In the field of materials science, the dynamic mechanical properties of silicone rubber materials play a decisive role in their applications in numerous fields. Accurately characterizing these properties and constructing corresponding constitutive models are crucial for a deep understanding of the mechanical behavior of silicone rubber, optimizing product design, and predicting the performance of materials under actual working conditions.

Dynamic mechanical analysis (DMA) technology is the core means for studying the dynamic mechanical properties of silicone rubber. Through DMA testing, key parameters such as the storage modulus (E'), loss modulus (E''), and loss factor (tanδ) of silicone rubber under periodic external forces can be obtained. The storage modulus reflects the material's ability to store elastic deformation energy and embodies the rigidity of silicone rubber; the loss modulus characterizes the degree to which the material dissipates energy in the form of heat during deformation and is related to the viscosity of the material; the loss factor, which is the ratio of the loss modulus to the storage modulus, is used to measure the damping characteristics inside the material. For example, during the study of the glass transition process of silicone rubber, the DMA test results show that as the temperature rises, the storage modulus of silicone rubber drops sharply near the glass transition temperature (Tg), and the loss factor reaches a peak. This indicates that in the glass transition region, the movement ability of silicone rubber molecular chains is significantly enhanced, the intermolecular interactions weaken, and the material changes from a glassy state to a high - elastic state.
Frequency has a significant impact on the dynamic mechanical properties of silicone rubber. In the low - frequency region, the silicone rubber molecular chains have sufficient time to respond to changes in external forces, and the relative sliding between molecular chains is relatively easy. At this time, the material exhibits high flexibility, a low storage modulus, and a large loss factor. As the frequency increases, the molecular chains do not have enough time to fully respond to external forces, the rigidity of the material increases, the storage modulus increases, and the loss factor decreases. This frequency dependence is of great significance in practical applications. For example, in the field of vibration isolation, it is necessary to select appropriate silicone rubber materials according to the vibration frequency range to ensure the best vibration - damping effect at specific frequencies.
Constructing a constitutive model of silicone rubber is an important method for describing its mechanical behavior. The constitutive model can relate the stress - strain relationship of silicone rubber to factors such as the material's microstructure and loading conditions. Commonly used constitutive models include the Mooney - Rivlin model and the Yeoh model based on the phenomenological theory. The Mooney - Rivlin model describes the non - linear elastic behavior of silicone rubber through two material constants and is applicable to the small - strain range. The Yeoh model is an extension of this and can better fit the mechanical response of silicone rubber under large strains. However, these traditional models have certain limitations in describing the complex viscoelastic behavior of silicone rubber. In recent years, some micro - mechanical constitutive models considering factors such as molecular chain relaxation and temperature effects have gradually been proposed, such as models based on the molecular network theory. Such models start from the molecular level, taking into account the structure and movement characteristics of silicone rubber molecular chains, and can more accurately predict the dynamic mechanical properties of silicone rubber under different loading conditions, providing a more solid theoretical basis for the design and application of silicone rubber materials.


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