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/53606 |
DOI: | 10.6342/NTU202002415 |
全文授權: | 有償授權 |
顯示於系所單位: | 土木工程學系 |
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