These constitutive equations are in two distinct categories: the first assumes that the strain energy density is a polynomial functions of the principal strain invariants; in the case of incompressible materials, this material model is commonly referred to as a Rivlin material; in the second category, it is assumed that the strain energy density is a separable function of the three principal stretches; Ogden, Peng, and Peng-Landel material models are examples in this categrory.
High order strain energy functions are of little practical value, because rubber materials are not sufficiently reproducible to allow one to evaluate a large number of coefficients with any accuracy. Therefore, the extra terms only do a good job in fitting experimental errors. The Mooney-Rivlin model remains the most widely used strain energy function in FEA, and should be the first choice due to its simplicity and robustness.
A neo-Hookean Mooney-Rivlin model has a first coefficient equal to one-half of the shear modulus and a second coeffcieknt equal to zero. This material model exhibits constant shear modulus and give s good correlation with experimental data up to 40% strain in uni-axial tension and up to 90% in simple shear.
A 2-coeffcieinmt Mooney-Rivlin model shows good agreement with tensile test data up to 100% strain, but it has been found inadequate in describing the compression model of deformation. It also fails to account fot the stiffening of the material at large strains.
A 3-term, or greater Moone-Rivlin model accounts for a non-constant shear modulus. Caution needs to be exercised on inclusion of higher order terms to fit the data, since this may result in unstable energy functions yielding non-physical results outside the range of the experimental data. The Yeoh model differs from other higher order models in that it depends on the first strain invariant only. This model has been demonstrated to fit various requirements on material testing.
Only when your stress-strain curve has more than two turning points, you can consider using higher order M-R models. When your stress-strain curve has a special shape, maybe Arruda-Boyce is better for you; at this time consider the handbook or research papers for the shape of statistical mechanics based models like Arruda-Boyce and Van der Waals.
Mooney-Rivlin好
简单、好用、我会！good starting point
I think this is a good starting point and this type of discussion should be appreciated and valued here... yeoh模型abaqus 里能直接调用的最好的一个模型
在abaqus的帮助文档中ogden的本构是不是错了??
在abaqus的帮助文档理论手册中ogden的本构是不是错了?? [quote]原帖由 [i]byhyj[/i] 于 2005-8-31 07:51 发表 [url=http://www.simwe.com/forum/redirect.php?goto=findpost&pid=571017&ptid=568080][img]http://www.simwe.com/forum/images/common/back.gif[/img][/url]本构模型的确是根据材料及模型的变形情况来选的，是综合考虑的结果，你刚才讨论的是有道理的，是一般的经验性的总结，选择本构模型最核心的一点是：利用某本构模型拟合得到的应力应变数据应最大程度能够反映你所使用 ... [/quote]
说的好!同意 看看是用在哪裡吧!我個人的看法是單純的拉伸應變數據所模擬出的橡膠模型就很夠用了!
致於油封件或輪胎...等等所使用的區間都不一致的!
但拉伸的區間我一向都根據ASTM的標準來做測試!!雖然比我實際應用的應變區間大很多...
但也是很準確的!!尤其是模擬出的曲線雖然都很接近二次MOONY曲線..但我還是直接用YEOH模式..
管它的~~~~最後的結果接近實驗就好了~~~ 大家好！新来乍到！！
我是从事橡胶减震件设计的。我们一直采用的是M-R这个模型，因为这种模型只要两个参数就可以了，而且在载荷不是超大的前提下，计算的静态刚度跟测试刚度的误差在＋/- 15%之内（毕业设计课题之一）。当载荷很大时，比如说直径为40mm的减震轴套承载4t的力时，这个模型就会出现误差，具体说就是, 导致高载荷下刚度下降，应变变大，从而导致疲劳强度估算的误差。目前我们正在考虑是不是要采用Yeoh模型。因为这个模型计算的刚度在高载荷下比MR要精确（已经比较过实验曲线，MR计算的刚度曲线以及Yeoh计算的刚度曲线）。但是用YEOH模型计算出来的应变比用MR小了将近有30％，这个可能是MARC的设置不对，不知道有没有人遇到过这种问题，出来交流一下。我用的是MARC
页:
1
[2]