高温Taylor撞击实验技术及其在金属材料本构模型验证中的应用
ON THE RESEARCH OF TAYLOR IMPACT TECHNIQUE UNDER ELEVATED TEMPERATURE AND ITS APPLICATION IN THE VALIDATION OF CONSTITUTIVE PARAMETERS OF METAL
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摘要: 高温Taylor撞击实验为应变率和温度相关的材料本构模型验证和参数优化提供了新方法. 基于空气炮装置, 突破了实验件速度实现与控制、实验件高温实现与装置设计、高温实验件冲击动力学响应量测试三项关键技术, 建立了高温Taylor撞击实验技术, 并将其应用于05Cr17Ni4Cu4Nb钢本构模型参数验证与优化中. 首先, 对05Cr17Ni4Cu4Nb钢进行了室温 ~ 900 °C以及1.0 × 10−3 ~ 1.0 × 103 s−1应变率下的拉伸实验, 获得了不同温度和应变率下的应力应变曲线. 基于参考应变率下材料流动应力随塑性应变变化、屈服强度随应变率变化以及屈服强度随温度变化规律, 拟合得到了05Cr17Ni4Cu4Nb钢应变率和温度相关的Johnson-Cook本构模型参数. 其次, 利用高温Taylor撞击实验技术对05Cr17Ni4Cu4Nb钢进行了室温, 300, 500, 570和710 °C下的Taylor撞击实验, 获取了不同温度下撞击后实验件外形尺寸. 开展了05Cr17Ni4Cu4Nb钢室温及高温Taylor撞击有限元数值模拟分析, 建立了本构模型参数优化流程和优化算法, 以实验件尺寸平均偏差作为优化目标函数, 开展了05Cr17Ni4Cu4Nb钢本构模型参数优化, 获取了优化后的Johnson-Cook本构模型参数. 优化结果表明: 由单轴应力状态获取的Johnson-Cook本构模型参数过高地描述了05Cr17Ni4Cu4Nb钢在复杂应力状态下的应变硬化行为、应变率硬化行为和温度软化行为.Abstract: The Taylor impact experiment under elevated temperature offers a novel approach to the validation of strain rate and temperature-dependent material constitutive model. Based on the air-gun equipment, the technique of Taylor impact under elevated temperature was established. Three critical techniques, which contain realization and controlling of specimen velocity, realization of elevated-temperature of specimens and designing the equipment, measuring the dynamic response parameters of elevated-temperature specimens, were successfully addressed. The validation and optimization of the constitutive parameters of 05Cr17Ni4Cu4Nb were carried out by using the Taylor impact technique under elevated temperature. Firstly, Tensile tests were conducted on 05Cr17Ni4Cu4Nb steel under the temperatures ranging from room temperature to 900 °C and strain rates ranging from 1.0 × 10−3 to 1.0 × 103 s−1. The stress-strain curves under different temperatures and strain rates were obtained. Based on the variation of flow stress with plastic strain under the referenced strain rate, the variation of yield strength with strain rate and the variation of yield strength with temperature, the strain rate and temperature-dependent Johnson-Cook constitutive model parameters were acquired. Secondly, using the Taylor impact technique under elevated temperature, Taylor impact tests were conducted on 05Cr17Ni4Cu4Nb steel under room temperature, 300, 500, 570 and 710 °C. The specimen sizes after impact were measured. Finite element numerical simulation analysis of Taylor impact under room temperature and high-temperature was carried out. Optimization process and algorithm for the constitutive model were established. The optimization of constitutive model parameter of 05Cr17Ni4Cu4Nb steel was carried out by choosing the average size deviation of specimens as the optimization objective function. The Johnson-Cook constitutive model parameters of 05Cr17Ni4Cu4Nb steel after optimization were obtained. It was found that the constitutive model parameters obtained from uniaxial stress state over estimate the strain hardening, strain rate hardening and temperature softening behaviors of 05Cr17Ni4Cu4Nb steel under complex stress states.
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