摘要
本文对相变增韧陶瓷材料提出两个相变准则:(1)体膨胀—剪切应变能相变准则,(2)最大正应变相变准则,并导出Ⅰ型应力—应变场诱发相变的增韧表达式。由此得出的理论增韧值与目前已有的相变准则相比,大大接近实测值。特别是能量型准则,所得结果能覆盖以实验为基础的Chen准则的结果。
The Present Paper Proposes dilatational strain energy-shear strain energy transformation criterion and maximum principal strain transformation criterion for transforming ceramic material, and farther obtains the corresponding theoretical toughening expressions of I-type stress-strain field induced transformation. The theoretical toughening values which We can evaluate by above expressions more approach the experimental measurement values than other values by some earlier transformation criterions. In particular, the results based on dilatational strain energy-shear strain energy transformation criterion very consist with the results of Chen criterion based on experiment.The strain energy U of the material element is divided into pure dilatational strain energy U_v and shear strain energy U_s When both respectively achieve critical values U_(v.c) and U_(s.c) both respectively induce transforming pure dilatation ε_(kk)~T and transforming shear plasticity ε_e^T. We suppose the stress intensity induced by the corresponding trans-forming strain over whole transformed region are (ΔK_(tip))_(U_v) and (ΔK_(tip))_(U_s) then the total toughening contribution is (ΔK_(tip))_(U_v) plus (ΔK_(tip))_(U_s) . For I-type steady-state growth crack probrem , the plane transforming strains ε_(αβ)~T can divide into ε_(kk)~T=θ~T and ε_e^T=γ~T. For supercritical materials, We use the method given by Hutchinson et al. and according to above mentioned U_v-U_s transformation criterion obtain the toughening expression ΔK_(tip)=kEθ~T (H_v)^(1/2), Where the coefficient k concerns poisson' s ratio v and ratio λ(=ε_e^T/ε_(kk)~T/θ~T), and H_v is the height of trans formed Zone due to transformation dilatation θ~T.
出处
《应用力学学报》
CAS
CSCD
北大核心
1991年第3期29-37,148,共9页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金
关键词
陶瓷增韧力学
相变增韧
体膨胀
ceramic toughening mechanics, transformation toughening, dilatational strain energy-shear strain energy transformation criterion.
