Si_3N_4结合SiC耐火陶瓷裂纹萌生细观数值分析
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摘要
将复合球模型导入损伤力学模型中,模拟了材料在高温环境下受拉和受压损伤时的细观演化过程;推导了材料损伤参数与界面相参数之间的函数关系。研究表明,当外加载荷小于材料损伤临界值、介于材料损伤临界值和最大承载值之间时,不论材料承受拉载还是压载,都存在无损伤演化的线弹性阶段和微裂纹扩展区逐渐增大的损伤强化阶段;若应力达到最大承载值后仍继续增大,材料损伤将过渡到损伤局部化阶段,损伤局部化的连续也就是材料宏观裂纹萌生的开始。
In order to investigate the thermal damage mechanism of Si_3N_4 bonded SiC refractory ceramics,the damage evolution of the materials under tension and pressure at high temperature was simulated on a micromechanical scale,which was based on a composite sphere model incorporated with the damage mechanics model.And the function relationship between the damage parameters and the interface parameters was deduced.The analyses suggest that there is a linear elastic phase without damage evolution when the load is less than the critical value;and a damage strengthening phase with increasing micro-crack expanding region when the load is higher than the critical and lower than the maximum.The above facts are true whether the material is under tension or pressure.If the load keeps increasing,the damage localization phase would occur,in which the damage development is the beginning of the macroscopic cracking of the material.The results provide references for preventing these materials from fatigue fracture at high temperature.
In order to investigate the thermal damage mechanism of Si_3N_4 bonded SiC refractory ceramics,the damage evolution of the materials under tension and pressure at high temperature was simulated on a micromechanical scale,which was based on a composite sphere model incorporated with the damage mechanics model.And the function relationship between the damage parameters and the interface parameters was deduced.The analyses suggest that there is a linear elastic phase without damage evolution when the load is less than the critical value;and a damage strengthening phase with increasing micro-crack expanding region when the load is higher than the critical and lower than the maximum.The above facts are true whether the material is under tension or pressure.If the load keeps increasing,the damage localization phase would occur,in which the damage development is the beginning of the macroscopic cracking of the material.The results provide references for preventing these materials from fatigue fracture at high temperature.
引文
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[2]C.Vinet,P.Priou.Micromechanical Damage Model Taking Loading-induced Anisotropy into Account[J].Aerospace Science and Technology,1997,1(1):65~76.
[3]甘荣飞,廉俊盛,姚博.脆性基复合材料破坏过程细观力学研究[J].江西建材,2016(1):10~11.
[4]郑恒伟,彭向和,丁剑平,等.陶瓷颗粒增强复合材料细观力学模型[J].中国陶瓷,2016,52(7):39~42.
[5]袁硕伟,杨自春.氮化硅结合碳化硅砖的微观结构模型及热冲击载荷下裂纹起始行为[J].耐火材料,2015,49(12):426~431.
[6]曹卉,芮执元,罗德春,等.加载速率对单晶γ-TiAl裂纹扩展影响的分子动力学模拟[J].材料科学与工程学报,2016,34(2):321~325.
[7]邵彬彬,徐颖,等.C/SiC复合材料的动态力学性能及微观结构分析[J].材料科学与工程学报,2016,34(4):603~606.
[8]杨康,王志刚,刘昌明.基于细观力学的耐火材料单轴拉伸微损伤模型研究[J].耐火材料,2014,48(10):352~355.
[9]赵嘉煜,杨自春,曹跃云,等.增压锅炉耐火砖疲劳裂纹扩展特性研究[J].耐火材料,2015,49(4):117~119.
[10]Zvi.Hashin.The Elastic Moduli of Heterogeneous Materials[J].Journal of Applied Mechanics,1962,29(1):143~150.
[11]J.W.Ju,T.M.Chen,Micromechanics and Effective Moduli of Elastic Composites Containing Randomly Dispersed Ellipsoidal Inhomogeneities[J].Acta Mechanica,1994,103(1):103~121.
[12]J.W.Ju,T.M.Chen.Effective Elastic Moduli of Two-phase Composites Containing Randomly Dispersed Spherical Inhomogeneities[J].Acta Mechanica,1994,103(1):123~144.
[13]宋文章,杨自春,李昆锋,等.增压锅炉耐火砖衬结构的断裂失效分析[J].锅炉制造,2014(7):14~19.
[14]陈小祥.基于细观力学方法的耐火材料损伤模型研究[D].武汉:武汉科技大学,2012.