簡易檢索 / 詳目顯示

回結果列表
研究生： 陳婷容
Chen, Ting-Jung
論文名稱： 非均向性泡沫材料之多軸破壞包絡面
Failure Envelopes of Anisotropic Open-cell Foams Under Multiaxial Stresses
指導教授： 黃忠信
Huang, Jong-Shin
學位類別： 碩士
Master
系所名稱： 工學院 - 土木工程學系
Department of Civil Engineering
論文出版年： 2004
畢業學年度： 92
語文別： 英文
論文頁數： 123
中文關鍵詞： 破壞面 、軸對稱載重 、破壞包絡面 、非均向性泡沫材料
外文關鍵詞： failure envelopes, failure surfaces, anisotropic ratio, anisotropic open-cell foams
相關次數： 點閱：64  下載：4 
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報

    • 　　由於泡沫材料已漸廣泛應用於輕質三明治板之心材，而且此類輕質結構所處環境多屬一多軸載重的狀態，因此，對於輕質三明治板而言，泡沫心材於多軸載重作用下之力學性質與可能破壞機制所對應的破壞準則，成為分析與設計輕質三明治板之重要依據。但由於泡沫材料的製造過程容易導致其微觀結構呈現非均向性，因此，泡沫材料的力學性質與可能破壞機制，將受到其內部幾何結構亦即非均向比之影響。本研究將推導非均向性開放型泡沫材料之多軸破壞包絡面，藉由探討不同可能破壞機制之破壞準則，進而組構此泡沫材料之多軸破壞包絡面，所分析之破壞機制包括塑性降伏、脆性破壞、彈性挫屈及拉裂破壞等。最後，針對開放型泡沫材料於軸對稱載重條件下，將前述各可能破壞機制之破壞準則相互比較，以獲得所對應之多軸破壞包絡面，然後，分析並探討非均向比將如何影響開放型泡沫材料之力學行為與其多軸破壞包絡面。

    　　Open-cell foams are typically used as core materials in lightweight sandwich panels which are always subjected to a general state of multiaxial stresses. Thus, the mechanical properties and the failure criteria corresponding to different failure mechanisms for open-cell foams under multiaxial stresses are essential and important to the structural integrity of lightweight sandwich panels. Since open-cell foams are normally anisotropic due to processing, their mechanical properties will be affected by their cell geometry, namely the anisotropy ratio. In this paper, the failure envelopes of anisotropic open-cell foams are generated and presented. Different failure mechanisms including plastic yielding, brittle crushing, elastic buckling and fracturing are taken into account to construct the failure envelopes of anisotropic open-cell foams. For the case of axisymmetric stress state, the effects of the anisotropy ratio on the mechanical behavior and the failure envelopes of open-cell foams are evaluated.

    Chapter 1 Introduction----------------------------1 Chapter 2 Literature Review-----------------------4 2.1 Plastic yielding----------------------4 2.2 Brittle crushing----------------------6 2.3 Elastic buckling----------------------8 2.4 Brittle fracturing--------------------8 Chapter 3 Plastic yielding-----------------------13 3.1 Uniaxial plastic yielding strength---13 3-1-1 Along the X3 direction---------14 3-1-2 Along the X1 or X2 direction---14 3.2 Pseudo-isotropy for anisotropic open-cell foams----------------------15 3.3 Fully plastic moment for multiaxial stresses-----------------------------16 3.4 Plastic yielding of anisotropic open-cell foams----------------------17 3-4-1 Along the direction----------17 3-4-2 Along the X1 or X2 direction---19 3-4-3 Results and discussio----------20 Chapter 4 Brittle Crushing-----------------------31 4.1 Uniaxial brittle crushing strength---31 4-1-1 Along the X3 direction---------31 4-1-2 Along the X1 or X2 direction---32 4.2 Pseudo-isotropy for anisotropic open-cell foams----------------------32 4.3 Rupture moment for multiaxial stresses-----------------------------33 4.4 Brittle crushing of anisotropic open-cell foam-----------------------33 4-4-1 Along the X3 direction---------33 4-4-2 Along the X1 or X2 direction---35 4-4-3 Results and discussion---------36 Chapter 5 Elastic Buckling-----------------------45 5.1 Rectangular hexagonal prism model----47 5.2 Analysis for the elastic buckling of anisotropic foams--------------------47 5-2-1 Mode I-------------------------49 5-2-2 Mode II------------------------51 5-2-2-1 Mode II-1--------------52 5-2-2-2 Mode II-2--------------54 5-2-3 Mode III-----------------------55 5-2-3-1 Mode III-1-------------56 5-2-3-2 Mode III-2-------------58 5.3 Results and discussion---------------59 Chapter 6 Brittle Fracture-----------------------84 6.1 Analysis for brittle fracture--------84 6-1-1 Along the X3 direction---------85 6-1-2 Along the X1 or X2 direction---87 6-1-2-1 Type I-----------------87 6-1-2-2 Type II----------------89 6.2 Results and discussion---------------90 Chapter 7 Failure Envelopes---------------------108 Chapter 8 Conclusions---------------------------122

    [1] L. J. GIBSON, M. F. ASHBY, “Cellular solids” (1998)

    [2] L. J. GIBSON, M. F. ASHBY, J. ZHANG and T. C. TRIANTAFILLOU,
    “Failure surfaces for cellular materials under multiaxial loads
    – I. Modelling” International Journal of Mechanical Sciences 31,
    635 (1989)

    [3] S. K. MAITI, M. F. ASHBY and L. J. GIBSON, “Fracture toughness of
    brittle cellular solids”, Scripta Metallurgica 18, 213 (1984)

    [4] Y. Y. LI, Master Thesis, “不同微結構蜂巢材料之雙軸彈性挫屈強度”,
    Cheng Kung University Engineering Dept., Taiwan (2003)

    [5] J. ZHANG and M. F. ASHBY, “Buckling of honeycombs under in-plane
    biaxial stresses”, International Journal of Mechanical Sciences 34,
    491 (1992)

    [6] J. ZHANG and M. F. ASHBY, “The Out-of –plane properties of
    honeycombs”, International Journal of Mechanical Sciences 34, 475
    (1992)

    [7] L. J. GIBSON, M. F. ASHBY, J. ZHANG and T. C. TRIANTAFILLOU,
    “Failure surfaces for cellular materials under multiaxial loads
    – II. Comparison of models with experiment” International Journal
    of Mechanical Sciences 31, 664 (1989)

    [8] J. S. HUANG and C. Y. CHOU, “Survival probability for brittle
    isotropic foams under multiaxial loading”, Journal of Materials
    Science 35, 3881 (2000)

    [9] T. C. TRIANTAFILLOU and L. J. GIBON, “Multiaxial failure criteria
    for brittle foams”, International Journal of Mechanical Sciences
    32, 479 (1990)

    [10] J. S. HUANG and C. Y. CHOU, “Survival probability for brittle
    honeycombs under in-plane biaxial loading”, Journal of Materials
    Science 34, 4945 (1999)

    [11] A. T. HUBER and L. J. GIBSON, “Anisotropy of foams”, Journal of
    Materials Science 23, 3031 (1988)

    [12] S.TIMOSHENKO and J. M. GERE, “Theory of Elastic Stability”,
    McGraw-Hill, New York (1961).

    下載圖示 校內：2005-06-28公開
    校外：2005-06-28公開
    QR CODE