聚合物ABS在对称循环交变应力作用下的应力疲劳性能及缺口敏感性研究
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摘要
随着材料科学的发展,聚合物材料作为新型的工程材料之一,越来越广泛的应用于工程领域。由聚合物制成的工程构件在交变载荷作用下的疲劳破坏日益显现,成为较为普遍的重要的破坏形式。而目前对聚合物的疲劳性能研究还比较少,远远没有金属材料充分。而聚合物构件往往都带有某种类型的缺口并承受交变载荷,所以研究聚合物缺口试件在交变载荷作用下的疲劳性能,以及缺口对聚合物材料疲劳性能的影响,具有明显的重要意义。
本文研究了聚丙烯腈-丁二烯-苯乙烯(ABS)在对称循环交变应力作用下的应力疲劳性能及缺口敏感性。其中的实验研究采用两种方法,一是升降法测定有限疲劳寿命(规定为5×10~5)的疲劳强度,二是拟合S—N曲线法,即用实验测定不同应力幅值的交变应力作用下的疲劳寿命,并根据测定的数据拟合出应力疲劳公式及其S—N曲线,再由应力疲劳公式计算有限疲劳寿命的疲劳强度。
首先应用上述两种方法测定了聚合物ABS有限疲劳寿命的疲劳强度。同时给出了聚合物ABS的三参数应力疲劳公式及其S—N曲线;这两种方法测定的疲劳强度非常接近,误差仅为0.36%。其次用升降法测定了3个不同频率的交变应力作用下的有限疲劳寿命的疲劳强度,用拟合S—N曲线法测定了8个不同频率的交变应力作用下的有限疲劳寿命的疲劳强度。实验结果表明,在实验所涉及的频率范围内,交变应力的频率对聚合物ABS的有限疲劳寿命的疲劳强度没有影响。
针对聚合物在交变载荷作用下的缺口敏感性问题,本文用升降法和拟合S—N曲线法测定了聚合物ABS具有七种缺口底部圆弧半径的缺口试件的有限疲劳寿命的疲劳强度。缺口试件的疲劳强度明显小于光滑试件的相应的疲劳强度,缺口对聚合物ABS的疲劳性能有显著影响,这种影响用疲劳缺口系数来表达。根据实验结果计算出的聚合物ABS的这七种缺口试件的疲劳缺口系数在1.40—1.75之间,并且证明了计算疲劳缺口系数的代表性公式—Neuber公式适用于聚合物ABS材料,其中的材料常数a对于聚合物ABS可取为2.5。
本文探讨了应用有限元计算软件ANSYS对聚合物ABS缺口试件进行疲劳计算的可行性。对聚合物ABS缺口试件应力疲劳曲线的有限元模拟和疲劳缺口系数的有限元计算设定了计算流程、计算控制和计算步骤。由有限元计算的聚合物ABS的七种缺口试件的有限疲劳寿命的疲劳强度及疲劳缺口系数与相应的实验结果比较,符合程度是比较好的,误差很小。
With the development of materials science, as one of the new engineering materials, polymer is applied in engineering widely. The fatigue failure of the engineering components made of polymer occurs often, and become an important mode of failure. The research on the fatigue behavior of polymer is lack relatively when compared with metal materials. Because many component of polymer have some notches and they are subjected to cyclic loading, The research on the fatigue behavior and notch sensitivity of polymer under cyclic loading has obvious Significance. The stress fatigue behavior and notch sensitivity of Acrylic nitrile -Butadiene-Styrene (ABS) under cyclic loading are studied in this paper. Two experimental methods are used, One is the "up and down method" by which the fatigue strength of finite life (the number of set cycles is 5×10~5) is determined. Another is the "fitting S-N curve method", by this method the number of cycles-to-failure with some different stress amplitude of cyclic load are determined, and the stress fatigue formula and the S-N diagram are fitted, and the fatigue strength is estimated accord to the formula.
First, the fatigue strength of finite life of polymer ABS is determined by above two methods, and the fatigue strength formula with three parameters and the S-N curve are given; the fatigue strength determined by two methods are close to each other, the error is 0.36 percent only. Then, the fatigue strength of finite life under cyclic loading with three different frequencies are determined by "up and down method", and the fatigue Strength under cyclic loading with eight different frequencies are determined by "fitting S-N curve method". It is show by experimental results that the fatigue Strength of finite life of polymer ABS is not affected by the frequency of the cyclic loading.
For the notch sensitivity of polymer ABS, the fatigue strength of notched specimens with seven arc radius of notch bottom are determined by "up and down method" and "fitting S-N curve method". The fatigue strength of notched specimens are obviously smaller than the fatigue strength of smooth one, the fatigue behavior of polymer ABS is significantly influenced by the notch, and the fatigue notch factor is used for expressing this influence. The fatigue notch factors of the seven notched specimens determined by experimental results are between 1.40 and 1.75, and it is proved that Neuber formula- the representative formula for calculating fatigue notch factor is applicable to polymer ABS, in which the material constant "a" is equal to 2.5.
The possibility of the fatigue calculation for notched specimens of polymer ABS with the finite element computers software ANSYS is discussed in this paper. The calculation process, control and steps are set for simulation the stress fatigue curve of the notched specimens and calculating the fatigue notch factors of polymer ABS. The fatigue strength and fatigue notch factors of the notched specimens of polymer ABS are calculated, and conform to the corresponding experimental results, the error between the calculate value and experimental value is small.
本文研究了聚丙烯腈-丁二烯-苯乙烯(ABS)在对称循环交变应力作用下的应力疲劳性能及缺口敏感性。其中的实验研究采用两种方法,一是升降法测定有限疲劳寿命(规定为5×10~5)的疲劳强度,二是拟合S—N曲线法,即用实验测定不同应力幅值的交变应力作用下的疲劳寿命,并根据测定的数据拟合出应力疲劳公式及其S—N曲线,再由应力疲劳公式计算有限疲劳寿命的疲劳强度。
首先应用上述两种方法测定了聚合物ABS有限疲劳寿命的疲劳强度。同时给出了聚合物ABS的三参数应力疲劳公式及其S—N曲线;这两种方法测定的疲劳强度非常接近,误差仅为0.36%。其次用升降法测定了3个不同频率的交变应力作用下的有限疲劳寿命的疲劳强度,用拟合S—N曲线法测定了8个不同频率的交变应力作用下的有限疲劳寿命的疲劳强度。实验结果表明,在实验所涉及的频率范围内,交变应力的频率对聚合物ABS的有限疲劳寿命的疲劳强度没有影响。
针对聚合物在交变载荷作用下的缺口敏感性问题,本文用升降法和拟合S—N曲线法测定了聚合物ABS具有七种缺口底部圆弧半径的缺口试件的有限疲劳寿命的疲劳强度。缺口试件的疲劳强度明显小于光滑试件的相应的疲劳强度,缺口对聚合物ABS的疲劳性能有显著影响,这种影响用疲劳缺口系数来表达。根据实验结果计算出的聚合物ABS的这七种缺口试件的疲劳缺口系数在1.40—1.75之间,并且证明了计算疲劳缺口系数的代表性公式—Neuber公式适用于聚合物ABS材料,其中的材料常数a对于聚合物ABS可取为2.5。
本文探讨了应用有限元计算软件ANSYS对聚合物ABS缺口试件进行疲劳计算的可行性。对聚合物ABS缺口试件应力疲劳曲线的有限元模拟和疲劳缺口系数的有限元计算设定了计算流程、计算控制和计算步骤。由有限元计算的聚合物ABS的七种缺口试件的有限疲劳寿命的疲劳强度及疲劳缺口系数与相应的实验结果比较,符合程度是比较好的,误差很小。
With the development of materials science, as one of the new engineering materials, polymer is applied in engineering widely. The fatigue failure of the engineering components made of polymer occurs often, and become an important mode of failure. The research on the fatigue behavior of polymer is lack relatively when compared with metal materials. Because many component of polymer have some notches and they are subjected to cyclic loading, The research on the fatigue behavior and notch sensitivity of polymer under cyclic loading has obvious Significance. The stress fatigue behavior and notch sensitivity of Acrylic nitrile -Butadiene-Styrene (ABS) under cyclic loading are studied in this paper. Two experimental methods are used, One is the "up and down method" by which the fatigue strength of finite life (the number of set cycles is 5×10~5) is determined. Another is the "fitting S-N curve method", by this method the number of cycles-to-failure with some different stress amplitude of cyclic load are determined, and the stress fatigue formula and the S-N diagram are fitted, and the fatigue strength is estimated accord to the formula.
First, the fatigue strength of finite life of polymer ABS is determined by above two methods, and the fatigue strength formula with three parameters and the S-N curve are given; the fatigue strength determined by two methods are close to each other, the error is 0.36 percent only. Then, the fatigue strength of finite life under cyclic loading with three different frequencies are determined by "up and down method", and the fatigue Strength under cyclic loading with eight different frequencies are determined by "fitting S-N curve method". It is show by experimental results that the fatigue Strength of finite life of polymer ABS is not affected by the frequency of the cyclic loading.
For the notch sensitivity of polymer ABS, the fatigue strength of notched specimens with seven arc radius of notch bottom are determined by "up and down method" and "fitting S-N curve method". The fatigue strength of notched specimens are obviously smaller than the fatigue strength of smooth one, the fatigue behavior of polymer ABS is significantly influenced by the notch, and the fatigue notch factor is used for expressing this influence. The fatigue notch factors of the seven notched specimens determined by experimental results are between 1.40 and 1.75, and it is proved that Neuber formula- the representative formula for calculating fatigue notch factor is applicable to polymer ABS, in which the material constant "a" is equal to 2.5.
The possibility of the fatigue calculation for notched specimens of polymer ABS with the finite element computers software ANSYS is discussed in this paper. The calculation process, control and steps are set for simulation the stress fatigue curve of the notched specimens and calculating the fatigue notch factors of polymer ABS. The fatigue strength and fatigue notch factors of the notched specimens of polymer ABS are calculated, and conform to the corresponding experimental results, the error between the calculate value and experimental value is small.
引文
[1]武艳霞,陈维毅.高分子材料研究进展.太原理工大学学报,vol.36,No.6,NOV.2005
[2]李强.玻璃态高聚物细观损伤断裂统计力学[J].力学进展,1999,25(4):451-470.
[3]David J Krzypow,Clare M Rimna.Cyclic steady state stress-strain behavior of UHMW polyethylene[J].Biomaterials,2000(21):2081-2087.
[4]冯力军.聚甲基丙烯酸甲酯疲劳裂纹扩展的研究[J].高分子材料科学与工程,2000,16(6):121-123.
[5]ABS R MARISSEN."The effect of material defects on the fatigue behavior and the fracture strain[J].Journal of materials sdence,2001(36):4167-4180.
[6]姚卫星,顾怡.论疲劳缺口缩减系数K_f.工程力学,vol.12,No.3,1995.8.
[7]叶笃毅,王德俊.疲劳缺口系数K_f和随机疲劳寿命估算.机械强度,vol.13,No.1,1991.12
[8]叶笃毅,王德俊.一种估计疲劳缺口系数K_f的新方法.尔北大学学报,vol.15,No.6,1994.12
[9]谢根栓,王茂廷.疲劳缺口系数K_f确定方法的研究.力学与实践,vol.13,No.2,1991
[10]郑修麟,金属疲劳的定量理论[M].西安:西北工业大学出版社,1994
[11]王从曾.材料性能学[M].北京:北京工业大学出版社,2001.
[12]何其笙.高聚物的力学性能(M].合肥:中国科学技术大学出版社,1996.
[13]张胜民.基于有限元软件ANSYS 7.0的结构分析[M].北京:清华大学出版社,2003.
[14]杨晓翔,毛银洁,匡震邦.Ⅴ型切口的断裂研究[J].固体力学学报,1996,17:353-359.
[15]陈传尧,疲劳与断裂[M].武汉:华中科技大学出版社,2002.1
[16]许凤利.高分子材料力学实验[M].北京:科学出版社,1988.
[17]束德林,工程材料力学性能[M].北京:机械工业出版社,2003.7
[18]刘瑞堂,刘文博.工程材料力学性能[M].哈尔滨:哈尔滨工业大学出版社,2001.8
[19]张朝晖.ANSYS8.0结构分析及实例解析[M].机械工业出版社,2005.3,453-477
[20]S.Suresh.材料的疲劳[M].国防工业出版社,1993.10
[21]程育仁.疲劳强度[M].中国铁道出版社.1990.11
[22]杨晓翔,毛银沽,匡震邦.Ⅴ型切口的断裂研究[J].固体力学学报,1996,17:353-359
[23]周武雷,蔡长安,魏桂耀.聚丙烯腈-丁二烯-苯乙烯(ABS)的缺口敏感性研究.贵州工业大学学报[J].2006,35(3):61-65
[24]陈耀明,评价及估算切口疲劳强度的新方法[M].北京:航空工业出版社,20
[25]周维祥.塑料测试技术[M].北京:化学工业出版社,1997.
[26]Meyer RW,Pruitt I A.The effect of cyclic true strain on the morphology,structure,and relaxation behavior of ultra high molecular weight polyethylene[J].Polymer,2001,42(5):293-306.
[27]Wang B,Lu H.Strength of damaged polycarbonate after fatigue[J].Theoretical and Applied Fracture Mechanics,2003(39):163-168.
[28]R.E.Peterson:Analytic Approach to Stress Concenfration Effect in Fatigue of Aircraft Materials,Proc.of the Symposium on Fatigue of Aircraft Structures,273-299,WADC Technical Report 59-507.August(1959)
[29]Mills,Walker.Fatigue crack initiation in glassy plastics in high strain fatigue test[J].Journal of materials science,1980,18(15):32-40.
[30]Manson J A,Hertzberg R W.Comment on a model of fatigue crack growth in polymers[J].J Mater Sci,1979(14):1754-1758.
[31]ASTM Committee E-9 on Fatigue.Handbook of fatigue testing[M].Philadelphia,American Society for Testing and Materials,1974.
[32]Karr C L,Week B.Least median squares curve fitting using a genetic algorithm[J].Engineering applications of Artificial Intelligence。1995,8(2):177-189.
[33]JI Fengxian,YAO Weixing.Weighted least square method for s-n curve fitting.College of Aerospace Engineering,NUAA,29 Yu dao Street,Nan jing,210016,P.R.China) 06.1
[2]李强.玻璃态高聚物细观损伤断裂统计力学[J].力学进展,1999,25(4):451-470.
[3]David J Krzypow,Clare M Rimna.Cyclic steady state stress-strain behavior of UHMW polyethylene[J].Biomaterials,2000(21):2081-2087.
[4]冯力军.聚甲基丙烯酸甲酯疲劳裂纹扩展的研究[J].高分子材料科学与工程,2000,16(6):121-123.
[5]ABS R MARISSEN."The effect of material defects on the fatigue behavior and the fracture strain[J].Journal of materials sdence,2001(36):4167-4180.
[6]姚卫星,顾怡.论疲劳缺口缩减系数K_f.工程力学,vol.12,No.3,1995.8.
[7]叶笃毅,王德俊.疲劳缺口系数K_f和随机疲劳寿命估算.机械强度,vol.13,No.1,1991.12
[8]叶笃毅,王德俊.一种估计疲劳缺口系数K_f的新方法.尔北大学学报,vol.15,No.6,1994.12
[9]谢根栓,王茂廷.疲劳缺口系数K_f确定方法的研究.力学与实践,vol.13,No.2,1991
[10]郑修麟,金属疲劳的定量理论[M].西安:西北工业大学出版社,1994
[11]王从曾.材料性能学[M].北京:北京工业大学出版社,2001.
[12]何其笙.高聚物的力学性能(M].合肥:中国科学技术大学出版社,1996.
[13]张胜民.基于有限元软件ANSYS 7.0的结构分析[M].北京:清华大学出版社,2003.
[14]杨晓翔,毛银洁,匡震邦.Ⅴ型切口的断裂研究[J].固体力学学报,1996,17:353-359.
[15]陈传尧,疲劳与断裂[M].武汉:华中科技大学出版社,2002.1
[16]许凤利.高分子材料力学实验[M].北京:科学出版社,1988.
[17]束德林,工程材料力学性能[M].北京:机械工业出版社,2003.7
[18]刘瑞堂,刘文博.工程材料力学性能[M].哈尔滨:哈尔滨工业大学出版社,2001.8
[19]张朝晖.ANSYS8.0结构分析及实例解析[M].机械工业出版社,2005.3,453-477
[20]S.Suresh.材料的疲劳[M].国防工业出版社,1993.10
[21]程育仁.疲劳强度[M].中国铁道出版社.1990.11
[22]杨晓翔,毛银沽,匡震邦.Ⅴ型切口的断裂研究[J].固体力学学报,1996,17:353-359
[23]周武雷,蔡长安,魏桂耀.聚丙烯腈-丁二烯-苯乙烯(ABS)的缺口敏感性研究.贵州工业大学学报[J].2006,35(3):61-65
[24]陈耀明,评价及估算切口疲劳强度的新方法[M].北京:航空工业出版社,20
[25]周维祥.塑料测试技术[M].北京:化学工业出版社,1997.
[26]Meyer RW,Pruitt I A.The effect of cyclic true strain on the morphology,structure,and relaxation behavior of ultra high molecular weight polyethylene[J].Polymer,2001,42(5):293-306.
[27]Wang B,Lu H.Strength of damaged polycarbonate after fatigue[J].Theoretical and Applied Fracture Mechanics,2003(39):163-168.
[28]R.E.Peterson:Analytic Approach to Stress Concenfration Effect in Fatigue of Aircraft Materials,Proc.of the Symposium on Fatigue of Aircraft Structures,273-299,WADC Technical Report 59-507.August(1959)
[29]Mills,Walker.Fatigue crack initiation in glassy plastics in high strain fatigue test[J].Journal of materials science,1980,18(15):32-40.
[30]Manson J A,Hertzberg R W.Comment on a model of fatigue crack growth in polymers[J].J Mater Sci,1979(14):1754-1758.
[31]ASTM Committee E-9 on Fatigue.Handbook of fatigue testing[M].Philadelphia,American Society for Testing and Materials,1974.
[32]Karr C L,Week B.Least median squares curve fitting using a genetic algorithm[J].Engineering applications of Artificial Intelligence。1995,8(2):177-189.
[33]JI Fengxian,YAO Weixing.Weighted least square method for s-n curve fitting.College of Aerospace Engineering,NUAA,29 Yu dao Street,Nan jing,210016,P.R.China) 06.1