當細胞型材料應用於較高溫之環境下（組成材料熔點之0.3倍以上），其將產生依時性的潛變或應力鬆弛，而非彈性變形、彈性挫曲或塑性變形，設計時必須加以考量其影響。本研究首先推導細胞型材料的應力鬆弛表示式，從表示式中發現細胞型材料的應力鬆弛速率與細胞型材料之相對密度、施加之初始應變及組成材料之應力鬆弛參數有關，藉由泡沫水泥之應力鬆弛實驗驗證，此表示式可適當地評估已知相對密度之泡沫材料，在承受定量之應變下，所產生之應力鬆弛速率。

　　其次，為探討具微構件變剖面對蜂巢材料之潛變及應力鬆弛的影響，本文理論推導出潛變及應力鬆弛速率表示式，其結果亦指出潛變及應力鬆弛速率，受微構件之固體質量分佈情形所影響，且與蜂巢材料之相對密度及其組成材料之潛變或鬆弛參數有關。

　　最後，考量潛變可能導致之破壞機制因所施加之應力方向而異，壓應力將導致潛變挫曲或因潛變彎曲產生過大的應變量，拉應力將造成潛變破裂，本文理論推導出具微構件變剖面之蜂巢材料之潛變挫曲表示式，同時也發現，固體質量分佈情形將影響潛變挫曲與潛變彎曲等破壞模式之轉換。至於，潛變挫曲或潛變破裂時間，本文亦有所探討，在蜂巢材料之相對密度、固體質量分佈情形及組成材料之潛變參數已知的條件下，此表示式可用以評估蜂巢材料應用於較高溫之環境下其服務時間之評估。

　　When loaded at higher temperature than about 30 percent of the melting point, cellular materials deform by creep or stress relaxation, which is time-dependent, other than elastic deflection, elastic buckling and plastic collapse of cell edges. It is of importance and should be taken into account in design. The expressions for stress relaxation rates of hexagonal honeycombs, open-cell and closed-cell foams are derived first. Theoretical results show that the stress relaxation rates of cellular materials depend on their relative density, the imposed strain and the stress relaxation parameters of the solid material, from which they are made. Experimental results indicates that the stress relaxation rates of foamed alumina cements can be estimated well from the theoretical expression we proposed if their relative density and imposed strain are known.

　　The creep strain rates and stress relaxation rates of hexagonal honeycombs with plateau borders are derived. Results indicate that the creep strain rates and stress relaxation rates of hexagonal honeycombs depend on their relative density, the solid distribution in cell edges and the parameter of solid cell edges. The effects of solid distribution in cell edges on the creep strain rates and stress relaxation rates of hexagonal honeycombs with plateau borders have been discussed in detail.

　　The theoretical expressions for describing creep-buckling and creep-rupture of hexagonal honeycombs with plateau borders are also derived. Results indicate that the service life for hexagonal honeycombs with plate borders loaded in compression or tension can be estimated if the relative density, the solid distribution and the creep parameter of solid cell edges are known.

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