CAJ | 학술논문

用数值方法研究了船体表面微裂缝在海水腐蚀以及外荷载耦合作用下扩展的机理.实验表明,在给定材料和腐蚀环境的条件下,外荷载越小,微裂缝扩展并最终导致材料断裂破坏过程越长;但当荷载小于某个值(门槛值或称疲劳极限)时,这种延迟的腐蚀断裂破坏现象可以避免.为研究方便,文中假设了在腐蚀环境中工作的材料为各向同性材料.根据数值计算结果,共发现了三种可能的裂缝扩展形式,并证实了导致腐蚀疲劳断裂临界条件的存在性.最后通过计算,针对不同材料以及不同环境条件,勾勒出导致腐蚀疲劳断裂相应的临界条件曲线.
용수치방법연구료선체표면미렬봉재해수부식이급외하재우합작용하확전적궤리.실험표명,재급정재료화부식배경적조건하,외하재월소,미렬봉확전병최종도치재료단렬파배과정월장;단당하재소우모개치(문함치혹칭피로겁한)시,저충연지적부식단렬파배현상가이피면.위연구방편,문중가설료재부식배경중공작적재료위각향동성재료.근거수치계산결과,공발현료삼충가능적렬봉확전형식,병증실료도치부식피로단렬림계조건적존재성.최후통과계산,침대불동재료이급불동배경조건,구륵출도치부식피로단렬상응적림계조건곡선.
A front-tracking finite element method is used to compute the evolution of a crack-like defect that propagates by stress driven corrosion in ship structures, assumed as an isotropic, linear elastic solid. Experiments have shown that for a given material and ambient environment,the lesser the applied stress, the longer the time to fracture. However, when the applied stress decreases to a threshold level, known as a fatigue limit or a stress corrosion limit, failure of the solid can be avoided. Through the numerical simulations reported in this paper,three possible behaviors for the flaws are observed and the existence of a threshold stress level is confirmed. Finally,by computations,fracture mechanism maps showing the range of values of parameters required to cause crack blunting or sharpening are attained, i.e., a map of fatigue limits corresponding to various conditions.