2. For extra credit (10 point maximum) A ring-shaped seal made from a viscoelastic material is used to seal a joint between two rigid pipes. When incorporated in the joint, the seal is held at a compressive strain of 0.2 (note that the strain is imposed at t=0, when the joint is assembled. Assuming that the seal can be represented by a single Maxwell model, how long does it take before the seal begins to leak. The internal pressure in the pipe is 0.3Pa and you may assume that the seal leaks when the stress of the of the seal becomes lower than the internal pressure. The polymer has an instantaneous modulus of 3Pa and a zero-shear rate viscosity of 1.59106Pas. Hint: The stress of the seal is given by (t)=tM(tt)dt where is strain. 2. For extra credit (10 point maximum) A ring-shaped seal made from a viscoelastic material is used to seal a joint between two rigid pipes. When incorporated in the joint, the seal is held at a compressive strain of 0.2 (note that the strain is imposed at t=0, when the joint is assembled. Assuming that the seal can be represented by a single Maxwell model, how long does it take before the seal begins to leak. The internal pressure in the pipe is 0.3Pa and you may assume that the seal leaks when the stress of the of the seal becomes lower than the internal pressure. The polymer has an instantaneous modulus of 3Pa and a zero-shear rate viscosity of 1.59106Pas. Hint: The stress of the seal is given by (t)=tM(tt)dt where is strain