SEMI-ANALYTICAL MODEL AND TEST METHOD OF CONE INDENTATION BASED ON ELASTOPLASTIC PROPORTIONAL SUPERPOSITION
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摘要: 基于能量密度等效,考虑圆锥压入(锥压入)过程中线性律纯弹性和幂律纯塑性的应变能比例叠加,提出了弹塑性应变能比例叠加的锥压入载荷-位移模型(Load vs. Displacement Model based on Proportional Superposition of elastoplastic-energy under conical indenting,LDM-PS),进而提出了获取材料Ramberg-Osgood律(R-O律)应力-应变关系的锥压入试验方法。针对80种设定材料,通过LDM-PS预测的载荷-位移曲线(正向预测)与有限元分析结果密切吻合,并且以有限元分析(Finite Element Analysis,FEA)所得载荷-位移曲线作为试验模拟曲线,采用两种锥角圆锥压头分别对平滑材料表面进行两次单锥压入加载(双锥压入),可通过对双锥压入的两个载荷-位移曲线的加载阶段按抛物律(Kick律)回归可实现R-O律参数的求解。由LDM-PS预测的R-O律应力-应变关系曲线(反向预测)与FEA的条件关系曲线密切吻合;针对8种金属材料完成了双锥压入试验,通过锥压入试验新方法预测的应力-应变关系、弹性模量和强度与传统单轴拉伸试验结果吻合良好。Abstract: A load vs. displacement model LDM-PS is proposed, and a conical indentation test method for obtaining the stress-strain relationship of the material under the Ramberg-Osgood law (R-O law) is proposed by the grounds of energy density equivalence, considering the proportional superposition of strain energy between linear law pure elasticity and power law pure plasticity in conical indentation. For 80 set materials, the load-displacement curve (forward prediction) predicted by LDM-PS is in a close agreement with the results of Finite Element Analysis (FEA), and the load-displacement curve obtained by FEA is taken as the experimental simulation curve. Two kinds of cone angle conical indenters are used to carry out single conical indentation (double conical indentation) twice on the surface of smooth material, and the R-O law parameters can be solved by parabolic law regression of the two loading vs. displacement curves of double conical indentation at the loading stage. The stress vs. strain curve of R-O law predicted by LDM-PS (inverse prediction) is in a close agreement with the condition curve of FEA. The stress vs. strain relationship, Young's modulus and strength predicted by the new method are in a good agreement with the results of the traditional uniaxial tensile test.
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表 1 纯塑性锥压入模型参数值
Table 1. Parameters of pure plastic conical indenting model
压头半锥角θ/(°) 有效体积系数k1 有效应变系数k2 53 26.42 0.1715 60 24.95 0.1789 65 23.40 0.1866 70.3 21.01 0.1997 表 2 弹塑性比例因子c参数值
Table 2. Elastoplastic scaling factor c parameter value
压头半锥角θ/(°) 比例系数c1 比例指数c2 比例指数c3 53 0.6225 −0.06703 −0.05327 60 0.6406 −0.06287 −0.06503 65 0.6245 −0.06544 −0.06877 70.3 0.6304 −0.06404 −0.08170 表 3 材料力学性能与单轴拉伸R-O律塑性参数
Table 3. Mechanical properties of materials and plastic parameters of uniaxial tensile R-O law
材料 材料常规力学性能 材料R-O律塑性参数 弹性模量
E/GPa屈服强度
Rp0.2/MPa抗拉强度
Rm/MPa硬化系数
Κ/MPa硬化指数
N6061-T6511 71.00 376.1 390.6 498.2 14.310 7075-T6511 71.40 517.6 631.9 845.2 11.970 5083-H116 70.30 159.3 276.2 519.4 3.623 6082-T6 71.50 326.4 348.1 448.2 14.710 P92 210.0 548.3 715.1 1076 7.337 16Mn 212.0 309.9 521.1 876.8 4.978 1Cr12Mo 219.9 616.6 767.1 1119 8.446 2Cr12MoV 216.9 772.2 976.1 1314 9.661 表 4 压头系数β模型参数
Table 4. Parameters of indenter coefficient β model
压头半锥角θ/(°) 弹性模量E/GPa 模型系数e1 模型指数e2 60 60~80 0.8055 −0.1958 180~220 0.6258 −0.2075 70.3 60~80 0.6929 −0.2004 180~220 0.4944 −0.2509 表 5 R-O律参数及σ-ε曲线优度
Table 5. Parameters of R-O law and σ-ε curve goodness
材料 R-O律参数 弹性模量E/GPa σ-ε曲线
优度/(%)弹性模量
E/GPa硬化系数
Κ/MPa硬化指数
N单轴拉伸 误差/(%) 6061-T6511 68.32 563.9 9.195 71.00 3.770 98.0 7075-T6511 75.20 927.1 9.202 71.40 5.320 98.0 5083-H116 68.74 475.3 5.291 70.30 2.220 97.0 6082-T6 71.90 472.6 13.230 71.50 0.557 96.0 P92 209.10 1041.0 7.074 210.00 0.409 97.0 16Mn 209.70 883.5 4.633 212.00 1.090 97.0 1Cr12Mo 213.00 1117.0 10.060 219.90 3.120 96.0 2Cr12MoV 219.70 1277.0 10.890 216.90 1.290 99.0 表 6 抗拉强度与单轴拉伸结果的对比
Table 6. Comparison of tensile strength with uniaxial tensile results
材料 抗拉强度Rm/MPa 锥压入 单轴拉伸 误差/(%) 6061-T6511 397.3 390.6 1.73 7075-T6511 653.4 631.9 3.40 5083-H116 287.2 276.2 3.98 6082-T6 360.5 348.1 3.57 P92 685.4 715.1 4.16 16Mn 511.4 521.1 1.86 1Cr12Mo 804.3 767.1 4.85 2Cr12MoV 935.8 976.1 4.12 表 7 屈服强度与单轴拉伸结果的对比
Table 7. Comparison of yield strength with uniaxial tensile results
材料 屈服强度Rp0.05/MPa 屈服强度Rp0.1/MPa 屈服强度Rp0.2/MPa 锥压入 单轴拉伸 误差/(%) 锥压入 单轴拉伸 误差/(%) 锥压入 单轴拉伸 误差/(%) 6061-T6511 345.9 363.5 4.84 347.7 364.8 4.67 351.1 376.1 6.65 7075-T6511 582.9 590.2 1.24 585.4 592.1 1.13 590.1 517.6 14.00 5083-H116 156.2 157.8 1.01 161.9 159.1 1.76 188.5 159.3 18.30 6082-T6 333.1 324.6 2.62 334.5 325.9 2.64 337.0 326.4 3.25 P92 497.5 529.9 6.11 504.6 537.0 6.03 517.1 548.3 5.69 16Mn 246.2 275.7 10.7 257.1 285.4 9.92 274.4 309.9 11.50 1Cr12Mo 659.0 611.8 7.71 665.9 618.2 7.72 678.0 616.6 9.95 2Cr12MoV 819.4 766.4 6.91 824.5 774.1 6.51 833.6 772.2 7.95 -
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