Elastomers: Versatile and ubiquitous

4
Feb

Elastomers

Elastomers – widely available and low cost – are ubiquitous. They have a long list of properties that make them extremely useful and versatile. For example, they have excellent damping and energy absorption characteristics, flexibility, resiliency, long service life, ability to seal against moisture, heat, and pressure, non-toxic properties, moldability, and variable stiffness.

Among elastomers, rubber is a very unique material. During processing and shaping, it behaves mostly like a highly viscous fluid. After its polymer chains have been crosslinked by vulcanization (or by curing), rubber can undergo large reversible elastic deformations. Unless damage occurs, it will return to its original shape after removal of the load.

These unique properties mean that rubber components require special material modeling and nonlinear FEA tools that are very different than those used for metallic components. Some of the unique properties of rubber that require a robust FEA program include:

  1. It can undergo large deformations under load, sustaining strains of up to 500 percent in engineering applications.
  2. Its load-extension behavior is markedly nonlinear.
  3. Because it is viscoelastic, it exhibits significant damping properties. Its behavior is time- and temperature-dependent, making it similar to glass and plastics in this respect.
  4. It is nearly incompressible. This means its volume does not change appreciably with stress. It cannot be compressed significantly under hydrostatic load.

For certain foam rubber materials, the assumption of near incompressibility is relaxed, since large volume change can be achieved by the application of relatively moderate stresses.

The nonlinear FEA program, Marc possesses specially-formulated elements, material and friction models, and automated contact analysis procedures to model elastomers.

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