摘要
【目的】研究初始缺口为圆形的样品在纵轴拉伸应力作用下起裂,并在样品裂纹扩展方向确定后,再加上横轴压力下裂纹的扩展情况。观察横轴压力对其扩展方向的影响,从而得出施加压力修复正在扩展的裂纹样品的模拟结果。【方法】使用晶体相场法(PFC)进行模拟,获得裂纹扩展的演变图。【结果】在纵轴拉应力条件下,应变在达到一定数值后圆形缺口开始发射位错和空位,位错向前运动;之后柏氏矢量相反的位错相遇并相互湮灭,没有湮灭的位错组合成位错对并产生裂纹;最后微裂纹之间、微裂纹与原始缺口之间相互合并。裂纹稳定地朝着横轴方向扩展,在此基础上施加横轴的压应力,发现左侧裂纹扩展方向发生两次改变,并往裂纹扩展方向发射位错。同时初始设置的圆形缺口也有形状变化,并往纵轴发射位错。【结论】晶体相场法能有效模拟晶体裂纹扩展的微观现象。
【Objective】The sample with a circular initial gap was cracked under the tensile stress of the longitudinal axis,and the crack propagation under the transverse axis pressure was added after the crack propagation direction of the sample was determined.The effect of the transverse axis pressure on its direction of expansion was observed to derive the simulation results of applying apressure to repair the crack sample that was expanding.【Methods】Phase field crystal method(PFC)was used for simulation to obtain an evolution map of crack propagation.【Results】Under the tensile stress condition of the longitudinal axis,after the strain reaches a certain value,the circular notch starts to emit dislocations and vacancies,and the dislocations move forward.Then,the opposite dislocations of the Berth's vector meet and annihilate each other,and the dislocations without annihilation are combined into dislocation pairs and cracks are formed.Finally,the micro-cracks,micro-cracks and original gaps merge with each other.The crack spreads stably toward the horizontal axis,and the compressive stress of the transverse axis is applied on the ba-sis of this,and it is found that the direction of the crack propagation on the left side changes twice,and dislocations are emitted in the direction of crack propagation.At the same time,the initially set circular notch also has a shape change and emits dislocations to the vertical axis.【Conclusion】The crystal phase field method can effectively simulate the microscopic phenomenon of crystal crack propagation.
引文
[1] MOELANS N,BLAINPAIN B,WOLLANTS P.An introduction to phase-fileld modeling of microstruture evolution[J].Calphad,2008,32(2):268-294.
[2] WANG Y Z,LI J.Phase field modeling of defects and deformation[J].Acta Masterialia,2010,58(4):1212-1235.
[3]罗志荣,卢成健,高英俊.相场法研究初始微观观结构对晶粒长大的影响[J].广西科学,2016,23(5):432-436,442.LUO Z R,LU C J,GAO Y J.Phase field study on effect of initial microstructure on grain growth[J].Guangxi Sciences,2016,23(5):432-436,442.
[4]刘瑶,袁龙乐,卢强华,等.晶体相场模拟取向角对晶界湮没过程的影响[J].广西科学,2016,23(5):437-442.LIU Y,YUAN L L,LU Q H,et al.Phase-field-crystal simulation of effect of different orientation angle on annihilation of grain boundary[J].Guangxi Sciences,2016,23(5):437-442.
[5]黄世叶,李胜男,胡绪志,等.晶界位错运动的空位晶体相场模拟[J].广西科学,2016,23(5):459-464.HUANG S Y,LI S N,HU X Z,et al.Vacancy phasefield-crystal simulation of dislocation motion of grain boundary[J].Guangxi Sciences,2016,23(5):459-464.
[6]杨瑞琳,刘瑶,胡绪志,等.双位错滑移运动的晶体相场模拟[J].广西科学,2016,23(5):443-447.YANG R L,LIU Y,HU X Z,et al.Phase-field-crystal simulation of double dislocation gliding[J].Guangxi Sciences,2016,23(5):443-447.
[7]叶里,胡绪志,黄礼琳,等.拉应力作用下晶界位错运动过程的晶体相场模拟[J].广西科学,2016,23(5):470-473,484.YE L,HU X Z,HUANU L L,et al.Phase-field-crystal simulation of grain boundary dislocation motion under tensile stress[J].Guangxi Sciences,2016,23(5):470-473,484.
[8]高英俊,黄礼琳,周文权,等.高温应变下的亚晶界湮没与位错旋转机制的晶体相场模拟[J].中国科学:技术科学,2015,45(3):306-321.GAO Y J,HUANG L L,ZHOU W Q,et al.Phase field crystal simulation of subgrain boundary annihilation and dislocation rotation mechanism under strain at high temperature[J].Scientia Sinica:Technologica,2015,45(3):306-321.
[9]卢昱江,孔令一,邓芊芊,等.微裂纹起裂扩展机理的晶体相场模拟[J].广西科学院学报,2017,33(4):240-245.LU Y J,KONG L Y,DENG Q Q,et al.Phase field crystal simulation of nucleation and propagation of micro-cracks[J].Journal of Guangxi Academy of Sciences,2017,33(4):240-245.
[10]宁岁婷,胡绪志,黄礼琳,等.三角缺口与圆形缺口起裂和裂纹扩展的晶体相场模拟[J].广西科学,2017,24(6):540-544,550.NING S T,HU X Z,HUANG L L,et al.Phase filed crystal simulation of nucleation and extension of crack at notch with circle or triangle[J].Guangxi Sciences,2017,24(6):540-544,550.
[11]满海,胡绪志,宁岁婷,等.晶体相场模拟晶界萌生裂纹扩展[J].广西科学院学报,2017,33(4):246-249,260.MAN H,HU X Z,NING S T,et al.Phase field simulation of crack nucleation and extension from grain boundary[J].Journal of Guangxi Academy of Sciences,2017,33(4):246-249,260.
[12]高英俊,罗志荣,黄礼琳,等.韧性材料的微裂纹扩展和连通的晶体相场模拟[J].中国有色金属学报,2013,23(7):1892-1899.GAO Y J,LUO Z R,HUANG L L,et al.Phase-fieldcrystal modeling for microcrack propagation and connecting of ductile material[J].The Chinese Journal of Nonferrous Metals,2013,23(7):1892-1899.
[13]阚盈.塑性变形中孔隙的产生、修复模型及数值模拟[D].大连:大连理工大学,2014.KAN Y.Initiation and healing models f pores and numercialsimulation in plastic deformation[D].Dalian:Dalian University of Technology,2014.
[14]马凯.金属内部微裂纹的热塑性修复的元胞自动机模拟[D].上海:上海工程技术大学,2013.MA K.Cellular automata simulation of micro-crack thermoplastic healing in metal[D].Shanghai:Shanghai University of Engineering Science,2013.
[15]袁朝龙.大型锻件内裂纹缺陷修复的物理模拟研究[D].北京:清华大学,2002.YUAN C L.Study on healing of interior crack-type fault in heavy forging by modeling[D].Beijing:Tsinghua University,2002.
[16] CHEN N Z.A stop-hole method for marine and offshore structures[J].International Journal of Fatigue,2016,88:49-57.
[17]孔璞萍,刘志平,周凯,等.起重机金属结构裂纹的复合修复方法[J].中国机械工程,2018,29(13):1610-1614.KONG P P,LIU Z P,ZHOU K,et al.Composite repair method of crane metal constructions[J].China Mechanical Engineering,2018,29(13):1610-1614.