Strain rate and thermal effects on tension and shear properties of polyureas

Polyureas can be used as a retrofit material for existing buildings to enhance the level of protection (LOP) of various building components, e.g., windows and walls. Tensile and shear are the basic loads that a polymer may experience during a blast event. Strain rate and thermal data combined with previous full scale validation testing will allow engineers to design polymer retrofits for Anti-Terrorism Force Protection (ATFP) applications. The data from the laboratory testing will assist in the development of resistance functions for numerical simulations, without the high cost of full scale testing.

Polymers are only identified as A, B, C, and D to protect proprietary information. Each particular polymer application was considered during planning and not all polymers were tested in shear; since they may not be subjected to shear loading during a blast event. Three loading rates were used: 2-in/min, 30-in/s, and 60-in/s for three temperatures: 5°C, 25°C, and 50°C. Low and high test temperatures were selected to encompass assumed operating temperatures. Tests were run to the point of specimen failure. To determine repeatability and develop a meaningful database, three specimens were tested at each specified load rate and temperature.

The loading rate affected the strength of all four polyureas more than the operating temperatures. A detailed explanation of the test setup, test procedure, and data analysis are provided. A general description of how to generate a resistance function to include the temperature and strain rate variability will also be discussed. Conclusions about the data trends are discussed and more specific comments are identified on the various charts in the appendices.