Specific Performance in Different Temperature Ranges
1. Low-Temperature Range (< -10℃ to 0℃, slightly varying by material formula)
- Significant decline in energy-dissipating capacity: The loss factor (tanδ) drops sharply (may fall below 0.2, far below the standard range of 0.3-0.8 at room temperature). Molecular chains are difficult to slide, internal friction energy dissipation decreases, and the area of the hysteresis loop is significantly reduced;
- Abnormal increase in stiffness: The storage modulus (G') rises sharply, and the VED approaches a "rigid support" from an "energy-dissipating component". During structural vibration, the deformation resistance is large, and a "hard impact" response is likely to occur;
- Risk of material brittleness: Some rubber-based materials may lose viscoelasticity, showing brittle characteristics. Cracks and tears are prone to occur under large deformations, and even the energy-dissipating function may be lost;
- Application limitations: Ordinary VEDs cannot meet design requirements in this range, and low-temperature special formulas (such as modified silicone rubber-based materials) must be selected.
2. Room-Temperature Range (5℃-40℃, optimal design temperature zone for VEDs)
- Stable and efficient energy-dissipating capacity: The loss factor is maintained in the core range of 0.35±15%. The internal friction of molecular chains is sufficient, and the hysteresis loop is full and symmetrical, which can efficiently convert vibrational mechanical energy into thermal energy;
- Balanced stiffness and damping matching: The storage modulus (G') and loss modulus (G'') maintain the design values, providing stable additional stiffness for the structure and quickly dissipating wind vibration and small earthquake energy through damping;
- Strong performance consistency: Temperature fluctuations have little impact on indicators (usually the stiffness/damping change rate is <10%), adapting to the conventional service environment of most buildings and bridges.
3. Medium-High Temperature Range (40℃-60℃)
- Gradual attenuation of energy-dissipating capacity: The loss factor decreases slowly, the internal friction efficiency of viscoelastic materials reduces, the area of the hysteresis loop shrinks, and the energy-dissipating efficiency decreases by 20%-40% compared with room temperature;
- Continuous decrease in stiffness: The storage modulus (G') shows a linear decline, and the additional stiffness support of the VED for the structure weakens, which may lead to an increase in structural displacement response;
- Risk of material creep: Long-term exposure to this temperature may cause slight creep of some rubber materials, affecting long-term energy-dissipating stability, but it does not reach the failure level.
4. High-Temperature Range (>60℃)
- Near failure of energy-dissipating function: The loss factor drops below 0.15, the viscoelastic material is close to "complete viscosity", internal friction almost disappears, the hysteresis loop is flat, and energy cannot be effectively dissipated;
- Significant attenuation of stiffness: The storage modulus (G') drops to 30%-50% of that at room temperature, and the VED is difficult to restrain structural deformation, which may lead to the loss of control of structural vibration response;
- Permanent material damage: Long-term exposure will cause thermal aging and molecular chain breakage of the material. Even if the temperature returns to room temperature, the energy-dissipating performance cannot be restored. In severe cases, material shedding and bonding failure may occur.