高强混凝土动态压缩试验分析
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摘要
准确测量混凝土动态压缩性能及其应变率强化效应一直是冲击动力学研究领域的重点和难点之一。针对混凝土大口径SHPB实验,分析探讨了其中几个主要问题:应力均匀性问题、恒应变率问题和端面接触问题。研究表明:对于此次试验中混凝土试件而言,应力均匀性假设限制试验最大应变率小于166 s~(-1);杆和试件端面接触不平和接触不良使得测算出的杨氏模量和屈服强度明显小于实际值;在此基础上,给出了五步测试法和预应力法;利用复合整形技术实现了近似恒应变率加载。利用以上所发展和改进的技术得到了C110混凝土动静态应力应变曲线,结果显示,在试验范围内混凝土杨氏模量并没有应变率效应,其单轴压缩屈服强度与应变率对数呈线性正比关系,其唯象应变率强化因子为0.10。理论分析表明,大口径SHPB试验所得混凝土应变率效应是一种唯象效应,对于混凝土类压力敏感屈服材料而言,应该根据其屈服面方程对其进行校正,从而得到其本构方程中材料的应变率强化因子,分别利用Tresca屈服准则和K&C本构中屈服面方程对其进行校正,得到C110材料的真实应变率强化因子分别为0.015和0.038。
Accurate measurement of the dynamic compressive performance of concrete and its strain rate enhancement effect is a key point in impact dynamics research. In this study, aiming at the dynamic compressive behavior test of concrete C110, we examined the stress uniformity, constant loading strain rate and interface contact in the large-size Split Hopkinson Pressure Bar test and found that the upper-limit strain rate in consideration of the stress uniformity hypothesis was less than 166 s~(-1) for the concrete specimens in this test and that, owing to the imperfect contact of the interface between the rod and the end surface of the specimen, the experimental young modulus and yield strength were obviously smaller than the actual value.Then we developed the five-step test method and prestress method, by which the approximate constant strain rate loading was realized using the combined pulse shaping technology. Using the above technologies the dynamic and static stress-strain curves the concrete C110 were presented. The results showed that the strainrate effect of the young's modulus of the concrete C110 was not observed and the yield strengths of the uniaxial compression were linearly proportionate to the logarithmic strain rates, with the experimental strainrate enhancement factor to be 0.10, and that the concrete-like pressure-sensitive material should be calibrated using the yield criteria. In this research, the strain-rate enhancement factor of the concrete material,respectively, were calibrated using the Tresca yield criterion and the K&C yield criterion, and then the strainrate enhancement factor of the concrete material were found to be 0.015 and 0.038 respectively.
Accurate measurement of the dynamic compressive performance of concrete and its strain rate enhancement effect is a key point in impact dynamics research. In this study, aiming at the dynamic compressive behavior test of concrete C110, we examined the stress uniformity, constant loading strain rate and interface contact in the large-size Split Hopkinson Pressure Bar test and found that the upper-limit strain rate in consideration of the stress uniformity hypothesis was less than 166 s~(-1) for the concrete specimens in this test and that, owing to the imperfect contact of the interface between the rod and the end surface of the specimen, the experimental young modulus and yield strength were obviously smaller than the actual value.Then we developed the five-step test method and prestress method, by which the approximate constant strain rate loading was realized using the combined pulse shaping technology. Using the above technologies the dynamic and static stress-strain curves the concrete C110 were presented. The results showed that the strainrate effect of the young's modulus of the concrete C110 was not observed and the yield strengths of the uniaxial compression were linearly proportionate to the logarithmic strain rates, with the experimental strainrate enhancement factor to be 0.10, and that the concrete-like pressure-sensitive material should be calibrated using the yield criteria. In this research, the strain-rate enhancement factor of the concrete material,respectively, were calibrated using the Tresca yield criterion and the K&C yield criterion, and then the strainrate enhancement factor of the concrete material were found to be 0.015 and 0.038 respectively.
引文
[1]高光发.混凝土材料动态压缩强度的应变率强化规律[J].高压物理学报,2017,31(3):261-270.GAO Guangfa.Effect of strain-rate hardening on dynamic compressive strength of plain concrete[J].Chinese Journal of High Pressure Physics,2017,31(3):261-270.
[2]高光发,李永池,罗春涛,等.混凝土靶高速侵彻的率相关相似律研究[J].弹箭与制导学报,2011,31(3):98-100.GAO Guangfa,LI Yongchi,LUO Chuntao,et al.The study on rate-dependent similarity law of high velocity penetration into concrete target[J].Journal of Projectiles,Rockets,Missiles and Guidance,2011,31(3):98-100.
[3]高光发,李永池,胡秀章,等.一种改进的混凝土抗侵彻模型及算法[J].兵器材料科学与工程,2011,34(2):11-15.GAO Guangfa,LI Yongchi,HU Xiuzhang,et al.An improved anti-penetration engineering model and algorithm of concrete[J].Ordnance Material Science and Engineering,2011,34(2):11-15.
[4]高光发,李永池,刘卫国.多孔硬脆性材料的SHPB实验技术[J].力学与实践,2011,33(6):35-39.GAO Guangfa,LI Yongchi,LIU Weiguo.Expermental technique of SHPB for porous hard and brittle materials[J].Mechanics in Engineering,2011,33(6):35-39.
[5]宋力,胡时胜.SHPB测试中的均匀性问题及恒应变率[J].爆炸与冲击,2005,25(3):207-216.SONG Li,HU Shisheng.Stress uniformity and constant strain rate in SHPB test[J].Explosion and Shock Waves,2005,25(3):207-216.
[6]LU F,LIN Y,WANG X,et al.A theoretical analysis about the influence of interfacial friction in SHPB tests[J].International Journal of Impact Engineering,2015,79:95-101.
[7]毛勇建,李玉龙.SHPB试验中试件的轴向应力均匀性[J].爆炸与冲击,2008,28(5):448-454.MAO Yongjian,LI Yulong.Axial stress uniformity in specimens of SHPB tests[J].Explosion and Shock Waves,2008,28(5):448-454.
[8]GORHAM D A.Specimen inertia in high strain-rate compression[J].Journal of Physics D Applied Physics,2000,22(12):1888.
[9]XIAN Qian,QIU Yun,YAN Peng,et al.Effects of imperfect experimental conditions on stress waves in SHPB experiments[J].Acta Mechanica Sinica,2015,31(6):827-836.
[10]GORHAM D A.The effect of specimen dimensions on high strain rate compression measurements of copper[J].Journal of Physics D:Applied Physics,2000,24(8):1489-1492.
[11]IWAMOTO T,YOKOYAMA T.Effects of radial inertia and end friction in specimen geometry in split Hopkinson pressure bar tests:A computational study[J].Mechanics of Materials,2012,51:97-109.
[12]MENG H,LI Q M.Correlation between the accuracy of a SHPB test and the stress uniformity based on numerical experiments[J].International Journal of Impact Engineering,2003,28(5):537-555.
[13]尚兵,吴立朋,庄茁.应力不均匀性对混凝土材料动态实验结果的影响[J].工程力学,2011,28(12):33-38.SHANG Bing,WU Lipeng,ZHUANG Zhuo.The effect of stress heterogeneous on test data of concrete using SHPB[J].Engineering Mechanics,2011,28(12):33-38.
[14]朱珏,胡时胜,王礼立.SHPB试验中黏弹性材料的应力均匀性分析[J].爆炸与冲击,2006,26(4):315-322.ZHU Jue,HU Shisheng,WANG Lili.Analysis on stress uniformity of viscoelastic materials in split Hopkinson bar tests[J].Explosion and Shock Waves,2006,26(4):315-322.
[15]刘瑞堂,果春焕,张智峰.分离式Hopkinson压杆系统冲击压缩过程中试样的应力均匀化过程[J].机械工程材料,2009,33(2):25-27.LIU Ruitang,GUO Chun-huan,ZHANG Zhifeng.Stress uniformization process in specimens during compression process with split Hopkinson pressure bar system[J].Materials for Mechanical Engineering,2009,33(2):25-27.
[16]丰平,张庆明,陈利,等.SHPB测试中斜坡加载对应力均匀性和恒应变率的影响分析[J].北京理工大学学报,2010,30(5):513-516.FENG Ping,ZHANG Qingming,CHEN Li,et al.Influence of incidentpulse of slope on stress uniformity and constant strain rate in SHPB test[J].Transactions of Beijing Institute of Technology,2010,30(5):513-516.
[17]RAMESH K T.High Rates and Impact Experiments[M].Springer US,2008:929-960.DOI:10.1007/978-0-387-30877-7_33.
[18]PAN Y,CHEN W,SONG B.Upper limit of constant strain rates in a split Hopkinson pressure bar experiment with elastic specimens[J].Experimental Mechanics,2005,45(5):440-446.
[19]RAVICHANDRAN G,SUBHASH G.Critical Appraisal of Limiting Strain Rates for Compression Testing of Ceramics in a Split Hopkinson Pressure Bar[J].Journal of the American Ceramic Society,1994,77(1):263-267.
[20]ZHANG Q B,ZHAO J.A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials[J].Rock Mechanics&Rock Engineering,2014,47(4):1411-1478.
[21]GUO Y B,GAO G F,JING L,et al.Response of high-strength concrete to dynamic compressive loading[J].International Journal of Impact Engineering,2017,108:114-135.
[22]毛勇建,李玉龙,史飞飞.用经典Hopkinson杆测试弹性模量的初步探讨[J].固体力学学报,2009,30(2):170-176.MAO Yongjian,LI Yulong,SHI Feifei.A discussion on determining Young’s moduli by conventional split Hopkinson bar[J].Acta Mechanica Solida Sinica,2009,30(2):170-176.
[23]方秦,洪建,张锦华,等.混凝土类材料SHPB实验若干问题探讨[J].工程力学,2014,31(5):1-14.FANG Qin,HONG Jian,ZHANG Jinhua,et al.Issues of SHPB test on concrete-like material[J].Engineering Mechanics,2014,31(5):1-14.
[24]GAMA B A,LOPATNIKOV S L,GILLESPIE J W.Hopkinson bar experimental technique:A critical review[J].Applied Mechanics Reviews,2004,57(4):223-250.
[25]GORHAM D A,WU X J.An empirical method for correcting dispersion in pressure bar measurements of impact stress[J].Measurement Science&Technology,1996,7(7):1227.
[26]LU Y.Determination of the radial inertia-induced transition strain-rate in split Hopkinson pressure bar tests[J].Journal of Mechanical Science&Technology,2011,25(11):2775-2780.
[27]FORRESTAL M J,WRIGHT T W,CHEN W.The effect of radial inertia on brittle samples during the split Hopkinson pressure bar test[J].International Journal of Impact Engineering,2007,34(3):405-411.
[28]DAVIES E D H,HUNTER S C.The dynamic compression testing of solids by the method of the split Hopkinson pressure bar[J].Journal of the Mechanics and Physics of Solids,1963,11(3):155.
[2]高光发,李永池,罗春涛,等.混凝土靶高速侵彻的率相关相似律研究[J].弹箭与制导学报,2011,31(3):98-100.GAO Guangfa,LI Yongchi,LUO Chuntao,et al.The study on rate-dependent similarity law of high velocity penetration into concrete target[J].Journal of Projectiles,Rockets,Missiles and Guidance,2011,31(3):98-100.
[3]高光发,李永池,胡秀章,等.一种改进的混凝土抗侵彻模型及算法[J].兵器材料科学与工程,2011,34(2):11-15.GAO Guangfa,LI Yongchi,HU Xiuzhang,et al.An improved anti-penetration engineering model and algorithm of concrete[J].Ordnance Material Science and Engineering,2011,34(2):11-15.
[4]高光发,李永池,刘卫国.多孔硬脆性材料的SHPB实验技术[J].力学与实践,2011,33(6):35-39.GAO Guangfa,LI Yongchi,LIU Weiguo.Expermental technique of SHPB for porous hard and brittle materials[J].Mechanics in Engineering,2011,33(6):35-39.
[5]宋力,胡时胜.SHPB测试中的均匀性问题及恒应变率[J].爆炸与冲击,2005,25(3):207-216.SONG Li,HU Shisheng.Stress uniformity and constant strain rate in SHPB test[J].Explosion and Shock Waves,2005,25(3):207-216.
[6]LU F,LIN Y,WANG X,et al.A theoretical analysis about the influence of interfacial friction in SHPB tests[J].International Journal of Impact Engineering,2015,79:95-101.
[7]毛勇建,李玉龙.SHPB试验中试件的轴向应力均匀性[J].爆炸与冲击,2008,28(5):448-454.MAO Yongjian,LI Yulong.Axial stress uniformity in specimens of SHPB tests[J].Explosion and Shock Waves,2008,28(5):448-454.
[8]GORHAM D A.Specimen inertia in high strain-rate compression[J].Journal of Physics D Applied Physics,2000,22(12):1888.
[9]XIAN Qian,QIU Yun,YAN Peng,et al.Effects of imperfect experimental conditions on stress waves in SHPB experiments[J].Acta Mechanica Sinica,2015,31(6):827-836.
[10]GORHAM D A.The effect of specimen dimensions on high strain rate compression measurements of copper[J].Journal of Physics D:Applied Physics,2000,24(8):1489-1492.
[11]IWAMOTO T,YOKOYAMA T.Effects of radial inertia and end friction in specimen geometry in split Hopkinson pressure bar tests:A computational study[J].Mechanics of Materials,2012,51:97-109.
[12]MENG H,LI Q M.Correlation between the accuracy of a SHPB test and the stress uniformity based on numerical experiments[J].International Journal of Impact Engineering,2003,28(5):537-555.
[13]尚兵,吴立朋,庄茁.应力不均匀性对混凝土材料动态实验结果的影响[J].工程力学,2011,28(12):33-38.SHANG Bing,WU Lipeng,ZHUANG Zhuo.The effect of stress heterogeneous on test data of concrete using SHPB[J].Engineering Mechanics,2011,28(12):33-38.
[14]朱珏,胡时胜,王礼立.SHPB试验中黏弹性材料的应力均匀性分析[J].爆炸与冲击,2006,26(4):315-322.ZHU Jue,HU Shisheng,WANG Lili.Analysis on stress uniformity of viscoelastic materials in split Hopkinson bar tests[J].Explosion and Shock Waves,2006,26(4):315-322.
[15]刘瑞堂,果春焕,张智峰.分离式Hopkinson压杆系统冲击压缩过程中试样的应力均匀化过程[J].机械工程材料,2009,33(2):25-27.LIU Ruitang,GUO Chun-huan,ZHANG Zhifeng.Stress uniformization process in specimens during compression process with split Hopkinson pressure bar system[J].Materials for Mechanical Engineering,2009,33(2):25-27.
[16]丰平,张庆明,陈利,等.SHPB测试中斜坡加载对应力均匀性和恒应变率的影响分析[J].北京理工大学学报,2010,30(5):513-516.FENG Ping,ZHANG Qingming,CHEN Li,et al.Influence of incidentpulse of slope on stress uniformity and constant strain rate in SHPB test[J].Transactions of Beijing Institute of Technology,2010,30(5):513-516.
[17]RAMESH K T.High Rates and Impact Experiments[M].Springer US,2008:929-960.DOI:10.1007/978-0-387-30877-7_33.
[18]PAN Y,CHEN W,SONG B.Upper limit of constant strain rates in a split Hopkinson pressure bar experiment with elastic specimens[J].Experimental Mechanics,2005,45(5):440-446.
[19]RAVICHANDRAN G,SUBHASH G.Critical Appraisal of Limiting Strain Rates for Compression Testing of Ceramics in a Split Hopkinson Pressure Bar[J].Journal of the American Ceramic Society,1994,77(1):263-267.
[20]ZHANG Q B,ZHAO J.A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials[J].Rock Mechanics&Rock Engineering,2014,47(4):1411-1478.
[21]GUO Y B,GAO G F,JING L,et al.Response of high-strength concrete to dynamic compressive loading[J].International Journal of Impact Engineering,2017,108:114-135.
[22]毛勇建,李玉龙,史飞飞.用经典Hopkinson杆测试弹性模量的初步探讨[J].固体力学学报,2009,30(2):170-176.MAO Yongjian,LI Yulong,SHI Feifei.A discussion on determining Young’s moduli by conventional split Hopkinson bar[J].Acta Mechanica Solida Sinica,2009,30(2):170-176.
[23]方秦,洪建,张锦华,等.混凝土类材料SHPB实验若干问题探讨[J].工程力学,2014,31(5):1-14.FANG Qin,HONG Jian,ZHANG Jinhua,et al.Issues of SHPB test on concrete-like material[J].Engineering Mechanics,2014,31(5):1-14.
[24]GAMA B A,LOPATNIKOV S L,GILLESPIE J W.Hopkinson bar experimental technique:A critical review[J].Applied Mechanics Reviews,2004,57(4):223-250.
[25]GORHAM D A,WU X J.An empirical method for correcting dispersion in pressure bar measurements of impact stress[J].Measurement Science&Technology,1996,7(7):1227.
[26]LU Y.Determination of the radial inertia-induced transition strain-rate in split Hopkinson pressure bar tests[J].Journal of Mechanical Science&Technology,2011,25(11):2775-2780.
[27]FORRESTAL M J,WRIGHT T W,CHEN W.The effect of radial inertia on brittle samples during the split Hopkinson pressure bar test[J].International Journal of Impact Engineering,2007,34(3):405-411.
[28]DAVIES E D H,HUNTER S C.The dynamic compression testing of solids by the method of the split Hopkinson pressure bar[J].Journal of the Mechanics and Physics of Solids,1963,11(3):155.