| The Charpy impact test determines the impact strength of materials using a specimen with rectangular standardized dimensions. However, a new procedure for performing this test on specimens that do not conform to current geometric standards was needed. The new method, devised at Utah State University for testing glass-reinforced 6/12 nylon rings that had been physically and environmentally aged, demonstrated good repeatability for rings in a vertical position, whereas those in a horizontal position had impact strengths that were not consistent and thereby precluded the use of the horizontal position with this method.; The effects of different types of aging were evaluated with this modified test. Physically aged specimens ranging from 12 to 23 years old were tested, and there was little indication that aging alone led to embrittlement of the rings. The environmentally aged specimens were subjected to four types of conditions to determine their effects on toughness---thermal cycle dry, thermal cycle wet, moisture cycle ambient, and moisture cycle warm---in four different time periods (10 days, 20 days, 30 days and 40 days). These test results indicate that the leading factor in the toughness of the rings is the nylon's ability to absorb water; temperature had little to do with the ring's toughness. |
