Crack Propagation in Polycrystalline Elastic-Viscoplastic Materials Using Cohesive Zone Models
-
摘要: 采用内聚力模型(CZM),模拟多晶体中起裂于晶界的二维平面应变裂纹扩展.结果表明,弹粘塑性体中,初始裂纹尖端不会最先开裂.晶体本构的率敏感指数表征了塑性变形和内聚力区耗散两种机制的相互竞争.率敏感指数越大,塑性耗散能越大,内聚力区粘着能越小,使材料的塑性变形越容易,内聚力区诱发的破坏越不易;率敏感指数越小,材料响应越接近弹塑性性质,塑性耗散能减小,粘着能增大,外力功易转化为内聚力区的粘着能,使内聚力单元更易分离.增大内聚力区结合强度或临界张开位移使晶内和晶界的三轴应力度减小,即提高内聚力区韧性也使基体材料抗孔洞损伤能力提高.Abstract: Cohesive zone model was used to simulate two-dimensional plane strain crack propagation at the grain level model including grain boundary zones.Simulated results show that the original crack-tip may not be separated firstly in an elastic-viscoplastic polycrystals.The grain interior.s material properties (e.g.strain rate sensitivity) characterize the competitions between plastic and cohesive energy dissipation mechanisms.The higher the strain rate sensitivity is,the larger amount of the external work is transformed into plastic dissipation energy than into cohesive energy,which delays the cohesive zone rupturing.With the strain rate sensitivity decreased,the material property tends to approach the elastic-plastic responses.In this case,the plastic dissipation energy decreases and the cohesive dissipation energy increases which accelerates the cohesive zones debonding.Increasing the cohesive strength or the critical separation displacement will reduce the stress triaxiality at grain interiors and grain boundaries.Enhancing the cohesive zones ductility can improve the matrix materials resistance to void damage.
-
Key words:
- crack propagation /
- elasto-viscoplastic /
- cohesive zone model /
- polycrystal /
- grain boundary
-
[1] Xie W D,Sitaraman S K.An experimental technique to determine critical stress intensity factors for delamination initiation[J].Engineering Fracture Mechanics,2003,70(9):1193—1201. doi: 10.1016/S0013-7944(02)00090-5 [2] Dunn M L,Suwito W,Cunningham S.Stress intensities at notch singularities[J].Engineering Fracture Mechanics,1997,57(4):417—430. doi: 10.1016/S0013-7944(97)00019-2 [3] Meith W A,Hill M R.Domain-independent values of the J-integral for cracks in three-dimensional residual stress bearing bodies[J].Engineering Fracture Mechanics,2002,69(12):1301—1314. doi: 10.1016/S0013-7944(02)00007-3 [4] Espinosa H D,Zavattieri P D.A grain level model for the study of failure initiation and evolution in polycrystalline brittle materials—Part Ⅱ Numerial examples[J].Mechanics of Materials,2003,35(3/6):365—394. doi: 10.1016/S0167-6636(02)00287-9 [5] Bjerke T W,Lambros J.Theoretical development and experimental validation of a theramally dissipative cohesive zone model for dynamic fracture of amorphous polymers[J].Jouranl of the Mechanics and Physics of Solids,2003,51(6):1147—1170. doi: 10.1016/S0022-5096(02)00145-X [6] Dugdale D S.Yielding of steel sheets containing slits[J].Journal of the Mechanics and Physics of Solids,1960,8:100—108. doi: 10.1016/0022-5096(60)90013-2 [7] Barrenblatt G I.The mathematical theory of equilibrium cracks in brittle fracture[J].Advances in Applied Mechanics,1962,7:55—125. doi: 10.1016/S0065-2156(08)70121-2 [8] Needleman A.A continuum model for void nucleation by inclusion debonding[J].J Appl Mech,1987,54:525—531. doi: 10.1115/1.3173064 [9] Li H,Chandra N.Analysis of crack growth and crack-tip plasticity in ductile materials using cohesive zone models[J].International Journal of Plasticity,2003,19(6):849—882. doi: 10.1016/S0749-6419(02)00008-6 [10] Chandra N,Li H,Shet C,et al.Some issues in the application of cohesive zone models for metal-ceramic interfaces[J].International Journal of Solids and Structures,2002,39(10):2827—2855. doi: 10.1016/S0020-7683(02)00149-X [11] Madhusudhana K S,Narasimhan R.Experimental and numerical investigations of mixed mode crack growth resistance of a ductile adhesive joint[J].Engineering Fracture Mechanics,2002,69(7):865—883. doi: 10.1016/S0013-7944(01)00110-2 [12] Tvergaard V.Crack growth predictions by cohesive zone model for ductile fracture[J].Journal of the Mechanics and Physics of Solids,2001,49(9):2191—2207. doi: 10.1016/S0022-5096(01)00030-8 [13] Kysar J W.Energy dissipation mechanisms in ductile fracture[J].Journal of the Mechanics and Physics of Solids,2003,51(5):795—824. doi: 10.1016/S0022-5096(02)00141-2 [14] Foulk J W,Allen D H,Helms K L E.Formulation of a three-dimensional cohesive zone model for application to a finite element algorithm[J].Compute Methods in Applied Mechanics Engineering,2000,183(1/2):51—66. doi: 10.1016/S0045-7825(99)00211-X [15] Tvergaard V.Effect of fiber debonding in a whisker-reinforce metal[J].Materials Science Engineering A,1990,125(2):203—213. doi: 10.1016/0921-5093(90)90170-8 [16] Rice J R.Inelastic constitutive relations for solids: an internal-variable theory and its application to metal plasticity[J].Journal of the Mechics and Physics of Solids,1971,19:433—455. doi: 10.1016/0022-5096(71)90010-X [17] Lemaitre J,Chaboche J L.Mechanics of Solids Materials[M].U K:Cambridge University Press,1994.
点击查看大图
计量
- 文章访问数: 2742
- HTML全文浏览量: 98
- PDF下载量: 1361
- 被引次数: 0