On the gradient of the yield plateau in structural carbon steels
On the gradient of the yield plateau in structural carbon steels
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DOI：
10.1016/j.jcsr.2016.11.024
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发表时间：
2017-03-01
影响因子：
4.1
通讯作者：
Ummenhofer, Thomas
中科院分区：
文献类型：
--
作者：
Sadowski, Adam J.;Rotter, J. Michael;Ummenhofer, Thomas
新的设计方法正在开发中，以使粗壮的钢构件达到并超过全塑性条件。对于理论验证，这种方法需要表征结构钢的单轴应力-应变行为超出理想化的弹塑性表示。然而，碳钢的应变硬化性能目前没有得到标准或任何钢铁制造商的保证。因此，必须假设这些属性的值是适当的，通常是基于有限的信息，在个人的应力-应变曲线的形式。所做的选择几乎没有一致性。本文首先举例说明，使用一个例子弹塑性有限元计算，一个敦实的管状结构可以达到充分的塑性条件下的细长度与现行标准中定义的和支持的实验时，只使用一个非常温和的应变硬化水平，开始在第一屈服。然后假设，结构碳钢的应力-应变曲线中的屈服平台，经典地被视为平坦的并且具有零切线模量，实际上具有小的但统计上显著的正有限梯度。最后，从225个拉伸试验中提取的屈服平台梯度的一组稳健的线性回归分析似乎支持这一假设，发现平台梯度为初始弹性模量的03%，与有限元实例表明的情况一致，足以在实验支持的slendemesses处再现全塑性条件。(C)2016作者由Elsevier Ltd.发布。这是CC BY许可下的开放获取文章。
New design methodologies are being developed to allow stocky steel members to attain and exceed the full plastic condition. For theoretical validation, such methods require a characterisation of the uniaxial stress-strain behaviour of structural steel beyond an idealised elastic-plastic representation. However, the strain hardening properties of carbon steels are not currently guaranteed by the standards or by any steel manufacturer. Assumptions must thus be made on what values of these properties are appropriate, often based on limited information in the form of individual stress-strain curves. There is very little consistency in the choices made. This paper first illustrates, using an example elastic-plastic finite element calculation, that a stocky tubular structure can attain the full plastic condition at slendernesses comparable with those defined in current standards and supported by experiment when using only a very modest level of strain hardening, initiated at first yield. It is then hypothesised that the yield plateau in the stress-strain curve for structural carbon steels, classically treated as flat and with zero tangent Modulus, actually has a small but statistically significant positive finite gradient. Finally, a robust set of linear regression analyses of yield plateau gradients extracted from 225 tensile tests appears to support this hypothesis, finding that the plateau gradient is of the order of 03% of the initial elastic modulus, consistent with what the finite element example suggests is sufficient to reproduce the full plastic condition at experimentally-supported slendemesses. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.