中国机械工程
中國機械工程
중국궤계공정
China Mechanical Engineering
2015年
21期
2963-2969,2970
,共8页
高红俐%郑欢斌%刘欢%刘辉
高紅俐%鄭歡斌%劉歡%劉輝
고홍리%정환빈%류환%류휘
高频谐振载荷%疲劳裂纹尖端%动态有限元%位移%应变场%应力强度因子
高頻諧振載荷%疲勞裂紋尖耑%動態有限元%位移%應變場%應力彊度因子
고빈해진재하%피로렬문첨단%동태유한원%위이%응변장%응력강도인자
high frequency resonant load%fatigue crack tip%finite element method(FEM)%disG placement%strain field%stress intensity factor(SIF)
为研究高频谐振式疲劳裂纹扩展试验中带有Ⅰ型预制裂纹的紧凑拉伸(CT)试件裂纹尖端力学参数的变化规律,利用动态有限元方法,采用 ANSYS 和 MATLAB 软件编写程序,计算了 CT 试件在高频恒幅正弦交变载荷作用下,在一个应力循环及裂纹扩展到不同长度时裂纹尖端区域的位移、应变场及裂纹尖端的应力强度因子,并分析了其变化规律。在计算裂纹尖端应力强度因子时,首先采用静态有限元方法和理论公式验证了有限元建模和计算的正确性,然后采用动态有限元方法研究了裂纹扩展过程中裂纹尖端应力强度因子的变化规律。最后进行了高频谐振式疲劳裂纹扩展试验,采用动态高精度应变仪测量了裂纹扩展到不同阶段时裂纹尖端点的应变,并对有限元计算结果进行了验证。研究结果表明：在稳态裂纹扩展阶段,高频谐振载荷作用下Ⅰ型疲劳裂纹尖端位移、应变及应力强度因子均为与载荷同一形式的交变量；随着裂纹的扩展,Ⅰ型疲劳裂纹尖端的位移、应变及应力强度因子幅不断增大；静态应力强度因子有限元计算值和理论值的误差为2??51％,裂纹尖端点应变有限元计算结果和试验结果最大误差为2??93％。
為研究高頻諧振式疲勞裂紋擴展試驗中帶有Ⅰ型預製裂紋的緊湊拉伸(CT)試件裂紋尖耑力學參數的變化規律,利用動態有限元方法,採用 ANSYS 和 MATLAB 軟件編寫程序,計算瞭 CT 試件在高頻恆幅正絃交變載荷作用下,在一箇應力循環及裂紋擴展到不同長度時裂紋尖耑區域的位移、應變場及裂紋尖耑的應力彊度因子,併分析瞭其變化規律。在計算裂紋尖耑應力彊度因子時,首先採用靜態有限元方法和理論公式驗證瞭有限元建模和計算的正確性,然後採用動態有限元方法研究瞭裂紋擴展過程中裂紋尖耑應力彊度因子的變化規律。最後進行瞭高頻諧振式疲勞裂紋擴展試驗,採用動態高精度應變儀測量瞭裂紋擴展到不同階段時裂紋尖耑點的應變,併對有限元計算結果進行瞭驗證。研究結果錶明：在穩態裂紋擴展階段,高頻諧振載荷作用下Ⅰ型疲勞裂紋尖耑位移、應變及應力彊度因子均為與載荷同一形式的交變量；隨著裂紋的擴展,Ⅰ型疲勞裂紋尖耑的位移、應變及應力彊度因子幅不斷增大；靜態應力彊度因子有限元計算值和理論值的誤差為2??51％,裂紋尖耑點應變有限元計算結果和試驗結果最大誤差為2??93％。
위연구고빈해진식피로렬문확전시험중대유Ⅰ형예제렬문적긴주랍신(CT)시건렬문첨단역학삼수적변화규률,이용동태유한원방법,채용 ANSYS 화 MATLAB 연건편사정서,계산료 CT 시건재고빈항폭정현교변재하작용하,재일개응력순배급렬문확전도불동장도시렬문첨단구역적위이、응변장급렬문첨단적응력강도인자,병분석료기변화규률。재계산렬문첨단응력강도인자시,수선채용정태유한원방법화이론공식험증료유한원건모화계산적정학성,연후채용동태유한원방법연구료렬문확전과정중렬문첨단응력강도인자적변화규률。최후진행료고빈해진식피로렬문확전시험,채용동태고정도응변의측량료렬문확전도불동계단시렬문첨단점적응변,병대유한원계산결과진행료험증。연구결과표명：재은태렬문확전계단,고빈해진재하작용하Ⅰ형피로렬문첨단위이、응변급응력강도인자균위여재하동일형식적교변량；수착렬문적확전,Ⅰ형피로렬문첨단적위이、응변급응력강도인자폭불단증대；정태응력강도인자유한원계산치화이론치적오차위2??51％,렬문첨단점응변유한원계산결과화시험결과최대오차위2??93％。
This paper explored the variation law of mechanics parameters at fatigue crack tip of compact tension(CT)specimen with type Ⅰ pre??notch based on dynamic FEM in the high frequency resonant fatigue crack propagation tests.The displacement fields,the strain fields and the SIFs at CT specimen fatigue crack tip in one stress cycle and at different crack lengths under constant amplitude high frequency sinusoidal alternating loading condition were calculated and the related variation laws of mechanics parameters were analyzed.In order to calculate the dynamic SIF at fatigue crack tip,the static SIF was calculated first,the comparing results of the static finite element analysis with the theG oretical calculation show that finite element modeling and calculated method and results are accurate. Secondly,the variation law of SIF at crack tip during the process of fatigue crack propagation tests was studied by dynamic FEM.Finally,the high frequency resonant fatigue crack propagation tests were performed,and the dynamic strain gauge was used to measure the strain at crack tip during one stress cycle.The research results show that during crack stable propagation stage,the displacement, strain and SIF at type Ⅰ fatigue crack tip are the same form with the high frequency resonant load, and the displacement,strain and SIF amplitude increase with the crack growth.The error of static SIF between the calculated result by FEM and the theoretical result is as 2??5 1%.The maximum error of the strain at crack tip between the calculated result by FEM and the experimental result is as 2??93%.
