The polyurea aerogels (PUA) were created by reacting triisocyanate Desmodur N3300a and water using triethylamine as a catalyst in a solution of acetone. Three PUA with densities 0.12 g/cm3, 0.17 g/cm3 and 0.33 g/cm3 were fabricated tested and used in model simulation. Quasi-static testing was conducted for mechanical strength in tension, compression, and shear. Testing was also conducted in dynamic tension and bending. Simulations were performed to develop a better understanding of structure-property response of PUA. Micro-scale effects such as particle stiffness, bond strength, and particle frictional coefficients were incorporated into the macro-scale structure-property relationship for the prediction of the Young's modulus. the results indicate that polyurea aerogels are not particularly sensitive to various mid-range frequencies. the change in storage modulus across the tested range was minimal. the 0.17 g/cm3 damped the oscillatory motion more effectively in tension than the other two densities. Compression simulations using PFC3D were completed using the PUA model. Simulations showed that the shear and normal stiffness of the particles were equivalent rather than a ratio as suggested by literature.
Available at: http://works.bepress.com/lokeswarappa-dharani/113/