(True/False) Number of cycles depends on the frequency of truck traffic and the ambient temperature.

• A. True
• B. False
• C. Not sure
• D. Both

Answer: (B)

Fatigue life is driven by the stress range per cycle and the material’s resistance to fatigue, not by a simple rule that the total number of cycles is set by how often trucks pass or by ambient temperature alone. The number of cycles to failure (the fatigue life) comes from the material’s SN behavior and the actual load amplitudes. How often trucks pass determines how quickly those cycles accumulate over time (the rate of damage), but it doesn’t by itself set the total cycles needed to reach failure. Temperature can influence fatigue properties and crack growth rate, which can shift the fatigue life, but that effect is about material behavior per cycle, not a direct, straightforward dependency of total cycles on temperature. So the statement isn’t correct—the cycle count to failure is governed mainly by load range and material properties, with traffic frequency affecting only the rate of accumulation and temperature altering the per-cycle damage indirectly.