【作者】 李林安；

【导师】 佟景伟；

【作者基本信息】 天津大学 ， 实验力学， 1994， 博士

【摘要】 在本文开始简要综述了霍布金森杆测试技术的研究历史、现状及发展，着重介绍了研究应变率历史影响材料高应变率下本构关系的各种方法，并对霍布金森杆测试中信号记录方法的发展进行了简要总结。在此基础上，利用自制的高频响放大器，实现了霍布金森杆测试中瞬态数据实时A／D采集和计算机分析的一体化，减少了中间环节，使触发更为简单、操作更加方便，并编制了相应的数据分析软件。同时对于扰强烈地区进行霍布金森杆测试中如何克服不利因素的方法进行了有效的探索。然后利用改进记录方法的分离式拉伸霍布金森杆设备研究了形状记忆合金、预应力钢筋和高强度铝合金在高应变率下的本构关系，研究表明：它们都呈现出应变率强化特性，形状记忆合金的延性在高应变率下提高了，而另两种材料的延性降低了。利用该设备还研究了高应变率历史对形状记忆合金和预应力钢筋在另一高应变率下本构关系的影响。研究发现，高应变率历史对材料有强化作用，目前还未见到这一方面的报道。 本文还利用分离式扭—拉复台霍布金森杆设备测试软铝在高应变率扭—拉复合载荷作用下的本构关系，并将该设备经特殊改装测试了蒙纳尔合金在高应变率双向剪切下的力学特性，目前也尚未见这方面的公开资料。 在本文的数值分析中，首先利用一维应力波理论，推导出霍布金森杆在任意加载脉冲下试件和输入、输出杆上任意位置的动力响应，它可以为测试的分析提供参考依据。然后利用快速付里叶方法和动有限元法分析了拉、压霍布金森杆中纵波传播的频散现象，研究发现由于频散的影响，测试圆杆内传播的纵波其上升前沿时间有一下限值，对于直径10mm的弹性钢质测试杆，当传播距离大于200mm时，纵向冲击波上升前沿不可能小于7μs，随着霍布金森测试杆直径的增加，这一下限值还会增大。同时频散的存在还会引起测试杆内冲击波伴有高频振荡成份，但当施加给霍布金森输入杆的冲击波上升前沿大于11μs时，高频振荡基本可以忽略；另外，冲击波在传播过程中随传播距离的增加而变缓，并且变缓的趋势随着继续传播而减弱。 本文利用动有限元法分析了霍布金森杆测试中由于加载杆受力端不均匀受力对冲击波形的影响，研究表明，在加载端附近区域有明显的二维应力效应，但当传播距离大于2倍的杆直径时，应力基本演化为一维应力波。 利用动有限元法，在本文中还模拟实际的分离式拉、压霍布金森杆测试中输入、输出杆与试件采用螺纹连接对实验结果的影响，发现试件和杆在连接区域有较大的二维应力，而离开连接部位2倍的杆半径以后，二维效应就很小了。因此螺纹连接是可靠的。它对实验结果的影响也较小。同时还研究了试件更多还原

【Abstract】 At the beginning of this thesis, a brief summary of the researching history , present situation and development about Hopkinson bar technique is presented and various aspects in researching the influence of strain—rate history on material constitutive relation under high strain—rate is emphatically introduced, A concise summary of development of signal recording techniques in Hopkinson bar experiment is also presented. Based on this, using high frequency response amplifier, the union of transient data A / D real time collection and computer analysis was realized with advantages of cutting down the intermediate links, simplify trigging and more convenient operation. Soft wares for data automatically processing has developed, too. In addition, effective investigation on how to overcome the noise—strong condition in Hopkinson test is conducted.Employing the improved split Hopkinson tension bar system, the constitutive relations of shape memory alloy, prestressed reinforcement and high strength aluminum under high strain—rate were experimentally studied, and it shows that except the ductile rising of shape memory alloy, all three materials emerging the behavior of strength rising and ductile descending under high strain—rate. The influence of high strain-rate history on constitutive relations of shape memory alloy and prestressed reinforcement under high strain—rate is also firstly investigated using same instrument, and results indicate that high strain-rate history will strengthen materials.Employing the Hopkinson torsion-tension combination bar system, the constitutive relations of soft aluminum under torsion-tension combined high strain—rate was obtained, The constitutive relations of Monel alloy under Dual—direction shearing high strain—rate was also investigated after special modification of above apparatus.In the numerical analysis, the formulae of dynamic response for arbitrary position in Hopkinson Bar system under arbitrary impact pulse were derived according one—dimensional(1-D) stress wave theory, and it is able to provide reference for test. Then the frequency dispersion in tension or pressure Hopkinson bar is studied using fast Fourier transform(FFT) method and dynamic finite element method(DFEM). Because of the influence of更多还原