Shape Targeting: A Versatile Active Elasticity Constitutive Model
Shape Targeting: A Versatile Active Elasticity Constitutive Model
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形状目标：多功能主动弹性本构模型
DOI：
10.1145/3388767.3407379
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Sifakis, Eftychios
中科院分区：
文献类型：
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作者：
Klár, Gergely;Moffat, Andrew;Museth, Ken;Sifakis, Eftychios
最近的“face”面部建模和动画框架[Ichim等人，2017]引入了弹性能量势的特定公式，该公式诱导网格元素接近特定的规定形状，模旋转。该目标形状被定义为每个元素的输入参数，是基于纤维的各向异性肌肉模型中激活参数的多维模拟。我们认为，由这种能量公式提出的本构律值得考虑作为一种高度通用和实用的活性弹性材料模型，并且可以被正确地视为活性弹性的“基线”参数描述，就像旋转弹性在很大程度上已成为各向同性弹性的原型旋转不变模型一样。我们以连续介质力学的有限元方法的精神和风格提出了这个本构模型的公式，并提供了用于隐式和准静态方案的应变张量和精确力导数的封闭形式表达式。我们通过使用活动元素的各种示例来演示该模型的通用性。
The recent “Phace” facial modeling and animation framework [Ichim et al. 2017] introduced a specific formulation of an elastic energy potential that induces mesh elements to approach certain prescribed shapes, modulo rotations. This target shape is defined for each element as an input parameter, and is a multi-dimensional analogue of activation parameters in fiber-based anisotropic muscle models. We argue that the constitutive law suggested by this energy formulation warrants consideration as a highly versatile and practical model of active elastic materials, and could rightfully be regarded as a “baseline” parametric description of active elasticity, in the same fashion that corotational elasticity has largely established itself as the prototypical rotation-invariant model of isotropic elasticity. We present a formulation of this constitutive model in the spirit and style of Finite Element Methods for continuum mechanics, complete with closed form expressions for strain tensors and exact force derivatives for use in implicit and quasistatic schemes. We demonstrate the versatility of the model through various examples in which active elements are employed.