Abstract The thermomechanical coupling of Mullins damage in filled EPDM has been investigated by analysing the self-heating via Infrared thermography (IR) and the voiding fraction by Digital Image Correlation (DIC). The volumetric strain measured during the rubber deformation is found to be predominantly associated with damage, while thermal dilatation caused by self-heating has a negligible contribution. On this basis, the thermomechanical coupling of Mullins phenomena has been identified by evaluating the strain and time dependence of the following criteria: the tangent modulus, the voiding rate and the heat sources. The tangent modulus that reaches a maximum at the strain transition from a series of cycle to another is found to be an appropriate mechanical signature of Mullin softening. At the same strain transition, both voiding rate upturn and heat source upturn are observed. These signatures suggest the Mullins damage to be mainly associated at high strain rate with the (re)-activation of dissipative cavitation mechanisms, by nucleation of new cavities and/or acceleration of cavities growth.

中文翻译：

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填充三元乙丙橡胶中穆林斯损伤的热源和空洞特征

摘要 通过红外热成像 (IR) 分析自热和数字图像相关 (DIC) 空洞率，研究了填充 EPDM 中 Mullins 损伤的热机械耦合。发现在橡胶变形过程中测量的体积应变主要与损坏有关，而自热引起的热膨胀的贡献可以忽略不计。在此基础上，通过评估以下标准的应变和时间依赖性，确定了穆林斯现象的热机械耦合：切线模量、空洞率和热源。发现在从一系列循环到另一个循环的应变转变处达到最大值的切线模量是 Mullin 软化的适当机械特征。在相同的应变转变下，观察到排空率上升和热源上升。这些特征表明，Mullins 损伤主要在高应变率下与耗散空化机制的（重新）激活相关，通过新空腔的成核和/或空腔生长的加速。