Using DMA to Study Protection Performance of Polyurethane Foam to Underwater Blast Bubble Impulsion

A new test method for analyzing foam protection performance to underwater explosion bubble impulsion was proposed. Applying DMA dynamic compress mode of “low frequency-high frequency-low frequency” circulation periodically, bubble impulsion of “expand-contract-expand” to objects had been simulated. Testing with this method, several kinds of low density polyurethane foam specimens with different isocyanate index were analyzed. Testing results indicate that the low density polyurethane foams with isocyanate index R equal 1.8 have much higher energy dissipation modulus and loss factor to shock periodically, and conform to the theories of molecular structure. The results show that the test method is valuable.